Chinese moped motor

[Hepc]

hello guys, recently i found out that there are lots of used chinese mopeds for sale because their lead acid bateries have gone bad and ppl sell them as low as 80 euro, so i bought 2, put 2 motors on the same moped and used 2 350w 17amp controllers and a 20ah 52v lion battery that i built....., the thing is that these wheels only have 16 inches so the speed is lower than on a 26 bicycle...., the hub motor says 250w 48v...., they have lots of torque even drove with a passenger uphill, anyone has sugestions to increase the speed on. this thing.... it goes 35km/h 40 if a bit downhill, i was thinking of extending my battery to 60,64 maybe 72v but i am afraid of destroing the motors.., what you guys think???? they look like this one:
€ 81,91 | 16 inch 36v 48v 350W Lithium Electric Brushless Motor brushless gearless hub wheel for Electric motorcycle scooter motor
https://s.click.aliexpress.com/e/_skSCc2

 

[e-beach]

In general, you can increase voltages for higher speed, but you might burn up you electronic components or over heat the motor. The first thing to do is to open the controller and see if the capacitors and mosfets can handle higher volts. You will have to look at the data sheets for your components to find out what they can take. If they can take higher voltages, then over-volting is an option if you don't over heat your motor and burn it out with you higher voltages. Warm to touch is probably ok, hot or too hot to touch is bad.

 

[Dauntless]

,Keep in mind anything you do would be considered 'Fun with Electricity.' The original 'Boy Mechanic' series from 'Popular Mechanics' had some pretty dangerrous larks for imaginative boys to go on, yours will be nothing in comparison.

Mmeanwhile, this particular experiment is definitely 'It worked right up until it didn't.' As with this guy that was trying to sell me hisnthree broken ebikes back when i was buying and fixing old junk to get the experience with them.

He explained they were all pulled apart because the died while he was trying to figure out about overvoltage. What a coincidence. He assured me that wpuld NEVER cause this problem. I assured him he was obviously unfit to conduct suuch experiments.

Meanwhile don't you experiment on anything youre not willing to burn up. In Southern Callifornia we are allowed much bigger than 350w, so if the weakling fries it fries. I can put on the bigger motor i was thinking about anyway. I understand you're not allowed. How important is it to take that chance?

My own experience says to look for a bigger controller, but what ddifference would burning up this one make? Just dont have it mounted to the bottom of your seat.

 

[dogman dan]

Well,,, first get a third one,, then volt it up till it melts quickly. Back down another 12 or 24v, and there you are.

Assuming they are direct drive type motors,, then whatever they say on the side, you can surely triple it. So typical 500w rated bike motors easily handle 1500w. 48v 30 amps. And they take 3000w for 30-40 min before getting seriously hot. if yours are rated 250w, Id try 1000w on them. 1000w will get you near 30 mph, in terms of human body on a bike like device wind resistance. So say you need 72v to get the rpm, that would be 14-15 amps on the controller. A cheap 72v controller should be easy to find, and if 40 amps, cut a shunt or even two, to lower the amps of the controller. You will need a watt meter, to know what the controller is actually pulling as you experiment.

Betcha they can take that, for a reasonable length ride, say 10 miles. That's per motor btw,, you have two. I'm saying feed each one 1000w at least, and then your motor rpm (speed) will be limited by volts, more than just by wind resistance. Takes about 3000w to reach 40 mph. I suggest just aim for 30 mph. 50 kph ballpark. Up to 72v, the controllers can be fairly affordable.

 

[markz]

It sounds like the used scooters for 80 euros is a make-a-hobby project. For the same kind of money, you could get a generic ebay rear wheel hub motor kit and slap it on your old circa 1990's bicycles and still go a thousand more places then a motorcycled scooter made for roadways and nothing else.

 

[Hepc]

thanks dogman thats the kind of answer i was hoping for...., i have 2 whatmeters, one for each wheel, my only problem is limiting the controllers.... , because most 72v controllers go until 35 40 amps wich i think its too much..... anyway my battery is rated to handle 60 amps max.... and that would be asking for problems later on because if i am on max specs often i think it will fail eventually...., anyways can you point me in the direction on how to limit the amps on the controller?, you speak about bridging something please can you write a bit about this , thanks a lot....,

 

[Hepc]

i mean how can i tell wich shunt to cut on the controller?, another question is when we speak about a 72v battery we are talking about a 19s (70. 3v) that is actually 79. 8 fullycharged right?, so it will pull say 79. 8x15amp = 1200 watts.....

 

[Hepc]

ok so i did some research and i found posts about the shunt mod.... in my 48v 17amp controller i found only one shunt.... , the mod consists on putting solder on the shunt to make it more conductive..... , should a less thick shunt do the oposite?, will order a 72v controller and check how many shunts they have....., anyway thanks again dogman.... you gave me all the right hints on how to proceed , will post my progress here but it will take at least a month for the controller to arrive......