Re: Wiring

Phil Kriley

A carburetor and NO EFI? And an auto engine?

Now there are some things to rethink, IMHO. Fuel injection is so much less hassle...

Phil Kriley

On Oct 4, 2020, at 10:56 AM, kent ashton <> wrote:

Nuckolls is good about answering this type of question but if you have a simple engine electrical system, why do you need two batteries? Bob will say, I think, that the battery is the least likely failure point and if it has the juice to start the engine, it is probably OK. If the battery gets low you have the alternator.

I have no personal knowledge of a car alternator going over-voltage but google “alternator overcharging” and read plenty of articles about it or google “forum alternator overcharging” and read personal descriptions. Maybe many of them are just gauge problems but apparently it does happen for real and can boil your battery. See

Here is Bob’s take on the matter.

Personally, I would use a B&C alternator and LR-x regulator and not worry about it. I have modified Denso alternators for one-wire LR-x controlled field current and not had a problem with them but I trust the LR-x regulator to protect me.

On Oct 4, 2020, at 10:15 AM, josrph berki <> wrote:

Can anyone recommend a wiring diagram for dual batteries as I am using an auto engine?
I started with Bob Nuckolls book but had to re think as I am shifting to a carb and simple ignition system instead of EFI.
I am re wiring the whole system.
The Nuckolls book examples introduce some risk due to some complications.
Another question, aircraft alternator systems emphasize control of the field wire so that the alternator does not run away and over charge?
Why does this not a factor in auto systems?
Thanks for any input

Joe Berki

Join to automatically receive all group messages.