New batteries with low sg/volts

[crankin21]

First post here, just looking for a quick answer. Got a new set of platinium 6v 420 Ah batteries wired up in a 48v bank. 2 of them have very low sg readings with a hydrometer - one cell in one is reading 1.18 even. The rest are 1.22 - 1.23 across the cells. I gave them a freshening charge for 3 hours as per the specs of the batteries, 62v for about 3 hours. All 6 of the good batteries are bubbling at this stage and the sg are drifting closer together but these two are still stuck with these low readings.

I've been on to the distributer but I just wonder am I right in thinking I've got two duds here. When they arrived they had low water even and exposed plates slightly so I was suspect initially but was told but the company it can happen.

[Mike90250]

Exposed plates are ruined (at the exposed portions)

take the 2 low batteries, wire as 12V and use a automotive charger to only charge the duds - you don't want to overcook the good batteries

[crankin21]

Thanks for the input. Don't have something that would drop enough amps into them, I have a 12v 120 Ah charger but that would be too low. They're brand new, I can probably get a replacement (been onto supplier) it's a hassle but seems more reasonable. Would charging them on 12v even do anything? Am I not looking at a shorter life anyway if they arrived like this (and we're probably stored like this for some time too).

[Mike90250]

....... Don't have something that would drop enough amps into them, I have a 12v 120 Ah charger but that would be too low.....

120A charger is not enough ? What size are the batteries ??

A slow 3 day charge on the 2 low batteries is still better than cooking the other batteries to recharge the 2 low ones.

[Tecnodave]

Mike90250,

im reading that he has a charger for a 120 a.h. Battery ?

Cranking,

Mike suggested the correct solution, separate the two lazy ones and use a 12 volt charger on them only, if it's a bit small it will take longer, keep checking the s.g. If it still does not show any improvement they need to go back to where they came from as they probably are sulfated from sitting too long, also exposed plates are not good for batteries.

A good knowledgeable battery dealer would not let that happen or sell you batteries in that state of charge, I would not buy batteries in that condition, Costco and SAMs club is not the place to buy batteries, they do not know how to care for or store batteries

What is the s.g. Of the ones that are doing better? Probably should be more like 1.265-1.270, but do get the manufacturers recommended charge rate and s.g. recommended for the exact battery that you have, do not use some generic charge profile.

[Xplode]

If the plates were exposed when you bought the batteries (i'm assuming they were sold to you brand new from an authorized distributor) then I'd feel most comfortable getting the distributor to replace them. but if that's not an option, then I'd top the water up (not full - just cover the plates or you'll risk overflow during charging) and put them on the 12V charger you've got for a good long soak. Keep an eye on them and hopefully they start gassing and come up a bit.

[crankin21]

Thanks for all the answers. Yes the charger is a caravan battery charger max 120 ah battery recommended, so low amps. I'm in ireland, batteries came from the UK From a big solar distributer. I can seperate them out but I'm off grid here so finding somewhere to charge them for 3 days would be a hassle (Was using a generator up till now) I've already been on to the distributer and he agreed to a replacement for the two bad ones so I'm going to see if he follows through with that, if not ill go down the recharge route. Maybe a garage in the nearest towns might do it for me if they had a good 3 stage with more amps.

Cheers for the help.

[Xplode]

At worst case, your distributor should be willing to plug them in for a couple days.
but fingers crossed you get new ones

[crankin21]

Distributer is in another country, makes everything much tougher. But he's sound, just got back on to him today, he's going to send me replacements and take back these two. Can't ask for more than that.

Where I am the main battery sellers all add crazy mark up so it makes more sense buying from abroad even with shipping. But risks like this are part of the deal. Glad he's come through. Thanks for all the advice.