Homebrewed Electricity > Storage

Reviving S550 Rolls

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bigrockcandymountain:
I'll confess, my battery maintenance isn't as good as I know it should be, but things got really bad the last couple days.  The inverter shut down with very little load, and it was the morning after a very sunny day.  So I shuffle down to the basement and test some things and yikes, SG on 2 cells is 1.100 or so. 

I'll admit, this has been coming on for a long time.  A few months ago I added water and noted that a couple cells were full and not down on water.  Odd I thought.  Better equalize. I didn't.

Anyway, two days ago I finally did an intensive corrective equalize. I ran the generator for 6 hours because, of course it was the only cloudy, calm day of the year.

I got the SG to 1.230 on the 2 bad cells and 1.265 on all the rest.  The batteries got to 50c which isn't too good.  Anyway, today is supposed to be sunny, but I won't be home.  I set the absorb voltage to 60.4v which is only 0.4 above normal.  Hopefully that brings the SG up the rest of the way. 

Do you guys think these batteries will recover or should I be shopping?

Any tips for bringing them back to life?

For the people that keep up with this stuff, if you were to buy batteries today, what would you buy?

I need about 10kwh to 20kwh usable storage.  I see 4kwh off brand lithium for $2500 cad which is getting down to almost lead price.

ruddycrazy:
have a look around for forklift batteries mate, secondhand can take a month or so to adapt to off grid use where power goes in and out at the same time but bang for buck they are the go in my opinion.

The 24 volt 735AH in my shed sat for years never really fully charged and when I found those half dozen 190 watt pv panels what a differnce it has made. Last weekend I spent 6 hours arc welding and the SG only dropped 3 points and with the next days charge they were back on float.

kitestrings:
Sorry to hear, and I'll probably ask more questions than I can answer, but:

How old are the current batteries?
How are they configured?  48V, but two strings, more?
Could any sort of rotation help?

I'm always surprised how long it takes to equalize a large bank.  We generally need a good, long solar day.  I'm not sure I can do it adequately with our generator.  The fact that they came back up is a good sign.  I'm thinking you'll have to see if they can hold there, or fall more rapidly than other cells.

Regarding new batteries - we replaced ours in 2016.  At that time FLA still had the lowest $/kWh/cycle at that time; about $.14 in our case.  We choose a single-series string of 12- 4V IND23-4 Trojans.  Not saying this is the best.  Just sharing our decision.

I do still like FLA over LI, especially where we/you have wind.  I think they are way more resilient to the large current swings that you can get.  A single string also reduces connection points and watering.  They also have a Hydro-link watering system, but we did not incorporate this in our case due to venting.

None of the good options are inexpensive, and I can assume that's only gotten worse.  ~ks

joestue:
If the cells wont recover the acid and stay sulphated.

Drain the acid add distilled water. Charge the cells at low amps for a month.

Drain the 1.1SG acid and put the 1.23sg back in, or use new acid.

Equalize the cells and use the 1.1sg acid to top up the cells as needed to recover the acid

Basically the distilled water encourages sulphate to return solution where as it wont otherwise. Ive done this to recover 20ah useable capacity from a car battery which had slowly degraded to just 3 amp hours.

bigrockcandymountain:
8 years old single series string 428ah at 48v.  Not a lot of storage for the amount of loads we have. Life was different when I planned the system.  3 kids, 2 freezers, dishwasher, miscellaneous junk that plugs in, etc have all been added since the planning stage. Luckily, so has the wind turbine.

It's quite windy today, with 1500w continuous and 2kw peaks, so I'm equalizing with wind right now.  Those cells haven't been dropping back, but not coming up the last couple days either. I'm hoping if I equalize another 3 hours or so I can get them within spec today. 

Joestue, i have read a bunch of your battery revival stories and I'm very glad for the advice.  A month long rehab won't do me much good for the house set that I need to work every day, but when I get a new set, I'll likely try your method on the old ones. Maybe use them for some outlying off grid cow waterers etc.

Ruddycrazy, thanks for reminding me about the forklift option.  I seem to forget about those.  Any tricks for finding them? I have tried kijiji (canadian buy and sell site) but have never found anything.

Maybe industrial auctions or....

I need to get an inverter stick welder.  I hooked the lathe and shaper up like yours with a vfd and l they run like a top.  Wind powered machining is sweet.

What do you mean by "adapt to offgrid use" of the forklift batteries.  What exactyl would you need to do to make that happen?

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