Twin alternators....and associated wiring

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Steve_R1979

Active Member
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634
Location
Horsham, West Sussex
Soooooo

When my RR eventually comes back from the specialist I hope to pursue a twin alternator set up.

My first issue is that I have a v-belt engine, not a serpentine belt, so a pre-made kit is out of the question.

So far I have the alternator bracket from and SD1 (Drivers side) and a refurb alternator for the same car.

This should give me a mounted 2nd alternator.

This leads on to my question......how do I wire the damn thing in, and how do I get a belt to it?!

I'm running a t-max split charge, with a pair of deep cycle batteries.

Would the answer to be to dedicate 1 alternator to the second battery and remove the split charge controller. This would leave the batteries totally isolated (I think), and somehow shut down the second alternator when I link the batteries via a switch or something???

As for the belt.......I need to see how the aircon compressor would have got a belt, had my RR had one. Anybody know if this set up can be modified to run a second alternator???

Any ideas?!

Thanks!!!!!
 
Nice :)

Something i have always hankered after but never bothered persuing so it will be good to read your thread and see your pics. There will be pics by the way!! :p

Anyway, good that you've got the SD1 bracket. You now need an aircon spec water pump pulley, tis a double. You then need to hope the belt alignment is right otherwise you have to get fabbing!

Could also try a rangey aircon pump mount, that has another tensioner identical to your water pump tensioner built in, and may offset the future alternator differently.

It's never been done as far as i know so there's no advice to draw on!! :eek:

Regards wiring, the whole point really is to ditch your split charge and has two fully separate systems.

Another sexy option is to have one 12v alternator and one 24v, then run the batteries in series, taking 24v for your winch and 12v for the rest of the car. One battery actually gets used in the 12v and 24v systems!

But that's just waffle cos you don't want that.

SO, the question is, do you want 2 completely separate systems? Ditch the split charge, run a common earth between the two batteries but keep the positives completely apart.

The downside to this is that though you run two alternators, either circuit never has the benefit of doubling the amps available.

The other option is keep everything as it is and just link the output cable from your current alternator to the output from the outer. The big power wires all meet at the bulkhead fitting on the pre-94 discos for instance.

This was, you have the batteries connected when the engine is running and everything has 140 amps or more available, and when switched off your systems are separate.

The first option is the more reliable option, keeps it simple, but the twin alternator double current option is very handy for heavy winching!
 
I like the idea of running the alternators together to give big amps for winching, but, I read somewhere that the alternators will fight each other (whatever that means) hence my intention to shut one down and keep the split charge.

If that's not the case then I might as well, as you say, ditch the split charge and run them together.
 
You only ditch the split charge if you are running the alternators as separate units looking after separate systems, basically a winch system and a car system.

To me there seems little point in that because for winching its better to have two batteries available. The only reason you would need split charge is if you want to have the option to flatten one battery with the engine off but have them together when the engine is running.

If winching is your focus then run both alternators on the same circuit. Keep of ditch the split charge, that is entirely up to you and doesn't make any difference in this setup really, it's a bonus tbh but some people don't need the complication of split charge.

Not sure I've heard of alternators working against each other!

Maybe the 14v fools the other alternators regulator and shuts it off, and vice-versa?!?
 
id love to see some photo's if you pursue this further, my only question is - does the split charger not provide you with enough of a recharge?.
im think of putting in one of these T-max jobbies some time in the new year as i work through my 'To Do' list.
 
This is where I display my ignorance.

Which wire senses the charging level.....i.e. where do you put the diode?? I assume its in the cable that runs to the battery light on the dash??
 
Anything come of this? looking to do this soon.
In regards to 2 alts powering when winching, What's the voltage drop down to when the winch is running? could be enough to keep it below 14.
If so could run a switch over relay to swap the alt simultaneously on to winch when winching
 
No idea for me either really, never looked at twin alts more than whether I need the amperage, which I don't think I do.

Get on a more competent forum and the answers will be seconds away, need a forum with lots of comp guys, LR4x4 has a lot of next level info mark as you may have noticed :)
 
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