Battery charging problems

Anawa · June 2017

I would start at 58v for absorb, but don't take that as gospel. If the needle starts going up, then bump-up the v's.

mcgivor · June 2017

Setting a higher voltage would be benificial, Rolls actually recommend 62.4 to 64.8V as the initial setting to get the process of breaking down any sulfation which may have occurred, started, probably in extreme cases?. Six weeks is not very long but still enough time to have some soft sulfation, it is interesting to many as we have probably been through something similar, I certainly did and researched as much as possible from multiple sources to obtain information, my voltage settings were initially too low, being conservative, through advice from others here and information gathered, my settings are now more aggressive and working well .Good luck, hope it all works out.

http://support.rollsbattery.com/support/solutions/articles/5964-battery-sulfation

metalguy21 · June 2017

Thanks guys.

Update. s.g. 1.150 at 5:00am. Raised bulk/absorb voltage from 56v to 58v. Ran 1 hr bulk followed by 4 hr absorb. s.g. read 1.220. I'm running an EQ right now at 63v. The system won't allow a setting change on the EQ time with 1 hr as default. I plan to do 3 EQ's today. I have a temp sensor and I'm getting no temp rise at all - a steady 75 degrees. It looks like progress but not necessarlly solved. I'm going to raise bulk/absorb another two volts to 60v tomorrow and see how things go.

One further question. How about float? It's currently at 53v. Should I raise it up by a proportional amount as the bulk/absorb?

Anawa · June 2017

Looks like progress is being made! When you get the SG up to 1.285 via absorb, you may consider raising the float to 55v. Good luck.

westbranch · June 2017

Are you doing a short, light discharge between charge cycles, it gets rid of the surface charge effect, same as letting the battery sit for 3 hrs or more.
yes you can set Float higher.

metalguy21 · June 2017

westbranch - I guess the answer is yes since the excess solar while on eq is passing through to the loads from the house.

westbranch · June 2017

The key is a load when there is NO charging occurring... between charge cycles..

If I understand your earlier posts you have a constant draw all day... if it exceeds the total watts passing through the charge controller or Inverter chargers, then yes you are always draining the battery

metalguy21 · June 2017

No I produce around 4 times what I use while the sun shines. Thus my disappointment at the utilities ban on hybrid systems. Lots of sun left today so I'll give it a rest for the next couple hours and then EQ it once more.

Photowhit · June 2017

Okay, first let me say forklift batteries are very durable, there is a chance your battery will survive.

Now;

metalguy21 said: s.g. is 1.15 and never rises.

It appears you have a hydrometer and I'll assume you know how to use it. The voltages back you up.

EQUALIZING ONLY HAPPENS WHEN A BATTERY IS FULL!
If you are trying to equialize a battery before it's full it's just a waste and damaging to your battery.

GB says you can use other chargers correctly sized for the battery; You are NOT using this battery in a forklift, don't treat it like you are! If you follow GB's instructions you would only charge when the battery was 80% discharged! They know forklift cycles, you will use this battery daily at lower levels.

http://www.battery-additive.com/ProperBatteryCare.html

They do NOT size batteries correctly for a 20 hour rate! Their stated capacity is much higher than the actual capacity.

This is hard to explain, but perhaps easiest to show you;

If you go and look at your battery spec's at GB it is a 12-125-15, that is a 12 cell battery with 125 amp/hours storage per positive plate (6 hour rate), with 15 plates per cell (7 of which are positive) and they come up with a (7x125=)875 Ah battery at the 6 hour rate. Some how they get 1379 for a 20 hour rate, which is about 1.575 x the 6 hour rate.

Lets compare Crown's rating, Here is a link to a Crown battery with a similar size at 20 hour rate. It's a 12-100-23 or a 12 cell battery with 100 amps/hours storage per positive plate, and 23 plates per cell, 11 of which are positive, (11x100=)1100 ah battery at the 6 hour rate. Somehow they get 1375 AH at a 20 hour rate, about 1.25x the 6 hour rate.

I have a 12-85-13 GB battery! I was more than a little upset when I was told this, but it makes sense. BTW-It's rated capacity for the 20 hour rate is also 1.575 x it's 6 hour capacity.

westbranch said:

I just did some quick numbers, 25 x 200w x .75 (overall efficiency) > ~ 3750W (actual) / 48v = ~ 78A max that your array will produce.....

So this number isn't quite as bad as it first looks. If we assume you have a (875 x 1.25) @ 1100 Ah 24 volt battery bank, you can charge it at about a 7% rate. We typically recommend a 10% rate for systems in use.

First you need to fully charge your battery, run the generator Now and as long as it takes for the batteries to reach a full charge. Set your battery charge controller for a reasonable rate for flooded lead acid batteries. I use 29 volts as my Absorb setting and 31.4 for equalizing. I set my float at 27.2 (many use a lower float setting for fork lift batteries around 26.4) I suspect the GB guy who gave you some numbers had some miss communication between the 2 of you.

Run your generator until you see the SG rise. Start when you read this and just check electrolyte levels for a while. Don't bother looking at the SG until tomorrow morning... If you at running an Air conditioner or other heavy load, It might be good to see how much current your battery is actually receiving, if you haven't reach float. Might be worth getting a clamp meter if you don't have a shunt based battery meter.

mcgivor · June 2017

westbranch said:

The key is a load when there is NO charging occurring... between charge cycles..

If I understand your earlier posts you have a constant draw all day... if it exceeds the total watts passing through the charge controller or Inverter chargers, then yes you are always draining the battery

metalguy21 said:

No I produce around 4 times what I use while the sun shines. Thus my disappointment at the utilities ban on hybrid systems. Lots of sun left today so I'll give it a rest for the next couple hours and then EQ it once more.

Understood the production is 4 times the load during good sun, but what about overnight, between charge cycles, is there still a load being drawn?
Personally, and I may be alone on this, I would treat the situation as a recovery process , isolating the battery completely from any loads with focus on getting it to full capacity. FWIW

Estragon · June 2017

I wouldn't necessarily isolate the battery the battery from all loads, but would treat this as a recovery process.

I'd run the generator until well into absorb, then eq with solar all day. If temps are ok (confirmed with feel test or IR) I'd hit it with whatever max eq voltage is within battery spec. Repeat daily until sg gets to normal.

After that, tweak Vabs and Vflt to keep the bank happy.

westbranch · June 2017

+3 on Recovery Mode,

metalguy21 · June 2017

"First you need to fully charge your battery, run the generator Now and as long as it takes for the batteries to reach a full charge. Set your battery charge controller for a reasonable rate for flooded lead acid batteries. I use 29 volts as my Absorb setting and 31.4 for equalizing. I set my float at 27.2 (many use a lower float setting for fork lift batteries around 26.4) I suspect the GB guy who gave you some numbers had some miss communication between the 2 of you. "

OK, got the s.g. up to 1.255 after 4 hour genset absorb run and the rest of the day on solar. I'll check it again in the morning. I plan to kick the absorb voltage up to 59.0v and do another 4 hour absorb run w/genset very early. I have no heating problems at all and the gasing on absorb is major to say the least. At the rate things are going I believe I should see full charge by the end of the genset run and certainly by the end of the day. I also plan 2 or 3 more EQs now that I am at full charge.

On mcgivors point about isolating the battery and getting it back I can't completely since the house is wired as only solar now but I will do my best to keep as much as possible off through tomorrow morning. To be clear on my loads I run pretty close to 1500w (12hr) all day down to 1000 in the evening (4hr) and early morning down to 600 (8hr) at night. 500 of this is the small ac unit i cool the battery mechanical room with 24/7 (VERY hot here now). I calc that at around 26kwh per day. No problem right now as I have all the sun I need. I'm hoping this will work in the winter as I'll drop the 500w AC load off which will save me around 12 kwh a day. Note I am making no efforts to conserve at this time either.

In any case I think I'm on the road to recovery. More tomorrow. Thanks for all the help. I had reached the end of my ability to do this on my own.

Estragon · June 2017

At 1.255 you're well on your way to recovery. Good job! If you're gassing lots, that's ok, but be sure to check electrolyte levels and add distilled water to cover plates if needed before next EQ. Don't completely fill (don't want to overflow) just to min level to cover plates.

mcgivor · June 2017

Good to hear things are going well, seems the more aggressive voltage is getting things happening, when the SG of all the cells reach the target reading, continue the EQ for a couple of hours extra.

Photowhit · June 2017

metalguy21 said:

OK, got the s.g. up to 1.255 after 4 hour genset absorb run and the rest of the day on solar. I'll check it again in the morning. I plan to kick the absorb voltage up to 59.0v and do another 4 hour absorb run w/genset very early. I have no heating problems at all and the gasing on absorb is major to say the least. At the rate things are going I believe I should see full charge by the end of the genset run and certainly by the end of the day. I also plan 2 or 3 more EQs now that I am at full charge.

Sounds good! As forklift batteries these are equalized every 2 weeks or 10 cycles, I would keep getting it topped off and equalize until you see no additional gain and expect to be back in that 1.275 area.

I know you are in a sunny area, but if you have a fixed array, you may only calculate @ 6.5 - 7 hours of direct sun as you will produce somewhat less at off angles. With the heat the 3750 watts of actual production will be a maximum, so with 7hours x 3.75Kw=26.25 Kwh

metalguy21 said:

I calc that at around 26kwh per day.

So between the panels being extra hot and with the extra losses in using stored energy (lead acid is only @ 80% efficient at storing energy) You are running a net negative so I would plan on running the generator some every day or every couple days.

Will your inverter do a 24 hour capture of energy use?

The reason for the losses/derating of the array has to do with NOCT values of the panels operating in the heat. Some manufacturers publish the Normal Operating Cell Temperature (NOCT) values for their panels while others just provide a derating value.

http://thegrid.rexel.com/en-us/energy_efficiency/f/energy_efficiency_forum/674/what-is-the-difference-between-stc-and-noct-in-photovoltaic-module-specifications

westbranch · June 2017

when this exercise is over , a good read would be about 'Virtual Arrays', where you have 1/2 facing due E and the other 1/2 facing W, so your solar day is much longer than a S facing array.
hth

metalguy21 · June 2017

Checked this morning and things had dropped a bit overnight from yesterday at 1.255 down to about 1.235. Running again now at a higher absorb V of 59.5. Getting a little hotter. My temp sensor says 82 degrees after about an hour of absorb. Room is at 77 degrees. Should I be concerned? Note that by feel they are in no way what i would call "hot".

Photowit - ya this is not going to be quite the powerhouse I was thinking but I think with a few adjustments it will all work out. It's unfortunate but I destroyed 2 panels in an accident (don't ask) so all I could do was reduce from the 2 x 3 strings of five down to 3 strings of 5 plus 2 strings of five = 25 panels instead of the 30 I had to start. And yes it will give a readout for total capture for the day (if that is what you are referring to. I checked yesterday and it was 30 kwh. Note there was still some day left and I'm not sure how the 4 hr generator run and multiple EQ might effect that readout. i'll have a full solar day tomorrow and see for sure.

Photowhit · June 2017

If you have temperature sensors attached from your charge controllers to the battery, I wouldn't worry. I do think they back off around 90, but that's from my faulty mind...

metalguy21 · June 2017

I believe it's configurable but it's still at the default so likely OK

metalguy21 · June 2017

Noon and finished 4 hr Genset run. s.g.'s vary between 1.270 and 1.285 so it looks like I'm good and this thread can be put to bed. Will EQ a couple times and hopefully that will even out the s.g. readings. Whew. Thanks for all your help.

westbranch · June 2017

The SG numbers should stabilize when a true ''full charge'' is achieved, then you can start backing off a bit on the high EQ voltage targets... and frequency

Battery charging problems

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