Battery chargers ?

[sunbeam alpine]

Jacuzzi101 said:

Bit of a thread hijack on this, but expanding on what has been discussed already. Hoping to get some help!

I have a flat 12V battery (reading 1.8V) which I'm looking to resurrect (it's probably only a couple of years old and the battery condition indicator on the top suggests it doesn't need to be replaced).

The trickle charger (AA branded 1.5A) I've tried won't charge it, returning a fault light, presumable due to the low voltage protection.

In the garage I found an old Heayberd 2A battery charger.
https://imgur.com/a/IRRe2
https://imgur.com/a/pqQcR
I've tried using this charger, but the label states 'keep pointer within green section,' which denotes 0-2A, and when I connect it to the battery the pointer jumps straight to the limit of the red section (4A+), so I've turned it off as I assume it might be unsafe to continue.

I'm just looking to coax the trickle charger into starting to charge the battery, even if it takes 2 or 3 days.

Is it safe for me to connect that 2A Heayberd charger and leave it on at 4A+ in the red zone for a period of time until the trickle charger recognizes 12V and begins charging?

Thanks!

If you have a good battery and jump leads, connect the good battery to the dead battery using the jump leads, and it should charge.

[Jacuzzi101]

sunbeam alpine said:

If you have a good battery and jump leads, connect the good battery to the dead battery using the jump leads, and it should charge.

Thanks. I don't have a good 12V battery atm, so have just been trying to see if I could find a work-around with what I had in the garage.

May well end up buying a new battery in the end if the current one can't hold much charge.

[AW111]

Connect the trickle charger
Connect the other charger in parallel, for about 15 seconds
This may lift the voltage enough for the trickle charger to start working.

[GreenV8S]

Jacuzzi101 said:

I have a flat 12V battery (reading 1.8V) which I'm looking to resurrect (it's probably only a couple of years old and the battery condition indicator on the top suggests it doesn't need to be replaced).

If that's an ordinary automotive 12V battery you've got two chances of resurrecting that: slim, and none.

Even if you're lucky and none of the cells have shorted out and they all eventually come up to voltage, the charge capacity and current capacity will be massively reduced by the deep discharge. More likely you will have some number of dead cells so you might end up with a very poor performing 10V battery, or 8V, or whatever.