Charging/Electrical Problems on Mondeo TD

Over the last couple of weeks I've been having charging problems on my P reg Mondeo TD. Used the car one morning - no problems. The same afternoon the battery was all but dead & I had to get a jump to get it started. Everything was working but the battery was dead. Splashed out on a new battery hoping that was the problem but the new battery also looses charge & I'm having to top it up with a charger every couple of days.

In looking for the problem I've tried to follow the instuctions in the Haynes manual. It suggests taking the Negative lead off the battery and testing for a current between the Negative Battery post and the disconnected Negative lead clamp. A current across the two when everything is off should indicate a problem.

When I do this I have a 12v current between the two. Also have 12v between the engine block and the Negative battery post. I've disconnected the alternator - still get 12v. I've taken out every fuse I can find - still 12v. I've taken the main lead off the starter motor

- still 12v and a live engine block.

The car is -ve earth.

Appart from the charging issue everything seems to be working fine. Only electrical issue is that the LCD display on the radio hasn't been working for a month or so. I don't think it's connected to the charging issue & the live block.

I'm assuming that, somewhere, I've got a short - but I'm confused because I'd expect a short to mess things up more.

If anyone has any idea where I should look for the cause of all my ills I'd be very very happy to give it a go. I'm completely baffled!!

Many thanks for any help in advance!!

Cheers Ian

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Reply to
ian
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What value continuous drain do you have?

It is normal to get a crackle when connecting the terminal, but this does not mean there is a continual drain, just a momentary one.

MrCheerful

Reply to
MrCheerful

That's because you're measuring voltage! Sounds like you're using a voltmemter rather than an ammeter here.

Reply to
Robert R News

Hi I've no idea to be honest - I'm using a voltmeter from the neg battery post to the negative lead clamp (when it's disconnected) and also from the top of the block to the negative battery post. Either way I get a constant voltage. As it's a neg earth car I'm assuming I shouldn't get a voltage between the negative and the earth - so I'm assuming something's wrong!

By the way - Most of the time the charge light is behaving as normal - comes on when I turn on the ignition - goes off once the car's started. Once or twice it's flickered very faintly when idling - but usually it looks fine.

Hope that makes sense

Cheers Ian

Reply to
ian

Yes - it's what you're doing that's wrong. ;-)

You mention a current of 12 volts. Current is measured in amps - not volts. If you're checking for discharge from the battery with everything off, you need to set your meter to amps. That's what you measure current in. Wiring a *volt* meter in series with the battery - ether lead - will give a reading of 12 volts. If you want the theory of why, look up resistors in series.

It only tells if there is any charge at all - not if the charge rate is correct.

Reply to
Dave Plowman

Just to add a few things... Make sure you understand how to use your meter to measure current (in AMPS). Beware: if you accidentally (or otherwise :-) ) put this *across* your battery it's more or less a short circuit and may well destroy your meter and more. Assuming you've connected it properly as an ammeter, the current drain (ign OFF

- DON'T TRY TO START THE CAR), should be near zero - or few milliamps. Check things like boot/interior lights etc are OFF.

Reply to
Dave

I've not come across a DVM that doesn't include a fuse to protect it. But it's good practice to re-plug the leads immediately after doing current measurements. Don't buy any meter that uses the same sockets for voltage and current measurements - it will almost certainly end in tears. ;-)

Reply to
Dave Plowman

Yes and and fuses are such fast-acting protective devices aren't they!

Reply to
Dave

Given that you're shunting across a lump of copper or whatever inside the meter on the current range, then yes, they tend to work fast enough. They're not so good at protecting against gross overloads on the other ranges, though.

Reply to
Dave Plowman

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