I need help

solargirl · November 2009

Hello all,

This is my 1st time posting, my husband has passed away and we were in the middle of updating our 48 volt system, we have 10- 170watt bp panels, and I just added 10-180 panels that he had ordered, got everything tied in, to a flex max 80 charge controller, today the controller read 10.5 kwh and 197 ah, I have a trace 4048 inverter. 16 surrette batteries, they are shot .

The new batteries he ordered should be here within a month, I will be replacing them with a crown 1381 amp battery.

Questions I have
With the information I have given can anyone tell me what size my system is?Kw.

The inverter says I am using between 3 and 5 amps ac 24/ 7, is that alot of power? I know my batteries are shot but I am still using the generator everynight at least 2 hrs. ( low battery)
Will the panels I have produce enough power to equilize the new batteries, or do you always have to use a generator?
Thanks you in advance for your knowledge.

halfcrazy · November 2009

Re: I need help

First off Sorry for your loss.

We can help with a lot of this but may need some more answers first.
first you have about a 3.5kw solar array. this should be sufficient to equalize but a lot depends on the daily poser usage. I would highly recommend a good battery monitor like the trimetric so you can figure out the daily usage.

Where are you located 10.5kwh for an array that size seems a little low but it really depends on where you are at?

icarus · November 2009

Re: I need help

Welcome to the forum, and I hope I speak for all when I say we're sorry for you loss.

I will try to begin to answer your question(s) and I know others will chime in.

First, power is the Sum of Volt X Amp =Watts

So your 3-5 amps at 120 volts (I assume you are measuring it at 120vac) it translates to between ~360-600 watts. Not a huge draw, but not insignificant either.

Your system is ~3.5 kw total
1.7 with one set, 1.8kw on the other.

A simple rule of thumb (with a battery based system) is take the name plate rating of the PV (3.5 kw) divided by two, and then multiply that by the number of hours of good sun you get,,,seldom more than 4. So under ideal circumstances your system might yield net/net out the outlets 3500/2X4=7000 watt/hours/day. (7kwh/day) Your consumption of 3-600 watts 24/7 might average ~5kw, plus any peak loads.

I suggest you buy an inexpensive Kill-a-watt meter to measure your real consumption.

If you have a dead set of batteries, my guess is that you have been consistently undercharging/overdrawing them.

Read some of the following links: http://www.batteryfaq.org/
http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

It will give you a pretty good idea on the 'care and feeding" of batteries.

Gotta run now, but I will write more later, as will others,

Tony

solargirl · November 2009

Re: I need help

Thankyou, and I appreciate your help, I am in central ca.

Cariboocoot · November 2009

Re: I need help

Summarizing:

10 - 170W panels = 1700 Watts
10 - 180W panels = 1800 Watts
Total = 3500 Watts peak

Trace 4048 inverter = 4000 Watts

Battery? 1381 Amp/hrs?

Average of 4 Amps @ 120 Volts = 480 Watts * 24 hrs = 11,520 Watt/hours.

That's a lot of electricity usage for an off-grid application.
Depending on what efficiency rating applies to your system, it could supply 7 kW/hrs per day up to perhaps 14 kw/hrs per day. For average system/sunlight, you are borderline on supplying as much power as you use in any given day. Doesn't look like there's any margin for even slight cloud cover. No wonder you're using the gen every night.

I think primarily you need to get a handle on your usage. 11 kW/hrs per day is four times what we use.

What are you running that's sucking up all that power?

halfcrazy · November 2009

Re: I need help

I would not put a lot of stock into the inverters amperage numbers that's why i recommended a good battery monitor. It will give you actual daily data that can help you design the system accordingly.

solargirl · November 2009

Re: I need help

I have a regular fridge, I just looked at the amp rating it says 7.9 (no watts) a lcd tv, with dishnet box, and the computer with monitor, since I use satelite for the internet, there is a box that stays on 24hrs a day at 1.5 amps. I use cfl lights.

But at any one time there are only 1 or 2 lights on, washer/ dryer/ blow dryer aren't used unless the generator is running.
I guess I need to get one of those kill o watt meters and a battery monitor.
the batteries are crown industrial, I think they are forklift batteries.

Solar Guppy · November 2009

Re: I need help

Put the TV , computer and sat box on power strips you can turn off when not in use. The Sat box alone probably pulls 40 watts or 1kWh day if its on 24/7

icarus · November 2009

Re: I need help

Ditto what SG said,

The sat tv box draws power 24/7.
Also turn you sat internet box (modem/router) off unless you use it for voip phone. Even the sat company tells you not to, the only consequence is that it will take a few minutes to boot.

Use the Killawatt to find all these phantom loads, as they add up to real numbers over the course of the day.

Consider going to the hardware store and buying a sheet of sytrofoam. 2" of foam on top of, and on the sides of, and even on the door of a fridge can reduce its run time significantly.

Tony

Cariboocoot · November 2009

Re: I need help

That 3 votes for the Kill-A-Watt testing.

That 'frige @ 7.9 Amps is pretty hefty; mine (16 cu. ft.) draws only 2 max when running (more for the defrost). But then appliance 'power plates' are notoriously inaccurate.

I also have a satellite set up for Internet & VOIP - all on a power bar which gets shut off at night. It uses 25 Watts just sitting there doing nothing.

BB. · November 2009

Re: I need help

And I will provide a link that lets you see what a Kill-A-Watt looks like.

Basically, old refrigerators can burn a lot of electricity (or if the coils need cleaning, vents blocked, etc.). A very good fridge will use around 1-2kW hours per day. A "bad" one can use much more.

Old stereos, TVs, and modern sat-receivers, DVR's, and even some other appliances (dishwashers, washer/driers, etc.) can use a lot of power when "off" (standby).

Switching from a desktop to laptop computer, turning of printers when not in use, etc. can also save lots of energy too.

And the other stuff--using CFL/LED lamps instead of filament lamps, power strips on desk lamps that use an external transformer, etc. (confirmed with Kill-a-Watt) all help... You may save 25-50% of your daily power usage with better conservation/more efficient appliances.

The Kill-A-Watt running from 1 day to one week per device/appliance will give you a really good idea of how much each draws (kWhr per day). And, you can see how much they may draw when "off".

-Bill

solargirl · November 2009

Re: I need help

Thankyou all for this useful info, I found the old energy rating on the refrigerater, energy star rated at 459 KWh /year, Checked the tv 4.0 amps and the satelite receiver 120 watts, I wish they would put everything in watts or amps, I can't add anything if I don't know what I am adding, kw, amps watts, Jez.
and will any Kill a watt meter work with my inverter, it says it will work with a modified sine wave inverter, ( I don't know if mine is a modified sine wave inverter)

Cariboocoot · November 2009

Re: I need help

Basically, Watts is Amps times Volts. So with a 'frige drawing 7.9 Amps @ 120 Volts = 948 Watts. (You will see spec plates use different Voltages too; it might say 125 V or 127 V et cetera).

Is your inverter the good ol' SW 4048? That qualifies as sine wave.
Anything that will work with MSW will work with 'the real thing'.

(Your refrigerator wouldn't 'like' MSW much, btw; harder starting, draw more current, shortened motor life).

BB. · November 2009

Re: I need help

Yes the Kill-a-Watt will work with both MSW (Modified Square/Sine Wave) or TSW/PSW (True/Pure Sine Wave) Inverters...

The kill-a-watt will make it much easier for you... It will read in Watts (i.e, 140 watts to run your fridge) and it will read in kWhrs for how much power you use in a day (i.e., 1.42 kWHrs per day)...

Details:

"k" is kilo or 1,000.... So 1,000 Watts = 1 kWatt

Watts is a rate (like gallons per hour)... And:

Power=Watts=Voltage*Current=Volts*Amps

So, if you know 4 amps and 120 Volts then:

P= 4 amps * 120 volts = 480 Watts

And for how much power you have used (such as Gallons total), we use Watts*time or Watt*Hour.,,

Energy/Work=480 Watts * 10 Hours = 4,800 Watt*Hours

For home electric meters and kill-a-watt, they give the Work as kWH or:

4,800 Watt*Hours * 1/1,000 = 4.8 kWatt*Hours = 4.8 kWH

There are more details (power factor / VA / VAR with alternating current--but we can leave that for another day). This will get you 95% of where you need to go.

-Bill

solargirl · November 2009

Re: I need help

Cariboocoot,

yes it is a Sw4048 , 8 yrs old.

Thankyou for you help

solargirl · November 2009

Re: I need help

BB

Thankyou, I think I needed to have it written out the way you did ... for me to get it into my thick head, I actually understand it. I will be purchasing a Kill A Watt meter tonight.
What a great site, Thanks again to all !

BB. · November 2009

Re: I need help

SolarGirl,

You are very welcome... By the way, I had the wrong number of zeros for "4,8000"--should be "4,800"...

-Bill "Oh Well--I Tried" B.

BB. · November 2009

Re: I need help

Also, I should add that when you use the Kill-A-Watt meter--for some appliances it will be necessary to run them for 24 hours or longer...

For example, the typical frost free refrigerator will start the motor at 500-1,000 watts for a few seconds, then fall back to 120-240 watts, then back to near zero watts for an hour and restart the cycle again (compressor maybe off 50% of the time/on 50% of the time during a warm day)... Then, sometime during the day the defrost heaters will turn on and the fridge will draw 500 watts for a few minutes to melt the ice on the cooling coils, then drop back down. Running the fridge for a day or 3 on the KaW meter will give you a much more accurate average power usage vs just plugging in the meter and reading off 120 watts.ug

Some appliances also have energy saver modes... For example, some refrigerators have heater strips near the door openings to heat the metal a little bit to keep it from "sweating" during humid summers. Turning those off can save power too.

-Bill

hillbilly · November 2009

Re: I need help

Very sorry to hear of your loss, I imagine this is quite the process trying to piece all of this together. I'll dito most of what has been advised thus far. One exception that caught my eye was you asking about Equalizing your new battery bank 1381 AH with a 3.5KW solar array. I don't think that you will find this quite sufficient for EQ'ing without some generator help. In particular, if you have any other loads on while attempting to EQ I don't think your voltage will ever quite get up high enough. You should have enough PV for normal everyday recharging, if you watch your loads (my wife and I frequently have to wait or delay certain tasks until the battery bank is sufficiently recharged). This can get a bit tricky in the winter months (we are also in central CA), co-ordinating your generator use can help a lot here (as you may well know already).
Good luck and keep us posted, hopefully your new system will work out well...

solargirl · November 2009

Re: I need help

Hillbilly,
Thankyou for the kind words, It has been hard.. but I have to keep things up for me and my daughter, I have ordered the Kill A Watt meter, apparently they are out of them till the 1st of Dec. I do think my husband said something about having to equalize with the generator, I think it is a good size, 20kw. that should charge them? and how often do I equalize? monthy? does that depend on the batteries?

Another question, my husband had a list and it says check on a 48 volt charger, thru this site. How do they work, do you plug them into the house to charge the batteries? that doesn't make alot of sense? maybe it does ? I don't know.
( kinda new at this)
Thanks in advance for any answers.

Cariboocoot · November 2009

Re: I need help

Solargirl; a 20kW generator will have no trouble supplying your loads and recharging/equalizing the batteries. It is my personal belief that batteries should be checked once a month and only equalized if necessary. Others may offer a different opinion. You have to check the Specific Gravity of each cell in each battery with a hydrometer. It will have a graduated scale on it and usually colour 'zones' indicating 'poor', 'fair', and 'good' or some such. If any cell is 'out of range' (in a different colour zones) the batteries should be equalized. Too often of equalization can lead to excess water loss. You've already mentioned your batteries are shot. This could be due to chronic under-charging or just old age (although Surettes ought to last 8 years easily).

Your husband was probably looking into an Iota charger like this: http://store.solar-electric.com/iodl48vo15am.html

It would be powered by the generator and be used to make sure the batteries are fully charged any time the solar fell short.

Yes it is an awful lot to have to learn all at once, and we're all very sorry you've been put in this situation. We're here to help as best we can.

solargirl · November 2009

Re: I need help

Cariboocoot,

I agree, we didn't spend alot of time taking care of those surrette batteries, I want to make sure when I do get the new ones online I do all the right things, I do have a hydometer , to bad we didn't use it.
Thankyou for the link, that is what he had written down, IOTA 48 volt, right now we have the generator wired in to a panel and when I flip a switch, It charges the batteries through the inverter, I guess I would be bypassing the inverter when I used the IOTA charger?
Sorry so many questions, again Thankyou and everyone else for all the helpful info. I really do appreciate it.

Solargirl

Cariboocoot · November 2009

Re: I need help

Yes if you run the Iota charge it is powered directly from the generator and hooks to the batteries. But if the inverter is charging all right, there's no need to add this. (I might be confused here - it happens a lot at my age/mileage:p).

When you get your new batteries; charge them fully, equalize them, then take a 'resting' Specific Gravity reading of each cell and write it down. You should compare all subsequent readings to this 'baseline' to know how the bank is performing.

I don't think we've touched on how big your existing battery bank is in Amp/hrs?

solargirl · November 2009

Re: I need help

All I know about the battery bank is , there are 16 batteries and it is 48 volts. the inverter is the 4048 trace, and I think I read something about the charging capabilities , 60 amp charger, but the inverter is using a certain amount and only so much is actually charging the batteries ? I'll have to go back and read about it .

BB. · November 2009

Re: I need help

Regarding how much generator power... A Crown 1,321 Amp*Hour 48 volt battery... The rule of thumb is to charge with ~5%-13% of your battery 20 Hour Rate (that 1,321 AH number) unless your battery manual says something different. Lets assume 10% (good sized charging current):

Power Gen = 1,321 AH * 0.10 charge rate * 57 volt charging * 1/0.80 charger eff = 9,412 watts

A 20 kWh Genset with a 10 kW battery charger is a good match.

If you are using 10kWH of power a day, you are looking at an hour to "bulk" charge and several hours to absorb (charging current tapering down).

Ideal, if you can schedule it... Run the Genset for an hour or so in the morning and let the solar array array do the finish charging.

To give you an idea how much power your panels can produce, use the PV Watts website. Assuming 3,500 Watts (3.5 kW) of solar panels, fixed array, 0.52 derating (off grid system) near Bakersfield California:

"Station Identification"
"City:","Bakersfield"
"State:","California"
"Lat (deg N):", 35.42
"Long (deg W):", 119.05
"Elev (m): ", 150
"PV System Specifications"
"DC Rating:"," 3.5 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 1.8 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 35.4"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:","12.5 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 3.47, 182, 22.75
2, 4.64, 216, 27.00
3, 5.63, 288, 36.00
4, 6.44, 316, 39.50
5, 6.78, 330, 41.25
6, 7.31, 335, 41.88
7, 7.28, 341, 42.62
8, 7.30, 347, 43.38
9, 6.90, 327, 40.88
10, 6.19, 310, 38.75
11, 4.67, 232, 29.00
12, 3.21, 164, 20.50
"Year", 5.82, 3390, 423.75

Your system should generate around 164 to 347 kWHrs per month (third column above). Looking at November, you should be generating around 232 kWhrs per month or 7.733 kWHrs or 7,733 Whrs per day... Basically if you use 10kWhrs per day, you need to use the genset from November through March to make up for the excess power you are using over what the panels are capable of providing.

Looking at the numbers, for a 1,312 AH system, you should be looking at a 5%-13% * C = 65 Amp to 172 Amp capable charger... (numbers are approximate range).

Today, you are using (very roughly) 15% of your battery capacity a day--which is about the right size for your system... It will carry you through 3 days of heavy cloud cover and still be a bit above 50% capacity. Running your battery below 50% capacity often will "wear" it out faster. Running your battery below 20% state of charge can damage one or more cells and ruin the battery.

Ideally, if your battery falls below 75% state of charge--you should plan on charging it back above 80% SOC the next day (keeping a Lead Acid battery below ~75% State of Charge will build up sulfate deposits and can age the battery quickly (spend a week or months way below 75% SOC will kill the battery in months or year or so--just a SWAG).

Your current amount of solar panels it a bit on the small side of 5% minimum charging current (somewhere around 55-60 amps)... But if you use the genset once in a while (when needed to get the battery back above 90% at least once a week or so)--you should be fine.

-Bill

hillbilly · November 2009

Re: I need help

Solargirl,
I'm not totally sure what you would want the Iota charger for "if" the inverter you have is indeed working. The Iota chargers are nice handy chargers but they do not EQ. I am guessing that the theory was that with an additional charger you could add more charging capabilities for times when the batteries are really low. This would potentially speed things up a bit, but probably wouldn't help out when EQ'ing (or having to finish absorb cycles during periods of excessive cloudy weather). This is because once the batteries are up to say 85%-90% they can only take so much current, so having a second charger at that point would be redundant.
By the way how much do you know about what your charging parameters are? Voltage settings for Absorb, EQ, Float, length of absorb time? Do you know for sure that your Surrettes are dead? The more details you can give us the better we might be able to help ya.
Good Luck

solargirl · November 2009

Re: I need help

Thanks Guys,

There isn't a whole lot I can do until I get the Kill A WAtt meter, and get the new batteries, I am pretty sure a couple of cell's in the battery bank are shot because of the readings with the hydrometer, hopefully I will get the batteries in the next couple of weeks and I will have an electrician hook them up, the junction box and the charge controller are up by the panels and my husband wanted to bring the charge controller closer to the batteries and inverter. So I will continue to read what has been written here, in order to get it into my thick head ! thanks again.

hillbilly · November 2009

Re: I need help

You might want to check out what settings you had as far as charging parameters on both the charge controller and the inverter before hooking up the new batteries. It is possible that could be partially responsible for the batteries decline, so worth checking into and posting here. Just out of curiosity, how bad are the SG levels when you measured them with the hydrometer?

BB. · November 2009

Re: I need help

Also, if I recall correctly, the Trace Inverter may have a menu setting to "save the settings"... If you don't do this, it may "forget" any changes made over the years when the bank is disconnected (I am not sure at all--just something I may have remembered from somebody else here).

-Bill

solargirl · November 2009

Re: I need help

The absorbtion rate on the charge controller is 57.9 float 54.9 I didn't see a time on that, the inverter, bulk 57.9 absorbtion time 2 hrs. float 53.6. Equalize 60.

hillbilly · November 2009

Re: I need help

Ok, that's what I was wondering. For those batteries that sounds like your absorb and EQ voltage settings are a tad on the low side, unless they were being cycled (used) very lightly. For the Surrettes, while you are still using them, I'd say look at upping the Bulk/Absorb setting to something more like 58.8V-59.2V and letting the Absorb cycle go for at least 3 hours. With your charge controller you can also set an end amps amount so that the Absorb cycle will switch to float if the amps into the battery falls below a certain setpoint (typically about 2% of the battery bank's rated capacity).
The idea here is that once the charging current is getting really low, AND the voltage is still remaining at the absorb level it's a good indication that the batteries are at or near full charge. You can double check this with the hydrometer, and verify that the SG levels are indeed reading full when the charge controller says they are full. Two hours at that voltage is likely to only bring the batteries up to perhaps 90% SOC or so, but almost certainly not enough to fully recharge them. As for the Crown batteries, check and double check what they themselves recommend for charging parameters.
For Equalizing there are sort of two types: preventative (monthly maintenance) which would probably be somewhere in the 60-64V range for about 2 hours or so. Corrective Equalizing is typically a much bigger ordeal, lots of generator run time, lots of checking the battery cells with the hydrometer, carefully watching the battery temps... etc. I don't know how abused your batteries are but they may have some extra life in them with some corrective Equalizing, you may or may not want the hassle. How old are the Surrettes now?
I have also found Surrette to have very good technical support when I have had some issues with my batteries (made a few of the typically beginner boo-boo's in the early days). They also have some good info on their website that's worth reading. I presume Crown also would offer good service on this end...

I need help

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