Offgrid-House: Battery bank suddenly losing power rapidly?

mtdoc · July 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

I think he has a FlexNet DC which is a very good battery monitor. It does take some setting up to be useful.

PorkChop - If you haven't done so already you need to read THIS Tech Note from Outback and follow the steps to set up your FlexNet DC. I think that any battery monitor that is measuring SOC by tracking amps in and amps out needs to be set up and calibrated - will need to start with battery full - absorb stage completed - to get the initial baseline 100% SOC and be able to track amps from there. If you haven't done this already, I would run your generator and get through a good long absorb stage. I would get the SGs as high as they'll go. Then reset the FNDC (to 100%SOC) and go from there.

You really should get that serial to USB connector, spend $50 on WattPlot and run it on a PC. After one day, with the FNDC calibrated, you'll know what loads you've drawn and how your battery bank has responded.

I find that the Mate Display can be a little cryptic and WattPlot makes it much easier and strait forward to track and log all of the info you need.

PorkChopsMmm · August 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

Sorry for the lack of updates -- I have been trying to finish the power shed and one of our cars overheated. Not fun times

BB. you have some very interesting information. Thank you. Although... it does scare me that I don't have enough panels for the size of my battery bank. You said I would need 8.3 KW to recharge my bank from 50%. Today, on a relatively very sunny day with temperatures in the low 70's, I got 5.44kWH. In summary, 5.44 kWH in total, 1.5 kWH out, and just under 4kWH to the batteries. This is all from the shunts measured on my MATE and today was a very low use day.

Again, this worries me because I have ~1.4 kw of panels and while I do have plans to buy 3 more panels (totaling 2.1 kw) in the near future I also I wanted to double my battery bank size. I am starting to think that is not a good idea. Also, if it is summer and I can't charge my battery bank enough right now what am I going to do this winter? I guess I will need to rely on the generator more. Hmmm... The generator specs are 6.1KW continuous, 7.2KW surge, and 50.8 Amps continuous, 60 Amps peak. I haven't used this generator much to charge my battery bank, I normally use a 2KW smaller generator, but I am switching to this larger generator when I get my Auto Generator Start relay in the mail (Maverick Solar, tsk tsk).

mtdoc -- thank you for the reference to properly programming the FNDC. It definitely isn't a plugin deal -- it needs to be calibrated. I will make sure I follow the guide again tomorrow after I go exchange my Sam's Club GC2 batteries for new ones. Wish me luck! BTW I did get the USB to Serial cable and did download the trial version of WattPlot. Honestly, I am not that impressed. I didn't see anything very useful for historical trending, but then again I didn't did in too far. It was all line graphs and not very easy to get a quick glimpse of where you stand. It's also hard when the computer is out in the old power shed and not easily accessible -- this will be fixed in the new power shed when I trench the lines to run power to the cabin. I did use the VisualMate program, which is cool, but you can only run one serial program at a time and so running that app loses the ability for WattPlot to collect historical information... at least this is what I have found out. Am I missing something?

BB. · August 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

PCM,

But what is your daily load?

If you are discharging the battery bank from 100% to 50% state of charge in one day (overnight, etc.)--Then you don't have enough battery bank.

If you are only taking the bank down 25% overnight--Then it is probably big enough for now.

Do you use most of your power at night, or a fair amount during daylight too? (that will reduce the charging current to the battery bank and mask your daily usage if only measuring the current through the battery shunt).

Regarding the gensets--What size of AC battery charger do you have (model name/number/link)? I am a big believer in matching AC loads to generator capacity--The more you can keep the AC loads (Watts) near 50% or higher, the better your kWH/Gallon fuel economy.

You where asking about supporting a 450 AH at 48 volt battery bank--Using the standard 5%-13% rate of charge rule of thumb:

450 AH * 59 volts charging * 1/0.77 charger+panel derating * 0.05 rate of charge = 1,724 watt array minimum
450 AH * 59 volts charging * 1/0.77 charger+panel derating * 0.10 rate of charge = 3,448 watt array nominal
450 AH * 59 volts charging * 1/0.77 charger+panel derating * 0.13 rate of charge = 4,482 watt array "cost effective" maximum

If you assume 2 days of "no sun" (1-3 day range) and 50% maximum discharge (for long battery life), then the "nominal" daily loads from your battery bank:

450 AH * 1/2 days no sun * 0.50 max discharge = 112.5 AH daily load @ 48 volts
112.5 AH * 48 volts * 0.85 inverter efficiency = 4,590 Watt*Hours = 4.59 kWH per day
450 AH * 48 volts * 1/8 hour discharge rate * 0.85 inverter eff = 2,295 Watt max continuous inverter load
450 AH * 48 volts * 1/2.5 hour discharge rate * 0.85 inverter eff = 7,344 Watt max surge inverter load

Using a fixed array for Cleveland OH tilted from horizontal to Latitude:

Month    Solar Radiation
(kWh/m 2/day)    AC Energy
(kWh)
1      2.49          245   
2      3.34          294   
3      4.09          391   
4      4.94          443   
5      5.48          487   
6      5.56          462   
7      5.55          475   
8      5.47          470   
9      4.90          416   
10      3.91          353   
11      2.18          189   
12      1.68          153   
Year      4.14          4378

Using February at 3.34 hours of sun per day as the break even point for 4,590 WH per day (AC):

4,590 WH per day * 1/0.52 end to end sys eff * 1/3.34 hours of sun per day = 2,643 Watt Array Minimum

Anyway--that is how I guess at the numbers based on the size battery bank you asked about.

Hope everything works out in the end for you and your family. Life does get bit complicated at times.

-Bill

mtdoc · August 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

PCM,

Glad to hear you are getting things more set up. I agree that Wattplot's pen-plot graphs could be set up better for quick "at a glance" viewing but the important thing is that they do record all the relevant data on production, loads, battery amps in and out, voltage, temp, etc.. Once you get a chance to play with it more you'll see that you can easily go back and look at any of this historical data for a user defined time period.

For quick summary view, I find the FX and DC snapshot bars and the FNDC accumulated values bar very useful for "at a glance" summary (use the view menu to enable these). I find it is much easier to quickly view all the relevant info on one computer screen than by navigating the Mates many screens to find each value. For a specialized, limited market piece of software that only costs $50 I find it pretty darn good.

As BB points out - for diagnosing your issues it's all about the loads! You can see what your loads were overnight (orany period) and see if there were any unexpected current draws causing your battery bank to draw down.

As far as the location of your computer - do you have network access (wifi or ethernet) at your power shed ? If so you can run a free VNC server program (i use ulraVNC) that will allow you to view that computers screen with Wattplot on any network connected computer (local network or internet if connected).

I have a small netbook in my utility room that runs Wattplot and can view its desktop anywhere in he world on a computer with internet access or on my iphone. Very useful when traveling. I keep a window with this open on my home laptop and on my computer at work to watch my system there as well!

PorkChopsMmm · August 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

BB. -- my battery charger is built into my Outback inverter. You bring up an interesting point and I am having trouble coming up with the answer... isn't a bank of 8 batteries at 6V and 225 amp hours each a 225 amp hour bank at 48V? I think I spoke wrong when I said I had a 450AH bank.

mtdoc -- thing are never easy around here. I do have wifi but it is from a small Verizon MiFi hotspot. It limits devices to 5 (boo) and it's range is very bad. The netbook in the powershed picks up and loses signal every few minutes. I have an extra Linksys WRT54G router that I should put in repeater mode. I think that would help the netbook get connected.

In other news I exchanged the batteries and have been monitoring them. I EQ'ed them the day I got them and tried to EQ them again tonight. I have a question -- should I EQ until I hit 1.275 SG or should I give it a few charge cycles for the batteries to come up to operating at 100%? I EQ'ed the batteries tonight and when I went to measure SG (only an hour after EQ'ing stopped, no loads) the SG was 1.260+- across all cells.

Blackcherry04 · August 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

PorkChopsMmm wrote: »

BB. -- my battery charger is built into my Outback inverter. You bring up an interesting point and I am having trouble coming up with the answer... isn't a bank of 8 batteries at 6V and 225 amp hours each a 225 amp hour bank at 48V? I think I spoke wrong when I said I had a 450AH bank.

mtdoc -- thing are never easy around here. I do have wifi but it is from a small Verizon MiFi hotspot. It limits devices to 5 (boo) and it's range is very bad. The netbook in the powershed picks up and loses signal every few minutes. I have an extra Linksys WRT54G router that I should put in repeater mode. I think that would help the netbook get connected.

In other news I exchanged the batteries and have been monitoring them. I EQ'ed them the day I got them and tried to EQ them again tonight. I have a question -- should I EQ until I hit 1.275 SG or should I give it a few charge cycles for the batteries to come up to operating at 100%? I EQ'ed the batteries tonight and when I went to measure SG (only an hour after EQ'ing stopped, no loads) the SG was 1.260+- across all cells.

Unless you have airplane batteries I doubt you'll ever hit 1.275 SG. Your batteries were probably filled with 1.260 - 1.265 electrolyte, you can't raise it past the ratio of that. You can destroy your batteries though.

BB. · August 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

What BC04 says--You can only charge until the battery SG stops rising. That is your new/current 100% state of charge (charge at recommended absorb voltage, stop charging once SG stops rising--check every 30-60 minutes).

Note that equalization is only needed when the SG is around 0.015 to 0.030 different between high and low cells. Then you charge at equalization voltage until the SG stop rising (again, check every 30-60 minutes).

When you connect batteries in series, the voltage increases (2x6 volt batteries at 220 AH = 12 volts at 220 AH). When you connect batteries in parallel, 2x 6 volt 220 AH batteries in parallel, then you have 6 volts @ 440 AH. Note that this does not violate physical laws. Power=Voltage*Current -- So the two remain the same power wise (12v*220AH=6v*440AH).

-Bill

Photowhit · August 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

BB. wrote: »

Note that equalization is only needed when the SG is around 0.015 to 0.030 different between high and low cells. Then you charge at equalization voltage until the SG stop rising (again, check every 30-60 minutes).

For flooded lead acid batteries, here are other reasons for Equailzing, most if not all battery manufacturers, other than Trojan, recomend an equailizing charge from once a month to 2x a year. If only for mixing the cell's chemistry and preventing stratification. NAWS Battery FAQ's

PorkChopsMmm · August 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

Thanks guys, I appreciate the help. I will continue to monitor my charge levels and give you all an update. I'm not sure if my MATE reset itself or if I always had the wrong battery AH, but it was programmed for 450 when I really have 225. I updated the settings and followed the FNDC configuration procedures linked in a previous message by mtdoc. Hopefully this will allow my measurements to be more accurate.

I have one other question. The large construction generator I mentioned earlier has GFI outlets. My smaller Coleman generator does not. The GFI breakers pop every time I plug in the cord from the Outback inverter that charges the battery bank. If I reset and plug in they pop immediately. Even with the inverter turned off (so no attempted charging occurring) they pop the breaker on the GFI outlet. I checked the wiring to the inverter and the +, -, and grounds are wired correctly and tightly and the little Coleman with no GFI generator runs the Outback inverter just fine. All of my solar components are grounded via a ground buss bar to a single 8ft copper rod driven into the ground. Any idea why the GFI breakers on the large genny are being blown? This threw me for a loop when I re-installed my new battery bank.

Thanks!

inetdog · August 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

PorkChopsMmm wrote: »

I have one other question. The large construction generator I mentioned earlier has GFI outlets. My smaller Coleman generator does not. The GFI breakers pop every time I plug in the cord from the Outback inverter that charges the battery bank. If I reset and plug in they pop immediately. Even with the inverter turned off (so no attempted charging occurring) they pop the breaker on the GFI outlet. I checked the wiring to the inverter and the +, -, and grounds are wired correctly and tightly and the little Coleman with no GFI generator runs the Outback inverter just fine. All of my solar components are grounded via a ground buss bar to a single 8ft copper rod driven into the ground. Any idea why the GFI breakers on the large genny are being blown? This threw me for a loop when I re-installed my new battery bank.

Thanks!

If you ground the neutral (or any other part) of the battery/inverter setup and also ground the neutral at the generator, you are asking for normal load current to flow through the ground system, outside the return path of the GFCI breaker. This will cause a trip. Even if you connect the two ground rods with a bonding conductor, you must not have the neutral bonded to the ground at more than one point.

There may also be some small incidental current to ground from filter components, etc. So GFCI may not be usable in this particular situation.

If you are comfortable with it for testing, you can disconnect the earth ground wire at the generator to see if the tripping problem goes away.

BB. · August 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

In general (as I recall), generators under ~3.5kW have "floating" neutral connections (AC Neutral/White Wire). So GFI's on the genset (if any) are rarely going to trip.

Larger gensets (5kW and above?) have the Neutral tied to the frame ground (green wire) inside the genset. If you plug such a genset into a home wired per North American 120/240 VAC standards), will also have its neutral bonded to earth ground/ground rod/cold water pipes) inside the main panel.

Connect a large genset (H/H/Neutral/Ground) to such a home (neutral/ground bond) will basically put the green wire and neutral wire in parallel--Which is a "ground fault" from the generator's point of view (i.e., black wire+red wire does not equal current flow back through the white wire) as the ground/green wire is carrying >> 5mAmps (0.005 amps)--which trips the GFI outlet on the generator.

The fix:

Lift the green/neutral connection in the genset

Lift the green/neutral connection in the home main panel (use an insulated neutral bond wire)

Use a transfer switch which will lift the green/neural connection in the home panel and use the green/neutral connection in the genset.

"Fix" the Neutral/Ground connections (should only be one neutral/ground bond in your AC Wiring setup) and get rid of GFI outlets in main power path. Only have GFI where needed (near sinks, on out door outlets, etc.). I don't like a GFI from an inverter/genset supplying the "whole home". Somebody trips the GFI (drops bender in sink)--It will cut power to the whole home, putting you into darkness--If happens at night, can leave you with more problems finding a flashlight and "addressing" the problem in near darkness before you can get the GFI reset and the power/lights back on-line.

Anyway--my guess what is happening in your setup (note, even capacitors use to reduce radio noise in AC charger/inverter chargers connect between "hot" and earth/green wire ground--That can be enough to trip a GFI outlet too).

-Bill

PorkChopsMmm · August 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

BB. wrote: »

Larger gensets (5kW and above?) have the Neutral tied to the frame ground (green wire) inside the genset. If you plug such a genset into a home wired per North American 120/240 VAC standards), will also have its neutral bonded to earth ground/ground rod/cold water pipes) inside the main panel.
The fix:

Lift the green/neutral connection in the genset
-Bill

You guys are geniuses. I will try the method mentioned above in the next few days. I just had one of those "Doh!" moments... knowing this or thinking through it would have saved me some time this weekend swapping generators.

PorkChopsMmm · September 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

Lifted the neutral from the frame but it was still blowing the GFI. I then took a spare extension cord and pulled out the ground connection and the generator works great. It can provide more than twice the power of my other generator to the inverter/charger.

Now I am having an issue getting the Automatic Generator Start function going. I have the AGS system set up and it is attempting to start the generator. The starter looks something like the one below. When I connect the 2 wires from the AGS to the generator I can hear it trying to start the generator as there is a whirring sound from the starter... or little solenoid on the starter? When I switch the wires from positive and negative on the starter it has the same behavior (these wires are polarity insensitive). If I manually start the generator by pushing the starter button it fires right up. Is there a way to tell if a generator is 2 wire or 3 wire? I assumed mine was 2 wire since it is more common and this seems like a run of the mill generator.

I need to verify that 12V is coming from the AGS relay. I am using very small gauge wire and the ends felt like they were getting warm while attempting to start. Maybe the gauge is too low? I don't even know what it is -- similar to telephone wire, maybe smaller.

Cariboocoot · September 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

You need a wiring diagram!

Normally an AGS does two things: activates the ignition and momentarily engages the starter. There are many ways of doing these two things, unfortunately.

Just to err on the side of caution, you do realize the AGS should be activating a relay which activates the starter, not trying to power the starter and/or solenoid directly?

Wires should not be getting hot. You need to know the current involved and the distance so you can calculate proper wire size to avoid V-drop.

PorkChopsMmm · September 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

Sorry, I didn't want to go into extreme detail, but I am using the 2-wire relay kit available from Maverick Solar (kit was easier to buy then components and it came with schematic). Looks just like this and is wired up correctly per the schematic included with the relay (you can see it folded up in this picture). I am hoping the wire size is my problem although if it is not sending 12V over I will check for shorts. I called Outback and that is what they are recommending. We shall see.

PorkChopsMmm · September 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

Here are some pictures of the starter and the electric start button. I have tried searching but for the life of my I can't find a diagram for hooking up any remote electric start. From what I have read I may need to hook it up to the actual ignition button but I can't find a clear answer. I tried calling Ingersoll Rand but they sold their generator business to a company called Doosan. Hopefully they will have some info on this generator even though it was built/sold before they bought the biz from IR.

Notice how the outlets and switches are in an enclosed/sealed box. I am afraid to crack this open if I don't have to.

I hooked up the wires from the AGS relay to the positive and negative terminals on the starter. It just whirred. I will be checking voltage coming from the AGS relay in the next day or two.

Any advice on where to hook the wires to, e.g. ignition switch, starter, etc. would be appreciated.

Cariboocoot · September 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

That looks like a three position rocker switch: in the center it allows ignition so the generator can run; push it to one side to activate the start; push it to the other side to kill the ignition and shut it down. If that is the case this won't be a simple hook-up. You're going to have to get out the surgical tools and operate.

The 'Ignition Off' will either be a disconnect for ignition power or a short-out of ignition power, depending on design. Probably the former. In either case it has to be held to one side until the motor stops, correct? Disconnect will be easiest to wire for.

If you can get the AGS relay to do the right thing you'll know, because all you'll bypass is the starter actuation. The AGS should control a relay at the generator the contacts of which will take the place of the start push button.

It sounds like at present you are supplying an insufficient Voltage from the AGS directly to the starter motor, which will whir lazily but not engage the Bendix drive.

The shut-down will be somewhat more difficult, as you will have to arrange for a second relay to bypass the ignition on/off function. With the center position being 'ON' as default it will have to have the wiring interrupted; you can just put parallel connection across it as you would with a default 'OFF' (which would have a different type of switch on the generator).

Confused yet?

PorkChopsMmm · September 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

Cariboocoot -- I think I get what you are saying but yes, I am confused

Could I do what you are recommending with just fancy wiring or would I need additional relays, servos, etc?

This generator is starting to feel like a curse somewhat -- it was free but does not have an automatic choke function so I am skeptical of it auto-starting all of the time anyway.

Cariboocoot · September 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

I don't know what the output of the Maverick kit is.
You need to be able to control two relays remotely; one to activate the ignition, which will either be on or off; one to activate the starter, which will engage only momentarily.
The AGS system should be able to detect incoming AC from the gen to know whether or not to try and restart, but some of them aren't that sophisticated.
Without knowing what the AGS actually is trying to do it's difficult to say how to interface the two.

This is why I go out, twist the switch, flip the choke, and pull the rope. I'm not a big fan of automation.

BTW, I had an automatic choke engine once which used a simple spring-loaded flap on the air intake with a vacuum pull-off; choke was closed all the time unless the engine was running and creating vacuum to open it.

Ralph Day · September 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

"BTW, I had an automatic choke engine once which used a simple spring-loaded flap on the air intake with a vacuum pull-off; choke was closed all the time unless the engine was running and creating vacuum to open it. "

That sounds just like the new Husqvarna mower with Onan engine I almost bought (Honda engined I bought instead...you choke and a spring slowly releases choke) The Onan engine , just pull the rope. Choke always on. Everything old is new again (never throw out old ties or suits).

Ralph

PorkChopsMmm · September 2012

Re: Offgrid-House: Battery bank suddenly losing power rapidly?

Interesting -- I wonder if I could jerry-rig the choke. Not sure if it would help much as AGS only has one relay, I believe. From Outback...

This feature requires a generator with electric start and automatic choke. Additionally, you need to determine if your generator controls are classified as “two-wire-start” or “three-wire-start.”

.........

A three-wire-start generator has separate controls for starting, and for running and stopping. This requires three or more control wires. Because timers and other devices are required, OutBack products can only control this generator with the help of external products. You can usually identify one because it has multiple switches, or it has one switch with three positions, like “start”, “run” and “stop.”
If you have a three-wire-start generator, you can adapt it into a two-wire-start. Atkinson Electronics is one company that makes these adapters. You can get more information at www.atkinsonelectronics.com.

I thought I could get by with the manual choke. I need to research the Atkinson product, but I probably won't buy anything since a) my generator has a manual choke and b) I am looking to upgrade it in the Spring/Summer with a different generator. My requirements will be 2 wire and auto-choke.

Offgrid-House: Battery bank suddenly losing power rapidly?

Comments

Categories