how to connect 2nd alternator

[Bartso]

a couple of questions

1. i have a 24v alt just for my winch (i have usual 12v for rest of car) now i have 2 12v bat in series do i ground the negative side to the chassis will this interfere with my 12v system?

2. how do i connect my alt it has 4 terminals one marked B i assume this goes straight to the positive of the 24v bat, one marked e not sure what goes on this is it ground? and two others that are in a terminal block and not marked i assume one of them is the exciter? (sp) which also get connected to the posite of the 24v bat? does it go through the ignition usually? and what is the other one the charge light maybe? does it need to be connected to work? if it does what can i connect to it instead of a charge light or could i just put a light on it?

any help appreciated
cheers

[spannercrab]

Should be no problem grounding the 24v to the same chassis ground as your 12v batteries (assuming that you are running a 12v battery normally and then additionally another 2 12v's in series for the winch).

The alternator will be grounded via it's case anyway.

Assuming this unit has an internal regulator:

B+ is the battery terminal, which goes straight to the (+) terminal on your 24 v battery system.

E may be an additional earth as was fitted on some alternators - you can check this with a meter - between 0 and 1 ohms between the case and the terminal - both ways (i.e. reverse the leads and make sure you get a reading).

The two in the "terminal block" (which I'm assuming would be a twin spade type connection), one is the field terminal, the other is the charge warning light - as you assumed.

You can just hook up "any old light" to the warning light terminal (although I've never seen one of these lights "actually work") - remember that this light needs to be rated at 24v. Or you could use a dropping resistor and a couple of diodes and splice it up to your existing charge light.

The field (or exciter) terminal needs to be connected to the 24v side of things, but it needs to be swtiched via the ignition - suggest a 12v relay with coil connected to the 12v ignition circuit and 24v connected to the SPST normally open contacts would be the go here.

[toughnut]

I had the same concerns as you when I wired mine up. As spanner said you just run a wire ( I used a battery cable that I already had from the old setup) to the positive side of your 24V system. Make sure it is the outside + terminal not the one that joins the 2 batteries. Then just run an earth from the - terminal to the chassis somewhere. It isn't a problem to run a common earth, just don't run a common +. I ran a wire from the battery through a 24V light in the dash to the positive terminal on a standard 12V 40amp relay and then to the charge terminal on the alternator. I wired up the switch wire of the relay to an accessory wire on the vehicle so there is only 12V switching on the relay. Once the alternator starts charging the light will turn off because the alternator changes the polarity of that wire to +.

[Bartso]

thanks guys is there any way of telling which terminal is which the exciter and charge?

[toughnut]

Did you buy the alternator new or second hand. If it is new then the destructions should tell you If not then you could look up the brand on the net. I can't tell you without looking at it.

[Bartso]

the alt is off a patrol safari 24v