I'm seeing a rash of posts about difficulty starting ... I'm gonna add to it as the symptoms seem different. I'm also not electrically inclined and get lost easily.

Within the last month my 01 won't start if it sits more than ~18-20 hrs. Under that and it starts right up. Starts pretty quickly on a jump. I replaced the battery right off, then had the alternator tested at a shop, checked the terminals/cables, then I had that shop test for any draws while off but they couldn't detect any. I recently replaced the head unit and amp (with stock) but turn the radio off before turning off the rover. I've seen the threads about bad starters and grounds, but this really feels like a draw.

I don't know how else or what else to check, any ideas?

 

I would still suspect a current draw with it turned off. Get a clamp type ammeter (you can get one for under $50) and put it around the battery cable with the vehicle switched off and read your amps. I’m not sure off hand what a reasonable reading is, but someone here will know.

 

I’ve been working on the same thing for a while...so much so that I got a quick battery disconnect so I can easily connect the battery before a drive and disconnect it afterwards (my Disco is primarily a weekend vehicle). There is a TSB from Land Rover which states the quiescent current draw should be no bigger than 35 to 45 mA, mine is like 350mA. The best way to narrow this down is to get a multimeter, set it to the mA setting and pop open the fuse box. Remove one fuse at a time and carefully put the probes in to the slots where the blades of the fuse go. This will complete the circuit and the multi meter will read the current draw from that particular circuit. Mine happens to be from fuse 2, which controls the ECU and all of the associated electronics, basically the most complicated system on the truck . I’ve got some 02 sensors that are starting to go so I’m hoping that’s the problem...just gotta find time to swap them out!

 

So, is the new battery low after 18/20 hours? You can check each fuse, as mentioned above, or you can also just connect meter between negative post and ground...and remove each fuse and watch for amperage drop.

If new battery is going dead over night, you've got a pretty good amperage draw. My guess would be starter solenoid is not totally disengaging or alternator diode is bad. Try disconnecting either starter main cable or main cable on alternator...and see if this makes a differences.

 

This is what the shop did ... and didn't notice anything.
I can try this.
Thanks for the suggestions.

 

Huh, I started noticing my current drain problem around the same time my starter (suspected solenoid problem) was going wonky. I just replaced the starter but haven’t had time to reinvestigate the power drain. I’ll have to check it out again now that my starter is sorted.

 

If they didn't find anything, could be intermittent issue. Unless it does it every time it sits for that length of time. Had an intermittent issue with our 03, sometimes sit for weeks, fine...then once in a while...after three days...dead as a door nail. Eventually, the short to ground became more frequent and evident, when smoke was raising from under the engine compartment fuse box. Pulled fuse box and found the wires for starter relay were rubbing on a piece of the inner fender/metal. Repaired wire, added conduit to harness and rubber over the inner fender...and all good.

 

I second that, a clamp ammeter is a great help. I have a UNI-T UT210, which comes with a voltmeter too. I carry that in my tool box. I am an electronics professional and needed one in my lab. It got good reviews (lots on youtube) by other pros. I can recommend it too.