Diode on main contactor

Stretch, looked at the drawings I have for the 2008. You are correct, Page 5-36 shows the main contactor coil is energized at 72 volts. That being the case, a diode could easily see 150 vdc spikes - I would put something rated at 400 vdc or more. (agree with Dave). Could not find a listing for 1N5404 but did see a 1N5406 600 v 3 amp which should do it.

Sounds like you’ve got an interesting project going. I don’t have my GEM in the shop yet so I don’t know what all I’m facing. If the motor is OK, will likely just keep it stock for now. If the motor is not serviceable - that will open a whole new can of worms.

Good luck,

By “in the shop” I hope you mean your own shop and not somebody’s retail shop. Sounds like you have the savvy to fix your own. This website is probably a pretty good user group to help you thru the parts you cant figure out on your own (for me too). My data plate is a 2007 e4. Just bought a couple of months ago. Hope to have road worthy in the next few weeks. I am new to GEMs.

I would say that most of what you have (motor, controller etc.) is usable in one form or another with application of insight from this website.

Good luck to you as well.

Will you be running a 48v system?
Only practical way to use a 48v contactor.
I have some new 12v economize contractors. They will be for sale after I get the specs on them.

My work shop - here on the funny farm!! I try to avoid commercial shops when ever possible. This is the rural south – electricity is still considered black magic for the most part. There are a few exceptions in and around Huntsville - but that’s all DOD - nothing to good or pricey for Uncle!!

I don’t know the complete history of this GEM, As best I can tell I bought it from the original, institutional owner with a very capable in house maintenance shop. it’s been in continuous service since new as part of a fleet of several. Hopefully it hasn’t suffered from too much redneck engineering!

Got to make some room for it in the shop - next few days. Once I get into it will let you know what I find.


Probably will run on a “72v” setup. I got the contactor out of an older gem. I dont have a bench power supply but have 48v at the ready and just thought I would try it. It seemed to actuate ok.

Sounds good. So far I have found the Gem pretty easy to work on compared to a regular golf cart. Easy to take apart at least… Easier than working on a Bonanza!

The good news about Bonanzas - the Beech engineers who designed them were some of the best, as were the Continental Engine guys. I’ve owned my 1949 model since 1972 and she is still going strong! Will likely out last me!!

Tell me about your AC conversion. Whose motor? Controller? Is the motor mounting face a NEMA standard - common on most golf carts or LSV differentials? If my motor is cooked, I would very likely consider an AC conversion - done it in a number of industrial applications but no golf carts or LSV’s. Did you look at Navitas? Batteries?

I have surplus ac induction motors, pmac motors.
Standard spline for Gem and golf carts.
Also matching Sevcon controllers.
What I don’t have is the time to get them working. :frowning:
$200 ac motors, $500 pmac, $500 Sevcon.
All unused.
I will pay for programming information if someone can get them working in a Gem.

Any spec sheets available - I’m new to this and I don’t know anything these products. Might as well be “moon pies”!

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What would you exactly need for programming information to get them working in a Gem? That pmac motor would fit nicely in the first gen Gems!

I obtained the sevcon programming sw and dongle.
I can communicate, and loaded the Pmac files into one of my controllers.
A Pmac motor is mounted in a test Golf cart.
Then ran out of time. All on hold until a batch of 800 batteries are tested and disposed.
My contact is in a similar situation. Mounted and ready to run. He tells me it only needs some fine tuning to run.
I have no idea what it will take to get a Gem running.
Anyone with Sevcon knowhow wants $100/hr and no promise of success.

If someone can convince me of a good chance of success, I will supply parts and programmer with deposit. Another license is nonrefundable $50.
Not doing me any good on the shelf.
The easiest test would be on a new Gem, as the sevcon is wired.
With a new controller and motor, it should not cause any damage.

I use eBay for the quick and easy. I see the 1N5404 can be purchased for .99 for (10) of them with free shipping…


The motor and controller I have is from Navitas ( TAC 1.0) I hope to have it in and working this week. Will have more info in a couple of Days. I picked the Navitas because I have seen them on some golf cart stretch conversions locally and test driving them they seemed to work pretty good.

I’m on the fence with batteries. I like the idea of Lithium and what I have read about here on the Forum. However one of my neighbors put some Lithium batteries in one of his golf carts a couple of years ago and then got afraid of them and stopped using it and pulled the system out and went back to lead acid… He works for Porsche, drives a Nissan Leaf back and forth to work (because it is cheap and he can plug ii in at work). Occasionally he has a company Tesla sitting in his driveway and works on what Porsche has coming down the line with electrics. Also in the neighborhood a house went up in smoke from a golf cart charger fire… I do have a buddy who really likes his Chevy volt…

".99 for 10 ", beats Amazon at one for 8 bucks from a golf cart dealer…

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Look into lifepo4 batteries for safety. I should have some for sale soon. Bench testing is done. Hope for a real world test in an ev soon.

A 4s battery makes a perfect 12v drop-in replacement. My test will use bottom balance and no bms.
Each 70ah 12v battery will be about $200.

Pictures is similar from my last shipment.

Your 4s battery looks interesting. What are the dimensions and weight? Lifepo4 is what my neighbor had. Found out the real issue was not the batteries per se but a DC to DC converter that got left on and drained them down too much.

Got my motor in. It doesn’t fit with out a bit of interference on the frame… Might have to do a little modifying . Need to work on the inputs next.

Thanks for pix, Hope it works as good as it looks. AC is the way to go given the present controller technology. ( Brushes are for shoe polish!!) You can fix the fit-up problem with a “fire wrench”!!

Brush guards go on the outside !! :man_farmer:

That’s the package I am looking at should I need a motor transplant.

Been looking at Lithium options - pretty sure I’m gonna need batteries. Looks to me like the Nissan Leaf battery pack is pretty easy to work with - just wonder what the collective opinion is on this site.

Any idea where to buy a complete pack out of wreck? Not real popular around here!

Good progress - Zoom Zoom