# The wrong charger (too many amps) - what will happen?



## KneesUp (15 Feb 2021)

Mrs K's tiny Citroen has a flat battery, so I've dug out the jump start battery-pack thing but it too is low on charge. I can't find it's proper charger, despite my owning a box of tangled cables that seems to be the preserve of the middle-aged-man. I have, however, found a charger with the correct plug, the correct polarity and the correct voltage, but it produces too much current - the booster battery says the input should be 12v / 1.5A and the charger I've turned up is 12v / 2.5A

What are the implications of using this charger, if any?

Ta?


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## Electric_Andy (15 Feb 2021)

This is not advice, but I'd just plug it in and keep an eye on it.

The rule of thumb for modern batteries is 50%. E.g. if the battery in your jump starter is 5Ah then you should not exceed 2.5Ah when charging. What sort of battery pack is it? Can you tell what Ah the battery is?


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## Electric_Andy (15 Feb 2021)

Or can you jump start the car off another car? Might be quicker and easier...assuming it's just gone flat due to inactivity and that there are no other issues with either the battery or charging system


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## Mr Celine (15 Feb 2021)

Cut out the middle man. Connect your charger to the car battery. 2.5A is nothing compared with what the alternator will chuck out.


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## KneesUp (15 Feb 2021)

Electric_Andy said:


> Or can you jump start the car off another car? Might be quicker and easier...assuming it's just gone flat due to inactivity and that there are no other issues with either the battery or charging system


It's the OH's car - she's taken mine, and it has the jump leads in :-) I think the battery is shot though; the car has been sat for a while so once I started it (the booster thing was fine on the wrong charger) I took it for a drive to fully charge and I'll give it a try tomorrow afternoon and see if it starts.


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## SkipdiverJohn (18 Feb 2021)

Don't condemn any battery without giving it a sustained period of low rate charging or you might be throwing away both a good battery and your cash.
I was given a large and expensive AGM battery by someone at work, and was told it was duff. At the time, the battery on my Land Rover was about 11 years old and getting past it's best. Having nothing to lose apart from a couple of hundred quid if I bought a new tractor-sized battery for nothing, I decided to see if the AGM was really duff or not. I charged it at a very low rate using an old school charger with an analogue ammeter - for the best part of a week, before fitting and testing it. Far from being duff at all, the AGM battery was easily as strong as the 11 year old battery had been when that was new and it's holding it's charge for weeks and will still spin the engine like a good'un.


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## KneesUp (18 Feb 2021)

This is a fairly small battery as it’s only a C1 but pleased to say it has been fine since.


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