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Second Alternator


Les Brock
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Well, being fed up of split charge systems not working to there full potential and burning out several, I've gone for twin alternators

as many know I have air con pump for the on board air system which has twin pulleys already, so it was'nt going to be as straight forward as sticking it where the pump normally sits...as errrr... its there already

so knock up a bracket becase the legs are the same distance apart on both the alternator and pump !

so here it is, 6mm plate, Nige would be pround....well maybe not the welding, but the penetration is there, but the welder was playing up and wire kept sticking !!!!...well thant's my excuse

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Bracket in place, I used M10 Zeb for the mounts, so no faffing with two spanners to adjust as they lock into place and can't turn

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Pics of the Alternator mounted

The alternator in the normal position is a 120 Amp one so this will become the Winch battery (just route the W and sense cable to the other side of the block), and the new one the rest of the truck

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How many belts..........

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The adjuster was a bit of a head scratcher :unsure: , as the alternator is lower than the far mounting hole on the pump, the solution works very well but pretty it ain't :lol: (putting heat shrink over to hide it)

basically its a length of M10 stainless threaded rod, with "T" M10 joiner, one section is drilled out and the bar passess through it, the other plane, bolts to the mounting hole on the Alternator which allows it to change angle, and two nuts on the trheaded bar which you use to tention the belt and lock into place...and yes...its been cut right back and covered so it don't take yer eye out..

Working on a prettier version

The wiring is pretty simple, new 25mm feed to the battery position, battery sense via the 24 Volt altenator lamp in the dash (military) via relay switched from the normal ignition circuit, so the sense cable is

only connected to the alternator with the ignition on

fitted a link switch in the battery box, so If one alternator packs up, close the link switch and the two will charge from the one good alternator to get you home

So there you go....

Just the rest to do now

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Les,

Thank you for posting this, you have saved me a great deal of head scratching on how I was going to mount a second altenator on my discovery for this purpose. Just a quick question, do you know off hand the reference for the belt form the aircon pump to the altenator?

Thanks again. Tony

'86 110V8i CSW

'93 Discovery V8i GS

'96 Discovery V8i ES

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Guest diesel_jim
Well, being fed up of split charge systems not working to there full potential and burning out several, I've gone for twin alternators

Good man! just like i did!

as many know I have air con pump for the on board air system which has twin pulleys already, so it was'nt going to be as straight forward as sticking it where the pump normally sits...as errrr... its there already

A problem i'll be having, except that my pump is one of the square York ones... space will be very limited! :huh:

The wiring is pretty simple, new 25mm feed to the battery position, battery sense via the 24 Volt altenator lamp in the dash (military) via relay switched from the normal ignition circuit, so the sense cable is

only connected to the alternator with the ignition on

Done properly as well!!!!! 11 out of 10!!! B)

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If you don't mind me making a suggestion Les, Looks good BTW.....

How about turning the front face of the alternator around 120degrees?

That would put the current adjuster bolt hole in line with the rear mounting hole, and the mounting hole would become the adjuster underneath the alternator. You could then run a ring with thread on from the air pump mounting plate, using your T piece with a straight piece of rod?

Still with me?

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My challenge truck runs two alternaters on 2 batteries in parallel and wots more the alternaters are different sizes and makes. Total charge 155 amps. Now I realize about two dozzen people who know more about these things than i do will tell me it wont work-last. However in my expieirence (you cant have too many i,s) it does work very well.

Davew

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batts and alts in parallel original exiter as was and extra exiter on its own charge light but fed from same place as original, so to recap yes ,I did think the exciters were seperate but thinking as i type they are not.

One day i will find some one with a big ammeter and do some tests to see what is chargeing when as i think one charges and one shuts down unless sensed volts are loww ie when winching when both alts will be banging out charge i hope. Batts seem to last well under winching however.

Dw

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Guest diesel_jim
i'm still tryin to work out if i can have two alternators, stay on 12 volts and only have one battery :blink:

The military Wolf FFR's have twin alternators, along with a unit that joins them together to give one large output (not like the old 90/110' FFR's that had two separate circuits)

it's a "RRC8643 Twin alternator control unit" you see them on eblag sometimes. although they are 24v, i'm not sure what's in them, probably just a type of blocking diode, but working in reverse, two inputs, one output but each alternator blocked by the diode to stop current feed-back.

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The military Wolf FFR's have twin alternators, along with a unit that joins them together to give one large output (not like the old 90/110' FFR's that had two separate circuits)

it's a "RRC8643 Twin alternator control unit" you see them on eblag sometimes. although they are 24v, i'm not sure what's in them, probably just a type of blocking diode, but working in reverse, two inputs, one output but each alternator blocked by the diode to stop current feed-back.

cheers, i'll have a search ;)

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Got two alternators on my G-reg Disco 3.9EFI (it's a long story ok?) one 65 Amp, one 80Amp and two batteries, one each side of the rad (12Volt) all in parallel. Had a problem with one warning lamp flickering, turned out to be a faulty regulator on one of them, fitted a new one, no problems since. You need two warning lamps, I used the brake pad wear lamp as the second one on mine as the system had been half ripped out by the previous owner anyway.

There is no problem with doing this, just bear in mind that they don't load share unless they are absolutely identical. What happens is you run on just one (the one with the highest voltage) and the other one is effectivelya backup for when the load is high. When I start winching they both get Bl**dy hot so I know they're working :D . It's excellent for jumpstarting dead vehicles as well.

What I also did was run the output wire from the second unit to the second battery so there is a bit of resistance between the two (so they don't "see" each other too much, if you get what I mean).

When I changed engines the old one was a 3.5 with the alternator on the driver's side the new one was early 3.9 with the alternator on the passenger side, so I just used both sets of brackets and the 3.5 water pump, as a result it's all Land Rover :rolleyes: .

Hope this helps someone, Shaun

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