Battery charging with external charger

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Andrew S
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Battery charging with external charger

Post by Andrew S » Thu Jan 04, 2018 8:19 am

Last weekend I tried to charge my daughters 2004 1.2 Polo but when I put the clips from the external charger onto the battery, it didn't like it. I put the red clip off the charger + onto the battery terminal with the thick red wire and then black clip off charger to the black wire on the battery. It was quiet sparky and the needle on the charger kept flicking. Normally this would mean the polarities are round the wrong way but I can't see how.

The thick red wire on the terminal is on the drivers side as I see it.

The battery is not flat but I just wanted to top it up when it was cold weather and it only has short runs around town.

So, my question is, was I doing the right thing in charging directly to the battery and am I getting the polarities round the right way?

Any advice appreciated
Andrew

RUM4MO
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Re: Battery charging with external charger

Post by RUM4MO » Thu Jan 04, 2018 9:31 am

I can't see what you did would be a problem, I'm guessing that you switched your charger on before connecting it to the battery? I'd never do that, connect it to the battery first then switch the charger on, maybe your charger or its leads are faulty? As you have said that the battery was roughly okay before you connected this charger, I would not have expected any sparking at all!

bvs
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Re: Battery charging with external charger

Post by bvs » Thu Jan 04, 2018 10:52 am

Is your charger quite old ?
I have only ever used a smart charger to charge an in situ battery (CTEK mxs 5.0 which is a smart charger/conditioner).

Charging a car battery in situ should never be more than a trickle charge,a ctek charger is normally connected as Red onto + ve battery terminal and Black onto a good earth/ground point - not to battery -ve terminal.And keeping the charger as far away as possible from the battery.
A good modern charger should be able to charge a battery in situ but older chargers might be a little too unstable in their charge current delivery to be completely safe with the car's elec system.

RUM4MO
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Re: Battery charging with external charger

Post by RUM4MO » Thu Jan 04, 2018 12:12 pm

Fair point wrt age of charger, I use a CTEK MXS 5.0 to keep my much underused Audi S4's AGM battery happy, it tends to be connected all the time that car sleeps in the garage.

I seem to have given away all my older "dumb" chargers to a less discerning person to charge up old tractor batteries, very little harm to be done there!

As a minimum, I would only every use a modern charger that has the ability to drop back the charge to trickle charge when the battery is fully charged, although most of the older basic chargers were only half wave rectification and would run "out of puff" when the 12 volt battery was fully charged, so very little danger of "boiling" the battery if left on too long.

My rough but slightly smart everyday charger is just an "RAC 8Amp" one bought in a panic from Argos, so you can get a safe enough charger without buying a CTEK product, but they are good, maybe a bit late to ask for one for Christmas?

Andrew S
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Location: Leigh on Sea, Essex

Re: Battery charging with external charger

Post by Andrew S » Thu Jan 04, 2018 12:41 pm

Thanks for the responses.

The charger is older but works well on my 5 series BM and my other car. I'll check it for damage and maybe check it on the daily car to see if its faulty and if so, will treat myself to a new one

Cheers
Andrew

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