Battery keeps going flat!

[S3THUNDER]

Hi all, My battery is dead after one week in the garage. It's the second week in a row this has happened,which worries me ,as the battery is only just over one year old. Even the alarm wasn't flashing. The only thing I have changed lately is the stereo,which has a removable front panel. I will remove it,but I can't see if it's switched off,how it could drain it. I will also switch the alarm off. Any ideas what can kill a battery so quickly?

[Bobhon]

2 weeks to a flat battery is more the norm on TVR's, so I suspect that you have a rogue drain somewhere. The Radio unit usually has a slow drain on the system. 1 of the wires to it is a permanent live and it uses this to constantly retain the memory of your tuned in stations and the CD track it was playing.

You can identify and remove this, but you will lose all stations and CD position every time you key off.

The alarm also constantly drains the system.

Connect an ammeter to the battery to see what current it is drawing with the ignition off. Pulling the fuses 1 by 1 then watching the ammeter will show which circuit is constantly pulling current out of the battery. Then all you have to do is to 'fix' the leaky circuit.

If the car is kept in a garage or within reach of a 240v socket then buy and connect up a smart battery charger. Optimate or Accumate or the cheap one that Aldi occasionally sell. These keep the battery topped up and clean up any sulphation on the plates.

Bob

[phillpot]

If it were me I'd disconnect the battery completely, if it still goes flat it has got to be duff!


Not something daft like interior light on is it, might not show up in daylight?

[S3THUNDER]

Thanks.Some great ideas. I will check to see if the battery is duff first. I'm sure I didn't leave the interior light on?

[QBee]

Don't forget that many batteries have a 2 or 3 year warranty.

[iplod999]

Trickle charger?



£16 in Lidl.

[S3THUNDER]

Good thinking. I forgot about the warranty.

[v8s4me]

phillpot said:

...Not something daft like interior light on is it,..?

That was the cause on mine.

[QBee]

Might be worth just putting your multimeter on it. Fully charged the battery shoud be 12.4 volts standing, 13.5 to 14 volts engine idling.

My Audi battery was flat Friday morning. 2.7 volts. Not been driven for a week. Battery charger didn't believe there was a battery there. Had to connect the jump leads to another car, then clip the battery charger on, then disconnect the jump leads. After 24 hours charging I had 10.3 volts, so battery clearly one cell down. Checked again ths morning, a further 24 hours later, back down to 2.7 volts. So a defective battery could be the cause of your Symptoms.

New battery solved it.

[Buzzlt]

Yep you need a multimeter which you connect inline with the battery to see if you have a drain or if you have an alarm - how much drain you have.

Alternatively you can remove the fuses from the fuse box and connect an ammeter (multimeter set to amps) accross the terminals you have removed the fuse from. This will highlight which circuit is causing the problem. Make sure that everything is turned off first though as the multimeters usually have a 10amp fuse which will blow if you have left the lights on.

How did you get on with the fuel gauge it's unlikely but possible the two faults could be related.

Battery aid from Halfords for a fiver is also worth a punt if it is just a dodgy battery and not under warranty.

Cheers Greg

[greymrj]

Happens on mine too, annoying isn't it! All sorts of strange things can happen with the electrics on g.r.p. cars which do not use a body earth. I have tried, several times, to trace it using a meter but I have been 'chasing my tail'! However there is an easy solution, with other advantages. Fit a simple battery isolator switch. It has the added advantages that you can remove the 'key' when added security is a good idea (quite often with a softtop car), you can readily isolate the battery when doing work on the car, and you have quick battery isolation if that dreaded fire/smoke starts.
I have simply got one of these fitted:
http://www.carbuildersolutions.com/uk/battery-isol...
I have it fitted on a (stainless!) plate next to the battery, so I can access the switch via the wheelarch when the car is on lock. Turn the steering straight again and the switch is hidden. Obviously I can also access it easily with the bonnet up.

My battery is good, and lasts weeks with the switch off. 2-3 days if it isnt!

[S2Mike]

I found the central locking solenoids were clicking, not quite enough to lock or unlock the door but enough to drain the battery. Sitting in the car in a very quiet place and lock the doors..........."...whats that noise ?" was the prequel to finding the cause.

[TurboTony]

If you wish to isolate the battery you could use a discarnect or similar.

http://www.amazon.co.uk/Battery-Cut-Off-Switch-Uni...

Easier to fit. I do not have an alarm (or a quiescent drain problem) or a radio so have not a need myself.

Presumably the ECU will have to re-learn when the battery is reconnected but I do not think that is an issue.

[S3THUNDER]

Thanks again. I've been on holiday,so the petrol gauge is still on the to do list. I think it's the sender that's knackered ,which I hope to replace soon. The list of jobs never ends.

[glenrobbo]

S2Mike said:

I found the central locking solenoids were clicking, not quite enough to lock or unlock the door but enough to drain the battery. Sitting in the car in a very quiet place and lock the doors..........."...whats that noise ?" was the prequel to finding the cause.

Sounds a bit Halloweeny to me


Was that when you decided to sell it Mike?
And get something without that enormous centre console in the way

[Top Gear TVR]

I have never really understood the point of locking a car with a fabric roof?

[S2Mike]

Exactly, and why with only 2 doors do you need an extra electrical device just to lock a door, when you can reach over and pop it open ??
I have the two solenoids/motors, if anyone needs them, for the cost of postage only!