Electrical problem

Hi there Gentlemen,
First of all, Merry Christmas, and may I be the first to wish you all a very happy Easter too.

I have a bit of a weird problem. Back in September, I went to my Disco, only to find the battery to be almost flat. It had been fine and it (the battery) wasn't very old. I just assumed I'd left something turned on overnight even if I couldn't think what. I forgot all about it.

A few days ago, I found the same thing except that as it had been 48 hours since last using the car, the battery was so flat, it wouldn't even work the remote locking.

I had a problem a year or so back where, although fully charged, the battery failed to start the car. The symptoms were that of a dodgy earth. I cured this by adding an extra earth lead direct from the battery terminal to the bodywork. I mention this just in case the two problems are related.

Does anyone have any suggestions? Please be gentle with me, I'm still pretty ignorant.

check all other earth leads chap i belive one to the engine and one to the bolt of a starter motor both on the other side on mine.

i also had an alternator fail and discharge the battery all i could here was the alternator huming a while after the engine was turned off

hope it selps

If it was just a starting problem then i'd suspect the earth leads, the red wire and the starter motor itself. There's a number of tests to do with just a set of jump leads. But it not having enough power to do the central locking sounds like it's being drained to the point of proper flat.

Have you checked the voltage of the battery itself when it is flat? Can you jump start it and measure the voltages when running also?

When I say it was flat, I mean proper 'wow I don't believe it' flat. Not enough power to display the LCD clock. Insuficiant juice to show any dashboard lights. Really, absolutely and indefatigably flat.
It made a certain Norwegian Blue parrot look lively and raring to go.
That battery was dead!
It acheived that state from one of being fully charged just 48 hours before.
I ran an extention lead out to the car and put it on charge. After about an hour I tried starting it... successfully.
Giving it a run up the M11 from Harlow to Bishops Stortford and back took it back up to fully charged and, touch wood, I've not had any problems since.
I would rather like to find out what caused this problem and get it dealt with ASAP. The only other thing I can call to mind is that just over a year ago, the alarm started going off every 5 minutes. I disconected it and haven't reconected it since. Could there be a link? I do not remember if that was before or after I put in the extra earth lead.

It would still be interesting to know the voltage at the battery both when running and when off. You need to know that the alternator is properly charging the battery and that the battery is properly holding its charge. Just because its new doesn't mean its working correctly.

Also, you could get one of those current testers (link below) and go through the fuses one by one when its off. See what circuit is drawing what current.

Re the alarm: its possible of course, it depends how its wired in and what you did to disconnect it. What other modifications are there to the electrical system?


Automotive Current Tester - STANDARD Fuse CF-02 | eBay

I know only a little about electrics (Actually, I know only a little about most things) but would have thought the battery would be pretty consistant. That is to say, should it be the battery that's faulty, if I leave the car for two days, and the battery fails to hold any charge, then this would happen on each occasion I left the car for that length of time. This is not the case,I can leave the car for a week or more and all will be well....but very occasionally, it will not "all be well". That's the problem!

I once had a similar problem on a Lancia, turned out to be a sticky central locking solenoid.

sometimes it just wouldn't pull all the way, the car would lock but the solenoid would stay energised & drain the battery. Took me ages to suss it though.

Those intermittent faults are the worst as they're so hard to track down.

Don't get me wrong, you're probably right. Checking (by that I mean measuring) the battery and charging circuit is more to get an idea whether the basics are working. It takes only a minute to check and rules out a lot.

Chances are you have a current drain somewhere, which you will only find quickly if you're prepared to break out the ammeter (aka Current meter, or mutlimeter in DC Current mode) and actually test stuff.

It doesn't have to be the one I posted earlier, any ammeter will do. Just get to the fuse board when the car engine and all lights etc (including interior lights) are off, remove one fuse after another and measure the current across its terminals.

Thanks MrGrumpy, I'll certainly look at the locking, as that has shown a fault now! When I lock the car, the indicators flash 3 times, as they should. When I unlock it, they should flash once. They don't. They don't flash at all on unlocking.
Also, many thanks to you Mundungus. I will get an ammeter/multimeter and see what happens when I stick it's little pointy things where I've never stuck things before Well, the fuse box anyway!
I suppose I should really admit that the electrics on the car generally need a thorough looking at. I have reversing lights that are afraid of the dark, rarely if ever coming on these days. The alarm took to going off very 5 minutes for no real reason, so I disconnected its horn and just monitored the indicator lights. They behaved fine, so after a few weeks, I re-connected the horn. All seemes well!
Could there have been a link between the mysterious alarm and the equally mysteroius occasional battery flattening? I rather think there may be, except that the alarm (or the indicators) didn't go off when the battery was flattening on the previous two occasions!