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/?nav=item.view&id=171332154608&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 (http://www.rangerovers.net/forum/7-range-rover-mark-ii-p38/28663-sticky-electrical-troubleshooting-updated-2010-a.html)

The BECM will :censored: 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.

http://www.aulro.com/afvb/general-chat/200504-electricity.html

Steve

[mtb_gary]

So all we really need is more smoke? :D

Gary

[TheTree]

So all we really need is more smoke? :D

Gary

Or a way to keep the smoke in :p

"On a more serious note it seems Magneti Marelli alternators, apparently a Lucas design are more prone to failure from overheating and "losing their smoke" than eg ones made by Bosch."

I still intend to measure the Bosch Alternator for you as well !

Steve

[TheTree]

I finally have a little time to document some of what I found during my research;

My MY96 had a 150 amp alternator (supposedly from a classic) fitted and it seemed good though I got an alternator fault message on the dash.

It started to get very noisy so I got a new 120 amp one and fitted it.

I eventually got around to replacing the bearings in the 150 version and refitted it to the car. It definitely held the voltage a little higher. However one of the new bearings decided to fail after a couple of weeks :mad:

So it was back on with the 120 amp version! But about 2 weeks later my voltage started to flick very high, up 1to 16v :o So a dead regulator in that one. I then took the regulator our of the 150 amp one and put it in the 120 amp one and it worked fine! Whew.. now all I have to do is replace those bearings again :(

Details follow, note the regulator is physically the same so I was able to fit the Transpo IX123 regulator to the Marelli but that does not make it a 150 amp alternator

The 150 amp alternator uses Transpo rectifier and regulator and different stator windings as well I imagine.
Transpo IX123 regulator
Transpo IXR642 rectifier 6 x 50a; 300A
The casings are marked 4135 and 4136 but I can't see any other markings on them

The Marelli 120 amp (Denso DAN 016) uses
Marelli RM2000.05 regulator
Marelli 63624201 rectifier

There are transpo versions of these as well
Transpo IX124 regulator for Marelli
Transpo IX638 rectifier for Marelli 6 x 40A; 240A

A little about transpo here
https://alternatorparts.com/transpo-company-information.html

These guys are listing a 200 amp alternator !!

Land Rover Range Rover High Output Alternators (http://www.qualitypowerauto.com/item_379/Land-Rover-Range-Rover.htm)

Might check those out in the future!

Steve

[Keithy P38]

Those high output alternators look very tempting!

[TheTree]

Those high output alternators look very tempting!

I agree mate !

[Rob Hse]

Curious as to what amp rating were used on the UK Police P38??

Sent from my A1601 using AULRO mobile app

[TheTree]

I think I am going to go for one of these fairly soon

Land Rover Range Rover 1995 1999 4.0L 4.6 160 HIGH AMP NEW Alternator /Generator | eBay (http://www.ebay.com.au/itm/Land-Rover-Range-Rover-1995-1999-4-0L-4-6-160-HIGH-AMP-NEW-Alternator-Generator-/252743671676)
Steve

[prelude]

These guys are listing a 200 amp alternator !!

Land Rover Range Rover High Output Alternators (http://www.qualitypowerauto.com/item_379/Land-Rover-Range-Rover.htm)

Might check those out in the future!

Steve

Many moons ago I bought that exact unit and although it worked quite well in my, let's call it medium duty setup not utilizing the full 200A from the alternator. When I started pushing it charging lithiums and trying to run a water heater. A/C etc. it got way too hot. So, warning: if you plan to actually pull the full 200A and you are not driving at a decent pace with decent airflow it will burn out. I reckon even with sufficient airflow it would struggle to say the least. I did order spare parts with the alternator just to be safe and indeed this unit uses the IXP123 regulator.

I did look for an alternative, WOSP makes very high output alternators of which one fits in the standard position and is GEMS compatible. It is rated for 320A but after pushing the manufacturer they suggested I derate by as much as 20% when driving slow, as you would on desert or rocky tracks.

Now, 320A - 20% is still a lot of power mind you, around 250A which is "more" than the quality power unit and if that is enough for you, go for it! Personally I got a bit freaked out with overheating anxiety ;) so I went a completely different way. I found a water cooled alternator from a VW phaeton that can do 190A and have fabricated a bracket. It fits perfectly where the original sat and can be plumbed into the plenum return line without issue. I have ran it with the pulley from the original alternator which fits like a glove and got 199A at a little over 1000 engine RPM. I might go back to the other pulley (which is larger and thus will run it slower) since I might spin it too quickly at full tilt. To increase the power output I'm simply going to run a second unit in the position where my A/C compressor used to sit.

The unit is a hitachi (model 2506161) used in VW phaeton and Touareg, Porsche Cayenne and the Audi A8.

Cheers,
-P

[p38arover]

I saw a YouTube video recently that said not to connect lithium batteries directly to your alternator. It can bugger the alternator. I seem to recall it’s because the lithium can take all the current the alternator can deliver so overloading it. I can’t recall the exact reason.

[prelude]

Yes, I have seen plenty of those too however it has also been mentioned on this forum that an alternator should be able to push max output in modern-ish vehicles without trouble. After that the voltage should simply drop to below a point where batteries will charge. ie. your lights will start to dim. I am still on the fence on this one but the same test on the water cooled unit did not result in a hot alternator though it is hard to get to the stator windings since they are water cooled ;) I did notice however that switching on even more load eventually just limited the current into the batteries due to voltage drop. Mind you, it's not easy to get a 200+ Amp load just for testing [bighmmm]


-P

[prelude]

Another update on this: I now have two of the hitachi units mentioned above, the second one mounted in the AC compressor spot since I went electric AC anyway. Things seem to run fine but the proof is in the pudding later on. This does mean I have my 200A unit left lying around, which I would recommend not pushing above say 180A continuously. But for those who are interested, send me a PM. I also have a spare regulator and rectifier that I will toss in since I have no more use for them.

Cheers,
-P