Help me keep my 6v Rolls Alive!

[joe4324]

I have been searching on info all over the place and I'm not coming up with much help.  I can't resort to grid power for charging so alot of advice doesn't work for me.   

Here is my situation.

I'm off grid,  to get these batteries to the grid power requires a car ride.   I have 4,  400ah/20hr 6v Rolls Deep Cycle batteries that were given to me free 2 years ago by a neighbor.  They leaked from the top and were not holding a charge well when I got them for free.  I've since been using them as my sole power source.  Knowing they were free and going to be replaced 'soon' I've used the hell out of them and have no actively neglected them,  But they have suffered some pretty major abuse.

I only have a 250watt mppt controller and one 200watt 24v panel charging them.  (I know its not enough)  I have a diesel/veggie generator that puts out 2.5kw that I run a couple hours a day to dump more power in and to run my heavy power devices.  Of course I keep adding more loads to the system but total daily draw is still 1-1.5kw total if that.  I am using a Xantrex 1750 mod sine inverter.

I have been using a 50amp 12v charger that was only 100$ from tractor supply to dump power into them when the generator is running.


I have just found out recently that my complete RE system upgrade isn't coming anytime soon so I'm in damage control. I may have to limp by with these batteries another 8 months or more! 

Its a completely make-shift cobbled together system that I built for remarkably little money, but I have to get aggressive because I think the batteries are really on theyre way out.

Before hooking them up last year I took them to town to a friends place and charged them with a automatic charger @10 amps for 3 days.   They seemed to bounce back to life.  They held steady at 12.7V  even after running a electrolyzer drawing   35amps for 20 minutes.    Since then they have been slowly getting weaker and weaker.

Infact I cannot get them to hold above 12.1v no matter how long I charge them with the generator.   Even if I blitz them with 50amps for 3 hours, then second the generator is off even just running a laptop and 13w light they fall off to 11.9-11.7v. 

Fearing that they are on the verge of completely dying I'm not sure what to do.  I suspect the lack of reaching 100% SOC 'ever' combined with frequently setting at or below 12v is quickly coating the plates with sulfation and that with-in a couple months they won't even run a laptop for a night anymore.

I can run the generator for extended periods of time, but I've been trying to over charge them (even at 50amps, they never read above 12.7v during charging with no loads).  But it has no impact.

I do not have a hydrometer,  and perhaps my 12v charger is on the fritz or does not like the generator power even though everything else likes it just fine, even things that hate the mod sine wave inverter.


What else can i do?  they are full of water of course.

Thanks so much,  This is going to be an adventure!

[RP]

Just a few thoughts:

1.  Are you sure your volt meter is okay?  If you use it on your vehicle battery does it ever read above 12.7volts?

2.  I'm assuming these are wired series-parallel to form a 12 volt bank.  Have you considered breaking the system down to 2 separate banks so you could try to identify the bad battery? (one bad battery could be causing these problems, not necessarily all of them).

3.  If you suspect the generator-charger combination, can you try charging 1 pair of batteries from your vehicle alternator (jumper cables)?  Maybe you can get the voltage up that way.

[dnix71]

Try adding a small amounts of epsom salts to each cell. [Magnesium sulfate].

That will replace the sulfate lost to hard sulfation. Charge them slowly after that and see if they come up again.

[bob g]

"That will replace the sulfate lost to hard sulfation."

i for one would like to hear more about this theory!

bob g

[kurt]

it really sounds to me like you are massively undercharging those batteries 50 amps x 3 hours is only 150 amp hours and you have 800 amp hours of battery there or at least you did when new you should be charging them until they hit 14.5-15v get those batteries boiling a little it will help them not hurt them.

[joe4324]

I'm showing some small signs of success.   I ran the generator for 6 hours yesterday and I got them to 12.8V but they sat there for almost 2 hours and did not go above it I just couldn't run the generator anymore.  I need to get more amps into them somehow.  I wish I knew someone I could borrow a charger from.  Over the next couple days I'm just going to pummel them with power.  I think Kurt is right I have just been massively undercharging them and they slowly wore themselves down.  I'm going to over the next couple days try to push them into the 14.5V area by double-timing my generator.  I wish i could just get another 50amp charger...

[Volvo farmer]

If you split the bank in half, you are effectively doubling your charging rate. I assume you are doing all this charging at 12V. Have you thought about splitting the bank and charging two batteries at a time to get them full and equalized?

[CraigCarmichael]

IF your batteries are "on their way out" and not just undercharged...

Someone suggested Epsom salts... That's the worst of the sulfate salts to use to rejuvenate a battery. Alum is better, sodium sulfate is the best one.

I worked out how much sodium sulfate to add. Other sites will give you instructions for battery renewal with alum.

The best time to put in Na2SO4 or NaAl(SO4)2 is when the battery is new - then you can just add it to the electrolyte and the battery will last much longer. When it's old, you have to dump the acid and do the renewal procedure. Don't just add sulfate salt to a mid-life battery.

Craig
Did you know: linking offsite to less-than-practical idea websites is frowned upon even if you are a wonderful person 99.8% of the time - thanks for your understanding.

[Rollo]

here is something you might try;this is out of an old book.
Drain all the acid out,rinse out all the accumulated crud,fill several times with distilled water and charge the hell out of it whenever you add new water.Refill with acid and check for increased capacity.Adding alum sulfate might help.I reconstituted some Golf cart batts some time ago,did not use the alum.
BTW,the drained acid did not kill my grass  :<)

[kurt]

BTW,the drained acid did not kill my grass  :<)

i hope you or none of your neighbors has a well in the area because you just contributed to the contamination of the local ground water i pretty much guarantee it. that acid and flush water would be full of lead. lead has a tendency to show up in ground water when it is dumped in a soluble form.  about as dumb as poring used motor oil on your gravel driveway to kill weeds. they set up lead acid battery recycling programs years ago for a reason you know...

[ricie]

I think you should break the batterys in 2 banks and charge them and test them to see if there getting the right reading, if there not see which is the bad battery and replace it it can make your system work harder to charge and the energy is lost do to heat.

[CraigCarmichael]

When I say "dump the acid", how its done is of course up to you.

As I say on my Na2SO4 web page that I'm not allowed to "pimp", with comprehensive instructions and safety pointers for doing all this, dump the battery contents into a plastic container. Let the lead settle out and pour off the acid. Dump the lead/lead oxides into some other battery that's going for recycling anyway - it's just more of what's already in it.

I then neutralize the acid, which now has just trace lead contamination, with potassium hydroxide, at which point it's a safe bio-degradable salt, potassium sulfate.

My complete researches on the subject are in my monthly newsletters, available on line, from September 2009 to May or June 2010.

--Craig

[bob g]

Craig:

i realize you are really excited about your assertion that adding salts to an otherwise good battery is the way to go
and it would also appear there are those that are equally excited about desulfators being used on otherwise good batteries
from the git go...

i however am not sold on any of this bullcrapola, (ok, perhaps that is too harsh)

can you direct me to some unaffiliated testing facilities that have done double blind testing, that supports your claims?

the problem i have with most that hawk this stuff, is they usually always refer to "sulfation" as something that should be avoided
at all cost, when clearly it is an ordinary and normal part of the battery discharging process.

now allowing the normal sulfation to let sit and harden by improper charging (undercharging) and no equalization clearly is a cardinal sin
if not a mortal one.

it seems to me that if one needs to resort to adding salts, or pulse desulfators, he ought to first take a hard look at his improper charging
practices, or insufficient capability to charge them properly to start with.

perhaps you can pm me some links to some solid information and not anecdotal evidence from those that have something to sell.

i have been researching this topic for a very long time now, and to date i have found nearly nothing from an independent test lab that would support the addition of salts, or the use of a desulfator when the batteries are maintained/charged properly.

bob g

[thirteen]

I do not know your battery connections. As a suggestion check your cables for hot spots or poor connections and check each battery by it's self. You will have to try and charge them fully and to me it seems as if you could have a couple of bad cells. Maybe barrow a different volt meter and check it againest your meter. They may be dieing, best of luck with them. Just a couple of ideas to ponder or toss.