Originally Posted by toaster61
Hi - we have an 04 Liberty (Cherokee here in UK) 2.8 CRD Ltd - I put in a new optima battery a year or two ago which should be fine in itself but we find that if we don't run the vehicle every few days, the battery gets drained and I can't find anything obvious that should be doing it (ie lights are off etc) - this week it was run last Sunday and yesterday the whole thing was /completely/ dead. Recharged now, it's fine. How can I find out exactly what it is that is pulling all the juice out of it?
First have the battery tested properly....Optima have picked up a bad reputation lately. The battery could have low internal resistance so it is draining itself. Then check that at idle the battery has a voltage of about 13.6 volts across it.
Then you need to put an Ohm meter in series with the battery....do not start the Jeep...and measure what milli amps you are drawing...should be less than 30 ma......you may need to monitor this voltage while driving with a voltmeter plugged into your front cigar lighter/power point.
If it is drawing much higher current than 30 ma at standstill then it could be your anti-theft/immobilisor/radio.
Either way you now have to pull out fuses one by on to see where the bulk of the current draw is going but first start by disconnecting the alternator...you may have a bad diode there.