P38 alternator - upgrade for GEMS

[davidsonsm]

Anybody tried one of these or have any comments about it as a suitable upgraded alternator for a GEMS:

http://pages.ebay.com/motors/link/?n...154608&alt=web

[RR P38]

Smaller pulley on the higher amperage units?
Are you running lots of extra power hungry gear? do you need all that extra power?

[davidsonsm]

Reckon what's being run now uses way more power than what was originally intended. Winch (engine running & rare use). 400W amp. 2nd compressor (soon). Phone charging. DVD screen. VHF. Deep cycle batteries. IPod. GPS. LED worklight. Spotties. Trailer occasionally. Obviously LR thought it wise to upgrade to 150amp in the 99 on version.

Just wondering if anybody had upgraded their GEMS alternator? The posting looked promising.

[Hoges]

there was a forum member on here and rr.net years ago who was having no end of strife with the Marelli OEM alternator on his GEMS P38. He bought/returned several replacements and eventually the problem turned out to be the wire on the small terminal on the alternator which connects directly to the BECM... needed replacing.

I only raise this for the fact that you need to be sure that whatever replacement is obtained, it can be correctly connected and that if you are considering an increased amp delivery, that the magical electronics in the BECM can cope with it and the added amps won't fry anything...

[TheTree]

Hi

I would stick with the later model Bosch alternator, it's solid an reliable and we know it will work.

The extra amps will only be going into the battery, not to the BECM so that will not present a problem.

The issue will be if the new regulator has the same setpoint as the Bosch, 14V i believe. There is an electrical sticky in the RR.net forum which goes through all the voltages you should expect to see in the system.

Sticky: Electrical Troubleshooting Updated 2010

The BECM will if it does not see the correct voltages. It causes all sorts of mayhem as we know from experience when batteries and alternators start failing, earths get corroded etc.

Steve

[davidsonsm]

I've asked this question before, but is the later Bosch (150amp) compatible with the GEMS? Has anybody got a cheat sheet on the mods needed?

[TheTree]

I've asked this question before, but is the later Bosch (150amp) compatible with the GEMS? Has anybody got a cheat sheet on the mods needed?

Mate

I can't speak physically, but electrically I would say they are 100% compatible, given that the rr.net sticky does not distinguish between model years.

I am happy to measure my pulley diameter as closely as I can so you can compare it with yours.

Steve

[davidsonsm]

Yeah I guess the only other aspect would be if the bracket needs modifying.

[TheTree]

Hi

Not sure about that, I can take some measurements for you

I guess as as long as the MM alternator has a 14V setpoint it should be fine from that point of view

I wonder what the voltages are for a D2 ?

Steve

[TheTree]

Hi

A non serious thread here, but it there is a post about the MM Alternator and a little mod to make it more reliable.

Electricity

Steve