Complete electrical death (intermittent...)

[jackkelleher]

Moggy has a new trick! Pull the starter and everything dies. Right down to the courtesy light, which means it's a problem with power coming from the battery... No fuses blown, I removed and put back on the terminal lead that leads to the starter and the system came back online- til I pulled the starter again, at which point everything promptly died again...
Suggestions anyone?

[bigginger]

First thought (as ever) is the cleanliness and security of the fuse holders. Give 'em a clean and maybe a gentle bend to hold the fuse better
a

[jackkelleher]

Did that, no joy... The fuses are really well held but the problem remains!

[jackkelleher]

Just got worse. I turned the ignition and the car blacked out, tried removing and replacing all the fuses, terminals on the battery etc, but nothing could coax life back into the old girl... The battery wasn't low, so it's not that either.
Mystery.

[bigginger]

The lead from the starter solenoid to the starter? The battery lead itself? Try bypassing those with a jump lead (separately)

[MoggyTech]

Gearbox to body earth strap, or battery failing under load. I've seen batteries that measure 12.5 volts with no load, but collapse to 7 volts when load applied. I would check the earth strap first though. Also the battery lead from battery to bulkhead earth.

[forbesg]

Gearbox to body earth strap, or battery failing under load. I've seen batteries that measure 12.5 volts with no load, but collapse to 7 volts when load applied. I would check the earth strap first though. Also the battery lead from battery to bulkhead earth.

Yep agreed, or one of the terminals on the battery isn't tightened up properly.

[RogerRust]

My suggestion (from experience) is that the battery terminals need cleaning and re tightening.

Out of interest I put my meter across the earth strap from the chassis to the gear box and was amazed to see 1.2ohms. I know that this isn't much but it will represent a voltage drop across the whole system. I'm going to replace it with a copper one soon.

Roger

[Willie]

RogerRust. Do what I hav e done and fit an additional earth strap between the near side engine mount to chassis bolt and the stud which clamps the breather tube to the crankcase or somewhere similar because you can keep an eye on it more easily since it is not hidden underneath the car.

[bmcecosse]

Sounds to me like internal fault in the battery - one of the 'posts' has probably come loose inside. New battery i'm afraid.

[Willie]

Jack, if the starter itself doesn't turn despite all the other items going dead then you either have a faulty starter motor, a faulty battery, or a faulty main battery lead between the battery and the starter switch/solonoid. I hope you do not have one of the battery cables which have an end shaped like an upturned cup which is held on to the battery terminal with a self tapping screw? These are notorious for not making good contact( the clue is that when operating the starter you can hear fizzing and the terminal gets hot).

[rcbowman]

Unlikely anything like this is your problem, but I had a similar failure two or three times and eventually figured out it was that the jury-rigged battery holder the previous owner had installed was not completely tight, but allowed the battery to slip forward slightly when braking hard (or jog when going over bumps) and one of the battery leads contacted metal on the said holder, and killed everything. I fixed it by putting a few layers of insulating tape over the holder strap and then tightening it carefully. As I say, unlikely you have a similar issue, but worth checking if there's a chance of the battery moving so its lead contacts something.

[bmcecosse]

Better to turn the battery round rather than rely on a bit of tape! Shorted battery can explode - and can also ruin the alternator.

[Willie]

Wise words BMC, turn the battery around or cut suitable metal away on the battery clamp so that a short cannot possibly occur. Insulating tape is not the answer.