Arctic Monkey wrote:

What should a good battery read when started? I'll take it the garage Saturday to be tested.

Now being a Disco, is changing the battery going to cause any problems! Lol

You need to measure the battery before trying to start - if you measure after, that's your charging system taking over. A good battery first thing in the morning cold will read 12.7v or more, discharged will read 12.3v or less. However, you need to wait a few minutes after opening the bonnet and closing all the doors, otherwise the battery voltage will be pulled down by interior lighs, and anything else that D3 likes to switch-on in readiness to leave you stranded by the side of the road - before you have even got the key in the switch.

Battery is an easy change, but exchange like-with-like. You'll need a decent rated unit to cope with your vehicle, so the biggest that will go in, that's best. The D3 battery is slightly flatter profile than the footprint would suggest, an 019T model is the sort of thing you are looking for in a good make like Varta or Yuasa. Don't be fobbed off with a Jaguar battery, you need a model for a Landrover.

You might find that your earth lead is loose (and that might be all) as this is the achilles heel of the D3 battery box; the terminal gets mashed by the (rubbish) clamp slipping around when it's tightened at the back, under the bulkhead, also damaged by people struggling against the lead to get the clamp on and off in one clean movement. So eventually, the (rubbish) clamp has insufficient material to grip onto, and remains loose. 20thou" shim is more than enough to get the clamp tight on the post again, that's how sensitive the design is....