restricting a 1000w hub motor

[Dumsterdave]

would restricting my 1000w rear hub to 250w increase battery life? I have the option to do this and I rarely need the speed or power that 1000w gives me, but will this really save much battery since the motor is still a 1000w motor, but just made to go slower. Right now my battery consumption is terrible. I ride almost exclusively on PAS 2 and never use the throttle and I live in an area that has absolutely no hills, but i still only get about 40 km on my 48v 12ah battery. Is this normal?

 

[Dumsterdave]

also, my speed is usually about 20-25 km/hr

 

[gogo]

The hubmotor consumes according to load. The way to make it consume less is to lower the load. The energy needed to maintain 25Km/h is 44% more than 20 Km/h. (185W vs. 106W) http://www.kreuzotter.de/english/espeed.htm

40 Km from 576wh might be a bit low, depending on how many start/stops. What is your battery chemistry and how are you measuring actual energy used?

 

[Sunder]

Yes, using a software/firmware restriction to reduce the power output to 250w will substantially save you power, however, it will not be 1/4 of the 1000w consumption. There's two reasons for that:

1. On a flatish route, it is very unlikely that you are consuming anywhere near 1000w, even though that's what your setup is capable of. At 20-25km/h on flat ground, you are likely to be consuming 200-300w, less whatever you're contributing.

2. Electric motors are less efficient when they are below their unloaded speed. If your bike can spin at say 50km/h with no load, then riding at 20km/h, puts it in the inefficient zone. The lower the speed, the lower the efficiency. It's not really noticeable below ~50% of top speed though.

From the sounds of it, I don't believe you would gain more than 30-40% extra range, and while it might not feel much different when cruising, starting and going up hills will seriously be impacted.

 

[d8veh]

How are you going to restrict it to 250w? What does that mean? All you need to do is use a lower PAS level or less throttle to use less power and get more range. Both of those devices are already there to restrict power.

If you're thinking about legal aspects because you live somewhere where EN15194 applies (250w limit), you can't make your bike legal by restricting it in some way. Your motor would not be allowed. It has to have a maximum rating of 250w, which comes from the manufacturer.

 

[Dumsterdave]

I have a cyclotricity 1000w rear hub that comes restricted to 250w for legal reasons, but if you sign a waiver then they will send you the derestriction codes which you enter through the display and then the motor supposedly can use teh full 1000w (offroad of course :wink: ). There is a considerable difference in acceleration and power when the modes are switched. The pas levels also are lowered quite a bit when the motor is restricted, level 5 restricted is close to level 2 unrestricted.

 

[dogman dan]

Your range is a bit low for 25 kph, but the reason may not be the motor, so much as the battery.

It sounds about right for 10 ah, so you might be in reality getting only 10 ah from your battery. Or, it could just be you have a ton of starts and stops.

Restricting the motor will help, since you won't be able to draw higher loads when you start. It won't change a thing about the motor's basic efficiency, but it's likely to prevent using as much power when you ride in wind, up hills, and particularly on starts.

Unrestricted, riding full speed, you should have 10-12 miles.

 

[Dumsterdave]

not sure what the kind of batteries they use inside their packs. I asked their dealer in the UK and was told that they use exclusively panasonic cells, but the dealer in Sweden told me that they use samsung.

 

[Dumsterdave]

The hubmotor consumes according to load. The way to make it consume less is to lower the load. The energy needed to maintain 25Km/h is 44% more than 20 Km/h. (185W vs. 106W) http://www.kreuzotter.de/english/espeed.htm

40 Km from 576wh might be a bit low, depending on how many start/stops. What is your battery chemistry and how are you measuring actual energy used?

not sure what the kind of batteries they use inside their packs. I asked their dealer in the UK and was told that they use exclusively panasonic cells, but the dealer in Sweden told me that they use samsung.

Im not using anything to measure energy use.

 

[gogo]

not sure what the kind of batteries they use inside their packs. I asked their dealer in the UK and was told that they use exclusively panasonic cells, but the dealer in Sweden told me that they use samsung.

Im not using anything to measure energy use.

Without a device that measures energy usage, its hard to know if your range is normal. A comparison with someone using the same battery could help, or your dealer might be able to shed some light. Measuring your starting and cut-off voltage would be easy to collect data.

Your height of 6'2" could make some air resistance if you ride in an upright position. Also, a high total weight combined with enough starting and stopping can lower your range.

If you're assisting with your own pedal power, your range numbers do seem a bit low.