Not getting complete charge on fork lift batteries

metalguy21

Some months back I went through a long thread here about my battery system not charging up correctly.  I run 2 large fork lift batteries and they weren't charging up hardly at all. That turned out to be the Bulk, Absorb and Float voltages.  The suggested setting by the manufacturer turned out to be far too low for a solar operation.  Since getting these right things have hummed along ... but (always a but) while system operates, charges and seems to have the calculated energy available I am never able to get past 1.265 on SG.  They charge right up and go into float but the SG never gets above 1.265.  Sun availability is not an issue as I'm out in the AZ desert but they never get to 1.285 which I believe is what a fully charged battery should be.  As a starting point I have seen suggestions that fork lift batteries don't charge the same as car and typical L16's - one won't ever get to 1.285. 

Anyways, any suggestions?  Oh, and I am completely confidant in my SG readings.  I've bought 3 different hydrometers.  The one I depend on is a very expensive highly accurate one.  The other two read in the same ballpark.

mcgivor

What do the specs say for SG, if filled to 1.265 that's the maximum it will ever go, unless there is sufficient loss of water to concentrate the electrolyte. Posting a signature is useful to let others see your system details.

metalguy21

Ya sorry, I got lazy and didn't bother with the sys info.  5000w - 25x200w Evergreen panels, Xantrex XW 6048 inverter, 2x Xantrex XW-MPPT 60-150 charge controllers, 2x 12-125-15 875AH (6 hour) 24v Giant Battery 

So you're saying that by design these batteries might just be loaded with electrolyte that at full charge has a 1.265 SG?  That would be in line with what people have told me about Fork Lift batteries not being speced like your average car battery.  I can give them a call today and ask them about that.  Giant has an excellent support team. Unfortunately while they knew a lot about solar applications they didn't know about the proper voltages for Bulk/Absorb/float.  I got those out of the last thread I did here a year ago.  I assume one can open that from this page.  You did a lot of commenting on that one too.  

mcgivor

875Ah at 6 hours is used for high discharge for short periods, in solar applications the 20 hour rate is used, less current over longer periods, read this it provides much of the information you're seeking 
http://gbindustrialbattery.com/Battery_Options/AH_Ratings.html
Lower SG will extend the life at the expense of capacity, based on your  PV capacity versus battery capacity you would be cutting it close for full time off grid, about right for part time.

jonr

While 1.285 is common, a 1.265 initial fill is quite possible.    I believe it's also possible that you had a 1.285 initial fill but some permanent sulfation has occurred, bringing maximum possible SG down.  Stratification can also cause lower measured SGs.

If a battery gets what is certain to be a full, well mixed charge (say an equalization) and SG peaks at X, then going forward, I'd use X as your full charge SG.

metalguy21

I seem to running OK on capacity.  So much sun here it's almost impossible not too.  I had thought I might have oversized the batteries but things seem to be working out.  On the point of damage, yes that seems entirely possible.  The clown show that installed the panels put them in strings of 3 so the system never came close to the proper voltage.  I went severely discharged for almost t=wo months before I insisted they come back and rewire it too strings of 5.  That immediately solved the charging issues but it's entirely possible they killed some of my capacity through their incompetence.  Unfortunately it's hard to be certain as I didn't check the SG when I first got them.  I'm hoping things will last for many years as is.  

In any case, from the comments I'm getting this reading of 1.265 is not entirely unusual and hopeful not that much to be concerned about.

Photowhit

metalguy21 said:

I had thought I might have oversized the batteries but things seem to be working out.  

I don't know if you have read here about GB over estimating the size of their batteries at the 20 hour rate. Their true size will be about half way between the 20 hour rate and the 8 hour rate.

I own one and it came with the electrolyte at around 1.29, a few cells measured 1.3 after commissioning equalizing. I received it about 7 years ago, so things may have changed. 

Photowhit

BTW - SG need to be temperature compensated, a battery that had electrolyte measuring 1.275 at 68 degrees in a factory will likely measure around 1.265 at 85 degrees. Is your battery outside?

Estragon

I didn't see anything about having done an EQ. After absorb is completed, an EQ cycle will charge at higher than absorb voltage and low-ish current. If SG doesn't rise past 1.265 after 1/2hr to an hour, it probably never will

Photowhit

Estragon said:

I didn't see anything about having done an EQ. 

Nice catch! 

@metalguy21 Have you been versed in forklift batteries? They need equalizing every month and possible even more often.  If you haven't done one yet it should become part of your routine.

metalguy21

"... electrolyte measuring 1.275 at 68 degrees in a factory will likely measure around 1.265 at 85 degrees. Is your battery outside?"

That would certainly explain some.  I keep the room they are in ACed to 85 degrees.  As to the EQ, yes I have EQed quite a few times and do so once a month.  It does indeed give a bit more SG like maybe 1.270 for a time.  But over the next few days things return to 1.265 max at float.  

I'm kind of convinced the installers did some damage to them by setting things up so they ran for a couple months at 80% or even more discharge.  However the Giant Battery guy didn't think that should be a problem.  As he said these take insane levels of abuse from fork lift operators are seem to just keep on chugging.  

Oh and ... I have read about Giant gaming their specs.  I imagine I'm about right in my ration of panels wattage to battery AH at this point.