Max alternator S3

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Snuffles

Snuffles

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Kent
So I've looked at a lot of alternators as an upgrade from the 16ACR.

As far as I can tell I can go up to 125A on a disco alternator with the same mounting if I change the pull and it's cheaper than the "race version" (if they can really call any S3 a "racer") I found on one site for £400. That put out 125A

I'm just wondering what the catch is. Does anyone have any experience of an extreme alternator upgrade?

I'm reducing power usage by installing LEDs but I'd still like 100A plus if I can but that's a 300% increase (i can easily upgrade the look and have already upped the battery)
 
I don't think you'll need 125A, I would say 60 to 80 should do. If the alternator does ever draw 125A it will put a lot of strain on the belt, OK if its a modern multi-vee but in my expreince a single Vee struggles by 70A, the tension has to be kept tight and adjusted regularly
 
I went 65a a long time ago. Its given me all I need and I have quite a few additional electronics and a split charge system. No problems as yet.
 
What are you trying to run that you need 125A?

When I put the 200Tdi in my Series someone had attempted to retro fit a bigger alternator. I think it's a 100A from a 300 or something. While it fitted the mounts ok, the pulley didn't fully align causing lots of belt issues. I now run an aftermarket 85A one that works much better, but can still cause issues with the Vee belts at times, despite aligning fully now.
 
I run a 100amp on the 110 with a disco 200tdi, and that needs a lot of maintenance to prevent the belt slipping. Any more and I dont think the belt would cope. I fitted it when I fitted the winch. I then fitted the 65amp that I removed to the series (2.25diesel) and had no problems with that.
What do you need 125A for, that would also require a serious wiring upgrade to be able to run.
 
People requiring extra amps have fitted an additional alternator on the top of timing case.
Some one was manufacturing the mount.
 
Shirly the alternator will only produce as many amps as is asked of it anyway.
Unless you have a durdy great winch or are running a cow shed off it the damn thing won’t require much more turning force than a normal one.
Sure seems overkill though to run a 1972 wireless and a battery light.
 
I think the problems come when just after starting when the charging current could ramp up a lot and perhaps more than the engine would like as its still only at low revs, and because it can put out more power at lower RPM is needs a lot more belt tension. If you look at the latest high power alterntors, a) some are now mechanincally driven - no belt, and they are "intelligent" so they pull max power only on the overrun and cut out under accleration so they don't drag on the engine.
From haveing driven vehicles with a range of alternators I would say 30A and 45A are not enough, they can't power halogen headlights and a heater and fan below meduim revs so you loose charge in a traffic jam. I have a (I think) 67 or 70A one on the series and its fine, my fogs are LED so I can run fogs, heads, fan and it charges fine, but fan belt usable life is a year as I have a low revving engine. I don't think I would gain from a bigger alternator.
 
I run a 200DI ex disc engine with modified series alternator bracket mounting , I think this arrangement does not give sufficient wrap on the alternator pulley so slips on high load. I made a military style tensioner for the alternator.
 

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rob1miles said:
I think the problems come when just after starting when the charging current could ramp up a lot and perhaps more than the engine would like as its still only at low revs, and because it can put out more power at lower RPM is needs a lot more belt tension. If you look at the latest high power alterntors, a) some are now mechanincally driven - no belt, and they are "intelligent" so they pull max power only on the overrun and cut out under accleration so they don't drag on the engine.
From haveing driven vehicles with a range of alternators I would say 30A and 45A are not enough, they can't power halogen headlights and a heater and fan below meduim revs so you loose charge in a traffic jam. I have a (I think) 67 or 70A one on the series and its fine, my fogs are LED so I can run fogs, heads, fan and it charges fine, but fan belt usable life is a year as I have a low revving engine. I don't think I would gain from a bigger alternator.
Click to expand...
Fan belt usable life is a year!, I've been driving all sorts for 45 years and I can only ever remember changing a fan belt once on a mk1 escort cos it snapped. What are you using for fan belts, elastic bands?

Col
 
I think the problem is I run a Perkins 4203 so we do most of our driving at 900 to 1500 rpm, 2000 rpm is 60 (RR doffs, OD etc) and we have a 100AH main batt plus 100AH leisure batt so the alternator is often pulling a lot of amps at low revs. to get the alternator revs up we run a small alternator pully. This time I've gone for a notched belt that will fit the small pulley better so I'm hoping for a longer life. What did for the last 2 was wearing too thin to fit the pully but if the tension is slightly off they slip.
 
Blackburn said:
I run a 200DI ex disc engine with modified series alternator bracket mounting , I think this arrangement does not give sufficient wrap on the alternator pulley so slips on high load. I made a military style tensioner for the alternator.
Click to expand...
Me too! except I have an ordinary slide adjuster, the belt is quite loose as well but I haven't had any problems with belt slip. Why is the belt quite loose I hear you ask... (Crickets), it's because I have to be underneath with a tyre lever on alternator moving duty while somebody else tightens the bolt and there is never anybody around when I want to do the job. Nine years this has been going on... Has anybody got a round tuit? good condition and cheap...?
 
Does the belt tension not have an adverse effect on the wear of the water pump bearing? I'm thinking of uprating alternator on my 2.25 petrol so interested in other peoples experience.
 
I do not excessively tighten the belt, the adjuster I made just makes it seconds to retigthen.
Generally I check by trying to turn alternator fan by hand any movement and I tighten belt.
 
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