Harley Davidson 4-wheel electric cart caught fire

[OldFolksHome]

We have a 4-wheel Harley Davidson 36v electric cart. Last week, we purchased all new batteries. After installation, everything worked fine, until I smelled something coming from under the cart, and there were flames coming off the resistor board. It's a 6+ inch fiberglass insulation board. Two of the four bolts that run through it were a little loose, and we were advised to tighten up everything. After we did that, and replaced one bolt, of the 4, it still runs, but was smoking (the board) after about 4-5 minutes of running wide-open.

The board shows some damage from the aforementioned fire, but is still intact, and all bolts are tight.

Any ideas?

Thank you!

[jdunmyer]

Disassemble that resistor board, clean all connections until they're shiny, then reassemble, making sure things are tight. When you first run it, check all connections for heat and fix any hot spots immediately, not "soon" or "when I get around to it". Hot connections are doing real damage, and simple tightening won't always fix things.

Edited to add: make a diagram before disconnecting anything, you will probably not remember how to reassemble it. Also, use your digital camera.

[OldFolksHome]

I was told that it is supposed to be warm-hot after running. Was I mis-guided?

[scottyb]

The resistors can be glowing hot after operation - caution. This is normal, fire is not.
You might need to find a new piece of board and then replace the damaged board and clean all the contacts.

[jdunmyer]

OFH,
Scottyb is correct, the coils themselves can actually get red hot if you've been idling along. The coil connections shouldn't show signs of burning, nor should any other connections get more than very slightly warm. Be sure to check your F/R switch for heating also.

It's been explained many times on this site how a hot connection quickly leads to a death spiral: warm -> very warm -> hot -> very hot -> meltdown/fire. Good connections won't get even warm. A connection can be shiny and clean, yet still get hot if the crimp on the cable eye is poor or there's some corrosion inside it. Many people solder those connections, which is fine, but if a cart is very old the connections might still be corroded.

Don't overtighten your connections, especially on the batteries. Those should be about 100 in. #, or 8 ft. #. If you have any question on the torque, it'd be a good idea to borrow or buy a torque wrench that reads in in. #. Harbor Freight has this one: http://www.harborfreight.com/1-4-qua...ench-2696.html. They show it on sale now for $22.00, regular price $35.00, but I've seen it for as low as $10.00 in their various sale flyers in magazines.

[OldFolksHome]

Thank you very much! We will order the new resistor board and check everything again. It hasn't caught fire since we tightened everything down, and yes, occasionally, we run the cart kinda slow, which for the motor on this beast isn't so easy. It's my understanding that running wide-open is better than running slow. The battery connections are never warm to the touch, and it has six new deep-cycle 6v bats, so we are good there. I think the previously burned fiberglass resistor board is prone to smoking because it has been burned to the point of fire before we tightened everything... if the coil gets hot, the soot on the board smokes.

[jdunmyer]

OFH,
It doesn't hurt anything to idle around, but the resistor coils do get hot. My old Legend had that setup and I could feel the heat coming from under the seat if I put my hand near the joint of the seat and body, where there was a slight crack. If you run WOT, the resistors are completely shorted out and there should be NO heat from them. You're losing a bit of efficiency with that configuration, but it's relatively bullet proof as long as no connections get loose. You can do some pretty bad things to your cart, such as mis-wire stuff, and you won't probably do any permanent damage.

OTOH: a controller setup is smoother in operation and a bit more efficient, especially if you spend a lot of your run time idling along. Scottyb sells a complete conversion kit that brings you to the 21st Century, and his stuff gets good reviews from customers. I did my own conversion of an old CC, using a controller and potbox from an old Cushman Truckster at the scrapyard. It worked great, and I felt it was a definite step up from the Legend.

BTW: you were concerned in your other thread about buying parts: much of the stuff, especially electrical, is fairly generic. Things like the F/R switch, solenoid, and little microswitches are all available, and not all that expensive. One of the first failures I had on my Legend was the solenoid; I stopped at the local NAPA store and asked for a "36-volt solenoid, like the old Ford starter relays". They pulled one off the shelf, and the price was quite reasonable at the time.

Good luck to you!

[PAPABEAR1]

Weve been hacked.....