Trojan 6 volt batteries ruined?

[Bilgediver]

Due to the lockdown issues I had not been down to the boat for 1 month +, when I did manage to get there , I found the 4x 105 6 volt batteries were showing around 2- 3 volts ,
they are in series for a 12 v system on board .
I have slowly recharged them up and they are at 1270+ now , after 2 days rest .

My question is , have they been irreversibly damaged by this low voltage event ?

I would usually see them up at 13.5 / 14 volts after full charge but now they will only reach 1270+
Batteries are 5 years old and always on charge from 300 watts of solar panels .

I wouldn't give up on them if mine. I would cycle them by charging and discharging them and would expect them to respond. I usually use a car headlight bulbs to discharge. I was once given an old Aldis Lamp lead acid battery that was considered goosed. I used it to power a car 8 track player/ radio on board ship. It was like new when I gave it back to the mate 6 months later.
Definitely worth a try .

 

[vas]

I'm surprised that a wet cell array which is open to atmospheric pressure would ever be able push out the sides although, from personal experience with a different brand, I know that a blocked vent will do that without fail. I wonder what the mechanism is with the Trojans?

Richard

Richard, I think (not sure!) that it's the heat that does it to them. Overheated by charging them dry (embarrassed to say that they took around a litre of water each...)
following that incident I've fitted the watering kit so I have one 4lt distilled water can always full next to them and when fully charged and relaxing (late afternoon) once a month I lift and hold the canister above them and in five-ten mins all floaters are up.

 

[RichardS]

Richard, I think (not sure!) that it's the heat that does it to them. Overheated by charging them dry (embarrassed to say that they took around a litre of water each...)
following that incident I've fitted the watering kit so I have one 4lt distilled water can always full next to them and when fully charged and relaxing (late afternoon) once a month I lift and hold the canister above them and in five-ten mins all floaters are up.

OK, I understand now. I misunderstood your point and thought that you were referring to batteries which had reached the end of their useful life under more normal circumstances.

Richard

 

[Boater Sam]

Get one of these to load test them

Totally useless for testing leisure battery banks, designed for testing high current discharge on starter batteries.

 

[differentroads]

Thanks everyone for the feedback .
some further info ,

Trojans are set up as two separate banks of 2x 6v batteries in series as a 12v supply .
Both have solar panels connected through individual MPPT controllers.
...
As both pairs showed this low voltage when connected in the boat I am now thinking that there is possibly some type of drain occurring ?
they keep the charge on the bench .
In the next few days I will refit them and monitor the voltages

What is the best way to load test them ?

3v across the 12v output of your battery bank is very low and the conventional wisdom about lead acid cells is that they will have lost a proportion of their capacity. But how much depends on their condition beforehand and how much the actual capacity matters to you. A liveaboard has a very different need of the batteries than a weekend sailor.
My domestic battery bank is four six year old T105s wired up the same as yours. I'm a full time liveaboard and often go a week to 10 days without mains or engine charging, just solar. In my case I'd be saving up to replace batteries that had been discharged as low as yours sooner than later. But not immediately. Trojans are tough.
But if I was a more normal sailor with your batteries, even losing half their nominal capacity will be fine for weekends and a week or two here and there.
That said, you need to find out what load was on them to discharge them so low, so quickly. It would need something like a fridge or a regularly running bilge pump to run them down while you had solar panels attached. Or a short circuit in one of the batteries draining the others, though that should have shown up during or after recharging. The other potential culprit is the charging circuit itself. It should have at least shown higher volts while the batteries were connected in the boat.

Fingers crossed for a few more years from your batteries yet!

 

[sailaboutvic]

Differentroads has hit the nail on the hit when he used the words , liverboard.
Most of us have large batteries banks not for show but because we need the capacity, so even if the voltages hold up if you lost say a third of your capacity, the question is can you manage with it .
My trojan has gone to another cruisers who can manage with 120 usable AH , his very happy getting a free set of batteries he can work with.
So although they where still good and most wouldn't even known they lost so much capacity and would probably be posting , ( my trojan are X years old and as good as new) for my uses they was U S .

 

[grafozz]

3v across the 12v output of your battery bank is very low and the conventional wisdom about lead acid cells is that they will have lost a proportion of their capacity. But how much depends on their condition beforehand and how much the actual capacity matters to you. A liveaboard has a very different need of the batteries than a weekend sailor.
My domestic battery bank is four six year old T105s wired up the same as yours. I'm a full time liveaboard and often go a week to 10 days without mains or engine charging, just solar. In my case I'd be saving up to replace batteries that had been discharged as low as yours sooner than later. But not immediately. Trojans are tough.
But if I was a more normal sailor with your batteries, even losing half their nominal capacity will be fine for weekends and a week or two here and there.
That said, you need to find out what load was on them to discharge them so low, so quickly. It would need something like a fridge or a regularly running bilge pump to run them down while you had solar panels attached. Or a short circuit in one of the batteries draining the others, though that should have shown up during or after recharging. The other potential culprit is the charging circuit itself. It should have at least shown higher volts while the batteries were connected in the boat.

Fingers crossed for a few more years from your batteries yet!

I am more the week / weekend sailor , but do need the capacity for running a fridge at 2/3 amps . I will try connecting some loads and then re charging them a few times before launching . We are still in lockdown here so little chance of sailing anytime soon . The sun shines most days at this time of year so hopefully the solar panels can take over now .
If it all goes pear shaped with the Trojans I am reading up on Life P04 batteries , prices have dropped and the appeal of losing 20kg x 4 is very enticing !!
That , is another thread , however .....