Flat battery....again

[bobob]

If i don't drive my Feli for a few days the battery goes flat.
I thought it was a duff battery so changed it for a new one 3 weeks ago,
last used the car on Wednesday but it was as dead as a dodo today.
I can't understand why it's doing this, the interior and boot light aren't left on, all that seems to be running is the flashing stereo and immobiliser lights.
Anyone got any ideas what could be draining the battery

[Lummox]

You need to see what current is there draining the battery down.

This means connecting an ammeter in line with the battery or use an amp clamp to see what the drain is. Once you have this info the best method is to pull each fuse in turn until the drain goes then that gives you the system that is draining the battery.

[Lummox]

Either that or the alternator isnt charging and gradually the battery voltage is getting dragged down until it wont start, check the charge rate out.

[harryhill]

I had a similar problem on a Rover 200 and the problem was with the voltage regulator on the alternator.

Basically the charge was not getting back to the battery. Perhaps this could the problem.

[bobob]

Thanks both, though i haven't got or got a clue how to use an ammeter

[anewman]

Get yourself a cheap multimeter, maplins and wilkinsons sell something suitable. All it is is a device with two wires, black and red, with metal probes on the end. You shove these on what you want to test.

For the alternator you should get about 14v off the battery with the engine running. For voltage regulator test with engine running put on everything headlights, fans, heated rearscreen basically everything, and see if the voltage stays the same. Usual precautions apply, no dangly clothing or jewellery and be careful.

[surprising_skod]

if its your alternator, its not going to charge the engine whilst you use it, but that will mean after a long run, you wont be able to restart. if when you constantly use the car, it doesn't drain, as seems to be the case, that means its another system draining power, but leaving enough overnight to start the car and charge the batt up again.

therefore i highly doubt its alternator related, and as above just pull out any fuses for systems you may be unsure about, and keep a spare battery charged for changing over until you have it diagnosed.
also, if your radio has a code, get the code before you disconnect it!

[harryhill]

Originally Posted by surprising_skod

if its your alternator, its not going to charge the engine whilst you use it, but that will mean after a long run, you wont be able to restart. if when you constantly use the car, it doesn't drain, as seems to be the case, that means its another system draining power, but leaving enough overnight to start the car and charge the batt up again.

therefore i highly doubt its alternator related, and as above just pull out any fuses for systems you may be unsure about, and keep a spare battery charged for changing over until you have it diagnosed.
also, if your radio has a code, get the code before you disconnect it!

Alternators can have intermittent faults

[KenONeill]

Originally Posted by harryhill

Alternators can have intermittent faults

What are the chances of that then eh?

[bobob]

Originally Posted by harryhill

Alternators can have intermittent faults

Sods law, it will be my alternator

Thanks for the replies, still haven't got around to doing anything about this
i know the battery will last 6-8 weeks if i use it everyday
i'll be taking a look in the summer holidays, if summer ever comes.