Reviving a little used car battery!?

I would stick it on a slow charge with another battery connected in parallel with leads to get it going.
If the cells start bubbling after a while you're onto a winner.
It's worth a go, you've nothing to lose.

I knew a guy who used to swear by them but I've never tried them.
Look a bit snake oil to me.
I bit of googling might turn up some hard evidence either way.

Thanks all.

Will I risk killing my good battery though by sticking it in parallel?

I have some SLA batteries about half the size of a car battery that hold decent charge...I don't mind killing those so much. Can I use one of those to get the charger going even though they are much smaller capacity?

Could try Epsom salts
Ttfn Glenn

Batteries self-discharge. A car IME will only ever give a surface charge, so if the battery does run low, it really needs going onto a proper car charger to revive it. The electrolyte will still be above the plates since as the water level drops the plates also suphate with them eventually forming hard crystals. Of course, this reduce the volume in the battery for fluid, so the fuild level won't tend to drop. IME it only tends to drop if either the battery is leaking somewhere, the battery is being boiled from overcharging, or the solution is boiling off from normal use, generally down to the electrolyte becoming weaker as the battery becomes sulphated.

My knackered Merc battery had water above the plates. It was a 2013 battery, on a car that hadn't been run for 2 years. It was bubbling away on the CTEK and despite various attempts at recharging, it's days were numbered. Yes I did try it, but God that car struggled to turn over with it. A week prior to this shot, it was floating at 12.5V off the car, with it never going back into the car.



It sounds like yours is too late in some ways.

You can attempt to revive it as stated above; I've heard mixed stories myself ; once the plates become suphated over a period of time that stuff becomes pretty rock hard. But if it were me I'd attempt to do the following:

-Recharge it on a battery charger until full. That is if the battery charges. Some charges can do full charges. People say the smart chargers can't do this. My CTEK can ; it has a supply mode for testing purposes which can lend itself well here. If it works on a fancy charger like a CTEK, try the Reconditioning function
-Put it onto a capacitance tester; the Foxwell BT-100 is available for little money and IME gives far more conclusive proof of what's going on over a simple voltmeter. If it comes back as dead there, as in less than 50% of the CCA is available in the battery, it's goose is cooked.

At this time of year, it's not really worth trying solutions, especially if you need the car IMHO.

I wrote a post on it a while back, as TBH I've been there, and keep going there!

forum.retro-rides.org/thread/201788/car-batteries-testing-charging-maintaining