Battery keeps going flat???

[Tom-os]

Hi guys.
I've got a problem with the my battery keep going flat if left for more than about 8hours at a time?

I think i remember being told that it could be a bad earth somewhere on the car but not sure if this is correct.

Could someone tell me if there is an easy way of finding a bad earth or if this is even the right cause of the issue?

Cheers for any replies

Tom-os

[stuartswan]

check the amps your battery is draining with the car off

remove fuses till you see a large drop

i would recommend starting with any aftermarket electic items

[Tom-os]

Ok, but how would i check the Amps?

[stuartswan]

best bet is to use an amp clamp

or if not you could use a multimeter, but be careful its easy to blow one if you put to many amps through it

[Tom-os]

Alright, cool.
I'll see if i can get hold of one from a friend, if not any idea what cost to buy one new?

[Steve-O 2007]

I used a cheap maplins style multimeter that looks like this -

http://www.maplin.co.uk/Module.aspx?ModuleNo=37279


Set it to amps, disconnect the earth and connect one lead of the meter to the battery and the other lead of the multimeter to the cars earth lead.

It should read a very small amount, now open the door so the light comes on and it should jump up if its all connected right.

If its high with everything off and the doors closed etc then start pulling fuses untill it drops.

You should also arm the alarm and see what its drawing incase your alarm is the problem.

http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

[Tom-os]

I honestly already did have a feeling it might be the alarm or the turbo timer?!
I'll probably just pick up cheap multimeter tomorrow and see how i get on.
So fingers crossed i find the issue, how would i solve it? Would i just need to re-earth the offender?

[black gts]

i had this problem for about a week and my fault was the boot light was staying on.
how i found that out was the car didn't get put in the garage one frosty night ,so the heat off the bulb stopped the rear wing from frosting up.
car was white with frost and a black patch of unfrosted paint

[Tom-os]

Black gts, how did you solve the issue? Is it as simple as just re-earthing the offender?
Cheers

[black gts]

i just took the bulb out mate , which iv remembered that i havnt fixed it yet.

[Tom-os]

But if the problem is say the alarm or turbo timer then I can't just take them out, so how can I solve it?

[toxo]

You need to find out what's causing it first, as the fix will vary depending on the offending item. It could just be a knackered battery, it could be related to the charging circuit. Basically, it could be all sorts, you need to do the finding-out stage before you know what is required in the problem-solving stage.

[Tom-os]

I've ordered a multimeter, so as soon as it arrives i'll get to work and let you all know what it is (provided i do find the problem ) and then hopefully someone can give me some further help then

[sanchi]

Check your alternator too, could be its not charging the battery when you are driving and then when left for long periods of time it goes flat as it hasn't been charged. Might not be the case but something to think about if everything else turns out ok.

[sanchi]

Check your alternator too, could be its not charging the battery when you are driving and then when left for long periods of time it goes flat as it hasn't been charged. Might not be the case but something to think about if everything else turns out ok.

[Tom-os]

Cheers Sanchi, but pretty confident it's not the alternator as whenever I take the car on a long run (over 150miles) I can leave the battery connected over night and it will still start in the morning.
But when I drive to and from work during the week (only a few miles to work) I have to take it off or it will run dry after between 4-8 hours?
Tom-os

[toxo]

It is possible that it's your alternator. If it's supplying low voltage rather than being completely dead then it would require a longer journey to fully charge the battery.

[Tom-os]

I'll defo keep that in mind although it had a new alternator less than a year ago but did have another alternator about a year before that aswell so saying it was the alternator is there any reason you can think that it's need two in two years?

Once my multimeter arrives how will be able to check if the alternator is working properly?

[Slarty]

Configure the multimeter to read voltage (usually set up like this by default but check anyway) and select DC on the dial. Then put the black lead on the negative of the battery and the red on the positive.

With the engine idling it should read around the 12v mark and if you bring the engine up to fast idle it should go up to around 14.4v.

[toxo]

Configure the multimeter to read voltage (usually set up like this by default but check anyway) and select DC on the dial. Then put the black lead on the negative of the battery and the red on the positive.

With the engine idling it should read around the 12v mark and if you bring the engine up to fast idle it should go up to around 14.4v.

Yeah if the regulator on the alternator is broken! Once the engine has started and settled it should be around 14.4 at all times, regardless of engine speed.