300tdi Battery problem

Disco1BFG said:

3.88 Amps !?! ?!? - with everything orft ????? ... Houston, we have a problem !

Did you disconnect your alternator yet ? ( and insulate the live wire for safeties sake )

I suspect new rectifier required

Click to expand...

Wot he said :wow:

The drain has dropped to 3.45amps. Iv gone through and pulled each fuse individually and tested with the multimeter for each. Iv taken a few photos for reference and my findings. Iv not got as far as the alternator as I'm limited on space in my garage but that's the next stop, if only it would stop raining!

If you pull fuse 2 does the drain then drop to that amount listed?

3A+ at 12V is 45W you will be able to feel the alternator if that's the problem area. Is it warm - just grab the case and see - it should be quite noticeable if the engine hasn't been running for a while.

chris-the-gerbil said:

If you pull fuse 2 does the drain then drop to that amount listed?

3A+ at 12V is 45W you will be able to feel the alternator if that's the problem area. Is it warm - just grab the case and see - it should be quite noticeable if the engine hasn't been running for a while.

Click to expand...

If I pull fuse 2 it drops to 2.84 yes.

I'll reconnect the battery and leave it a while then check on the alternator.

Right it's been 45 minutes with the battery connected and engine off... I think we have found the problem, the alternator is pretty warm.

Have you tried unplugging the alternator, and then check current drain?

Jam5good said:

Right it's been 45 minutes with the battery connected and engine off... I think we have found the problem, the alternator is pretty warm.

Click to expand...

At a 3A plus drain it was never really in any doubt.

I have an unused spare alternator if it's any help - if you can wait a few days I can talk to my remanufacturing man if you want a new one making......

otherwise it's buy a new one or pull the existing one apart and try and fit a new rectifier pack.

chris-the-gerbil said:

At a 3A plus drain it was never really in any doubt.

I have an unused spare alternator if it's any help - if you can wait a few days I can talk to my remanufacturing man if you want a new one making......

otherwise it's buy a new one or pull the existing one apart and try and fit a new rectifier pack.

Click to expand...

What would you do? Is there a better upgrade choice than just a replacement?

I think you have a defender yes? So it could have either a 65A or a 100A alternator - the 100A ones come from the Disco's as they have more electrical toys.

If you are thinking about fitting light bars or spots or a winch then I would certainly upgrade the alternator. Otherwise the cheapest way is to buy a new rectifier and fit that. But if the rectifier has gone then it's perhaps old, could do with new bearings, brushes as well, and a remanufacturerd one would perhaps make more sense. Also depends on how quickly you need it back on the road - if it can wait till the weekend you could order a new one from Paddocks or Rimmer Bros. and fit it - then repair the old one and have a spare for overlanding trips - lots of options...

Thanks to everyone who commented in this thread. It's helped me diagnose one big issue for my 90. As I'm looking to do a number of things to it in the future, I think I'll get an upgrade on the alternator front.

10 years on the Falkland Islands, open to the elements probably means a few things need replacing. So I'm sure my next thread of questions won't be too far away.

Be aware when you get a new alternator it will come with the smaller 49mm pulley (so it spins faster). This will mean if you have a large pulley (63mm) you will also need a new drivebelt as you need a belt about 15mm shorter.

Also what condition is the belt tensioner in - if thats original it;s probably got a penny stuck behind it and you will want consider getting one of them as the belt could be chirping a fair bit too....

Glad you appear to have found the fault, one thing to keep in the back of your mind is that if you are contemplating repairing your old one you will need access to a fairly high power soldering iron to replace the rectifier pack.