1994 2.8 Exceed, xmas day car started then brokedown after 3 miles. Recovered the car to home charged both Batteries and put them back on the car. The following morning the car was dead, not even the central locking was working. Bought 2 new batteries and replaced the old one's on Tuesday evening (4th Jan), ran the car all day Wednesday no problems, ignition warning light went out the moment the car started to suggest the alternator was working ok. Came to start the car this morning (Thursday) and it was dead no electrics at all, can you please advise. Many thanks John

But thts not all it would read good voltage but as soon as the car hit a bump it would lose power and how id tell lights get dim andthe tack would stop working
I will say is the plug on the back of the alternator on the count of our Montero having that problem 1 minute the dash lights Work1 minute the dash lights won't work and then it will lose charge and then it will crank and run off of battery power and then and we'll die

It sounds like your alternator is bad. East way to confirm, take it to local auto parts store (IE: Autozone, Advance, etc) and have them do a FREE charging system test. Couple of thoughts; you have two new batteries and your poor alternator has to work twice as hard. After you put new batteries in, you've been running on straight battery power. Alternator normally runs all your electronics and recharges battery(s) but if Alt has gone "south" then you're on straight battery power.