Langers · Feb 11, 2012

Got a bit of a problem with the 110, with the battery being flat when I come to start it. The battery is a 110aH Bosch silver one, less than 18 months old.

I've got a multimeter and have been poking around a bit, the battery with the engine off is reading around 12.5v at the moment. The main feed off the alternator reads 14.5v with the engine running. The smaller wire (exciter?) only reads about 1.5-1.8v with the ignition on or the engine running. Is this right?

With the engine running the battery voltage jumps to around 13.5v. I've given it a 15-20 minute run to attempt to charge it, but it was flat again this morning.
The battery light on the dash seems to be functioning alright, it comes on with the ignition and goes out once started.

Any ideas where to look now?

air head · Feb 11, 2012

Might be a daft answer but have you checked the water in the battery or is it sealed

Langers · Feb 11, 2012

air head said:
Might be a daft answer but have you checked the water in the battery or is it sealed

It's a sealed one.

mundungus · Feb 11, 2012

Are you sure its actually a flat battery or is it just difficult to start?

I recently had the same syptoms with my daily driver (rover 200). I though the battery wasn't holding a charge. Turned out to be the starter. Basically when you energise the solinoid it throws out to engage the flywheel, and makes a high current connection to actually turn the thing. If the high current connection isn't very good, it sounds just like trying to start from a flat battery.

If it really is a flat battery, maybe you've got a current drain somewhere. With the engine off, and all lights etc off, pull each fuse one by one and measure the current across the two fuse terminals. Or whip off one of the battery terminals and connect the ammeter from the unconnected battery terminal to the lead you disconnected.

Langers · Feb 11, 2012

mundungus said:
Are you sure its actually a flat battery or is it just difficult to start?

I recently had the same syptoms with my daily driver (rover 200). I though the battery wasn't holding a charge. Turned out to be the starter. Basically when you energise the solinoid it throws out to engage the flywheel, and makes a high current connection to actually turn the thing. If the high current connection isn't very good, it sounds just like trying to start from a flat battery.

If it really is a flat battery, maybe you've got a current drain somewhere. With the engine off, and all lights etc off, pull each fuse one by one and measure the current across the two fuse terminals. Or whip off one of the battery terminals and connect the ammeter from the unconnected battery terminal to the lead you disconnected.

Thanks for the reply.

I've just jump started it and been for a run (20 mins or so), the alternator was reading between 14.5-14.6v when running. Turned it off, and tried to start again and the starter just barely managed to turn it over once.

The battery reads about 12.5 volts now, which I am led to believe is close to full charge??? Yet still won't turn over more than half a turn before dying...

The really odd thing is that it will start perfectly on the first turn when connected using jump leads to a friend's disco.

I've measured battery drain and it's less than 0.01 amps with everything turned off; nowhere near enough to drain it.

So it does look like it could be the starter motor itself not creating a decent connection.

Hampshire Jack · Feb 11, 2012

I'd say it is almost definitely your battery. A fully charged battery should be at 13.2V (2.2v for each of the 6 cells). it's difficult to check a sealed battery as you can't measure the specific gravity but you should have a bit more than 12.5v. It has probably lost its ability to hold a charge.

mundungus · Feb 11, 2012

I've got to admit, it does sound like the battery.

Just one more thing though. Where exactly did you connect your mates jump leads to? Both of your battery terminals or do you have some other arrangement?

I'm only asking to rule out a bad earth between your chassis and engine.

lynall · Feb 12, 2012

Ive had same before on a 200 disco and was battery earth to inner wing corroded

Lynall

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air head

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