Golf Cart/Bicycle Hybrid

[sonicj]

how old are the batteries? have they ever been deep discharged? both age and/or abuse can cause a spiral cell to suffer in performance.

a more practical test would be one like dougmcp suggested... test the pack under "real world" conditions. clip the test leads to the pack and watch the voltage as you try to make it up the driveway. that said, 5 to 6 volts at stall seems pretty low. this would lead me to believe that the batteries are having problems under load; a sign of old or abused batteries. *note - stalling the system like this can lead to smoke! if you choose to do this, don't do it for long as something might decide to catch fire or die.

if you know mechanics, you'll have no problem with the inner workings of the electric motor. its just nuts and bolts holding it together! take a picture before disconnecting anything and you'll have no problem putting it back together. things to look for when inside the motor: worn commutator, worn brushes, carbon buildup (DO NOT breathe this stuff! verry bad for your lungs! vaccum or dump into trash outside.), crunchy rear bearing, loose/broken weld from coil to stud, loose/broken weld from brush wires to stud.

other thoughts: change oil in gearbox if you haven't done so. check for dragging brakes. differential should turn easily by hand with the rear on blocks. cart should be easy to push forward & reverse.

the chain & pedals are funny, lol!
-sj

[sonicj]

heres a trick for a little more speed or torque... the photo depicts the brush plate inside my motor. i filled the factory mounting holes with jbweld. redrilling the holes forward of the stock holes (as shown) advances the motor timing making more speed/less torque. retarding the timing (unused holes) makes more torque/less speed.

if you're really good with mechanics stuff, you could make this plate adjustable on the fly via the shifter lever from the bicycle, or a mower throttle, etc.
-sj

[kuntrywelder]

Thanks for all the help. I will poke around awhile and see what I can do. The batteries seem fine as the pack voltage stayed above 37V under stall condition. I only stalled it a few seconds for test purposes fearing the smoke you suggested I watch out for. I need to try the real world test, that would give me more information. The rotating plate idea sounds good if I could do it. I considered decoupling the motor and hooking it up through a torqe-a-verter but never did figure out how it would work with an electric motor and knew it would take a lot of time and work to machine the parts and hook it up. I had the bike running with a 3 HP Honda engine with one of those torq-a-verters I had modified to fit on it and it worked good but the bicycle drive train couldn't stand the torque on the hills. Thanks again I will see what I can come up with.