Alternator load

[Tyke]

Been thinking about electrical demands on the alternator and a couple of questions came to mind.

1) How do we size an alternator in terms of output to cope with extras such as additional lights, winches or other external electrical accessories?

2) Who can supply said alternator as a service exchange unit or straight purchase.

3) Are there any other items which will need changing at the same time?


Don't want to burn up the standard alternator by overloading it so looking for an upgraded replacement.

[Damonski]

I asked something similar some time ago, there seems to be some rated at about 100amp, I would love one of these or info on how to make mine into a 100amper for my splitcharger needs.

[Range Rover Blues]

A local LR specialist will sell me the 140 amp one for £165 outright IIRC.  Your problem is that the later cars had serpentine belts, also called ,multi vee.  A single vee belt will not handle the load of a big alternator at full power, my 80amp one starts to shred belts when it's working hard.  These are to be found on fully loaded RRC or export models BTW.

[Tyke]

OK - so mines a '95 TDi, no aircon and the belt looks like what you could describe as 'multi-v' in as much as it has a number of 'longitudinal v's' around it's length.

I looked at the loading from the lighting I have and some more I was intending fitting and simple electrical maths say I have around 550W of lighting load. Divide that out by the voltage at 12V and I recon an alternator load of around 45Amps just on the lighting alone. I assume the standard alternator is 65Amps so I've not got much in reserve for charging and other equipment.

Assuming a winch and split charging may be fitted in the future then the standard alternator is simply not really up to the job so I was looking at fitting an uprated 100Amp jobbie. There are a few advertised here and there from around £95 upwards.

Looks like what you are saying is always carry a couple of spare belts if the high output alternators are fitted. Funny you should mention the belt shredding, I've heard it before from a couple of other places but never given it much thought and put it down to dodgy belts. Obviously when working hard the alternator is putting considerable strain on the belts. A good point mate and worth keeping mind.

Cheers for the advice  

[hobbit]

Or fit sprockets and use a bike chain :lol:

[muddyjames]

just an idea but if you have no air con why not just go and fit another alternator in the place the air con unit would go and have another battery for a winch and lights etc? A second hand alternator cant be that much and there was a thing in LRO mag last year sometime. It looked easy to do.

[hobbit]

just an idea but if you have no air con why not just go and fit another alternator in the place the air con unit would go and have another battery for a winch and lights etc? A second hand alternator cant be that much and there was a thing in LRO mag last year sometime. It looked easy to do.

Good point I was going to fit a 24v system into the disco and mount a 24v alternator on that mounting point

[Damonski]

grgrgr I bet the Mpi doesnt have a second mounting point :(

[Bush Tucker Man]

I recently found out that the new Mercedes ambulances that WYMAS have are fitted with 200 amp alternators :shock:  :shock:

(& 3 batteries)

[Matt_H]

running just lights and winch you don't really need more than the standard to be honest - I mean are you planning on using the extra lights all the time? - most likely not!

There is not an alternator in the world you could fit to cope with a winch drain though.  (dons flaem proof pants)

I twin batteried mine with the biggest car batteries I could get hold of 600 soemthing AH, wired in parrallel (you must get two batteries together) they were £35 each so not much money.

I had 4 x roof spots @ 55watt each, 80/100 mains, and a winch as well as the normal add ons (laptop, gps, stereo etc etc).. At peak I could draw around 700 amps.. I never had any problems restarting the motor or the batteries running down.

If you are thinking of night time winch challenges then yuo are going to have a problem, if you are like 99% of us and like a bit of green laning and some night time stuff then really don't bother changing anything until you find a problem and you probably wont if you have a decent battery.

Matt

[hobbit]

If you do run a second battery for winching on a split charge system, and its not time critical for winching, you should be ok, if the battery runs down, stop, wait and let it re-charge

At least you wont flatten the vehicle battery, and drop youself into a dead vehicle situation

[Tyke]

Lots of good comments guys - cheers.

Think I'll stick standard for now and see how it goes. Maybe I'm just fussing over nothing again.

Lights do get a bit of use at night time but so far no problems.

[ChrisW]

OK - so mines a '95 TDi
I assume the standard alternator is 65Amps

If it's a '95 300Tdi I think you should find that you already have a 100amp alternator anyway - the next one up from that was 140amp.

65amp were standard on the 200 models.

However, LR being LR none of the above could be true  :P

[Tyke]

Good point mate - better check that out just in case.

Will be happy if it is . . . . . save me spending on a new one thats no different.

[goblin]

mine is a 95 tdi 300 with serpentine belt but it is a 65 amp :?