running batteries directly to motor

[mntjohnson]

Can one just run the power (36v) from batteries down by wire to the motor? I know one has to watch overheating, and some other things. So, can one bypass the throttle and controller this way? TOM JOHNSON

UPDATE FROM ORIGINAL POSTER - - Motor finally ran when I hooked up straight to batteries, here are some pics. Thanks for all replies.

 

[spinningmagnets]

If it is a brushless motor, the coils have to turn on and off at just the right moment, so in that case it will not work at all, and the single coil-set (out of three phase-groups) will get very hot very fast.

For a brushed motor, I believe it might run full-speed until you disconnect it.

 

[liveforphysics]

Can one just run the power (36v) from batteries down by wire to the motor? I know one has to watch overheating, and some other things. So, can one bypass the throttle and controller this way? TOM JOHNSON

If you're brushed, you can do that.


Unfortunately, brushed really really sucks ass.

Controller/throttle setups are cheap and easy.

 

[texaspyro]

Unfortunately, brushed really really sucks ass.

Awww now, brushed motors do have their charms... particularly when the controller output transistor shorts

 

[dogman dan]

Easy to test does it run too. But none of it worth switching from brushless to brushed.

Free stuff, now that's different. Run it , burn it, laugh at the smoke. But running brushed with no controller sends your battery vicious amp spikes, so you might damage good batteries playing around. Old school golf carts used to work this way, As you pressed the throttle you got 12v, then 24, then 36. It was incredibly harsh on everything and for good reasons they all use controllers now.

FWIW once you get above 24v running a switch instead of a controller, you fry switches really fast. Sometimes they weld themseves into the ON position, so have a battery plug you can yank handy.

 

[TylerDurden]

It's not all bad.

Pulling from stop would be hard, because that's when current would spike: bad for switch, bad for brushes, bad for battery.

OTOH: if you pedal up to 15mph, then hit the switch, there would be much less torque required; pulling less current.

In the best case scenario, the motor and gears would be matched to your cruising speed, so you could pedal up to speed and energize the motor seamlessly (like driving when your car's clutch is shot ).


FWIW, brushed motors are still winning lots of races, but they are not the future.

 

[Jeremy Harris]

When I was a kid I made a primitive ebike using an old car dynamo as a brushed motor, together with a clapped out car battery. I just used a switch on the handlebars to turn the motor on and off and it sort of worked OK. The dynamo was a pretty crappy motor, plus the old car battery didn't have much poke left, but it was an interesting experiment.

Not sure I'd like to do the same with a powerful brushed motor and battery though, it's be pretty hairy trying to pull off.

Jeremy

 

[mntjohnson]

Sincerely thank you everybody for the advice, which told me the good and bad parts of bypassing straight to motor,,, but when I tried it led to nothing so maybe it is brushless,,,, I inherited this bike so I am still trying to identify it,,, again thank you everyone for advice. TOM

 

[TylerDurden]

Post a pic of the bike/motor and we can maybe tell ya whatsit-iz.

 

[dogman dan]

Only two wires to the motor is always brushed motor. If this is what you have, and a 12v battery didn't run it, then it's broken. Could be just the brushes.

 

[mntjohnson]

Is it bad for me to use 3 big marine batteries to test or maybe run bike, rather than 3 small 12v 12ah batteries? Would the higher amps hurt motor?????????????? TOM

 

[liveforphysics]

Is it bad for me to use 3 big marine batteries to test or maybe run bike, rather than 3 small 12v 12ah batteries? Would the higher amps hurt motor?????????????? TOM

The only down side is the weight you gotta carry. Otherwise, the bigger the battery the better for everything.