Recover SLA Batteries

[5teve]

HI Guys

I have 6x 100ah Dual purpose marine SLA batteries, split into 2 banks of 3 in parallel. One died a few weeks ago, so I shut one bank down. I have a LIFEpo4 that I am waiting for (should be another 2 weeks as its being made and shipped and shipping is slow across Aus at the moment) that is replacing all 6 batteries - ok my issue is that we lost some more last night while on the boat, so i have now pulled them all off and am trying to determine if I have any left at all that can be used for a trip we have next week.. I have a genset on the boat so i can top them up regularly.. but i would like them to last a bit longer than a few hours.

So question.. I have several that are on charge via a victron multiplus configured for wet cells and 25A max current.

When charging they go to bulk for a very short while and then straight into absorption (the other 20a 4 stage charger I have shows the same).

I assume they are mostly buggered, but i was wondering is hammering them with an equalisation cycle via the victon may wake them up a bit? They charge and float, and hold at 13+v unloaded, but pull down fairly easily with load (a 4a load pulled one down past 12.7v after about 30 minutes.)

Any ideas what I may try to kick a bit of life in them so that we can do our trip next weekend?

My only option other than this is a couple of 75ah deep cycle bosch batteries in parallel - but even those are suspect (old fire pump batteries dated 2017) but going to try and fire them up on the victron too.. OCV was 12.54 though..

Thanks in advance!

Steve

 

[OnTheRoadAgain]

The problem is loss of capacity most likely from sulfation and age.

If these were my batteries, I might start with an internal resistance check to see how far gone they are.
Are they dry? If so, top them up with DISTILLED WATER ONLY.
I have actually seen a battery low on electrolyte recover a bit of capacity after topping up.

Also check the specific gravity of the cells.

I've tried desulfating, rinsing deposits out and a number of "tricks" to get battery capacity back....all without success.
I've even tried the "Old Transformer based charger" trick. (sometimes the battery cells would crack the plastic shell and split open)
I have several optimate "Desulfating" chargers and I can't really say they have ever "recovered" a single battery.

The only thing I have yet to try is cutting the battery open and scraping the lead plates.
Since the problem is hard lead sulfate crystals, I've always wondered if the proper frequency of ultra sonic sound waves could dislodge and
break up the crystals causing the problem. I don't think I've seen any information on that.

If the batteries are mission critical, it may be time to replace with new unfortunately.

 

[5teve]

Thanks for that - some interesting methods there A new battery is on the way.. just not going to be here on time. Single lithium 326ah (2p4s)

the batteries are definitely not dry - you can hear them sloshing when moved. I was thinking sulphated.. but i'm not sure i'm gonna be able to do anything.. they are 7 years old now so its not like they havent done ok.. i just need to get one last trip due to delays in shipping of not only the battery but the DC2DC chargers.. i'm even going through my contacts to see who I may be able to borrow one from

The 2x75ah bosch extra deep cycle batteries I have, havent been charged for a good 6 months - showing 12.54v and went straight in to absorption too.. so not convinced they are going to be any good either... i reckon i could make do with 50ah a day.. if I was careful and charged with genset 2 or 3 times a day..

Steve

 

[OnTheRoadAgain]

7 years on Lead Acid batteries means you took good care of them.

But they are probably past ripe.

 

[5teve]

7 years on Lead Acid batteries means you took good care of them.

But they are probably past ripe.

Yep I know they lasted well.. being bought all at the same time and probably from the same batch (by previous owner) means they have all dropped at the same time..

Oh well.. i may try a few other things and see how I go.. its almost becoming not worth it as it literally one more trip.. !

Steve

 

[OnTheRoadAgain]

Yep I know they lasted well.. being bought all at the same time and probably from the same batch (by previous owner) means they have all dropped at the same time..

Oh well.. i may try a few other things and see how I go.. its almost becoming not worth it as it literally one more trip.. !

Steve

I've heard of someone saying "zapping" them with an arc welder breaks the hard crystalline shell on the plates.....
and I have an arc welder.....but that sounds dangerous. Not worth it to me.

If only you could "borrow" a few batteries just for the trip.

 

[5teve]

I have an arc welder too.. just not sure i'm game risking covering myself and the garage in acid..

Its looking likely that the 'trip' wont go ahead as the wind is not looking spectacular!

Steve