Valeo alternator

[atr]

Hi
Please dont laugh at me. I have a Valeo alternator that I've dismantled from my donor Xantia and I want to use it as a battery charger. I've installed it on a plate with a 3 phase motor to drive it. so far so good. now, my question is how to wire it. I've seen that it has 3 terminals - B+, D+ and a third one that I cant see how it's marked. could you please let me know how it have to be done? I guess that the B+ terminal should be connected to the battery + terminal.
Thanx for your help.

[white exec]

The third terminal is voltage-sensing, and should (also) be connected directly to your battery + terminal.
The reason for the separate wire, when installed in a car, is to sense the battery voltage accurately. This can't be done (decently) down the main alternator-to-battery cable, because this will frequently be carrying a hefty current, and will therefore have a voltage-drop along it. Hence the extra small wire.
______

Good fun to build something like that. Back in the 60s, the GPO Telephone Exchange on Ealing Green ran some of its exchange equipment from 2v DC. Amazingly, this was created from a huge 2v dynamo, directly coupled to a 240v motor, and a room full of lead-acid battery as backup.

[atr]

Hi Chris
Thanks for the reply. one more question - to where should be the third terminal connected to?

[white exec]

B (or B+) goes to battery + terminal, and is the main alternator output.

D (or D+) operates the IGN dash warning light. This must be connected for the alternator to work.
Connect this terminal to one side of a small 12v tungsten bulb (about 1W will do), and from the other side of the bulb to a switch, and from there to Battery + terminal. When you turn the switch on, the bulb will light (indicating no alternator output), but will extinguish when you start the alternator up.
Turn off this switch when system not in use, or you can drain any connected battery. It's the equivalent of turning off your IGN switch.

Ground (-) connection for the battery is from the alternator's frame.

There may or may not be a W terminal, which is a feed to a dash tachometer.

Sorry if I misunderstood you about the 'third wire'. Some alternators have this tiny wire and terminal, some don't. The latter sense the battery voltage from the main output cable.

[atr]

Thanx for the comprehensive explanation.

[Gibbo2286]

My younger brother had an alternator set up with a windmill to charge his batteries.