flat battery

[richard1705]

my battery is going flat if car not used for around 4 days
its a new battery ive checked alt belt taken all bulbs out inside lights and glove box
also now disconnected boot light
what else could it be
views appreciated as always
richard

[richard1705]

oh yes and the alternator was checked by the aa as I broke down it its all charging well

[1959terry]

Richard, what shape is it supposed to be😂 on a serious note I would start by checking the battery is good. Just because it is new does not mean that it is OK. Terry

[milothedog]

my battery is going flat if car not used for around 4 days
its a new battery ive checked alt belt taken all bulbs out inside lights and glove box
also now disconnected boot light
what else could it be
views appreciated as always
richard

Could still be the Alternator, It may be charging OK but it may also be draining the battery when the car is idle. Try leaving the battery disconnected and see what happens, If it still discharges then you have a duff battery. If's it's OK then the problem lies with the car and needs further testing

[Staggard]

You could pull the plug out of the back of the alternator to rule it out. you could also flick the fuses out one at a time and check for a discharge with a multimeter that would then tell which circuit you have the problem with. Graham

[Motorsport Micky]

+1 for both the above methods, should give you a handle on the problem.

Micky

[Paul Roberts]

Do not disconnect the alternator output connector whilst running the engine - or afterward, and then forget you've done it. It will fry its own diodes.

[Staggard]

I wasn't suggesting running the engine, So you are saying if I remove the plug from the back of the alternator and start the engine it will burn out the diodes. I though that the alternator had to have a charge going to it to produce power, as in the ign warning light acting as an exciter.

[wilf]

It is possible that residual magnetism will excite a disconnected alternator, an overvoltage then because of the no-load condition can indeed cause the diodes to reconsider their one-way attitude.

[Robmsharp]

It sounds like you have an excessive current drain. If you have an ammeter you could put it in series with the battery positive connection and see what current is being drawn with the ignition off.
Under normal circumstances there should only be a small drain (~ milliamps) caused by the clock and if you have an excessive drain, then you could fault find by removing the fuses to isolate the circuits one at a time. Hopefully this will help you determine which circuit is causing the drain and help you pinpoint the problem.

[milothedog]

It sounds like you have an excessive current drain. If you have an ammeter you could put it in series with the battery positive connection and see what current is being drawn with the ignition off.
Under normal circumstances there should only be a small drain (~ milliamps) caused by the clock and if you have an excessive drain, then

you could fault find by removing the fuses to isolate the circuits one at a time.

Hopefully this will help you determine which circuit is causing the drain and help you pinpoint the problem.

An easier and quicker way would be to remove each fuse one at a time and put the meter across the holder........

But you still need to unplug the Alternator to eliminate it (Not Fused) . You may also see a drain if you have an Alarm/Immobilizer or modern Radio/CD player


Just another thought, a failing alternator will sometimes give you a very, very faint glow of the charge light (best checked in total darkness)

[StagJonno]

I've had one of these meters for a few years now. Very useful for non-intrisive measurement of current (both DC and AC). Also does voltage. Sensitive enough for low currents (always worth testing both ways and averaging the result, especially at low current levels). Wouldn't want to use on starter motor currents, but range big enough for alternator charge checking.

http://cpc.farnell.com/tenma/ten01056/hand-held-digital-clamp-multimeter/dp/IN05268

No interest in this company other than as a punter etc...

Jonno

[richard1705]

thanks will check all of the above .when it stops raining .
richard