My battery soc

gww1 · October 2014

I know this has been covered a thousand times, but here goes. 48 volt 800 amp hour forktruck battery. I have my low voltage disconect set at about 45 volts. When it disconnects my cc says that the low voltage for the day was 45.7 volts. Usually when I get to the battery in the morning of disconect it has creeped up to, from between 48 volts to 48.8 volts. It is hard to tell where it really is as the mate does not go point one volt at a time but more like point four volts at a time. Either way the battery is setting there at 48 or above volts with no load and no charging. I always considered this as a 50% state of charge. I understand that sg is the gold standard however, what would be a good rule of thumb 75% state of charge resting voltage.
Thank you
gww

PS fork truck battery

Blackcherry04 · October 2014

Re: My battery soc

Since your electrolyte is 1.280 it will be a little different than the standard 1.265 chart. You ought to be able to find one on a Industrial Battery site you have confidence in. Google SG charts and you'll get 100's and they are all different.

My spread sheet numbers for 1.265 at 48.8 is 71.6 % + / - Loaded . So if you use that as 75% it won't be that far off. Thats a big voltage sag, but you knew that would happen depending on the load with a Fork Lift battery.
.

Cariboocoot · October 2014

Re: My battery soc

Your 45.7 Volts low is about 20% SOC, if there were no loads on. The fact that the battery 'rebounds' to 48 Volts is a good sign. 48 Volts with no load is indeed about 50% SOC. 70% SOC would be a resting Voltage around 49, perhaps a tad higher would be better (due to variations in temperature and even the meter doing the reading). Say 49.5 Volts.

If I were you I'd try upping the LVD by 1 Volt and see how that affects things.

I'd also be looking in to why your using 80% of your capacity. That's around 30 kW hours by my math.

gww1 · October 2014

Re: My battery soc

Blackcherry
Sounds good to me. I would say the sag is from the well pump. from the mate it looks to be around 2000 watt load not counting anything else going on Ie; coffee pot as the morning is when I know I have hit low voltage. Always have coffee before I check the battery. You definatly can tell nothing by voltage with a load. I have seen it carry over 6000 watt loads with out a hitch. I have one bad cercuit in the house. redid the kitchen and the microwave, coffeemaker, and my wifes hairdryer all ended up on the same line. pops a 15 amp breaker every so often. The batteries actually say on them 1.285 to 1.295 is fully charged. It sounds like I may not have been taking them down to the 50% discharge that I thought.

You know that twice on the outback forum while I was typing responses your responce was there when I posted. Good job.
Thanks
gww

Cariboocoot · October 2014

Re: My battery soc

gww1 wrote: »

redid the kitchen and the microwave, coffeemaker, and my wifes hairdryer all ended up on the same line.

Well I guess that answers my question about the 30 kW hours.

gww1 · October 2014

Re: My battery soc

Coot

The the giant battery rep had me set low voltage at 44 volts, the battery manufactuer had me set low voltage at 44.8 which is where it is now. even set there it seems to disconnect at about 45,7 or higher. I don't really know what causes this but it doesn't bother me as most times I have zero problim except durring cloudy days or when I drop loads to garentee full charge. They wanted the setting this low, expesially while the battery was new and forming the plates. The battery has had a few low sg cells since new and only last week did I ever see 1.280 out of cell 24 with the battery at 72 degrees f. 1.272 is as high as I ever saw it before at least consistantly. I am absorbing at 61.2 to get that and eq at 63.2.
I have no ideal about loads but watch sgs and production. It usually takes about 14kwh to hit absorb voltage after heavy nights. Mostly I get the sgs to there max at 61.2 atleast every 10 days and sometime a couple times during that period. I eq once a month and ad water. I eq till the sgs have stayed the same for an hour to two or intill the sgs start dropping due to heat i believe. Then I ad about a gal and half of water. I have questioned the capasity since I got them due to sgs and not thinking I was using as much as 30 kwh. I don't have a real way to mesure so I just babysit the battery and try to put it all together. I had the low voltage set at 46 but it always kicked to the grid. I figured I could run my house on 30 kwhs so I can't be using that much at night, but I do use alot. I made 400kwh last month with out the efficency reductions. I have spent hours and days on the battery trying to get it right and in the end I have what I have. The system as a whole does everything except on cloudy days. The last time I checked the morning sg prior to charging (low cell) it was at 1.220 and got to 1.272 at days end and got my highest ever the next day at 1.280. I have not seen that before even during very long eqs.
I did have three months of under charging with lower absorbs and lower eqs based on the guy I bought it from before talking to the manufatuer. back then I did 20 hour eqs trying to get the sgs up. The new rates don't raise the sgs but they also don't take 20 hours to get what I can get.
Thanks
gww

gww1 · October 2014

Re: My battery soc

coot

Well I guess that answers my question about the 30 kW hours.

All I can say is that before the solar and not during ac weather I had 600-800 kwh months. This was for the whole month not just the night time of the month. I do have big loads and maby something has changed since I moved back. The real truth is I don't know what I use now but I figure it the best I can by watching the battery. The battery will not run a full day without sun but it will come close and diconnect sometime at night and in the morning it will be at or above 48 volts. Buy full day I mean the night before and the night after. If I had to try and take an average of my usage I would say an average of 800 watts per hour and maby less. sometimes the mate says .2kwh sometimes it says .8 and sometimes 1.1
Then there are the big loads for short terms. I see .4 and .6 the most. When the opertunity load is on it usually reads 2.4.
Man I type slow.
Thanks for any imput.
gww

Photowhit · October 2014

Re: My battery soc

gww, Hang in there we have a chance for sun Sunday, I've been gone the last 2 almost 3 days and my 24v battery was at 25v as grey skies went to dusk, don't know if the fridge had just kicked off, but it's the only thing running. We have a chance Sunday then 2 more grey days, that might make a week with no visible shape in the sky!, I'll have to call people out of area and ask them is the sun still exists... Bright enough today I'm out of bulk, but when it's rained a couple hours on the zero chance of rain day it leads to depression...lol.

gww1 · October 2014

Re: My battery soc

Whit
Yea my inverter picked up my loads cause we had a bright spot that got my production up to 5000 watts but when I went out the clouds had prodution back to 1200 watts so I manually put the house back on grid to let the voltage build again. I knew it was going to be a strech of bad and the wind was only blowing while it was the sunny days. Just shows who the real boss is.
Cheers
gww

Blackcherry04 · October 2014

Re: My battery soc

I don't under why your not using the HBX mode and let your inverter chase all your voltage issues. Sounds like your working and worrying yourself when you own the equipment to do it.

HBX Mode:
• Stands for high battery transfer
• Is used with grid-connected FX Series Inverter/Chargers that have utility power as their AC
input
• Is a mode primarily used in applications that have enough renewable energy (RE) power
production to meet the needs of the loads most of the time
• Allows the FX to connect to an AC source if the battery voltage has fallen below a programmable
set point for a user configurable amount of time (MATE will then allow the FX to
remain connected to the AC source until the battery voltage has risen above a second set
point for a programmable amount of time)
The MATE detects when the battery is truly low and needs charging as opposed to a sudden
and momentary drop caused by a sizable demand for power from a device such as a motor.
At these times, the MATE directs the FX to use AC power until the battery is fully charged
again. The user programs in the amount of time a battery can be below the low voltage and
the amount of time after it’s fully charged before the MATE starts issuing its commands. The
MATE uses these times to switch back and forth between AC and battery power. Additionally,
in HBX mode, the FX charging function can be shut off to allow the alternative energy source
to recharge the batteries while the loads are powered by the utility grid.

zoneblue · October 2014

Re: My battery soc

I can relate to SOC anxiety int eh beginning, but theres only two solutions. Time getting to know your bank,... and battery monitors.

gww1 · October 2014

Re: My battery soc

Blackcherry

I am using hbx mode however I also know the battery has set at maby thirty percent discharge due to disconnecting and I have only made 5kwhs over the last two days and only 12kwh today and just because the voltage got high enough to reconnect the battery the sun went behind a cloud and all I was doing at that point was running loads and it may be cloudy tommorrow, hope not. Too much cloud this last week for hbx to work well as sooner or later I have to get a good charge. If I was out of town I wouldn't be worried but I am here so trying to make it better.
gww

zoneblue

I wan't a battery moniter but am too cheap and can't justifie it as I am always here to watch what is going on. I want more solar panels and maby a bigger wind turbine more. I ain't got them yet either.
Cheers
gww

zoneblue · October 2014

Re: My battery soc

Cost conscious is one thing, but even though as you say they dont add capacity, tools that help you protect that investment, are money well spent. You have invested quite a lot in your system, and it'd be a pity to damage it.

Cariboocoot · October 2014

Re: My battery soc

Agree with zoneblue: a battery monitor would be a good idea if only to keep track of how much power is being used and how much replaced (not necessarily relied on for battery SOC).

You seem to have some pretty big variables preying on your system. All things considered I hope you haven't lost some of that big battery's capacity already.

Blackcherry04 · October 2014

Re: My battery soc

I hear you, the last week in the midwest has been ugly. It should get better next week. Here is mine last 6 days, only one good day. This to shall pass, it's better than 15 days like last year.

6 ...14.8 kwh
7... 12.6 kwh
8... 41 kwh
9... 20.1 kwh
10...4.9 kwh
11...5.7 kwh

gww1 · October 2014

Re: My battery soc

zoneblue
I don't disagree with you. I am just using a hydrometer to do most of my monitering. I also know that even with battery moniters you have to be smart enough to use them or they can lead you astray. I am still learning but I installed every thing and watched over it well and know which forums to go to to get help. I would like a battery monitor but I am retired and at home 99 % of the time and can watch what goes on several times a day. I wish I knew someone close with the things I want so I could watch them in action prior to deciding how bad I want something.

gww

gww1 · October 2014

Re: My battery soc

Coot
by veriables, do you mean my low charging ragime in the beginning or my loads being too large and unknown?

Blackcherry.
I can switch to grid during these times but it is still dissapointing. I would get excited on the 40 kwh day though.
Cheers.

Cariboocoot · October 2014

Re: My battery soc

gww1 wrote: »

Coot
by veriables, do you mean my low charging ragime in the beginning or my loads being too large and unknown?

Yes.

The first may have cost you some small amount of capacity (they want the deep cycling to begin with to actually increase capacity to full expectations: if it was not fully charged then this will not have happened).

The second is a management problem that will plague you no matter what, as you don't really know how much power is being drawn and therefor what SOC to expect the battery to be at.

If you can say you've use 'X' Watt hours and therefor the SOC should be 'Y' percent but instead it's <'Y' then you know there's a problem such as unaccounted parasitic load or inaccurate Peukart factor or incorrect charging parameters resulting in incomplete capacity et cetera.

gww1 · October 2014

Re: My battery soc

Coot
Points well taken. I can't change the beginning cause the charging was done based on the giant batteries rep's recomendation and did happen. I came here for help and it was suggested that the voltages were too low. I contacted the battery maker. They agreed and thought the batteries were new enough that there would be no damage as it haddn't went on long enough. What I am doing now has helped alot. Even if the battery is worse I don't see much help for it. The only help offered by the battery guys was how to charge and to puposly cycle hard and watch for improvement.

A moniter would help know the loads but wouldn't change the sgs would it. Are there cases where the battery says 48 volts resting that would not relate to also being at 50 percent. Rule of thumb 48.4 might be 50 percent. So am I wrong in assuming that if resting voltage is not below 48 volts and if I build the battery up where sgs are as full as the can get, can loads really make a differance except on how long I can run the loads?
As long as it doesnt go too low and gets charged will loads matter in battery life?

If I get a monitor outback or trymetric?

I knew when I built this that I couldn't cover my loads and halfway through I knew I wouldn't save money but it is sort of my last hurra. worked a lot of overtime so it would be paid for then thought I would milk what it would give and not worry what my loads where just what I could make it do.

I always apretiate what you guys offer even if you tell me I am an idiot.
Thanks
gww

PS just checked my low cell sg. It is sitting at 1.242 and is 62.4 degrees f. The cc's show about 12.3 kwh production. Mostly with out running loads.

Cariboocoot · October 2014

Re: My battery soc

You're right: you can't change what has happened and the battery monitor won't alter the SG.
But keeping track of the loads can help because of being able to at least reasonably estimate how much capacity you are using.

12 kW hours back into the battery with "no loads" is a huge amount of power. Roughly 250 Amp hours or more than 25% of the supposed capacity. That one cell with a low SG is worrying.

To start with you might want to take all loads off the system and charge the battery fully, including doing an EQ to see if you can get that low cell up. I have this horrible fear you've been running at least a slight deficit charge and the battery capacity is well below 800 Amp hours now. If it's below 600 (and there's no practical way to test this as it requires controlled current discharge) you've probably lost it. At that point you cope with it until it fails utterly.

Which battery monitor you get depends on how much you want to monitor. The TriMetric will measure from one shunt and you could use that as indicator of outgoing current. Deduct from the total on the controllers and you get a number for how much goes in to the battery. The FNDC can do it all together with its 3 shunt ability but it's a lot more money (nearly double the price).

To do this with the TriMetric you put the shunt only on the load side instead of having it monitor all power in and out of the battery. This is quite contrary to the 'proper' install but you are basically using it to watch loads, not the whole battery.

gww1 · October 2014

Re: My battery soc

Coot
I just went 8 days without having a load on the battery. My inverter was out of commission due to lightning. I have equalized till the sgs start going down. I once eq till the battery was close to 100 degrees. The only thing I don't do is temp comp the sg readings. Still dont know how.

I don't mind trying anything including running with out loads but I have been working on this for about a year and except for a fluke here and there the battery has been pretty consistant. almost consistant enough for me to believe that the cell may have the wrong acid in it.

I have seen 1.300 out of the high cell although the last time when the low cell was 1.280 the high was only 1.290. It usually gets to 1.295. I have been eq untill the low climbs to 1.272 and then drops to 1.270 or around two hours at the same 1.272. The high cells also drop sg. I have always been scared to go past this point more then two hours. They say over charging kills also.

I can easily try anything. You give me an a,b,c charging plan to try and I will turn the loads off today (they are off now) and use the grid if needed. I have put twenty hour eq at 62 volts. I now eq at 63.2 and have did maby up to eight hours though it has been about three hours lately as I start with the cell from absorb at 1.272 and after 3 hours I am convinced it wont raise. You tell me and I will try it. When I first got this battery I charged and eq'ed and kept records. One time after I eq'ed for a really long time I went out to the battery after it sit all night and spot checked two high and two low cells and the high ones read 1.295 and the low ones read1.285 and I though i had it wupped. I was checking cell 22 as the low cell at that time. Now I check spot check 22 and it will be at 1.280 when cell 24 is 1.272. now I check cell 24 against cell eight and look at the original records to spot check others. I have noticed when using the ouback inverter to eq from the grid that at times it will take the batteries to 64 volts at times even though it is set at 63.2 volts. It don;t stay there long but is a bit disturbing.

Give me a plan and I will try it.

Thanks
gww

gww1 · October 2014

Re: My battery soc

sg when i recieved battery and prior to first charge.
1 1262
2 1262
3 1262
4 1260
5 1268
6 1260
7 1262
8 1260
9 1262
10 1268
11 1262
12 1259
13 1260
14 1259
15 1255
16 1265
17 1269
18 1269
19 1259
20 1259
21 1259
22 1259
23 1259
24 1259

Cariboocoot · October 2014

Re: My battery soc

I don't know how long you've been trying to get this thing to work for you but ... it may already be too late.

So work-around time.
You've got 24 235 Watt panels for a 5640 Watt array, right?
In theory that would end-to-end be (5640 * 4 hours * 0.52 efficiency) 1173 Watt hours AC. If your actual loads are anyplace near 1/2 the 30 kW hour estimate the battery is doomed.
But you say you've been running without any loads because the inverter is down. This also presents the problem of no AC based charging (unless you have a separate stand-alone charger and it would need to be pretty big). We also don't know how complete or incomplete the commissioning charge was.

Now, do you have any method of drawing the battery down? I'm thinking it may be possible to "start over" and exercise it a bit to improve capacity. This would be especially effective if the discharging has not been high.

Depending on how accessible the individual cells are you may be able to EQ the one low cell only, if you can rig a "3 Volt" charger. It may not respond, in which case we're left with the idea that the one cell is no good (for whatever reason). Just maybe you got landed with a bad battery to begin with. It happens. It may also be prudent to 'lose' the low cell and run at nominal 46 Volts (although this may be impractical).

If you can load the battery up, do so. When the LVD shuts off and the Voltage rebounds to 48 load it again. Turn the LVD way down if needed until you can pull the battery down to 45 Volts. Then charge it as fully as possible. Then do it again. You will either see a change for the better (good) no change (no loss/no gain) or a change for the worse (proof the battery is not going to live up to its specifications).

There's a downside to these big batteries in that they are designed for a charge regime quite different from what is available through solar or the built-in chargers. Part of this is an extraordinarily long Absorb time.

And no matter what you need to determine how much loading has really been put on the batteries. Whether by adding a TriMetric or measuring everything plugged in through Kill-A-Watt meters or something.

Cariboocoot · October 2014

Re: My battery soc

Those initial SG numbers look good: <0.010 variation.
The increase in difference with one cell sagging to 0.030 difference (I think) from the others is not encouraging.

gww1 · October 2014

Re: My battery soc

after first charge but before eq

1 1278
2 1278
3 1278
4 1275
5 1278
6 1270
7 1275
8 1275
9 1272
10 1278
11 1272
12 1269
13 1270
14 1272
15 1269
16 1278
17 1278
18 1280
19 1280
20 1269
21 1269
22 1265
23 1269
24 1269

gww1 · October 2014

Re: My battery soc

coot would like to add a bit more then will look at your post and try to follow you guidlines. I can always turn off the pv to run the battery down with loads. The inverter is fixed now that was two weeks ago. want to add maby for more sg line which should give an ideal of my start back on 9-23-2013.
gww

gww1 · October 2014

Re: My battery soc

one hour eq then went to bed

1 1282
2 1279
3 1280
4 1275
5 1280
6 1272
7 1280
8 1281
9 1280
10 1281
11 1279
12 1272
13 1278
14 1279
15 1272
16 1280
171280
18 1282
19 1271
20 1271
21 1271
22 1270
23 1271
24 1271

sears clamp meter said the temp was 68.8 and i added water here.

gww1 · October 2014

Re: My battery soc

next day after 4 more hours eq

1 1280
2 1276
3 1279
4 1272
5 1280
6 1272
7 1280
8 1280
9 1279
10 1281
11 1272
12 1272
13 1279
14 1271
15 1270
16 1275
17 1279
18 1280
19 1265
20 1270
21 1270
22 1269
23 1271
24 1270

spot check after 3 hour cool down

1 1280
4 1279
6 1278
8 1283
11 1279
14 1276
16 1278
18 1282
20 1271
22 1270
24 1271

gww1 · October 2014

Re: My battery soc

Spot check the next morning. resting voltage 51.2 volt
8 1295
18 1295
20 1285
22 1285
Thought I was done

in october i eq three times for 3 to five hours each the highest i got cell 22 was 1280

10 25 2013 i eq for 18 hours
8 1285
22 1271

the next morning after 8 hour rest the battery was 78 degrees f and cell 22 was 1287

I quit keeping records but still checked and did very long absorbs each month. somewhere in here I found that cell 24 did not recover like cell 22.

I changed my charging voltages about febuary of 2014. at four hours eq I got a reading of
8 1292
24 1280

I never saw that high before or after except once on cell 24

eq two more hours and sg was
8 1291
24 1275

battery was 92.7 degrees

Except once and, not during eq, I have not seen higher then 1272 on cell 24

That is all the written records that i have and a mouse has got to them.

Comments
gww

Ps I do eq every month.

gww1 · October 2014

Re: My battery soc

The battery is setting at 51.6 volts now. I got to thinking about the 1242 sg reading and wonder as the battery never really got to boiling today if that is a good reading. I know when I add water it takes a bit of boiling to get good readings.

I discussed this a bit on a different forum and there was some consenses that if the cells were getting to there max sg at the same time and one wasnt taking longer, that maby it didn't really hurt anything except capasity and could have been that way from the factory. The problim is twice I have seen 1280. I have seen 1300 out of cell eight though.

Thanks
gww

gww1 · October 2014

Re: My battery soc

In theory that would end-to-end be (5640 * 4 hours * 0.52 efficiency) 1173 Watt hours AC. If your actual loads are anyplace near 1/2 the 30 kW hour estimate the battery is doomed.

This leaves out that at least once every ten days I put my loads on grid for as long as it takes to get as good of a charge as they will take
with out eq and i eq once a month. unless there is something I am not understanding.

I have thought about trying to charge one cell. had some efforts to have it explained on how to do it but I am dence and don't know how to get that done.
Thanks
gww

basically I run nine days or so per month on grid to handle clouds, battery charging and eq. some times more. already lost around 5 or six days this month.

My battery soc

Comments

Categories