How long to charge a car battery

[Tony Starks]

I stupidly left the lights on and completely drained my battery, so bought a 9stage 5A digital charger. It hasn't come up with any errors, so the battery should be good. But it's been 44 hours now and it's still not saying its fully charged.

Is this normal or is the battery a problem? Its a bigger battery (630 CCA) for my MPS.

[10126 Torino]

44 seems excessive ,I would hope to charge up a battery in lot less than 1/2 that.
How old is the battery ?

[Tony Starks]

Not sure, only date I can see is 2016. Although the manual does say on rare occasions it can take upto 48 hours

[Tony Starks]

Probably a dumb question, but are these cables/terminals for hard wiring a connector in the engine bay or for a different type of battery?

Edited by Tony Starks on Saturday 11th April 07:56

[Benrad]

Is there a number on the battery that ends Ah? That's amp hours (a measure of the energy stored in the battery) divide that number by 5 (the rate your charger supplies current in amps) and you've got an approximate target.

It'll charge slowly when the battery is nearly empty and nearly full though, so it will take longer than that

[Tony Starks]

No Ah, but it does have a CCA of 630.

[Tyre Smoke]

That's Cold Cranking Amps of 630.

Does the battery start the car now? Or is it still dead? Could be your battery was on it's way and flattening it has been the final nail.

[breamster]

Tony Starks said:

No Ah, but it does have a CCA of 630.

Not that I'm bored waiting for my family to wake but I've googled this. Apparently the rule of thumb conversion is to divide CCA by 7.25 to give and approximate ah.

So 630/7.25 is approx 87ah which when divided by your 5amp charger suggests a full charge should take 17hrs. Don't blame me if I'm wrong!

I would try starting the car. It should start even if not fully charged I would have thought. But then I'm no spanner monkey.

[Tyre Smoke]

If it won't start, turn on the headlights. If they go dim when you try to start, it's the battery. If they don't it's likely the starter motor.
I know you said the battery went flat, but these things do happen.

[Tony Starks]

I does start now with the battery in, although it starts first turn its not the instant jump into life like normal. Although it's getting a charge I am thinking the battery is on its way out

[Tyre Smoke]

What's it fitted in? Lots of short stop start journeys?

From the 2016, it's at least four years old. If one cell had gone, flattening it will certainly kill the battery. It may decide not to hold charge now.

[E-bmw]

Tony Starks said:

I am thinking the battery is on its way out

A fully flattened battery will rarely fully recover, you have tried, which is the right first step but I suspect this is now the way forward.

[Tony Starks]

Tyre Smoke said:

What's it fitted in? Lots of short stop start journeys?

From the 2016, it's at least four years old. If one cell had gone, flattening it will certainly kill the battery. It may decide not to hold charge now.

Mazda MPS, mixture of everything. Although it had been sat for two weeks

[Tyre Smoke]

I think see how it goes. But be prepared to by a new battery.

[magpie215]

I think battery sales will rocket post lockdown....... I have been trickle charging my cars during this but I think most of my neighbours are expecting just to turn the key and go.

[breamster]

magpie215 said:

I think battery sales will rocket post lockdown....... I have been trickle charging my cars during this but I think most of my neighbours are expecting just to turn the key and go.

Absolutely. I went to use what I thought would be the most reliable of our three cars yesterday and it was flat, now recharged and working. I only have one plumbed in trickle charger so I can't easily use that on the other cars.

[Tony Starks]

magpie215 said:

I think battery sales will rocket post lockdown....... I have been trickle charging my cars during this but I think most of my neighbours are expecting just to turn the key and go.

Definitely, there's been about 3 flat batteries on my local FB group. After watching the latest Tyre reviews video on tyres I've now rotated them a bit too

[Baldchap]

breamster said:

magpie215 said:

I think battery sales will rocket post lockdown....... I have been trickle charging my cars during this but I think most of my neighbours are expecting just to turn the key and go.

Absolutely. I went to use what I thought would be the most reliable of our three cars yesterday and it was flat, now recharged and working. I only have one plumbed in trickle charger so I can't easily use that on the other cars.

I've charged and disconnected batteries in all but my dogbus and the missus' car.