Tongxin amp info?

[Geebee]

I am just checking if anyone would know what the max. SAFE amps I could pull on a 24v Tongxin running as a Stoke Monkey, I always pedal of the mark to keep initial load down?
Thanks

 

[jerrysimon]

Here's the spec sheet

Hangzhou Zhejiang University Tongxin Electricity Company

I usually set my controllers to max of 12Amps but that is for the 36V version. Given the power generated (looks like max is 400-450W) by the motor I would suspect that the 24V version could handle more than 12amps if you use the formula P=VI

Indeed their controller listed in the spec link posted above states 15Amps.

Regards

Jerry

 

[Geebee]

Whoops forgot to add it is currently running at 15 amps and has done a few thousand km at that and still sounds like new and never gets more than luke warm, I was wondering if it would be safe to push it higher but I gather probably not?
Cheers

 

[jerrysimon]

Well using that calculation P = V * I and selecting 425W I get

425 = 24 * X

X = 425/24 = 17.7Amps

I guess you could try and check to see if it gets warm. Is it more torque you want or more speed ?

If its more speed then over volt it to 36V but crank the current back down to about 12Amps.

Jerry

 

[Geebee]

More torque as the organic engine can't produce any , I will have a play with the shunt.
Cheers

 

[jerrysimon]

This morning I connected up my watt meter to my Brompton with the larger 36V Tongxin not KeyDe on it. Peak power was 480W and peak amps was 12.9Amps. My controller is set to 12Amps which shows there a somewhat generous error factor.

So 480W at 24V would give you a higher 20Amps. I would not try that though and maybe try 18Amps and see how warm it gets. From memory its current that kills these motors quick.

Note my measurements are with the smaller 80mm wide Tongxin. I think the wider 100mm Tongxin will deliver even higher power.

Jerry

 

[Deleted member 4366]

I thought that the problem comes from rollers slipping rather than heat. As far as heat is concerned, you can go very high on the current on most motors as long as you keep the speed in the efficient zone.

 

[Geebee]

Being setup as a stoke monkey isolates the hub from alot of road shock and vibration plus having 24 gears removes a lot of load as well, except for one stupidly steep hill to get home. So I am hoping that factor will extend its life.
It is one of the original 100mm hubs.

 

[jerrysimon]

Thanks for that reminder Dave as you say slipping rollers does result from too much current I had forgot that. On the smaller KeyDe motor it took me quite a while to find the sweet spot current wise where the roller didn't slip.

What's more it sounds pretty bad like the motor is about to destroy itself.

Jerry

 

[Geebee]

Well all things considered I decided to try it with again the 15 amp controller but with a LiPo battery as I had previously only used it with a small capacity SLA.
It proved easily capable of 800m at ~15% grade followed by 500m 10~12% and a short 20% grade, motor barely above ambient temp. obviously severe volt sag on the SLA was the reason for struggling previously even with me assisting.
The test above was done with no pedalling.