My battery soc

Cariboocoot

Re: My battery soc

The TriMetric should at least be able to tell you Amp hours in vs. Amp hours out to know if you've got a positive (battery charged providing the balance makes up for efficiency loss) or negative (uh-oh).

gww1

Re: My battery soc

Coot
Todays progress report. The battery absorbed for 3.34 hours. The low cell was 1.281 (the biggest number yet). The trimetric has the battery at 100% full. The battery is 67 degrees f. The hot water heater made 50 gal from whatever temp it started from and didn't pop the pop-off valve. I did run some down the sink incase it gets windy it will still kick on.

I had the hot water set that low incase I wasn't running off the grid and we had a storm, the inverter would kick on before the batt got to that voltage so the turbins would be controlled no mater the speed of batery volts raising. I do the oposite of you. on low production days I turn it off so all the juice can go to the batteries.

I can turn it off till I reach absorb on days I am home, I do have the fear that my mind is going and I may forget it off. I left a fying pan on the stove for eight hours one time and other things.

My garage is unheated where the batteries are. I used the wood stove all last year cause everything was new and I spent a lot of time there. I don't have as much wood cut this year yet.

All them numbers I wrote down were before I put any loads on the battery when new. My commisson charge was worked hard at and call were made to who I bought the battery from and the only answer was keep charging till the batterys get hot. They only got to 90 degrees in twenty hours.

I guess I will go and see if I can get how many extra amps I put in from the trimetric.

I got to collect eggs and then change the cc to 60 volts absorb, tommorrow is another day.

Thanks
gww

gww1

Re: My battery soc

The TriMetric should at least be able to tell you Amp hours in vs. Amp hours out to know if you've got a positive (battery charged providing the balance makes up for efficiency loss) or negative (uh-oh).

I went to the 8-1 or whatever to check if the amps were + or - but it just said "---" . Maby enough time hasn't elapsed yet. I think it is on a 23 hour cycle. I have the absorb at 6o volts set end amps to 14 and moved the opertunity load to .5 volt from absorb.
gww

jcheil

Re: My battery soc

gww1 wrote: »

j
I doubt it was 100% but it was pretty good. My sg on the low cell was 1.278 and I have only seen it that high maby during the last three full charge cycles. It used to only get to 1.272 even during eq. They were as charged as they get without eq. Since I set my charging at 16 end amps and absorb voltage, the next time it says 100% should be pretty close. Am I right on this?

Thanks
gww

Hey what do you use that measures SG to 3 decimal places as accurate as you do? Most of the ones I have seen you have to kinda guess if it is between (for example) 1.260 and 1.265 - they don't have gradients for the .1, .2, .3, .4

jcheil

Re: My battery soc

gww1 wrote: »

Coot I write down what the turbines do every day. Not much.
Don't get upset with me. I have read everything I can for the last 5 years and am trying to get it right. I still don't know what to look for exactly and don't really know what I am doing wrong. I talk and call the people who do know and get advice. I may not catch on that quick but am doing my best. I do ask a lot of questions trying to figure it out.
gww

Brother, most of us are in the same boat as you. Don't sweat it. Heck, I have "upgraded" my system 3 times since I started with a 12v system 10 years ago. Had I just listened to what everyone said 10 years ago I would have saved a boat load of money. But then again, I NEVER would have been able to afford the 7800w of solar I have now, 10 years ago when it was $5.50/w!

It a learning experience, and like people say here, everyone always MURDERS their first set of batteries.

gww1

Re: My battery soc

J

Hey what do you use that measures SG to 3 decimal places as accurate as you do? Most of the ones I have seen you have to kinda guess if it is between (for example) 1.260 and 1.265 - they don't have gradients for the .1, .2, .3, .4

It is an extech optical hydro meter. You use an eye dropper and put the electrolite on the glass plate and look through a eye piece. I am guessing also but it is so much clearer then the squeeze ball that my guesses are probly pretty close.

It a learning experience, and like people say here, everyone always MURDERS their first set of batteries.

I can't afford to murder my bank too early. I worked overtime to make up shortfalls but am retired now so no overtime. I did learn as much as I could, up to my ability, before buying a battery. I was stuck in a different state for 4 years while gethering stuff and did nothing but cruze the forums and read. I shouldn't be having the problims I have but there is nothing like doing.

I believe part of my problim was the advice I got from the seller. His veiw was never get the batteries hot and equalize once a month till they get hot and the battery will last forever. I couldn't live with 20 hour eqs so called the manufatuer. Here we are now.

It is hard to tell weather I am overcharging or under chargin. Advice has to be taken with a grain of salt also cause you wouldn't believe the advice I have gotten from different poeple who are living with their batteries dayly. I should write one post with it all and let them fight it out. I also may not always understand what people say cause I might refer the advice to something different then they ment..

I don't want guys like coot to get too discusted with me cause I do want to get it right as I can and it can sometimes take awhile for that light bulb to go off in my head.
Thanks for your interest and also the hose ideal, I should have thought of it but didn't.
gww

gww1

Re: My battery soc

J

Brother, most of us are in the same boat as you. Don't sweat it. Heck, I have "upgraded" my system 3 times since I started with a 12v system 10 years ago. Had I just listened to what everyone said 10 years ago I would have saved a boat load of money. But then again, I NEVER would have been able to afford the 7800w of solar I have now, 10 years ago when it was $5.50/w!

Yea, I built 2000 watts of homade solar panels. Using some for little things but mostly a waist and not cheaper then buying.. How many cieling fan turbine I have made or wind at all. I made .8kwh hours yesterday. That almost makes up for inverter tare losses but not quite.

I still don't want to kill my battery cause I don't want to look that stupid to my wife.
gww

Blackcherry04

Re: My battery soc

Of course Opinions are just Opinions, I still believe that your just getting to a spot that all the plates are formed (Top to Bottom ). That for the last few months you'v had partial plate charges and discharges and 100% of the plates have not been in play. A year ago I'd of never believed that it would take a summer of heavy cycling to get my Surrettes to a spot where they became predictable with the SG's , capacity and absorb times and voltage. If the Industrial Battery People say it takes 100 cycles, they mean to 80% discharges and recharges, you'v never been close to doing that daily. Yours may take longer.

The way you charge and discharge and do opportunity loads may just slowed down the process and made it more noticeable then it would be to others. Let's hope your on the right track now, it seems like your making progress. Just to see your low cell responding to normal charging and the SG's coming up says something.

gww1

Re: My battery soc

Blackcherry

The way you charge and discharge and do opportunity loads may just slowed down the process and made it more noticeable then it would be to others. Let's hope your on the right track now, it seems like your making progress. Just to see your low cell responding to normal charging and the SG's coming up says something

You can't believe how happy I am to see the cell that wouldn't go above 1.272 hit 1.281. I still want it to hit 1.285 though and the battery was only 67 degrees so that reading may be a bit high, still the best I have seen though.

I have not started the taking the battery down to the 80 percent discharge and then recharge yet. I intend to a couple of times and I am pretty sure it has been that low. I checked the sg this morning and it was 1.221. the trimetric said 77% charged but the sg puts it at about "50%?" in my opinion.

Also the voltage was like 49.4 and usually with that sg reading it is below 48.8 volts. As soon as I am sure that I can tell buy looking at the gages and sg and feel comfortable that I am not taking the battery to 100% didcharge I am going to take it lower and recharge a couple of times and see what happens.

Cheers
gww

PS when I get the low cell to 1.285 I am going to measure all 24 cells and record their values.

gww1

Re: My battery soc

Prelim report.

The battery has been in absorb for 1 hour at 60volts. The temp is 62.3 degrees. The sg on the low cell is 1.275. The trimetric says 99% full. The battery is only accepting 7.5 amps.

I am sure the sg will go up from here by the end of the day. It was 1.281 yesterday at 61.2 volts and over 3 hour absorb. May not get 3 hour today, high clouds.

Coot

Should I lower the voltage further to try and get the end amps, and sg to match better?

Depending on the sg at the end the 60 volt verses the 61.2 didn't seem to do any worse then the 61.2 volts.

The amps to the battery was a bit higher in the first part of the day till the clouds hit. I saw higher then 80 amps at times. In the end I still hit absorb about the same time as yesterday.

Thanks
gww

PS the trimetric had the efficiancy at 1.38 pos number and if I undrstand correctly how to do the math in the manual example that means I put 30 something more amps then the normal 6% it adds by defaut into my battery then I took out. I may not understand the math though.

gww1

Re: My battery soc

At 2 hours trimetric said the battery was full and the sg was about 1.279. I held absorb for 3.46 hours. checked the sg when the battery was at 53 volts and had a 7 amp draw on it. The sg was at 1.280 and the battery was 64 degrees.

I will be eq in a couple days. I am thinking of lowering the eq voltage to 62.4 from 63.2. that would be 2.6 volts per cell.

The amps going into the battery stayed at 5.5 for aleast two hours but the sg did rise just a tad.

I wonder if I should try 58.8 volts for absorb and see if more charge goes in before the battery quits accepting amps. Maby that would get me closer to having a charge by the time the battery would only take 16 amps. That would be 2.45 volts per cell, now is 2.5 per cell.

I do know on the full charge (EQ) the battery guy said they take each cell to 2.6 volts and no higher then 2.7volts per cell. I found I always had to have a caculator when I talked to him cause when i gave him the number of my battery he referred to it by the cells it held. All charging info was for one cell.

If I lower the voltage I am getting much closer to the voltage I had all the touble with which I think was 57.6 volts or 2.4 per cell.

Even charging with the high voltage I was using the battery seems to be raising the sgs better now then when I started the charging .

The battery is going from about 1.220 to 1.280 during charging much easier then it used to. I wonder if it will act in the old way of being hard to raise the sg if I take it down to 1.170.

Should I try 58.8 volts for absorb?
Thanks
gww

PS I did find one interesting thing. when the mate said I was running a 700 watt load it was taking 900watts from the battery. That doesn't sound like 94% efficiancy to me. I am sure that with higher wattage loads the efficancy would get better but it was kind of nice to be reminded that when looking at numbers you always have to do the convertion to what it really means.

gww1

Re: My battery soc

Wow now I know why they say ignorance is bliss. My mate says I am running a 400watt load but 8oo watts is leaving the battery. I might just hate this new trimetric. I need a bigger battery. I need more solar. I would have never known. Thats a lot of loss.
gww

CALLD

Re: My battery soc

gww1 wrote: »

Wow now I know why they say ignorance is bliss. My mate says I am running a 400watt load but 8oo watts is leaving the battery. I might just hate this new trimetric. I need a bigger battery. I need more solar. I would have never known. Thats a lot of loss.
gww

50% efficiency means something is wrong.

On wanting more solar and more batteries - we all do! It's addictive, and you can never have too much panel power (if your components can handle it that is).

The efficiencies I'm getting are as follows:

PV to batteries via. PWM controller: 75-85%
Battery charge to discharge ratio: 85% average in AH, 55-65% in kwh
DC to AC conversion: 85-95% efficiency.
Losses in wiring are totally dependent on load, there is a 5volt drop between my panels and charge controller at maximum power, but this makes almost no difference to a PWM charge controller as the PV output can go as high as 36.6 volts before the current starts dropping off significantly while the batteries only need 30v

CALLD

Re: My battery soc

The biggest efficiency thieves in off grid systems are the batteries! Not only will they only give you <85% of the AH back that you've put in, they also give it back at a significantly lower voltage than you put those AH's in at. This means that the worst possible thing to do if you're looking for efficiency is to use all the power at night and just charge during the day. The best thing to do with an off grid system in terms of efficiency is to keep the batteries as near full as possible and use as much of the PV power as possible during maximum production hours during the day.

gww1

Re: My battery soc

calld
I can't wait till I catch it with zero load and see what is leaving the battery, doesn't happen very often. I know about all them losses but the losses I am seeing is purly a convertion loss between the battery and inverter to the load. I do believe out back is notorious for their numbers being wrong on the mate. I believe they do a lot of rounding off of numbers and also have when the numbers change spaced pretty far apart. Like when the one cc has 1098 and the other cc has 1098 it will say the charge rate is 2000 watts.

When thier voltage reading goes up or down it does it buy .4 voltage spread not by .1 voltage spread. I don't know the tare losses on the two cc but think the inverters is 20 watts each. I saw a chart one time that ouback hits their 94% convertion rate at a spicific watt load and higher and lower watt loads have a different and worse convertion rate. Fifty percent is alot. I really like how outback works as far as seamlessness and the raw power it will run.

To your point of day time loads, thats why I make my hot water during the day.

Thanks for your interest.
gww

Blackcherry04

Re: My battery soc

Your Mate is reporting 400 watts in AC current, the 800 watts is in DC current on your Battery Monitor. Be lucky it not a 12v bank or it'd be 10 times. Again none of what you see is 100% accurate and drifts over time and the errors are cumulative over time.

gww1

Re: My battery soc

Blackcherry
in the end though isn't a watt a watt? I understand the voltage and amp ratio being differrent but a watt is a watt. I don't relie on the guages but for generalities. I just found it interesting.

Thanks
gww

Blackcherry04

Re: My battery soc

gww1 wrote: »

Blackcherry
in the end though isn't a watt a watt? I understand the voltage and amp ratio being differrent but a watt is a watt. I don't relie on the guages but for generalities. I just found it interesting.

Thanks
gww

That depends on your Inverter efficiency ( 90-95 % more or less ) and the way they calculate it.

gww1

Re: My battery soc

Yea, I am pretty sure it is 94 % at a spicific wattage not counting tare losses in the system. 50% still seems high, I aint worried cause I see no way to change it but it was still an eye opener as that don't count wire losses and panel in-efficiancies. In really do like outback, not that I have a referance point cause it is all I have ever owned.

That was a much more professional answer that you gave on the generator imput to the vfx inverter. I try but am glad guys like you come behind and do it better.
gww

Blackcherry04

Re: My battery soc

Maybe BB or Coot will come along and give you the actual formulas for the conversion of DC to AC for Voltage conversion. In big ole round numbers here is the estimate. So 400 W AC @ 48v = 800 watts is right in line with the estimate depending on your Inverter. Peukert Exponent also comes into play with FLA batteries based on the load factor.

@ 12v, 500 w AC is about 9.xx times in DC amps
@ 24v, 500w AC is about 4.xx times in DC amps
@ 48v, 500w AC is about 2.xx times in DC amps
.

BB.

Re: My battery soc

To add to BC's numbers:

Some "worst case" numbers:

• 500 Watts AC * 1/0.85 inverter eff * 1/10.5 vdc cutoff for inverter = 56 amps @ 12 vdc battery "near fully discharged/lots of wiring voltage drop"
• 500 Watts AC * 1/0.85 inverter eff * 1/21.0 vdc cutoff for inverter = 28 amps @ 24 vdc battery
• 500 Watts AC * 1/0.85 inverter eff * 1/42.0 vdc cutoff for inverter = 14 amps @ 48 vdc battery
• 500 Watts AC / 120 VAC = 4.2 amps @ 120 VAC

You can play with the numbers and get other values... For example, the most conservative wiring for a 12 VDC system with 1.25 NEC derating:

• 56 amps maximum continuous * 1.25 NEC derating = 70 minimum rated wiring+fuse/circuit breaker

While, the actual current when the sun is up and the battery bank is charging may be:

• 500 Watts * 1/0.85 inverter eff * 1/14.5 volts battery charging = 40.6 Amps @ 12 volt battery bank when charging

And remember that heating power = I²R -- So the heating your wiring when battery bank is near dead/lots of current draw:

• (56 amps/40.6 amps)² = 1.9x more heating in wiring (and inverter/battery bank/fuses/breakers)

So--You really need pay attention to current and worst case designs... The amount of heating (and losses) can be 2x greater as the battery bank discharges when supplying a constant power source like an AC inverter.

-Bill

Blackcherry04

Re: My battery soc

BB, your right. I was trying to give him something back in the same metric and he posted. He must have been reading it off his Battery Monitor. I believe it will express the DC in Watts or Watt hrs, Amps and Amp hrs.

gww1

Re: My battery soc

dc 16.3 amps x 50.03 battery voltage = 815 watts ac 3.33 amps x 120 volt = 399.6 dc 7.99 amps x 50.3 voltage = 400 watts

I understand that more amps leave the battery and the need for heavy wire and the P. effect on the battery. I have 4/0 from battery to inverter.

7.99 dc amps at the voltage the battery was at is more then the 3.33 but would still be 100% convertion. The inverter is rated for 94% convertion.

16.3 amps at that battery voltage is 800 watts and only 50% convertion. I would have more expected 28 watts convertion dc to ac, 40 watts for inverter and 40watts for Charge controllers.

I would have expected about a ten amp draw from the battery at that voltage like 508 watts. I am not worried too much, just exorcizing my thinking skills.

I have been screwed up before, am I this time?
Thanks
gww

BB.

Re: My battery soc

If you have two inverters running at the same time, that could be 20 Watts per inverter or 40 loads with them both turned on and not running any loads... That can affect your readings too (by 40 watts, not 200 watts).

-Bill

gww1

Re: My battery soc

Hey, here is a question I am really interested in knowing about. I lowered the absorb voltage on my battery to 58.8 volts. The battery is in absorb and has been for one hour. I checked the sg at the start of absorb and it was 1.260. There were close to 30 amps going into the battery.

One hour into absorb the battery is only accepting 5.9 amps and the sg is 1.269 and the trymetric says the battery is 7 amps from full. Everyting I ever heard was end amp should be about 2 percent of the bank rating and that forktruck batteries take very long absorbs. I do believe before the day is over that the sg will raise altough at this much lower voltage I don't know if it will make 1.280 or not. time will tell.

Am I on the right track with the lower absorb voltage?

When I discharge deeper then 75% will the battery still act the same once it reaches absorb altough it may take longer to reach it?

Am I absorbing too long even though the sg will still rise a bit, should I save that for the mothly EQ?

As I am absolutly lost, does anyone have an oppinion?
gww

gww1

Re: My battery soc

I went back to the 60 volt absorb cause at 1.5 hours it was only putting 4 amps into the battery and the trimetric said it was 7 amp hours from full.

60 volts got the battery to accepting 6 amps in charge.

The sg didn't seem to be raising as well at 58.8 absorb. It did in the beginning but not as well at the end.
gww

gww1

Re: My battery soc

I am going to turn off my pv to the charge controllers and see how low I can take the batteries tonight, tomorrow and the next night.

Then charge and do my montly eq. I hope I can get the batteries below 50% although I am not going to lower my already low cutt off voltage cause I am scared. If it is like normal it will cut off due to a heavy load and not go below 50 %. If that happens before I go to bed I will reset it to draw more, If not I guess I will recharge cause I don't want it to sit too long while being that discharged.

gww

gww1

Re: My battery soc

Change of plan, I turned the pv back on. I turned my night time loads off. I used 3kwh from the battery already per trimetric.

I am going to absorb tomorrow and then when the low cell is at close to 1.280 I am going to start an eq. I am going to eq till the cell goes up or I think the battery is getting too hot. Then I am going to measure all cells and record.

Then I am going to let the battery rest for at least 5 hours. Then I am going to measure all cells again and record. Add water.

Then I am going to turn the pv off and try to drag the battery down to what I hope is no more then eighty percent discharge.

Then I am going to turn the pv back on and try to charge the battery.

I read the rolls link that blackcherry posted and think that my low amps in absorb is due to stratification. High volts causing the cc to cut back amps even though the battery is not really charged. It said when the sgs break lose during eq and start to rise the battery should start accepting more amps.

If tomorrow, I end up with something else I read there (If your electrolight is black or dark it is from over charging) I will know I have done wrong.

The only thing I haven't decided is, to eq at the high rate of 63.2 that I have been or cut it to the minimun of 62.4. I guess I will sleep on it and do something in the morning.

If anyone was about to see a train wreck, surly if they could, they would try to stop it.

Cheers
gww

Cariboocoot

Re: My battery soc

I give up.
You keep changing things at random and that is no way to identify and correct problems.

gww1

Re: My battery soc

coot
don't give up! I looked at my schedual and today was the only day I was 100 percent sure I could be here long enough to finnish my monthly eq that is due by the 24th.. Mom and dad are having a furnace put in and it is kind of complicated cause He wants to be able to use his wood boiler in conjuntion with it. the guy is supposed to start work tommorrow or wends.

I just took the sg reading prior to starting a three hour absorb at 63.2 volts. The battery is at 63.2 degrees f.

1 1298
2 1290
3 1285
4 1295
5 1299
6 1290
7 1292
8 1299
9 1298
10 1297
11 1290
12 1295
13 1296
14 1284
15 1282
16 1291
17 1295
18 1300
19 1288
20 1286
21 1289
22 1288
23 1290
24 1282

I am not trying to change what I am doing, I just am not sure what I am doing. I don't do well with you are not going to talk to me. I do better if you say, "you are an idiot" why aint you discharging yet. I am going to undo the pv imput and try to take the battery down tonight and tomorrow and the next night. I just thought I shouldn't miss the eq and might have a little rougher schedual then normal which is usualy free. I really don't have much of an ideal what I am doing and keep reading trying to learn more. I am listening to you and am going to take down and recharge. I did ask one question about that plan. When I recharge are we talking about an eq each time also?
Thanks and I know you are a volinteer but I really do apretiate your help, I mean I really do.
gww

PS I also thought that having the best reading I could would give me some ideal on what the charge discharge was doing for me.