Need help with controller and 100v open panels

firefly101

Hello,

I bought the following 4 panels, I got them for $95 each plus shipping. But after learning more I find out they are 100v open circuit panels which means I just cant use ANY controller.

Model SUN-DA080-A
Power (W) 80 Watts
Open Circuit Voltage (V) 100.00 Voc
Short Circuit Current (A) 1.62 Isc
Maximum Power Voltage (V) 71.00 Vmp
Maximum Power Current (A) 1.27 Imp
Length 55.50" ( 1,409.70 ) mm
Width 43.70" ( 1,109.98 ) mm
Depth 1.40" ( 35.56 ) mm
Weight 49.00 lb ( 22.23 ) Kg



My problem is the Controller from BZ MPPT500HV I was going to get I FIND bad reviews here on.

I need a good controller, but I dont have the money for some really High priced models I see around. I need the best price for what I can get.

Also right now the weather is bad so I cannot test the panels out. But I worry that controllers rated for 100v may short out if the voltage on the panels went up by one volt.

I am new at this, but I wanted backup power but couldnt afford a full 20 panel system. I plan on using this panels with a 12v 4 150Ah Wet car battery set.

Also with the charge controller I should still get about 80watts per panel correct? I am not sure how the conversion to 12v system would go or how many amps it would convert to? I figured 24amps for the 12v system?

I noticed this controller which seems to do 125voc and Morningstar seems to gave good reviews. I only have the 4 panels or 320w max, and no plans to add to the array. This one below is cheaper than the same controller that handles 150voc and is $400+

Morningstar TriStar Charge Controller 45A 12/24/48 VDC, TS-45 $155.00 I am not sure if the spec sheet is correct for this one or if its for the higher rated model?


Firefly101

BB.

Re: Need help with controller and 100v open panels

You have to be careful--There are two MorningStar controller families.

One is the TriStar series--a PWM controller.

The other is the TriStar MPPT series--a MPPT controller.

Both are very good controllers, but the TriStar MPPT version is the one you need (Voc/Vpanel max is 150 VDC).

Morningstar TriStar 45 amp MPPT solar charge controller
Morningstar TriStar 60 amp MPPT solar charge controller

And, if I understand correctly, the digital display is a ~$100 or so option.

I recommend the Remote Battery Temperature Sensor Option--especially if the charge controller and the battery bank are not next to each other.

Midnite Solar, Xantrex, and Outback also make 150 VDC maximum input charge controllers (Midnite is also coming out with some higher voltage versions too). The Xantrex while a good controller is probably a bit less efficient with Vmp-array >> Vbatt-charging as in your setup (71 volts input, 12 volts output).

Unfortunately, all of these are ~3x, or more, expensive than the PWM controller you looked at.

-Bill

firefly101

Re: Need help with controller and 100v open panels

I was going with a BZ Products MPPT500HV but there were some complaints on this forum about its quality.

What I am unsure of is can the morningstar handle the 71v input from the unit their manuals say 48v array input?

This is really confusing since I have such simple needs with only 4 panels to use.

Is the BZ Products that bad or will it work since I am only producing 24amps 12v output? I figure very few contollers except the really expensive ones are really rated at the levels they claim.

If I may ask why will the other controllers not work with my setup and only a MPPT controller will? Is it my VMP that is messing things up?

Also the controller should be with the battery, I plan on keeping it close for little loss. since the panels are 100v or 71v I can use lighter wire to the controller and place it farther away.

BB.

Re: Need help with controller and 100v open panels

The BZ controllers (last time somebody looked at them several years ago here) were found to not perform well at all and had poor heat-sinking for their specifications.

Yes, you could use a PWM controller (if you can find one with high enough input voltage ratings) with your panels, but you would not get anywhere near the charging power you would expect/have paid for, into your battery bank.

A little electronics and math...

Power = Voltage * Current = V*I (and = V^2 / R = I^2 * R)

And your panels are rated:

Maximum Power Voltage (V) 71.00 Vmp
Maximum Power Current (A) 1.27 Imp

A PWM controller is essentially just a fancy ON/OFF switch... Want charging current the switch is ON. No more charging current, the switch is OFF. It can turn on/off hundreds of times a second, so you get an average current charging the battery bank (more ON than off, nearer 100% current. more OFF than ON, closer to 0% current--Pulse Width Modulation).

A MPPT Charge controller is a DC Switching Power Supply--More or less it can be thought of as a variable AC transformer... It takes High Voltage / Low Current and "down converts" the energy to Low Voltage / High Current to charge your battery bank.

The math. For a PWM controller with 71 volt panels charging a 12 volt battery:

• P = V*I = 14.5 volts battery charging * 1.27 Amps = 18.4 watts into battery
• Ibatt = 1.27 Amps

For a MPPT controller that is ~95% efficient:

• Pbatt = Vmp*Imp*Eff Charger = 71 volts * 1.27 amps * 0.95 = 85.7 Watts into battery
• Ibatt = Vmp*Imp*Eff / Vbatt-charging = 71v * 1.27a / 14.5v = 5.9 amps into 12 volt battery

That is why for panels with Vmp>>Vbatt-charging should use MPPT controllers... With PWM controllers, there is just too much loss in energy.

Make sense?

-Bill

firefly101

Re: Need help with controller and 100v open panels

Hello Bill,

Yes it makes perfect sense. I just needed it broke down a little as there is MORE information than a layman needs which just confuses us. lol the vmp and voc was confusing me on what the panel can do and how the controller has an effect.

This is what I was thinking, My panels at 14.5v should be about 5.9 x 4 = 23.6amps so the BZ MPPT should be able to handle it is their rating states 45amps which I am sure is overrated.

But looking on this forum the regulating of the power was in question with this unit, which would mean getting alot less power into the batteries. But it is Half the cost of the TS-45 MPPT. Which doesnt have a deplay but a very large heat sink which means quality parts = less features.

It seems the cheapest quality products is the TS-45 MPPT @ $455.00.

But this unit should do it all cut off voltage when the battery is charged , trickle charge, monitor battery heat... Its just a big jump from $225 to $455.

I still have to get the wiring harness done for the panels using MC-3 connectors. I got to say the Panels I got are Professional panels, well built. I can see how they have a 25 year warranty on them. The price was just too good, My original plan was to piecemeal the panels, but I had to buy in lots of 4.

I plan on using these as backup incase of power failure of the grid, just to keep basics running like fridge and cooking etc.

Any recommendations on my system I plan?

My system should be the following.

4 80w Panels like you seen.
1 Controller
1 Harness to panels
1 Inverter
4 150Ah Wet cell Batteries from Costco

Some cable system in 4AWG for Battery bank to controller
Fuse system for 12V Battery side and some Fure system for the Solar panel side.

Is there anything I am missing any suggestions that is affordable for such a small setup?

I plan later if money permits add a wind turbine and more batteries, but that is down the road.

Last would be if a Morningstar Controller last? does it have a good failure rate?

Thanks for all your help, you already help me toward another controller. There is no sense in having a backup power system if you cant rely on the controller.

Photowhit

Re: Need help with controller and 100v open panels

firefly101 wrote: »

I plan on using this panels with a 12v 4 150Ah Wet car battery set.

Gosh, more bad news. Standard car batteries will not work, you'll want a true deep cycle battery, cheapest option would be golf cart batteries. We have a few threads here about inexpensive , for golf cart batteries, from Sams club and/or Costco, about $80 each at 6 volts, I see your looking at a 12 volt system. Many here would discourage you from having 4 parallel strings.

Do you have an inverter already?

Might want to bail on these panels while you still have shipping boxes, and find a good deal on some panels designed to charge the system you desire with Pulse Width Modified (PWM) charge controlers. It might be cheaper in the long run, might even try Craigslist.

Photowhit

Re: Need help with controller and 100v open panels

WOW just saw your new post.

Might help keep a fridge running, but you basicly don't heat or cool with solar unless your directly using the sun to heat water. It just uses too much energy.

Buy and old coleman stove to use out side with your BBQ grill.

BB.

Re: Need help with controller and 100v open panels

FF,

Yea, unless we hear otherwise, don't even bother with the BZ...

firefly101 wrote: »

But looking on this forum the regulating of the power was in question with this unit, which would mean getting alot less power into the batteries. But it is Half the cost of the TS-45 MPPT. Which doesnt have a deplay but a very large heat sink which means quality parts = less features.

The TS MPPT controller family has lots of features--they just charge for them (digital display, remote battery temperature sensor, PC computer interface, etc.). The TS MPPT 60 Amp version even has a web server in it.

But this unit should do it all cut off voltage when the battery is charged , trickle charge, monitor battery heat... Its just a big jump from $225 to $455.

For Solar PV Array to Battery Bank charging--This unit should do everything you need, very efficiently, and for a very long time...

Just in general, I would plan on replacing major electronics roughly every 10 years... Things break and electronics are changing so quickly, many parts are no longer available 10 years after manufacture. Batteries may last 3-8 years or so (better batteries can last 15 or more).

I still have to get the wiring harness done for the panels using MC-3 connectors. I got to say the Panels I got are Professional panels, well built. I can see how they have a 25 year warranty on them. The price was just too good, My original plan was to piecemeal the panels, but I had to buy in lots of 4.

Also check the Series Fuse requirements for the panels... You may need 1 series fuse for each panel (typical, although for these type of panels you may not need the fuse per panel for smaller arrays).

I plan on using these as backup in case of power failure of the grid, just to keep basics running like fridge and cooking etc.

Any recommendations on my system I plan?

My system should be the following.

4 80w Panels like you seen.
1 Controller
1 Harness to panels
1 Inverter
4 150Ah Wet cell Batteries from Costco

You really need more solar panels... With the current system, maybe 200 AH @ 12 volt battery bank... You are looking at 600 AH @ 12 volts (if I understand you correctly)--Your current array would not do a very good job of recharging them.

Also, are these Marine Batteries or Deep Cycle type batteries... Marine batteries (and car) are just not suited for deep cycle applications (they will not last very long when cycling loads).

I plan later if money permits add a wind turbine and more batteries, but that is down the road.

Really need to review your power needs and current battery plans... We try to recommend "balanced" systems. If you have too many batteries, the solar panels just cannot properly (or quickly) recharge them... This is closer to a maintenance/trickle charger vs a off-grid / emergency power system.

Last would be if a Morningstar Controller last? does it have a good failure rate?

Just my two cents... I would plan on 10 years and count myself lucky if it when 15+ years. You may have to repair it within the first 10 years (my recommendations for any quality power product--they just do not last forever).

Also, review your inverter needs... If you are planing on recharging cell phones and computers from the inverter--you really should look at a quality TSW (True Sine Wave) type inverter instead of a large and inexpensive MSW type.

-Bill

firefly101

Re: Need help with controller and 100v open panels

Hello Bill,

I am using Batteries that are the same as my Ford Bronco. I believe they are DEEP CELL, It doesnt say on the battery but 150 Reserve Amps and 1000 Cranking amps sounds like a deep cell battery to me?

I'll have to double check to be safe, but I swore they are deep cell not your tiny car batteries. Anyway I only have one so far so I am not too worried yet.

On the backup power, I did say I plan on going wit ha Wind Turbine later should be a 1000watt model but I expect only to get average 500w if winds arent high enough.

The reason for the multiple battery bank is to have available power on hand, then conserve until power is restored. I agree I would have loved to had more panels but even at the price I got them I just didnt have the funds available for more. I planned on piecemealing them originally.

I look at the 4 batteries as 4 1 gallon containers. you can only fill 1 container a day with water but you got the other 3 gallons IF you need it.

My power requirements will be pretty low. I really dont need 4 batteries, but with the wind turbine I think the system will balance out.

Dont know about the fuse requirements on the panels, they came with nothing but the panels. Though at only 1.27amps you'd think combined would work with few panels I have? I'll check around.

firefly101

Re: Need help with controller and 100v open panels

Hello Photowhit,

Crockpots use only 225watts so my cooking with them should work ok, Lighting would be 14w bulbs that produce 100watts of light with the old bulbs.

Microwave, coffee pot and running a laptop possibly. VERY small power needs for Emergency for me. I do agree on heating water But I plan on having a 110v water heater 20gal and that will run off the system WHEN/IF I get the 1000watt wind turbine.

I do have a coleman stove and Propane grill.

why not have 4 parallel stings? I seen battery banks that had 20 batteries in parallel?

I believe my battery is Deep cell it has 150 reserve amps and 1000 cold cranks amps. It isnt small car batteries but ful size truck batteries. But I only have one now anyway so If I made a mistake not much is lost. I do know these batteries are suppose to like being cycled all the time and can hand deep draws of power.

No I have an inverter for the one battery that I use just to power simple things if the power goes out, but I plan on getting and quality inverter later, but nothing too out there in cost.

Can't bail on the panels, they are 50lbs each already arrived from freight and I got them for $135 ea shipped. I dont know anywhere else you can get 80watt outdoor panels for that price?

Photowhit wrote: »

Gosh, more bad news. Standard car batteries will not work, you'll want a true deep cycle battery, cheapest option would be golf cart batteries. We have a few threads here about inexpensive , for golf cart batteries, from Sams club and/or Costco, about $80 each at 6 volts, I see your looking at a 12 volt system. Many here would discourage you from having 4 parallel strings.

Do you have an inverter already?

Might want to bail on these panels while you still have shipping boxes, and find a good deal on some panels designed to charge the system you desire with Pulse Width Modified (PWM) charge controlers. It might be cheaper in the long run, might even try Craigslist.

mike95490

Re: Need help with controller and 100v open panels

firefly101 wrote: »

Hello Bill,

I am using Batteries that are the same as my Ford Bronco. I believe they are DEEP CELL, It doesnt say on the battery but 150 Reserve Amps and 1000 Cranking amps sounds like a deep cell battery to me? .....

Cranking amps = starting battery. Few, if any cars are supplied with deep cycle batteries, because they have few, fat plates for capacity. Starting batteries have many thin plates for high current surge (starting).

why not have 4 parallel stings? I seen battery banks that had 20 batteries in parallel?

I've seen folks glue wings to a car, but it does not fly well. More than 2 parallel batteries, and you need extensive percautions to get the power to share well.

Crockpots use only 225watts so my cooking with them should work ok, Lighting would be 14w bulbs that produce 100watts of light with the old bulbs.
Microwave, coffee pot and running a laptop possibly. VERY small power needs for Emergency for me. I do agree on heating water But I plan on having a 110v water heater 20gal and that will run off the system WHEN/IF I get the 1000watt wind turbine.

225w for 5 hours = 1125wh A 12V, 100AH battery contains 1200wh, so you would drain the battery to about 3% of full. Very bad for the battery.
Microwave = 1200W for .1 hr (.1 hr= 10 min) = 120wh not too bad
CFL lights are ok, laptop is 80W (roughly) but best to use coleman stove for the coffee.

firefly101

Re: Need help with controller and 100v open panels

Well I called Costco and the Battery is a start Battery and not a Deep cell. Doesnt matter as having an extra battery for my Truck is never a waste, I was just hoping to kill 2 birds with one stone.

They do carry Deep Cell 12v 600 starting Amps and 115 amp compacity. So its slightly smaller than the one I got. but that would work better for my current panels as 2 of those would be 230amps like you said. Plus they are only $70 each instead of the $100 I paid for the one.

I can always get more IF and when I get the Wind Turbine.


On the Parallels, what do you guys use to connect the batteries if not in Parallel? Remember this is a backup system. I am open to any suggestions on how I should charge more than 2 batteries?

ON the crockpot I plan on having more batteries than 1 which is why I wanted more as the battery only holds so many amps. The one I had was a 150ah but I have to get the 115ah deep cycle to have it last.

All this information is helpful and I appreciate it from all of you. Before I had to search around and funny how many sell Solar stuff but cannot answer questions. I am just glad I found this site to get the information I need.

BB.

Re: Need help with controller and 100v open panels

In general, you are not going to find Deep Cycle batteries with Cranking Amps, CCA, Reserve Capacity specified.

Starting batteries are usually designed to support a 15% discharge... Deep cycle batteries typically support 50% to 80% maximum discharge.

Also, all of those devices you mentioned (coffee maker, crock pot, microwave, and even running a computer 15 hours per day) are quite heavy users of energy...

Note, there are the basic electrical units and we need to pay close attention that we use them correctly.

Volts: "electrical pressure"... Typically we have 12 VDC car and small off grid systems; 120 VAC for home appliances (AC vs DC don't care for moment)
Amps: "electrical flow"... Specifically how many electrons per second are moving past a point in a piece of wire.
Volt*Amps = VA: Volts-Amps or Volts x Amps... For DC = Power (a "rate" of energy usage per unit time). For AC gets a bit more complex--use DC definition for now.
Watts = Volts * Amps (DC) = Volts * Amps * Power Factor (AC)--For now, sort of like VA
AH = Amp*Hour: typically used with battery systems to represent energy used/stored. Always need to know Volts to do most calculations
Watt*Hours = Used to represent how much power has been used over XX hours. Watts is like MPH and Watt*Hours is like Hours Driven.

Lets take some example loads. Use Watts (rate of energy usage) and Hours (time) per day:

• 500 WH = 1,500 watts * 1/3 hour (coffee maker running 20 minutes)
• 900 WH = 1,800 watts * 1/2 hour per day (microwave heating things during day)
• 900 WH = 60 watts * 15 hours (big laptop computer running 15 hours per day)
• 78 WH = 13 watts * 6 hours (13 watt CFL lamp 6 hours per night)
• Total WH per day = 2,378 WH per day

600 AH of 12 volt batteries, assuming a typical maximum of 50% discharge, will support the above load for:

• 600 AH * 12 volts * 0.50 discharge / 2,378 WH per day = 1.5 days

And with 4x 80 watts of solar panels assuming an average of ~4 hours of day of full sun equivalent (usually the minimum for 9 months of the year for much of the country if you live in a reasonably sunny climate, don't have marine layer, shading from trees/mountains, etc.) and a typical 0.77 system efficiency/derating:

• 80 Watts * 0.77 * 4 hours per day = 246 Watt*Hours per day

Basically, without taking any other losses into account (and there are more), your 360 watts of solar panels will run the above loads for about 1/10th of the planned time (i.e., 1 day use, 10+ sunny days to recharge).

For the most part, people tend to underestimate their power usage and overestimate the output from solar power.

Your power usage may be drastically different than my assumptions... But it should give you an idea of what you are up against.

This can still be a useful system for you--But either you need 10x the number of solar panels or a Honda eu2000i (1,600 watt) generator + 10-20 gallons of gasoline with fuel stabilizer (actually, that is my emergency power plan because my system is a "Grid Tied" solar PV system and they do not operate if the utility power is down).

I also have camp stoves that can run off of gasoline so I have one fuel type with multiple uses (electricity, cooking, hot water, fuel to bugout in an earthquake, etc.) and multiple sources (gas cans, siphon my car, etc.).

-Bill

firefly101

Re: Need help with controller and 100v open panels

Hello Bill,

Yes those calculations will be useful for me. But your calculations are based on the usage which except for the crockpot and maybe the light are way more than I would use while rationing my power.

I do find it horrible news on the solar panels ability. Why does anyone use them with their costs if they are not effective? I live in Idaho, but ironically we get alot of sun, sometimes all day with longs days lasting 16 hours in summer. Winter is rough, which is why I am thinking wind as we get alot of that also. But right now today the sun is shinning ironically. lol

Lets take some example loads. Use Watts (rate of energy usage) and Hours (time) per day:

500 WH = 1,500 watts * 1/3 hour (coffee maker running 20 minutes)

Coffe pot draws only 900 watts for mine (though I can live without it. and wouldnt be using every day anyway

900 WH = 1,800 watts * 1/2 hour per day (microwave heating things during day)

My Microwave is only 900w model also.

900 WH = 60 watts * 15 hours (big laptop computer running 15 hours per day)

Laptop is 40watts and I plan to only use when needed

78 WH = 13 watts * 6 hours (13 watt CFL lamp 6 hours per night)

This one is about correct or atleast its better to over estimate.

Total WH per day = 2,378 WH per day

1000 WH per days is what I estimate on the above tops, but the crockpot for cooking would add.

So 4 batteries should give me a good reserve for the above? Each battery holds 1350watts but since you cant drain down to nothing I figure Half that to be conservative 2700 watts I have to work with. 4 deep cell 115amp batteries at 12v.

Now what should I do to charge them. Parallel ok or what other method should I use?

For more power I plan on Wind, so I have a hybred system. As for absolute short term emergency I have a bugout kit and 3500w generator 20gal of gas and 10lbs of propane. The solar and wind are to allow a more longterm use for Basics. Power out for a month of more.

firefly101

Re: Need help with controller and 100v open panels

Bill another question that I cannot find a straight answer on. Reserve Capacity?

I am told that is the reserve Amps in the battery example 150 from Auto places. But when I read that is the minutes basically 150 minutes the battery can stay at a voltage to run things at 25 amps. Thats what Reserve Capacity is suppose to mean, by what I read.

So how is one to calculate the actual amps a battery has stored?

This confusion of answers is what makes these things harder than let say computer repair which is alot more logical and straight forward on what it is.

Also I am told a Deep cell should be able to be drained down to its limit, but then again I hear about 50-80% discharge? Seems to be different answers from different areas. :roll:

Anyway thanks for the help, all this information will allow me to build a system that will work well and not one that will fail right away.

mike95490

Re: Need help with controller and 100v open panels

Reserve Capacity

is an automotive term, for how long you can drive at night with a broken alternator (no charging)


Deep Discharge.

Automotive starting batteries will DIE after ten 90% deep, discharges.

A deep cycle battery can withstand 50 deep discharges.

BB.

Re: Need help with controller and 100v open panels

firefly101 wrote: »

Bill another question that I cannot find a straight answer on. Reserve Capacity?

I am told that is the reserve Amps in the battery example 150 from Auto places. But when I read that is the minutes basically 150 minutes the battery can stay at a voltage to run things at 25 amps. Thats what Reserve Capacity is suppose to mean, by what I read.

Yep--That is how long a fully charged battery will run a vehicle with the ignition and lights (25 amp load) if the alternator/generator fails.

Roughly, at a C/2.5 hour discharge rate (i.e., 150 minute / 60 min per hour):

• 25 amps * 150 minutes / 60 minutes per hours = 62.5 AH at ~2.5 hour discharge rate.

The C/20 discharge rate (20 hour discharge rate) would be >62.5 hours (probably closer to 70-80 AH capacity).

So how is one to calculate the actual amps a battery has stored?

There is something called the Peruket Factor

http://www.smartgauge.co.uk/peukert_depth.html
http://www.smartgauge.co.uk/peukert_depth.html
http://www.smartgauge.co.uk/peukert_depth.html

You can probably estimate the AH capacity by the weight of the battery (at least for the lower C/20 type numbers (at heavier discharge currents, the apparent AH capacity is reduced).

This confusion of answers is what makes these things harder than let say computer repair which is a lot more logical and straight forward on what it is.

Even the Peukert Factor is a "mixed factor" of resistance, mixing electrolyte, etc... So it is not a real prediction of all performance specifications (i.e., it is not a detailed model of battery performance over current, temperature, time, etc.).

Also I am told a Deep cell should be able to be drained down to its limit, but then again I hear about 50-80% discharge? Seems to be different answers from different areas. :roll:

Basically, for a lead acid battery, the deeper the cycle, the fewer cycles it will survive...

However, roughly, it works out that if you have a battery bank that will last 1,000 cycles to 50% discharge, it might last 2,200 cycles (2x more batteries, 2.2x longer cycle life). So, spending more money for more batteries is not really a clear advantage in costs.

The other issue about the 80% maximum discharge (20% state of charge remaining)... Basically, the typical lead acid battery bank (and even cell to cell) ability to store energy (Watt*Hours or Amp*Hours) can vary as much as 20% from high cell to low cell...

So, the 80% discharge limit assumes that one or more cells may become fully discharged to zero volts/state of charge. And with Lead Acid Batteries, if you keep discharging them (the other "higher capacity cell") can actually begin to "reverse charge" the "dead" cells. For Lead Acid, that is pretty much a death sentence for a Cell (or Battery if cell is not replaceable).

And why 10.5 volts (aka dead 12 volt battery) will frequently never be quite the same again. Discharging to ~11.5 volts is probably a better bottom limit--but that is even difficult. Battery Cell Voltage is charge, temperature, and current dependent--it is very difficult to accurately estimate the state of charge of a battery bank while under load/charge.

A couple of Battery FAQs:

Battery FAQ
www.batteryfaq.org

There are a lot of points of discussions about batteries and how best to take care of your battery. I am certainly not the battery expert.

-Bill

dwh

Re: Need help with controller and 100v open panels

EDIT: Bill beat me to it. But I'll leave it anyway.

firefly101 wrote: »

I am told that is the reserve Amps in the battery example 150 from Auto places. But when I read that is the minutes basically 150 minutes the battery can stay at a voltage to run things at 25 amps.

Not exactly. It's how many minutes it will take for a 25a load to drain it to 10.5v. 10.5v is a dead battery.

So how is one to calculate the actual amps a battery has stored?

You don't. You make an educated guess. The only way to know for sure is to drain it with a controlled load and time it.

Also, the amp*hour capacity depends on the load. If you put a 20a load on a battery, you might get say 4 hours. If you double that load to 40a, you'll get -less than- 2 hours. If you cut the load in half, you'll get -more than- 8 hours.

So the amp*hours stored is not an absolute - it's a ratio which it tied to the size of the load. The heavier the load, the less amp*hours you'll get out of the battery before it's dead.

That's called the "Peukert Effect":

http://en.wikipedia.org/wiki/Peukert%27s_law


This is why deep cycle battery ratings look like, "100 amp*hours at the 20 hour rate".

Also I am told a Deep cell should be able to be drained down to its limit, but then again I hear about 50-80% discharge? Seems to be different answers from different areas. :roll:.

Draining any lead-acid battery to totally dead will reduce its capacity. With a deep cycle type (thick lead plates) it's just not as noticeable. You can get away with that sort of abuse more times than with a starting type (thin plate) battery.

Batteries have a rating of "cycles". If you drain it 25%, it might do that 3000 times (cycles), take it down by 50% and you might only get 1500 cycles, drain it by 75% and you might only get 300 cycles - take it all the way to dead and...not many cycles.

As Mike said, a thin plate battery can handle only a few cycles to dead before it's ruined.

By ruined, I mean that where when new it had a capacity of say 100ah, after too many deep discharges it may only have a capacity of 20ah. It doesn't have to be shorted out to be ruined - just to have the capacity reduced enough to be useless.

BB.

Re: Need help with controller and 100v open panels

Regarding charging, you can connect the two 6v batteries in series and charge them with a 12 volt large automotive charger to start with.

-Bill

Photowhit

Re: Need help with controller and 100v open panels

Crockpots use only 225watts so my cooking with them should work ok,

Crock pots take time, you have enough panels to just about run the crock pot alone while the sun is out. ie NO CHARGING!
Lighting would be 14w bulbs that produce 100watts of light with the old bulbs.

Close, I the 14 watt put out what a 60watt incandesent it's 23 watts for the 100 watt light equivelent.

Microwave, coffee pot Not really as not only do these use more electric, you'll be drawing down the battery quick enough that you will get a multiplier by the "Peukert Effect" and running a laptop possibly. VERY small power needs for Emergency for me. I do agree on heating water But I plan on having a 110v water heater 20gal and that will run off the system WHEN/IF I get the 1000watt wind turbine. Indeed in fact you will need a dump load, but you'll want to talk with swomeone who does wind/hydro
I do have a coleman stove and Propane grill.

why not have 4 parallel stings? I seen battery banks that had 20 batteries in parallel? It has to do with keeping the strings in balance. read the battery FAQs

I see you've decided to go with a deep cycle, still might suggest going with 2-6 volt Golf cart batteries rather than 2-12 volt, half the cells to check and half thewatering and wireing.No I have an inverter for the one battery that I use just to power simple things if the power goes out, but I plan on getting and quality inverter later, but nothing too out there in cost.

Can't bail on the panels, they are 50lbs each already arrived from freight and I got them for $135 ea shipped. I dont know anywhere else you can get 80watt outdoor panels for that price? [/QUOTE] Sorry you didn't ask first...but I couldn't get you any better, but about the same, in a 12 volt version
To make current NEC code MC3 connectors need to have a clam shell or locking element, they cost about $1 each.
If you have very short runs I have some very short MC3 cords I'll give you for the cost of postage, I think I have 4 - 4' double sided cords, I'll check when next I'm home.

tonygcan

Re: Need help with controller and 100v open panels

Thanks for this battery discussion.

I wanted to find out if percentage of charge SOC has a direct correlation to Ah capacity. That is, if I had a 100 Ah string of batteries at 48 volts at full charge that would mean that I had 100 x 48 = 4,800 watt hours worth of energy.

Does this mean that at 60% SOC I would have used up, roughly, 4,800 x 40% = 1,920 watt hours?

My system in my farm starts the night at about 53.8 volts. I understand this is not the true voltage since the system has been under charge the full day, I also have an air x wind turbine connected to my batteries. I load my system with 111 watts of lights for 11 hours or 1,221 watt hours.

This would mean that I should have 4,800 - 1,221= 3,579 watt hours left and my batteries would roughly be at 75% SOC.

I understand that my power consumption is actually greater than my computations because the lights I power are perimeter lights and some of them are located 100 meters or so from my batteries and I think the resistance on the wires for that distance will be substantial.

However, many times my CC will show 47..9 volts in the morning and the inverter will shut down on it's own at about 9 hours of operation.

Today, my CC showed 44.9 volts in the morning from 53 volts last night and my inverter did not shut down. Can I conclude that there's something wrong with my inverter? It's a su-kam brand inverter from India.

BB.

Re: Need help with controller and 100v open panels

Sort of... (sorry).

From the first approximation, yes, you are correct.

A battery may have 100 AH of capacity at a 20 hour discharge rate (5 amps * 20 hours) but only have a 90 AH capacity at 10 hour discharge rate (~9 amp load).

Also, using Watt*Hours with a lead acid battery makes things a bit more complex for the math (more accurate, but more complex)...

A flooded cell lead acid battery may be around 80% energy efficient... For example:

• Discharge 10 amps * 10 Hours * 12 volts average = 1,200 Watt*Hours discharge
• Recharge 10 amps * 10 Hours * 14.5 Volts average = 1,450 Watt*Hours to recharge

Note, for a rough estimation, Lead Acid Batteries are fairly close to 100% efficient in terms of AH / Current flow (notice the above equations assumed 100 AH out and recharged 100 AH back--close enough for tonight).

Using a Battery Monitor can help you better keep track of how you are using your battery bank's capacity.

In this example, you can see that it is current flow in/out of the battery that matters... If you have remote lights, the extra resistance may simply reduce the current flow a bit (and reduce the light output some too).

I always like to review conservation measures... For example lighting.

For example, our eyes are "logarithmic" in how we see light. Basically, if you have an LED flash light and cut the current to the LED by 1/2, the output energy will also be cut by ~1/2, but for a human eye to see the reduction in illumination, you would have to do an A/B test (1 watt on, then 1/2 watt on comparison). For our eyes, roughly a factor of 10 change (1 watt vs 0.1 watt) is a world of difference (1 watt would overwhelm 0.1 watt light).

So, looking at your lighting requirements--perhaps you can cut back 1/2 on the size of bulb (or 1/2 as many bulbs) and still get adequate lighting.

Also you can look at using motion detectors to only turn on lights when need (people/animals in area). For security, typically motion detector lights are a better solution. The area starts dark (hard to plan mischief). Then turns on, attracting attention.

Anyway, hope this helps.

-Bill

tonygcan

Re: Need help with controller and 100v open panels

Thanks for the explanation.

Yes, I actually reduced my cfl bulbs from 18 watts to 11 watts. I will try 9 watt bulbs. That would be a reduction of 20 watts in load requirements.

I'm not too sure about the motion detectors because the leaves and branches might continuously activate the lights.

BB.

Re: Need help with controller and 100v open panels

Yea, unless you can mask the Motion Detectors to point at clear ground or something--leaves/wind can certainly set them off.

Could you use something more like a spot light (LED's)? 1-5 watt LED's can be pretty intense if you don't need a true flood light (such as a CFL). Such as trail/walkway lighting.

-Bill

firefly101

Re: Need help with controller and 100v open panels

Thanks Bill and DWH,

This helps alot as I understand what your saying, same effect happens on the smaller AA batteries which is why lithium run longer for cameras because of their high draw.

So the Main concern I would have to consider is KEEPING the Current Drain as low as possible. Don't run too much at once, one Item at a time. I think I SHOULD have just went with the wind Turbine, but I thought the costs would be more and the dumping of the load as well as different vendors selling junk. Also its a giant propeller in the sky that could fly away if the weather was bad enough.

We had a pretty bad storm recent shut the power down for 3 days and blew 150 transformers out, some think it was even tornado's even though they are not suppose to happen here.

I have a hand cranked Generator that will do 100 watts or 5 amps for a battery, its a solid 1960's model built like a brick, but requires a slow constant workout to crank. lol No wind or Sun I could use it. :roll:

I hope that a hybred system will help better? Any suggestions for a good turbine that does what they say, will work in light wind and can handle HEAVY winds 80mph+


Photowhit,

Do you sell panels or something? Because I have looked around and can't find anything close to the price I paid. They were $95USD each I had to get 4 and the shipping was $166 for 4. So I paid total 547.00 for 4 80w High Quality solar panels.

I see alot of Plastic Solar panels selling all over that claim so many watts but I doubt they match their ratings.

Good example is Global Solar, they claim their thin filmed stuff rates at 35w but in reality I find it charges at about 20w.

Also to prove this is really marketing the military SEAL teams used an Early version of a foldable panel, which was rating at 10w for charging standard 12v or 14,1 charge rates etc. While other thin filmed same number of cells claim 15w and really charge at the same rate. I dont know if its the same in the big panel industry but marketing something higher when you charge by the watt can cause exaggeration by the sellers.

Imo Solar is way to overpriced for the results, If they want people to go more solar and wind they need to lower the price. Otherwise no one will ever be able to afford for what you get.

tonygcan

Re: Need help with controller and 100v open panels

I've tried looking around at LED lights but have not found any available here that would suit my needs.. Will keep my eyes open for new models though.

I have a hybrid system in my farm. 4 - 60 watt sharp panels and an Air X 400 wind turbine connected to my batteries. The air x connects directly to the batteries since it has it's own charge controller. I have an amp meter attached to the air x and I measure an average of 3-5 amps on it. I see it fluctuate to 10 Amps on windy days and up to 15 amp peaks on really windy days.

Brochure says that it can with stand 100 mph winds. I bought mine for about 700 dollars.

firefly101

Re: Need help with controller and 100v open panels

Tonygcan,

Thats good information that that wind turbine has a built in charger. 5 amps would only be 5 amps. but I guess any amount is better than nothing. What type of pole system do you use? did you need cables and how high did you place yours?

How many batteries do you have in your bank?

Photowhit

Re: Need help with controller and 100v open panels

firefly101 wrote: »

Do you sell panels or something? Because I have looked around and can't find anything close to the price I paid. They were $95USD each I had to get 4 and the shipping was $166 for 4. So I paid total 547.00 for 4 80w High Quality solar panels.

No, just Old and been using solar for a long time, panels I bought last year cost just over $2 a watt delievered, and are quality panels UL listed (the NingBo are the heaviest construted panels I've even seen). I also recieved 30% tax credit, and can use them on my PWM charge controler, since my heavy draw is in the summer a MPPT CC makes less sense for me.

I and others here can see the added expenses, the clam shell to make code compliant, the MPPT charge controler, larger racking for the less effiecent panels. We've done the maintanance our the batteries every month, checking 6 cells rather than 12. Installed our batteries with extra wiring and fusing, for multiple strings. Tried to trouble shoot batteries banks with multiple strings (I've actually only run multiple strings once, and with new batteries, but I've been here and read the threads of people tracking down problems in multiple strings of batteries)

My break even point was likely 12 years until I decided to make the purchase last year for greater comfort (until the next hike in user fees at the silly power company) I haven't calculated where or if I have a break even point in my current situation after last year expenditures.

This year I'll buy a forklift battery, which I believe will last me 20 years and will cost, over time, equal to, or less than the golf cart batteries I have been using, and give me greater capacity (2x) for easier summers and spans of cloudy weather. It took me time, experience, and a lot of positive reports to make such a large purchase with the belief that they and I as a user and integal part of the system will remain healthy.

Sorry you didn't find any of my information helpful, perhaps over time you'll find it more so, If you have short runs the offer of the MC3 cables is real, I no longer have any use for them.

"Imo Solar is way to overpriced for the results, If they want people to go more solar and wind they need to lower the price. Otherwise no one will ever be able to afford for what you get."

Sorry you feel that way, in redundent systems like you will have you may only feel good about it when the power goes out and your light is still shining. If you have been reading, very rarely are battery based systems, ever as cost effective as the grid. Indeed generators are what are most often suggested for backup power, even here!

You may find, that you will discover cost benifits when you look at the energy costs of appliances because you have changed the way you think about total costs of something.

firefly101

Re: Need help with controller and 100v open panels

Hello Photowhit,

what do you have in MC3 connectors and how much you want? I must have missed that offer, there was another poster that highjacked the thread a little. lol

I got my panels for $1.19 per watt before shipping, I would say with shipping $1.68 per watt. I cant find any place at those prices the place I bought the panels from was a wholesale panel dealer there were 215 panel just 2 months ago and now none. Thats why I jumped on them as I knew I wouldnt find that price again. The only catch was the High voltage and special controller needed.

I think Wind is something I WILL go with also to balance out, but having both isnt too bad. I agreed with you on needing more panels, its just not cost effective compared to other projects I have to do and WHAT I am using this for. Power here is 6 cents a Kilowatt. So its more for longterm emergency.

There is no way I could store enough Gasoline, nor being safe with possibility of fires to last more than maybe a week with a generator. I think I get 12 hours on a 3.5gal tank at 50% load with my 3500w generator from Coleman.

As for Propane, again if the ONLY source of cooking would run out fast. But I do think I will get a large 15 gallon tank as a reserve.

How would possible Solar Flares effect the solar panels? In the early 1900s with telegraphs the wire and transformers were fried, there is actual old video showing the sparks. This of course was before electricity being used, so considering that MOST of our power nationwide is above ground we are proned for a massive power outtage. I know NASA is concerned, the next 2 years are suppose to be VERY active for Solar Flares. I can't imagine what would happen if the power grid goes down nationwide, I imagine the cities would be really bad off.

Let me know on what you have for sale and how much and shipping. Anything that can help save the costs is welcome as cables are expensive.

Photowhit

Re: Need help with controller and 100v open panels

firefly101 wrote: »

Hello Photowhit,

what do you have in MC3 connectors and how much you want? I must have missed that offer, ...

"If you have very short runs I have some very short MC3 cords I'll give you for the cost of postage, I think I have 4 - 4' double sided cords, I'll check when next I'm home." As it turns out I fell asleep with my glasses on and have to run home now as we have a big pool league match tonight. I'll let you know what I have. You might be able to use these if you can locate a combiner box near your panels. typically you buy a cable 2x the length you nead and cut it in half, use the male and female ends and the cut cable goes into your junction box.

As I said their yours for the postage, should fit in a priority mail envelope for $5

firefly101 wrote: »

...Power here is 6 cents a Kilowatt. .

I've been trying to get you to look at the total cost, it might look like it can't possibly be cost effective to do an off grid solar where I am, I could easily say electric costs 9 cents a KW here, but of course they have a $25 user fee before you buy any electric here (and talks of increasing that!) and I use very little electric, maybe 50 Kw a month other than summer (I actually use more now as I have more available, bad habits) so my per unit cost is much higher.

Your 'cheap' panels cost extra, in added space (less effiecent) and more expensive charge controller. You can check the history here, thin film panels have been selling for as little as 99 cents a watt, you can still get them for that in pallet loads, before shipping. It's the total costs that make them somewhat less attractive.

BTW - I haven't read up on your thin film panels, but others suggest they will produce as much as 30% above the panel rating for a short period, maybe a year?, before the settle into the panel rating.

BB.

Re: Need help with controller and 100v open panels

Regarding solar flares, my understanding is that they will only affect electrical grids/networks that are on the orders of miles or larger.

These are fairly low frequency radio waves and should not affect the typical home sized off grid systems--a long as you don't connect to the utility grid with gt or hybrid inverters/transfer switches (you might throw breakers/disconnect any grid/ac battery charger connections when major flares are forecast.

We have several detailed discussions here if you search/google search our forum. (on phone right now, not ready to insert links).

-Bill