Knackered battery

Didn’t ask him about receipt, will catch him tomorrow, I will have a look into them chargers.

rich28uk said:

I don’t think it could be much else, as I say once started runs fine no warning lights etc, turn off and voltage drops off so to me it’s taking power but not storing it.

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Once it's running the alternator is powering the electrics and the battery gets what's left over. If I leave mine for a few days it takes about 4 hours for my charger to fully charge it from around 12.4v.

backinblack said:

Once it's running the alternator is powering the electrics and the battery gets what's left over. If I leave mine for a few days it takes about 4 hours for my charger to fully charge it from around 12.4v.

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That doesnt sound good what does it drop to just standing?...

I meant to say from what voltage...

Shippers said:

Thats why I said there is a more complicated way to do it for a modern car it's an easy way to do it with a cheap diy dmm...if it sparks when you touch neg to post does that show a drain?

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Not on a modern car all the ecus will come to live with an initial hit

Shippers said:

I meant to say from what voltage...

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It's usually around 12.8v volt's after a run but it soon drops to 12.6v then obv loses a little each day.
I assume it's cos the suspension ecu keeps waking up every 4 or 6 hours (can't remember the exact time).

www.optimabatteries.com/experience/blog/fact-alternators-are-not-designed-to-charge-dead-batteries
Ignore the advertising of their own batteries.

Your neighbour's battery needs fully charging with a battery charger & then see what happens, but likely it's knackered.

20 miles will achieve little & his repeated short journeys will see the battery lose a bit more charge each time until it finishes up like this one.