Disco 300tdi phantom flat battery prob.

HI, i have a 94 disco 300tdi, i have fitted two new batteries in the winter as it has a two bat system, no winch or anything, somtimes it just wont start, its happened a couple of times, after a 10 mile run, jump started ok, batteries fully charged, its as though the bat is flat when i know it isnt, any ideas, thanks.

gecouger said:

HI, i have a 94 disco 300tdi, i have fitted two new batteries in the winter as it has a two bat system, no winch or anything, somtimes it just wont start, its happened a couple of times, after a 10 mile run, jump started ok, batteries fully charged, its as though the bat is flat when i know it isnt, any ideas, thanks.

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If you are sure the batteries are ok then it can only be bad connections or a bad starter motor.

First thing to do would be to take off the earths and give them a good clean.

Wifes Nissan Micra just gone through similar, battery read 12.6 on multimeter, but had no power to crank over and even immobiliser wasn't working, making us think it was an immobiliser problem. Put battery on charger and it said it was almost full, but 10 minutes later it had dropped to 20% full ... but still reading 12.6 when taken off battery charger, then suddenly dropped to 11 or so .. A cell had gone down.

I'd suggest taking the batteries off (why 2 without a winch etc?) and charging them up, but watching what happens during a charge.

If it's not doing anything much then follow the twin battery wiring and charging system and make sure the vehicle is actually charging, and that the two batteries aren't simply cancelling each other out! I'd not bother with 2 batteries if it doesn't need them for something, winch, on-board air, on-board welding etc etc ...

gecouger said:

HI, i have a 94 disco 300tdi, i have fitted two new batteries in the winter as it has a two bat system, no winch or anything, somtimes it just wont start, its happened a couple of times, after a 10 mile run, jump started ok, batteries fully charged, its as though the bat is flat when i know it isnt, any ideas, thanks.

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What's the battery voltage showing when it won't start? What's it showing when it's running with no electrical items turned on? What's the voltage showing when it's running and has the headlights, rear screen heater and fan blower on full?