Battery keeps going flat

twhitehousescat

a 5-10 mile drive without lights heater or heated screen should charge the battery

so its either not charging , or its going flat overnight

Rolandtheroadie

Findif wrote: »

Thanks for the tips guys..

If I have been driving long distance since I got the car jump lead started.... should that be enough to fully charge the battery?

I don't think there's any point buying a battery testing kit . If I'm going to end up buying a new battery anyway.

I do have a charger which can connect to the mains at home. But is this necessary? If I've been driving ?

An alternator tops up a battery. If your battery is totally flat, it would take a while/really long distance. A lot more than 5-10 miles of driving.

£8 could save you buying a new battery (the multimeter, not the battery test kit). It'll tell you the actual charging voltage (discount the alternator) and let you see if something is draining your battery.

A lot cheaper than a battery.

Over and above that, if your battery is being constantly under or over charged, you'll just destroy the new battery too. Might take a year or two though.

greyteam1959

Go to your local independent garage & get you battery tested free of charge.
Simple.

parking_question_chap

How old is the battery?

daveyjp

A simple voltage check won't tell you much. A battery could read 12.5v, but it doesn't mean it is in good condition. Checking CCA (cold cranking amps) is far more useful, for that you need a decent battery tester.

Before spending money check all the battery cells have adequate level of water.

AdrianC

When you replaced the alternator last year... Had the battery been flattened a few times?

If so, then it's almost certain your battery is dying. They really don't like being run flat, and the colder weather will highlight the reduced capacity arising from that.

Norman_Castle

Findif wrote: »

Should that sort of driving charge the battery to it's max capacity ? Whatever the max is.

It should charge it enough to keep it healthy. If it started easily with a jump start its probably low rather than flat.

Check that nothing is being left on in the car overnight such as interior lights or phone chargers. Car spares shops often do battery checks.

The_Fat_Controller

If a battery has failed, no amount of driving and charging will resurrect it !

Get the battery tested.

mollycat

Why not buy the £7 multimeter (or something similar) @rolandtheroadie linked?

Even if you need a new battery it's a no-brainer, because you will be checking either your new battery or the existing battery (if the problem lies elsewhere), on an ongoing basis, yeah?

I use mine on all the household vehicles as well as other DIY duties, plenty of youtube videos showing you how to use it for all the different things, really easy even if you're not mechanically/electrically minded.

TLDR; multimeter for pennies first, new battery, (or whatever) second.

Mutton_Geoff

To the inexperienced, a multimeter is useless, as DaveyJJ says, it's cold cranking amps you need to measure which involves measuring current, so you'd need a current clamp for the multimeter.


Measuring voltages across the terminals will not tell you much about the state of the battery. Just get it tested by a place with the correct gear and replace yourself or have them do it.