Alternators …. Again

I put one of those digital cigarette lighter volt meter in the old girl to sort out low battery power on starting. At the lights, in the rain with the heater on the charging rate dropped from 13.5 to 11.2 volts. Also around town it would occasionally just drop dramatically.
I took her to the electric man and asked him to replace the old Lucas with 120 amp Bosch. Just after picking it up I turned on the lights, AC etc and watched the volts drop way down again. I took her back to find he couldn’t get a 120 amp with matching bolt holes so he fitted a 65 amp Bosch instead. I pointed out that you can get a reconditioned 110 amp unit from a 1990-92 XJ40 with matching bot holes. But no he wanted a bolt on electric terminals, not the push on like the standard 75 amp Lucas that was there. After some weeks he located a new 150 amp unit with matching bolt holes and bolt on terminals. Car stays above 13.5 volts constantly now and for the first time in a long time she starts very easily.


Can you get that part number for future reference? It came with the v pulley?

That would be a helpful find. 150amps would be nice.

The alternator details as follows.
The alternator brand is JAS-Oceania (Bapcor - About - Our History - JAS Oceania) An Australian company trading in Japanese auto electrical products etc.
NB this is a different company to JAS Australia.
Rated at 150amps and with a shim and some bolt size reducers (no big effort) fits the XJS V12. The pulley wheel was swapped for the original Lucas.
The electrical terminals are bolt on.
Part number ANL900HO. Part cost retail $525 AU.
The auto electrician felt there was a need to run a heavy duty cable to the starter motor or fire wall terminal as there was about 0.5 of a volt drop at the battery using the original wiring. I am yet to do this.

150A is a bit excessive for this car me thinks.
My 2006 Range Rover has 150A but also has 23 different computers to run and a 11 speaker gezilian Watts sound system… Just the interior lights are about 50W…
120A are more than adequate and the Alt costs a third of the price.
Bolt terminals as well.

Me thinks you assume my XJS with all its electrical modifications has not the needs of your BMW with all its computers and speakers. I feel like I’ve inappropriately stepped into the elitists space…

Sorry make that Range Rover.

It’s I don’t know what modifications you have done Trev, and if you think you need 150A who is me to tell you what is appropriate for your car or not.
I was talking for the needs of an average XJ or XJS.
I too have done lots of electrical modifications in my car that have added quite a few Amperes in the system, including a 9 speakers sound system, and the 120A alternator copes just fine.
Sorry If I didn’t express my self correctly, there was no “elitist” intention what so ever. I am also obsessed with overengineering things…

The alternator will only produce what is needed if working correctly; also the power to drive it is dependent on electrical load (about 1 HP per 55 amps) so no harm going larger. Only issues are physical size and cost, I have heard $1 USD per amp over 100A…

No problems…. probably an over reaction at my end… sometimes we get a bit sensitive about about our rides.