Battery Optimizing

adas · July 2008

Aloha, as you probably have seen in my previous posts I am using old electric forklift batteries for my battery bank. I recently got 5 x 36 Volt 625 AH batteries and 4 x 24v 875AH free from a freight company. It seems that the company did not know where the water faucet was and each battery needed about 2-3 gallons of water. I filled them up with purified water (Hawaii water is low in chemicals anyway) and after 4 days charging I am up to 2.08 to 2.15 in each cell and if I leave them off the PV charger the voltage does not really drop at all. Most cells are at 2.12 My questions:

1: Did I just put on a "surface" charge with no real amperage to back it up?

2: Using the 4 x 24v 875 AH in daily use will it just get stronger with use?

3: Should I equalize (I have 150 amps @ 31+ V available) and can isolate each battery through my circuit breaker setup, while the inverter draws off the 3 other 24's. Or I can have one FM80 charge the 3 24's while one FM80 equalizes one 24 @ 75 amps/31V.

I am of the opinion from personal experience and what I have read that these forklift batteries are very rugged and are made to withstand 250amp charges at "Home Depot" lunch hours and then severe draining down to "dead" during the day.
So what is the best care to get the most out of these "retired" batteries?

thanks Frank

mike95490 · July 2008

Re: Battery Optimizing

My guess, is since they are forklift batteries, you need to get the Mfg specs on them, as the chemical package is different, and they may have a different EQ voltage.

But on the other hand, hitting them with your FM80 on EQ, one at a time, and maybe 2 cycles apiece, may be the way to insure a full charge. After the 2nd EQ (I think EQ is set by a voltage, and not necessarily Amps) they should be as equal as they are going to get. Different hydromoter readings will reflect either weak cells, or damaged by wrong refill juice (soda pop, tap water, coffee, whatever home depot had handy).

Any little bit of mineral or city water purification chemical (chlorine) will damage the cell, with no way to undo it, till you recycle the battery.

System2 · July 2008

Re: Battery Optimizing

If the batteries are not totally sulfated they could be giving you an acceptable voltage reading but not have much capacity. As a battery is discharged, the chemical reaction causes the specific gravity to go to 1.00. If some of the surface area of the plates is sulfated, that area if the battery will not charge and the specific gravity of the electrolyte will be lower than it would be if the battery were not sulfated at all. The more sulfation, the lower the specific gravity - the electrolyte is becoming water. As long as there is some active plate area, you could see a normal voltage reading. You need either a hydrometer or to load test to determine whether or not your batteries are good.

Cheers,

Bad Apple

adas · July 2008

Re: Battery Optimizing

Aloha, all. Well yesterday I logged 23KWH for the warehouse system and batterys were showing almost full charge. Last nite we had a party in the warehouse with about 90 guests, used lottsa lights, Speakers, 3 guitars, drums, bass, main speakers and monitors with mixer and sound traveled 4 to 5 blocks. (but we have no neighbors for 3 miles). Anyway the voltage started at 24.9 at 7 pm and by 9:30 PM I still was at 24.6V. So the batteries seem to be holding fairly well. Will keep charging them high and make sure they are not getting warm and see if they improve. The one dead cell I had (1.30V) is now holding 1.80V so we will see. Looking for 25 KWH today

Frank

niel · July 2008

Re: Battery Optimizing

those voltages do not sound good as you should have voltages about 27v and probably with the sun still charging them about 28v for fully charged batteries. a start voltage, with solar still delivering a charge at the time of 7pm, of 24.9v says you better get a good charge into the batteries as they've gone down too far.

adas · July 2008

Re: Battery Optimizing

niel wrote: »

those voltages do not sound good as you should have voltages about 27v and probably with the sun still charging them about 28v for fully charged batteries. a start voltage, with solar still delivering a charge at the time of 7pm, of 24.9v says you better get a good charge into the batteries as they've gone down too far.

Aloha, with the sun still charging I get 27-28.5V. Last nite with no sun I got around 26.4 or so and then when I put a load on I got 25.9. During the nite 7 pm (almost dark here) I used .4 Volts to 25.5 up to 9:15PM. I think the batteries will improve with a few cycles?
Frank

icarus · July 2008

Re: Battery Optimizing

I would get a good temp compensated Hydrometer. It's tough to do a good test without one. Voltage is only one way test batteries and not a very complete one at that.

Tony

adas · July 2008

Re: Battery Optimizing

Aloha, Hmmmmm. I have a meter for checking PH levels in some Hydroponic gardening I am experimenting with. Would that work to find Sp Gravity? (I should have checked the wisdom of my question above, but I am out of time to google and I know one of youse will know <g>)
Frank

icarus · July 2008

Re: Battery Optimizing

HMMMM, I don't think so. A battery hydrometer will read (very accurately) the specific gravity (acid strength). They are not very expensive and absolutely required if you want to prolong the life of lead acid batteries.

Make sure you wear glasses and old clothes. You will burn holes in them! You will splash acid sometime,,hence the glasses.

Good luck.

Tony

PS You might read the following links :http://www.batteryfaq.org/
http://www.rpc.com.au/products/batteries/car-deepcycle/carfaq4.htm#charge
http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

adas · July 2008

Re: Battery Optimizing

icarus wrote: »

HMMMM, I don't think so. A battery hydrometer will read (very accurately) the specific gravity (acid strength). They are not very expensive and absolutely required if you want to prolong the life of lead acid batteries.

Aloha, Tony. So how does one determine the difference between a cell that someone diluted with water and one that needs to be zapped or equalized to get the acid out of the plates and on bottom and mixed with the other liquid in the cell?

Thanks

Frank

icarus · July 2008

Re: Battery Optimizing

Charging the battery will change the battery chemistry so that the acid will become stronger. If after fully charging (When the Specific Gravity stops rising) if one (or more) cells are low that indicates a cell going south. If an Eq charge does not bring it up to normal, or almost normal, it is a bad sign.

Tony

PS Read the cautions on the battery links below about EQ charging

mike95490 · July 2008

Re: Battery Optimizing

So how does one determine the difference between a cell that someone diluted with water and one that needs to be zapped or equalized to get the acid out of the plates and on bottom and mixed with the other liquid in the cell?

You recharge, and charge and charge, till the SG stops increasing. That's an Equalize Charge, if it works.

niel · July 2008

Re: Battery Optimizing

adas,
very good on the low sun day.

"(I should have checked the wisdom of my question above, but I am out of time to google and I know one of youse will know <g>)
Frank"

isn't that pittsburghese? synonim-yinz

adas · July 2008

Re: Battery Optimizing

Aloha, so far all my mistakes have not lead me down the wrong road...so far.
Today may have been a typical day where we had a lot of high atmospheric clouds where the input was 80V @ 8A making [email]25V@26A......not[/email] enuf to keep my shop going. Whenever the sun came fully out I would zap up tp 27V@79amps! I did not take into account the 2 large 1/2hp fans chewing up 9amps @ 110VAC so I ended up with batteries at 24.5V Anyway I will run a better calculation in excel tomorrow and maybe get more panels or higher efficiency fans.

frank

mike95490 · July 2008

Re: Battery Optimizing

Just 2 words for your system:
"Deficit Charging"

Take a 2 day vacation and let the batteries charge, or start shopping for new ones now. You are running them 90% discharged daily, with no full charges.

niel · July 2008

Re: Battery Optimizing

i agree with mike as you can't have a bad solar day, use up much of the batteries during the evening, and come in the next day and have business as usual for the batteries just because the sun is out now. you must get them back up or you will run risk of shorter lifespan or premature battery death. more pvs are fine as a future cure or as you suggested about doing something different for the air circulation, but right now you need to charge those batteries fully even if it means using a generator.

adas · July 2008

Re: Battery Optimizing

Aloha, Ok it is a "redesign weekend" for me.

1: Getting the batteries up to 100%,
2: Shifting some load from the warehouse system to the office system
3: Adding more batteries to the office system.
4: Simplifying runs and upsizing some of the undersize wire
5: Adding another 12x190 blems and another FM80.

Wow, looking at the first system I put together (office system 3 months ago), I can't believe the idiot who put it together! So redoing that one now too!

I have learned so much from you guys here....thanks all!

Frank

BB. · July 2008

Re: Battery Optimizing

If you currently do not have one on each system, I would highly suggest a Battery Monitor for your system... The only way to check the current state of charge of your battery bank in real time (short of using a hydrometer).

It will answer 90% of your questions about over/under charge, panel wattage, and load usage. Also, it will make it much easier for others to monitor your system status when you are out of the office on vacation (hmmm where do you go on vacation? To a small 2 bedroom house in a San Francisco suburb?

)

-Bill

Battery Optimizing

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