Lion battery - 15 months old - car won't even turn over (no "click": nothing) so I replaced it with a hugely expensive and very lovely new Yuasa HSB010 via Halfords today. Fully charged and ready to go...... except I have exactly the same thing: the car will not even try to turn over. With the old Lion battery it was possible to boost-start it (and, yes, the alternator is charging the battery) but I don't see the logic in 'boosting' a new battery.
Any thoughts please? The old battery, because I considered it suspect, had been on a trickle-charger just to maintain it. Somewhat flummoxed.
..update... just tested old and new batteries: both have 13v (but cannot measure amps). Can it be an immobiliser/ignition fault? As I mentioned, however, slightly suspect because boost-starting/jumping did work with the old battery....
UPDATE
OK update: recovery guys (home start cover included with insurance) traced the fault to "no power to the trickle wire and thus no power to the starter motor". We hotwired it - and - hey presto - all starts fine. So we started the engine a couple of times and then tried it again with the key: nothing.
The car is a 1995 AJ16 4l 6 Celebration. Apologies now if this is an idiot question, but is there a relay or fuse that could be responsible for the trickle wire and starter motor not receiving power? Sorry if this is a dumb question.
That could well be the issue , the XJS has a meriad of electrical relays!!!! left hand front inner wing, and passenger side under dash removeable cover contain the majority of these, the difficult thing is finding out what relay controls what operation ! , the original 4 volume factory workshop manuals are IDEAL for issues like these they contain diagrams and labeling of all relays on these where they are, and what they do, a hard thing to get hold of today unfortunately but yes what you need is a relay diagram for the car that one sounds plausable regards