Can derestricting cause motor/battery problems

[Twangman]

i have been experimenting by derestricting now getting speed at 36kph on the highest power setting. This is done by changing the wheel size in the LCD display. Bike is a 20" wheel folder. But wondering what effect re wear and tear this might have on the motor its a Bangfun 250w and the Battery is a standard 36w 10a. The bike is over 2 yrs old now and is out of warranty.
Any thoughts?

 

[trex]

There is no free lunch. Derestricting pushes some parts of the system to the limit, thus exposing the system weaknesses.
The weakest link in this case is often the battery which will be stressed, internal temperature rises and dies prematurely. The next weakest point is the motor reduction gearbox and other running components (cranks, freewheel, chain in CD systems). Overheating the electric motor is the next point of failure.
If you manage to keep power consumption to under 400W that most e-bikes are designed for, then the bad effects would be minimal.

 

[Deleted member 4366]

It won't put any extra stress on the motor, battery or controller. It will actually give them an easier time because the motor current goes down as the speed goes up. There would be a minimal effect on wear of the motor because it'll be providing power more of the time you're riding, but it's low power and stress compared with travelling below 15 mph. The motors are tested to 40,000 miles. I doubt that you'll ever do that, although forum member Bazwaldo must be getting close.

 

[Deleted member 4366]

Here's a power graph of a typical 32 km/h motor like yours. You can see that both the torque and power are decreasing as the speed increases above 23 km/h. I'm not to sure what Trex is saying, but it doesn't apply to your situation. With all hub motors, it's a case of the slower you go, the more everything gets stressed (for the same battery, controller and motor). The idea is to go as fast as possible to reduce it

 

[trex]

I am saying that failures occur when the components are stressed beyond what they are designed for. Derestricting means that the normal operating margins that the manufacturers put in to protect the bike are removed.
The most obvious is average power consumption. You ride faster on a derestricted bike, the average air resistance is higher, average consumption higher, average trip time lower, average battery temperature higher and the power spikes are more frequent, thus increases the probability to kill your battery. On CD systems, the effect of derestriction on the rolling components is noticeable.

 

[SRS]

I believe in systems such as Bosch are designed from new to run unrestricted.

It is some sort of written law that forces the manufacturers to introduce a cut off. The manufacturers have not introduced it to stop it wearing out quickly.

An unrestricted model will undoubtedly be used more than a restricted version. So I guess all parts of the bike, not just the motor will wear out quicker.

 

[Twangman]

Mm I wondered but given that I assume that the same motors and battery's are sold in the USA. in most states e bikes are allowed to go to 20 or 30mph depending on individual state law and in some states there does not seem to be a limit at all! Though I understand motors can go from 250w to 750w.

I live in London and given most areas now have a 20mpg limit in residential areas I plan most to ride at around 15mph which is what I always done and only boost it up on main rds and when going up hill. Going flat out at 22mph I find the handling of the bike can be a dogey.

 

[Twangman]

Thanks d8veh for putting my mind at ease, it was your post on LCD settings that showed me how to deristrict.

 

[Deleted member 4366]

When you derestrict, it'll only affect level 5 and the throttle max speed because each level 1 to 4 gives a different speed restriction.

 

[Twangman]

Yes you that's right though the levels have changed ie level 4 now gives the same output that level 5 gave when it was restricted, result I can cruise quite happily on level 3 and only use 4 and 5 when I want too. It problem means that I can now use level 1 and 2 before I found the output on the lower levels pointless as the power was negible to peddling unassisted.

 

[flecc]

Mm I wondered but given that I assume that the same motors and battery's are sold in the USA. in most states e bikes are allowed to go to 20 or 30mph depending on individual state law and in some states there does not seem to be a limit at all! Though I understand motors can go from 250w to 750w.

There are always limits in the USA. If a state doesn't pass an individual e-bike law, the federal law prevails, which is a 20 mph assist speed limit and maximum 700 watts of power.
.

 

[steve.c]

Mm I wondered but given that I assume that the same motors and battery's are sold in the USA. in most states e bikes are allowed to go to 20 or 30mph depending on individual state law and in some states there does not seem to be a limit at all! Though I understand motors can go from 250w to 750w.

I live in London and given most areas now have a 20mpg limit in residential areas I plan most to ride at around 15mph which is what I always done and only boost it up on main rds and when going up hill. Going flat out at 22mph I find the handling of the bike can be a dogey.

Hi Twangman.I would hate to live in London where your only allowed to get 20 MPG !!!!!!!!!! I'm sure I don't put petrol in mine??.ha ha.