daniel82

Hi,

I'm new here, so hello everyone!

I'm having a major problem with the electric bicycle I purchased 3 and a half months ago; I bought it so I can travel a distance of about 35km, of which approximately 8 are uphill, with a somewhat steep gradient (especially the last few km). It's a 36v, 250w (front hub), 8Ah-battery bicycle that weighs approx. 25kg, I weigh 60kg, and I usually take cargo with me weighing somewhere between 10 and 20kg. So, total weight is about 100/105kg.

It's this one:

https://www.bergcycles.com/product/u...kking/ebike-e1 (I'm in Portugal)

Ok, so what's the problem? The problem is that the original motor burnt out at the end of that steep ascent the fifth time I climbed it, then the store replaced it with a new motor that burnt out the first time I climbed it, then they put a new one (always the same model) that also burnt the first time I climbed that hill. So, it's already the 3rd motor that burns, always at the exact same place (right when I get to the top of the hill). I didn't pay for any of the new motors, as it's in the warranty.

I've been using the bike these last days without using the motor (as it's not working), and am thinking of either taking it back to the store for a full refund or trying to find a motor that will not burn when I climb that hill (the bad part about this option is that I will have to pay for the motor). I was thinking maybe a 250w high torque motor (that will reach only about 15km/h instead of 25) or a 500w motor (which I'm not sure will work, as the controller is - I think, as it's not in the manual - only 14 or 15A and the battery is only 8Ah).

So, what do you think? Do you know any 250w motor that is high torque? I have only seen one at a store (this one Kits Platinium L1 Rubí sin batería ciclotek, kits de conversión eléctricos, motores eléctricos para bicicletas, bicicletas eléctricas - the one that says "alto par", which means high torque in spanish, in the "Elija su tamaño de llanta (platinium)" field, which means "choose your wheel size"), but it says it's for a 20" wheel (mine is 28").

I would really like to find a motor that suits the bike as I like the bike a lot, but if that doesn't happen I'll have to take it back to the store. :/

Thanks!

EDIT: the bike does not have an accelerator, it's only pedal-assisted

CliffordK

Does your vendor specialize with electric bikes?

What would happen if you put on a 500W or a 1000W motor. Even if you used the higher watt motor with a controller that was designed for the 250W. Most are regulated to 20 MPH or so too.

Does your controller have power control? Don't slam it to 100% for the hill climb. Run it at say 50%, and use your legs. A long continuous hill climb can be tough, and unfortunately your hub motor isn't designed to use gear reduction.

daniel82

Thanks for your reply

1 - No, they only had this electric bike model and it was end of the line (kind of a clearance sale). When I take the bicycle to the store they just accept it and then send it to the manufacturer for the motor to be replaced.

2 - Yeah, I was thinking that a 500w motor probably wouldn't work with this controller and battery, but assuming the controller is 14A, wouldn't the power output be 36V * 14A = 504w ? Or do I have to include the battery amps in the equation too?

3 - Yes, it has 3 modes (low, medium and high assistance), and I usually climb the hill on high.

CliffordK

The battery amps drop out of the equation. So, a car battery might put out 1000A, but your device may only use a few.

Running your controller on its highest power throughput might be hard on it too.

Try running your bike up those hills on low or medium assist, and paying attention to whether your wheel is overheating (stop and feel it?) Don't run your motor to the point of magic smoke.

2old

As you've determined, small hub motors aren't designed for steep hills. You need to be traveling 8-10 mph or the battery "energy" is being converted to heat which is not dissipated readily by a hub motor. As CK said, try lower power with hard pedaling and stop to feel your motor; if you can't hold your hand on it for 10 seconds, it's too hot (or get a small aquarium gauge and be more scientific). Best solution, get your money back and start over.

CliffordK

There are a number of IR thermometers available.

Infrared Thermometer - Non-contact, Digital Thermometer
Non-Contact Infrared Thermometer With Laser Targeting

Although I'm not quite sure what temperature one would cut off at. Too hot to touch is a good rule. So, somewhere around 100°C should be the top end, keeping in mind, of course, that the internals of the motor could be much hotter than the external shell.

One's hand may be as good as the fancy thermometers for the purpose. Just check a few times as you go up the hill and adjust your riding to compensate. Once you get to where the motor isn't overheating, then no need to stop as much.

2old

CK; glad we agree on a "rule of thumb" --- sorry.

CliffordK

Assuming a thumbprint isn't important.

ollo_ollo

Since you have a "pedal assist" bike, you likely can change the rear freewheel cog to one with more teeth. My e-bike, with 8 speed Nexus internal gear hub, has a 16 tooth rear cog, but I could go as high as 22 or 24 teeth if faced with steep hills on a regular basis. This gives you a better gear ratio and multiplies your human motor's input to take some load off the electric motor. Don

Doc_Wui

From the manual in your link:
"When climbing a very steep slope, the driver has to pedal to push the-bike uphill and can push the acceleration assistance button, of 6 km/hr. The motor will adjust the speed to help ypu push the e-bike uphill."

Some of my e-bikes have this button too. I've never used it, as it's really slow.

They are basically telling you to gear down and pedal, while pressing the walking speed button and the motor will turn at 6km/hr. If you can ride that hill with a dead motor, it shouldn't be that bad with assist?

deronmoped

China junk motor???

That is what I would guess, after three motors. Either that or the design of the drive/controller/battery was poor.

I would demand my money back and get a bike that works.

FlyingFranco

One of my bike have a 350 Watts motor on the back wheel. On Steep hills, it cannot climb by it self.
My other bike is rated 500 nominal and 1000 peak, but they say it has a the torques of 59 foot-pounds good for 15% hills. It does better that the other ones, but the steeper the hill, more difficulty it has.

If the motor is not strong enough, energy is converted to heat inside the motor. Then at a certain temperature, you have differential expansion, isolation start to crack, and then you have a short circuit.

I thing the best motor for very steep hill are the ones who work directly on the pedal assembly
that way, you can put the bike in a lower gear, going slower but with more torque.

powell

that is pathetic, really.
What is exactly brand of this electric drive installed on your ebike, is there anything printed on the motor? any label?
Here is e drive which is NOT "fail safe" designed obviously.
stop and feel motor by hand ?
seriously?
Now you wonder why people pay $$$$ for BIONX, BOSH, YAMAHA, EPLUS, etc.?
No way yoU can burn them,
thermal protection bulit in.

daniel82

Hello,

I just got a new bike as a replacement for the one that kept burning the motor! It's the same model but the motor is different (it's this one https://www.aikema.com.cn/En_ArticleS...rticleID=280); it's much quieter than the other one(s) and I will be treating it much better, too, after having read the advice that was posted here (thanks!). I have found an alternative route to the one that has a very steep ascent, and will be taking it instead, even though it's 5km longer. I think I will be doing it in the same time, as I won't have to go uphill. In fact, I can go through this new route without ever turning the motor on (I've done that with the old bike when the motor was broken).

I love this bike, it's very comfortable and fun to ride. I'm very happy that a solution was found. I had only ridden mountain bikes before buying this one, and find this one much funnier to ride! My back's also straight when riding it, so that's a bonus!

Here are some pictures of the new bike: