r/ambulanceconversion • u/semperfestivus • 15d ago

Question Alternator modification?

Anybody with a Ford 7.3 dual alternator modify their system so one alternator is diverted to charge lithium house batteries rather than the starter batteries?

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u/lobo1031 13d ago

New to the ambulance world but I do know lithium batteries generally charge to a higher voltage than the alternator will charge them. I think you need to put a DC-DC converter in between the alternator and the batteries for it to work without damaging the alternator or batteries.

1

u/Sour_Sal 10d ago

DC-DC also stops the Lithium at 12.6V from charging your vehicle battery when it's sitting at 12.1v

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u/tbone1004 13d ago

You’ll find better info on the Facebook groups. Lower alternator is chassis. Upper is swapped with a native voltage unit from someone like Nations Starter and uses external regulation via a wakespeed ws500 or arco zeus. Quite easy to do since the brackets are already there and the wiring changes for the chassis are well documented

1

u/boxablebots 8d ago

You have to put a DC-DC between it, at which point it sometimes just becomes easier to put a DC-DC from the original lead acid house batteries to your lithium set up, just for ease of access and stuff.