Forklift (Industrial Battery) consistently weak cell, problem solved

[home skillet]

I live off grid in Upstate NY. I have a 14400KW solar array, 4x Midnight solar charge controllers, 2x8048 Outback radians and a (1500 A/H, 6000 lbs,) 48 volt BBI "forklift" battery. and a 30KW Isuzu diesel generator

I was having issues with one cell always being 6 points lower (SG 1.22 vs 1.28) than the other 23. I could equalize the battery, but when I did, the other 23 cells would go up to SG 1.3 and hang there for hours waiting for the weak cell to catch up. The other 23 cells got very warm and I would shut down the equalization without truly equalizing. After the EQ was finished?? I'd have 23 cells at 1.29 and 1 cell at 1.26. I was looking for a way to charge the one weak cell at 2.5 to 2.6 Volts DC, without subjecting the other 23 to this voltage. 2.6 vdc applied to a single cell is "Equalize voltage".

Low and behold I found a company called Hindlepower out of Easton PA. They make a single cell battery charger that you can use while the battery is in service.....hooked up and powering your home. I was skeptical, but I bought one. It adjusted it to 2.6 volts / 10 amp output per instruction. Before I actually hooked it up to the weak cell....i thought....."at only 10 amps, this probably wont the moxie to bring the weak cell to 2.6 volts". Anyway, the weak cell was at SG 1.21 at this time and the other 23 were SG 1.25. I hooked it up to the weak cell and I was only getting 2.38 vdc going into the weak cell. I thought I had wasted 465 dollars. I left it charging the weak cell all day long. The test day was partially sunny, but far from clear, as far as solar charging goes. When the sun went down, I checked the SG's and I was shocked. The "weak" cell was now at 1.28 was the other 23 were at 1.27. IT WORKED. I can't honestly say it ever brought the weak cell to 2.6 volts........but I dont care. It did its job. It brought the weak cell inline with the others. That was one week ago and the weak "cell" still runs neck in neck with the other 23. I do think the weak cell is probably a weak cell by definition and will probably have to do this again every month or so (especially in the winter). I wont however, have to subject the other 23 to high temp and high voltage for hours in an attempt to bring the weak cell inline. Hopefully this can help someone out there dealing with a delinquent cell or two.

Single-Cell Charger · HindlePower; Model: BB0442-01. ...........Hindlepower will not sell to us lil guys directly. I bought it thru Dowd Battery in Buffalo NY and paid $465 for it.

 

[mtgstuber]

Thanks @home skillet. I have a similar system, and I also appear to have a weak cell or two. Not sure I'm ready to drop $465 yet, but I'm very glad I know about it.

Question: What voltage levels are you using on your BBI batteries? I purchased mine through Global Battery. I called and they gave me voltage levels, but they seem to leave things chronically undercharged. I'm wondering what settings for bulk / absorb / float / equalize work well for you. (I have a 1369 Ah 48 V BBI setup).

 

[home skillet]

Hello there, I have a summer time absorb voltage and a winter absorb voltage. My winter time absorb voltage is 58.8 vdc for 3 hrs
my summertime absorb voltage is 58.4 for 2 hours. I float at 54 volts in the summer and 55 in the winter. My batteries rarely go under 75% depth of charge (25% discharged).

I live in upstate NY where the sunlight goes out from Thanksgiving until March 1.....and on those rare days when the sun shines, my arrays are often covered with snow.

Once in a while.....Ill let the batteries drop to 50% or lower and when I do, neither 2 hrs of "summer voltage" of 3 hours of "winter voltage" will fully service them to full. My batteries seem to want to charge to SG 1.30. I know the data plate says 1.285, but my batteries love 1.30 and that is what I call a full cell. I have read that forklift battery manufacturers often build in a added degree of power and thats why I see an SG of 1.30. Do your batteries seem to charge to 1.30 or 1.31? How low do you batteries typically go? How big is your solar array?

 

[home skillet]

Sorry, I equalize at 62.5 volts for 1.5-3.0 hrs, Depending on what the SG at the start of EQing. As for Bulk......I take whatever mother nature will give me. I have a 14400 watt array, but on a sunny day, 12000 watts is a more realistic bulk charge........12000 watts is 218 AMPs at 55 volts. As the battery voltage level raises to the absorb voltage set point......the amps will start dropping to hold 58.? volts.
My battery is a 1500 A/H battery so my recommended charge rate is 150 to 300 amps. Very very very very often in the winter I dont come anywhere near 150 amps. Many times its under 100 amps. I just make sure once a week my batteries see 1.285 (or better yet 1.30)

 

[home skillet]

Here is a Enersys HUP battery brochure, HUP is another forklift battery adapted to solar. I wish i could have afforded HUP batteries. Anyway, HUP has good literature about their battery. BBI.....not so much.

 

[Ralo]

I live off grid in Upstate NY. I have a 14400KW solar array, 4x Midnight solar charge controllers, 2x8048 Outback radians and a (1500 A/H, 6000 lbs,) 48 volt BBI "forklift" battery. and a 30KW Isuzu diesel generator

I was having issues with one cell always being 6 points lower (SG 1.22 vs 1.28) than the other 23. I could equalize the battery, but when I did, the other 23 cells would go up to SG 1.3 and hang there for hours waiting for the weak cell to catch up. The other 23 cells got very warm and I would shut down the equalization without truly equalizing. After the EQ was finished?? I'd have 23 cells at 1.29 and 1 cell at 1.26. I was looking for a way to charge the one weak cell at 2.5 to 2.6 Volts DC, without subjecting the other 23 to this voltage. 2.6 vdc applied to a single cell is "Equalize voltage".

Low and behold I found a company called Hindlepower out of Easton PA. They make a single cell battery charger that you can use while the battery is in service.....hooked up and powering your home. I was skeptical, but I bought one. It adjusted it to 2.6 volts / 10 amp output per instruction. Before I actually hooked it up to the weak cell....i thought....."at only 10 amps, this probably wont the moxie to bring the weak cell to 2.6 volts". Anyway, the weak cell was at SG 1.21 at this time and the other 23 were SG 1.25. I hooked it up to the weak cell and I was only getting 2.38 vdc going into the weak cell. I thought I had wasted 465 dollars. I left it charging the weak cell all day long. The test day was partially sunny, but far from clear, as far as solar charging goes. When the sun went down, I checked the SG's and I was shocked. The "weak" cell was now at 1.28 was the other 23 were at 1.27. IT WORKED. I can't honestly say it ever brought the weak cell to 2.6 volts........but I dont care. It did its job. It brought the weak cell inline with the others. That was one week ago and the weak "cell" still runs neck in neck with the other 23. I do think the weak cell is probably a weak cell by definition and will probably have to do this again every month or so (especially in the winter). I wont however, have to subject the other 23 to high temp and high voltage for hours in an attempt to bring the weak cell inline. Hopefully this can help someone out there dealing with a delinquent cell or two.

Single-Cell Charger · HindlePower; Model: BB0442-01. ...........Hindlepower will not sell to us lil guys directly. I bought it thru Dowd Battery in Buffalo NY and paid $465 for it.

Hey home skillet, would you be interested in renting out your single cell charger? Probably more trouble than it's worth but I thought I'd ask. Shame to spend $465 for 1-2 uses per year.

 

[home skillet]

Ralo, where are you located? I use it when the SG difference reaches 3 points. As a matter of fact i am using the 2.6 vdc charger right now. How many A/H is your battery?

 

[OzSolar]

Sorry, I equalize at 62.5 volts for 1.5-3.0 hrs, Depending on what the SG at the start of EQing. As for Bulk......I take whatever mother nature will give me. I have a 14400 watt array, but on a sunny day, 12000 watts is a more realistic bulk charge........12000 watts is 218 AMPs at 55 volts. As the battery voltage level raises to the absorb voltage set point......the amps will start dropping to hold 58.? volts.
My battery is a 1500 A/H battery so my recommended charge rate is 150 to 300 amps. Very very very very often in the winter I dont come anywhere near 150 amps. Many times its under 100 amps. I just make sure once a week my batteries see 1.285 (or better yet 1.30)

Nice find on that charger and thanks for sharing! I've often wondered if you could do the same thing with an adjustable power supply but I'm not an electronics expert and I haven't had one with me when I would have be able to test that.

How many days of autonomy does your system have with that size of battery bank?

I've done a few dozen off grid systems with forklift style batteries. Most of them were HUP's but have some experience with Enersys, Exide, Rolls/Surrette and others. Please allow me to politely offer that in my experience I think your absorption voltage might be a bit low.

Until one of the engineers at Rolls explained to me just how aggressive you need to be to correctly charge these big 2v cells my systems were all struggling with SG issues. For absorption, 2.5 volts per cell (temperature compensated) common recommendation from the battery manufacturers. Most batteries are in unheated or barely heated spaces so in the winter that might be 61v or even higher. You as well as most off grid systems are only going to be able to regularly do that with in the summer or with a generator.

I can also offer, especially as these systems age, I regularly have to take 48v systems to 64v and hold them there for 6 to 8 hours to correct the outlying cells. Insane as that sounds the engineer at Rolls assured me that you if don't let the batteries get above 115f during this you aren't hurting them. In practice its very difficult to do that in one shot because the batteries warm up and refuse to go above 62 to 63 volts regardless of how many amps you throw at them.

 

[home skillet]

I EQ at 62.5 volts for 2 hrs. (48 volt system) and my batteries never go above 90 f. Also, my batteries are in my basement in a vented containment vessel environment (around 55-65 degrees in the winter, 75-85 in summer) They never get cold..so to speak. I used to EQ more often but manufacturer stated.....all i was doing was "creating excess heat". I now EQ every couple months.

 

[Ralo]

Ralo, where are you located? I use it when the SG difference reaches 3 points. As a matter of fact i am using the 2.6 vdc charger right now. How many A/H is your battery?

I’m in Louisiana.

Does you have to repeatedly charge the cell that was low to keep it in line?

I guess I may have to buy my own then. I have a few of weak cells across multiple batteries.

Does it max out at 2.6 volts?

 

[home skillet]

Hi Ralo. It maxs out at 2.6 VDC. at 10amps (although the meter sometimes shows 13 amp). I have a 1500A/H battery I am trying to boost charge with this charger soooo the charger is overmatched, but it works for me. For me, being off i grid, my battery usually charges every day. In the morning (once a month of so) I connect the Hindlepower to the defective cell. Though out the day, the cells (all 24 of them) charge normally via the solar charge controllers, but the (1) weak cell also has the Hindlepower attached to it. So the weak cell is always charging at a bit higher voltage. When it comes time for the battery to "absorb" charge, 23 cells absorb charge at 2.44 vdc for 2 1/2 hours, the 1 weak cell charges at 2.5-2.6 vdc (because its got the Hindlepower attached to it, giving it a boost in VDC. At the end of the charge day, all 24 cells are at at a SG of 1.30. Hopefully this makes sense. Since I have received the Hindlepower, the weak cell hasn't been more than 2 or 3 points diff in SG. I try to stay on top of it, probably more vigilant than need be. How many A/H's are your batteries? How much of a SG difference do you see?
Did you read this whole thread. Another person (with 25 yrs experience) got into a heated discussion with me about the way I was "EQ'ing" my battery. I am still not sure what I am "doing wrong" other than using a Hindlepower charger. He suggests a hobby R/C model battery charger. They are much cheaper but designed for charging a battery 1000 times smaller. Read the whole thread and see what you think. I will stick with the Hindlepower as it designed to charge industrial (forklift batteries)

 

[home skillet]

About your question on how often I boost charge the weak cell. In the winter my battery bank doesn't see a lot of sun so it doesn't charge properly every day. I think this erratic charging takes a toll on the weak cell more than the others. So in the winter, I boost charge every month or so to keep the weak cell in line. I am fairly certain in the summer, the weak cell will not need a boost charge but the jury is still out. For me living in the north, the light goes out (winter) from Thanksgiving thru March 1st and my battery doesn't charge fully everyday (short days and a lot of snow). From March to Turkeyday it seems to fully charge daily. If you have any questions, let me know.

 

[Ralo]

How many A/H's are your batteries? How much of a SG difference do you see?

My batteries are 510AH each. I have 4 of them. I don't check SG that much these days. Only when equalizing. It's alway low anyway. Someone suggested that I add acid to the batteries which I did, but now I'm reading that you should never do that. So hopefully I haven't done too much damage. I guess that artifically boost the SG and maybe even the voltage, causing the charger to think the battery is fully charged when it's really not. I wonder if it is now possible to reduce the acid concentration by removing some of the acid and replacing it with water.

Two of my batteries have shown to contain weak cells. When they get low, they actually go to negative voltage, so they drop the total voltage of the battery more than just 2 volts. Sends my inverter into Low Battery Protection Mode.

Can you post a link to where you got the charger. I'd like to try it. I replace one bad cell with a brand new one and that appears to be a bad idea also because it's so much higher than all the others in voltage. Cells are not balanced. I'm seriously looking at switching to LifePo4.

 

[Ralo]

Ralo, where are you located? I use it when the SG difference reaches 3 points. As a matter of fact i am using the 2.6 vdc charger right now. How many A/H is your battery?

I just bought one off ebay for $200. It was made in 2008 but they guarantee it to work. I hope it helps my weak cells. I have a few of them.