Dead(?) Battery

[Tony_C]

Preamble: This is non TR but an old Jag I have but more recently rarely use… I bought a new (Bosch) battery which was fine the rare occasions that I used the car, really only once or twice. However, I stupidly left it connected without any trickle or ‘maintenance’ charge for some time, to then find flat at only 4.5 - I suspect the alarm was the main culprit!

Maintenance and other modern ‘intelligent charging’ all failed. Therefore, as a last resort, I have resorted to this ‘old monster’ - any one remember them, what period? - which has slowly (over the last day and a bit) and progressively brought up to 10+volts, getting itself warm from the outset and registering a fairly consistent 1amp…. Question I would like to know from all you experts, will I do any ‘damage’ keeping going? - Don’t think I can go back to Bosch without any paperwork? - But, should it have died with so little actual use?

 

Good weekend to all

 

Tony

 

 

[RobH]

As you have found Tony, by design most smart chargers won't even start to charge a battery that is too far down.  You are doing the right thing in giving the battery a slow charge but it will depend on how long it was in a discharged state whether you will be successful in recovering it.  

If you do get it back to fully charged (around 12.8 volts when open circuit at rest), you will probably find it has lost a lot of capacity and it may take a number of full charge/discharge cycles before it returns to anything like normal (discharge to 12V when open circuit).  If it was down for a long time (months) it may never recover, as the sulphation could be permanent. 

 

[Tony_C]

Thanks Rob, and yes it was months (stupid me but time does seem to fly).. I’ll give it a couple of days and report back…

 

(I’m loving that this really old charger, full of cobwebs and all, is already getting so much farther than all the modern replacements with all the gizmos but, was /am slightly concerned that I threw out another old - but much newer charger - many years ago due to concerns…)

[Ralph Whitaker]

My smart chargers have a repair cycle on them, which as far as I can tell alternates between charge and discharge many times, designed to break down the sulphation, and I have successfuly recovered a couple of dead batteries using them. Once you have enough voltage in your battery to be able to switch to a smart charger you may well be able to rescue it.

Ralph

[ctc77965o]

Won't do any harm if the charging voltage stays in the ~12-14 volt range.... many smart chargers have a 'power supply' mode - i use that to bring-up a fully flat battery, a few hours like that and then switch to normal charging mode and all is good. In my experience, a battery that a 'smart charger ' says is dead can be fully recovered and used for many years this way.

[Tony_C]

Thanks Ralph and Dave, giving me some hope…. (Very) slowly and steadily coming up to just under 11volts - not enough! - with the charge still around one amp.

 

No concerns with a modern sealed for life battery ‘boiling’ ? - Remembering we used to loosen the caps and add distilled water in the old days

[RobH]

48 minutes ago, Tony_C said:

No concerns with a modern sealed for life battery ‘boiling’

Yes there is  - which is why the charge rate needs to be slow. Sealed batteries have a venting system for safety if the internal pressure gets too high but that will probably spray electrolyte if it operates, and negate the likelihood of successful recovery. 

[Tony_C]

Thanks Rob, that makes sense… I will give it a little longer slowly and steadily..

 

(Sure I should not really be asking this: Does sealed actually mean sealed, or can you - is it beneficial to - peel off the plastic sticker and can you still open the caps underneath to have a sight in at the level and what is going on?)

[RobH]

You may be able to do that Tony, it depends on the maker and exact type I guess.  From your description It sounds as though it isn't an AGM or gel-cell battery - you certainly can't on those. 

A maintenance-free 'sealed' flooded battery sometimes does have caps or a cover strip under the sticker that can be removed, but some makers glue them together. They usually have a good amount of excess electrolyte which is supposed to last the life of the battery without requiring top-up and if your battery is relatively new that is unlikely to be a problem.  

[Lebro]

Yuasa don't have accessable  caps, I know, I tries very hard to top up one that I had.

Bob

[Tony_C]

Bosch….. and looks like they really do not intend you to get access inside

[ianc]

I have an old charger, bought some 60+ years ago, and it will happily charge a battery from next to zero volts because it has (I believe) a selenium rectifier and charges at only some 1.5 amps, or less.

It's housed in quite a large metal box, but so what - it it does the job and is reliable.

Ian Cornish

[SpitFireSIX]

Hi,

 A smart charger is smart because it is smart! If the Battery is at minus SOC for a long period it will never recover to as-new. 
Charge a standard Lead-Acid @ 13.8 volts & it will not gas or overcharge. You do not need to regulate the amps, let it take as much as it wants. It's called Float.

Do not let a standard car battery discharge below 80% SOC. Ever.
 

Cheap battery testers that measure SOC, SOH are cheap these days; Buy one.

Cheers,

Iain.

Edited September 7, 2022 by SpitFireSIX
but to buy