Also you should fuse the controller +36V small wire, and the clock wire (it's better than having burned wires - see I do have a serious side :) ). The Ammeter fuse may not be needed but if the shunt ever comes loose, it'll save the meter from being fried.

Maybe like this?
https://www.gassavers.org/attachment....1&d=1168401800

Awesome - thanks.

OK, so maybe I should have an interlock. I never thought it was a problem, but if there's a law...

PS - didn't realize I was mis-using the chassis ground symbol. Learned sumpin' new today! Just in time too - the day's almost over, here.

I think it's more of a dummy-proofer. A boss of mine once told me "you can't make anything foolproof because fools are so ingenious." :)

I seriously think a kill switch would more worthy of your time and more likely to be appreciated by first responders. Another place for an interlock is on any opening compartment that exposes the traction wiring - but then again good insulating covers may be better overall. Those kind of interlocks too often get defeated while the thing is in "R&D."

Pretty much. Besides being a safety valve of sorts, it's also a way to disconnect parts of the circuit w/o putting switches everywhere. The potbox probably doesn't need a fuse because it's just a 'sense' circuit. The 5k pot varies from a dead short to 5,000 ohms and is just a voltage divider for the controller input. It shouldn't have much current flowing if all connections remain correct. Besides some controller internal malfunction, the only danger would come from some higher power wire coming in contact it. This is where the quality of your physical electrical connections will pay off in overall reliability.

It would be easier to wire if everything except 'power' was 12V but it depends on the parts themselves.

A 36 volt contactor coil energized with 12V won't pull more current because of the lower voltage (prob less) and thereby heat up, but there could be another problem with the lower V. If as you said, they came out of the forklilft as 36V devices, then 12V may not be enough to get them to close firmly. If they engage weakly, or worse chatter, then the power contacts will probably arc, self destruct, and otherwise ruin your day.

Also, if the correct V is 36V, then 48V into the contactor coils would entail more power draw and more heat, but I don't know if that's destructive. If it is and you still want to go to 48V or more, there are ways you could handle that with varying amounts of scope creep:
1. Just use a wire coming from the third battery (36V worth) for the contactor circuit. This one falls into the "if it's stupid and it works then it ain't stupid" category. It means assymetrical loading of the batteries but maybe only slightly.
2. Use an electronic regulator circuit to drop the 48V down to 36V for those coils (it's not as complicated as it sounds).
3. Change the contactors to 12V ones (prob the most expensive).

BTW, I'm pretty sure the small wire to the controller still has to be at full pack V.

Sometimes a circuit will have 2 different 'grounds.' Sometimes there is a chassis ground, and an earth ground. Sometimes they're just used to simplify 2 different circuit common points to reduce clutter in the drawing. In any case they usually each use a different symbol for clarity:
https://www.gassavers.org/attachment....1&d=1168407500
In your case, the traction battery negative side isn't really a ground, especially since the negative side is the part that is regulated (chopped by the PWM). OTOH, the -12V is a true chassis ground since it's used throughout the car.

BTW, cars used to have positive ground - or in the Healey, "positive earth." The convention changed to negative ground to reduce the effects of electrolytic corrosion in the body.

You mean like a big read panic button on the dashboard

Battery news: just got off the phone with the company that sold us the forklift.

Floodie = wet cell?

Yup. Flooded lead acid batteries, that need periodic watering to replace electrolyte lost during charging.

Golf carts, industrial floor sweepers, and most EV conversions use 6v floodies.

That's my car...
 

I was just browsing along seeing how things were going with Project Forkenswift and I clicked on the link and... THAT'S MY CAR.

That's so funny. :)

I just purchased it in December and while it does run, there are problems with it--the Forward/Reverse contactor spits blue-green flame in reverse and when I try to go forward at low speed it jumps like a jerky start in a clutch--if I press down the pedal more it evens out but apparently I can't use low speed.

With the problems I haven't tried taking it further than the end of the block so far.