Car battery or alternator

dinners

dinners

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I've a poor car battery - which I can easily replace but before i do...

I've two cars so jumping is easy but can the likes of National test to see whether the problem lies with the battery not getting a charge - alternator etc ?
 
dinners said:
I've a poor car battery - which I can easily replace but before i do...

I've two cars so jumping is easy but can the likes of National test to see whether the problem lies with the battery not getting a charge - alternator etc ?
Click to expand...

Go buy a cheap volt meter, place on terminal with engine off then start the engine and check again to see if the alternator is pushing a current to the battery
 
It's pretty easy to test yourself - if you can jump start...

Get it going then load the cars electrics - turn it all on... air con.. lights - main beam - fans on full.. heated rear window... Then see if the lights remain bright.. And see if the engine keeps running... If it can support itself it'll all keep going... If the alternator isn't charging it'll die in a few minutes, and the lights wont remain bright..
 
Do also remember that once a battery becomes discharged it will lose any charge very quickly.

As said check the voltage across the terminals to see if the alternator is ok. Buy your batteries online. I'm gonna order a new Varta one from tayna
 
Cheers folks - handy advice.

It's a Land Rover Discovery - the battery has a circular window on it which displays the battery 'condition'

Green = good, Dark = needs charging, Clear = buggered

It's either dark or clear - can't really tell.

Jumps fine so I'll try switching the works on and leave it running to see if it dies.
 
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If it is the same make I had then they're crap. I've had 3 in the last few months! Final one seems to be ok though. I've got a trickle charger and the 2nd one made it go orange (battery buggered) the first time I hooked it up. Current one is showing green (ok).

Modern batteries don't tolerate going flat at all. They also seem to die without warning much faster. Car was turning over slowly. Battery then dead. Normally they go a bit slow and work for months before dying or die in cold weather. This one was ok to dead in about 2 trips.
 
FWIW, which is probably not much, my last two car batteries have each last 6 years before needing replacing. First was original fit. First replacement was a midrange affair from a local motor spares shop. Second replacement was a fancy pants battery from carparts4less, with four year warranty, but at what I felt was a fair price. So how old is your battery? Is it reasonable that it is FUBAR by now?

For a cheap multimeter I have this one - http://www.ebay.co.uk/itm/DT830B-LC..._Measurement_Equipment_ET&hash=item416a3b359b. It seems to work well enough for my needs, but with delivery from the Far East, not much use if you're in a rush. Maybe Maplin has something.
 
Cheers folks

No idea how old the battery is as it was a used car.
 
You can get a decent manual ranging meter from B & Q for a tenner.
 
Any good car part shop should be able to test your battery and alternator for free, also with the disco check the engine earths are ok and also the one going to the gear/transfer box as they cause trouble aswell
 
Multimeter across battery when engine running, should be reading a good 13.7 - 14.5v, any less and it's alternator at fault.

Don't just jump it, charge it fully and if you can check the electrolyte levels and add some de ionised water if necessary. After that leave it be over night, and measure the voltage in the morning. Healthy = 12.4 or a thereabouts (or better), Anything under 11.5 bin it.

This modern batteries nonsense is pure bunkum. The only ones to watch out for are Gel batteries (not AGM, they're not the same thing at all) , they have their uses but should be nowhere near a car!
 
Thanks folks - lots to take in but lots of help.
 
I was going to say that no one jumped in with a correct answer, if you're running a charging circuit then your V meter needs to read 13.8V or higher to confirm an AC current from the alternator, if it's less than 13 then you know that the battery is regulating and supplying charge to the complete circuit ;)
 
Cheers Dave - I'll come back once I've get my head around that.
 
National should have a drop tester to check your battery and should also be able to check your alternator too.
 
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