Board logo

Alternator wiring
pekwah1 - 31/3/11 at 06:20 PM

Hi guys,

I know this has been asked enough times already buy I'm still confused.
I have the usual Lucas alternator on my crossflow.
I have 2 larger spades and 1 smaller one.
So, where do they go and more importantly, what type of wires should I be using for each?

Regards
Andy

r1_pete - 31/3/11 at 06:33 PM

The two large spades are common, and connect to the battery, you only need use one of them, assuming its an ACR alternator, IIRC the highest output version is 45 amps, so use 60 amp wire.

The small connector is the charge light, this connects to one side of the bulb, the other side to a switched live.

pekwah1 - 31/3/11 at 06:56 PM

Thanks, people are also usually talking about diodes with alternators, do I need one?

Krismc - 31/3/11 at 07:08 PM

Better get a pile, its me who normally talking diodes, get a in4003 from maplins white end too the alternator.

snowy2 - 1/4/11 at 07:00 AM

the two larger terminals are the same and they give the charging current to the battery, YOU DO NOT have to connect these directly to the battery, you could if you think its tidier connect it to the starter motor (or the solenoid) but connect to the terminal that has the live connection to the battery (very common on fords to be wired this way) You do not need to use both charging terminals, the smaller terminal is the charge excite wire, it is ignition switched and is connected via the battery light on the dash.
so that you switch on the ignition the battery light comes on, when the engine starts the light will go out.

the charging wires want to be quite thick and should be able to carry more current than the charging current and a tollerance of about 1.5-2X should be fine, the excite wire does not carry much in the way of current and can be quite thin with no problems.

alternators come with diodes in the regulator, if they are knackered ....so is the alternator, you can replace the regulator and brushes on an alternator, but its not always cost effective as there will likely be other things wrong with the alternator. (bearings for one) It is not easy or practical to replace diodes in a regulator pack on an alternator.
[Edited on 1/4/11 by snowy2]

[Edited on 1/4/11 by snowy2]