Dual Alternators? One or Both Is/Are Computer Controlled?

Question

There is a serious lack of intelligent information on the net about factory OEM dual alternator setups.

This is aimed at folks who own a dual alternator setup.

Are your alternator output circuits paralleled? This would mean both would require regulation via the ECU computer. Does the ECU throw a fault if one alternator is isolated from the system? They would have to measure both alternator's field current to know if a fault exists.

I can do my homework and see if the pair use the same point for voltage reference.

Thank you.

ductape · Answer

Might help to specify a brand, would GM, Ford, Freightliner use the same strategy?

I know Ford and GM provide a lot of schematics in their upfitter guides if you can find one for the vehicle in question.

royb · Answer

Mex - I added a second Alternator SEPUP one time to my truck when we Lived in Texas back in the 60s... It had it own charge regulator and its two OUTPUTs went to a two pin HD connector mounted on the rear of the truck... This was supporting my Ham Radio emergency setups when we was on Weather Alerts every time the sky turned green...

My battery bank (Multiple 12V Batteries in parallel) for this was mounted in a utility trailer and it worked rather well when plugged into the two pin connections point on the truck using 4AWG cable pairs... Watching this with a multimeter it performed much like the OEM setup alternator - different DC voltage levels depending on the battery charge status I guess...

I added a second battery for it in the truck just to keep the regulator happy... I used this second battery only for running my two Ham Radio units in the truck... It always stayed charged up... None of this was connected to the truck 12V system...

Roy Ken

mexicowanderer · Answer

I should have specified Ford, Dodge and GM.

s_davis · Answer

I have a 2013 Chevy with dual 120amp alternators, we have talked about before. I am setting up a charging on, what can I check for you?

mexicowanderer · Answer

What modifications to the system would throw a code and perhaps force the circuit into open loop. Limp home.
Ford ECU /Forces one alternator to work as much as 90% capacity then cuts in the 2nd alternator as needed. Or the check engine light comes on and a code is thrown.

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Dual Alternators? One or Both Is/Are Computer Controlled?

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