Hello.

I am restoring 1975 xj12c.

My Jaguar's battery voltage goes down when I turn on the air conditioner during idling on a hot day.

So I'm going to change the alternator and the battery.



Q1. I'd like to take off my 75A alternator (photo attachment) and install a new one. But I don't want to make major structural changes.



So I looked at YLE10100 RANGE ROVER CLASSIC 3.9L 92-94 ALTERNATOR 100 AMPS and ALT319 ALTERNATOR (Land Rover 90/110 Dhmc 3.5 V8 12V 120A).

I heard they can both be used without major structural changes. Compared to 120A ALT319, the 100A YLE10100 seems to have no problem with wiring.

So I would like to get advice from someone who uses YLE10100. And I wonder if charging is good even in low RPM.



Q2. I also want to hear the actual reviews of those who use the AGM battery.

 

If you are going to fit an upgraded alternator then make sure you upgrade your charging and earth cables to the alternator to suit charging current.

 

Do not rely on the "guage" on the fascia. It is a mere indictor. Use a meter. I made a patch cord for my meter. Plugs in to the cigr lighter. I read real volts in real time at varous rpm's and load conditions.

Kudos, a beautiful engne I delight in nice engines...
Whatever the specie.

Carl

 

As we are talking about Upgrading alternators, are there established upgrades for the series 3 XJ-6? I'd be more comfortable with a higher voltage at idle when the headlights and climate control are running.
Ian

 

My car is xj12c in Series 2. When I activate several electronic devices, the voltage goes down and the engine is about to shut down.

 

As the voltage goes down, the engine is about to shut down. I'll check the exact voltage. Thank you.

 

Thank you for your advice. I'll have to find out what charging and earth cables are.

 

The cables to consider are the cables form the alternator to the battery including the ones to the ammeter showing the amps, if fitted (the ammeter may also need to be upgraded), and the earth cable form the alternator., unless the new alternator earths through the body to the engine.
Unless you are adding extra electrical components eg big power amps then there's no need to upgrade any other wiring. If you are adding additional bits then the easiest way is to use suitably rated relays and fuses switched by the ignition.

 

Hi-
on my wife’s 71, I was having problems with the original Butec alternator and it’s external regulator.
I purchased a GM “one wire” from NAPA, and it was almost a straight bolt in. It required one Mr Gasket small block Chevy bracket and some spacers. All the original bolts and their locations stayed the same, but it requires a different belt. Wiring was literally the positive wire only. I did a write up, with pictures and part numbers on the forum.

Alternator was $80 and has a lifetime warranty. I also did the electronic ignition upgrade and spark plug wires. Zero issues.

 

Thank you. I'll look for your writing.

 

This is what I use to read my voltage as the dash meter is slow to respond and not digital. Purchased it off EBay for cheap money.