calculating miles per charge

[galactico]

hello ladies and gents!

can anyone link me to some info how to calculate the mileage possible per charge. i am aware this is not an exact science as conditions, rider weight, gradients etc all come into play but there must be a base that can be calculated from motor wattage and battery voltage and capacity. i want to able to get in the region of 40 miles with some pedal assistance on hills and into the wind. i will be very happy averaging 16-18mph.

any help appreciated.

regards

paul

 

[flecc]

There is no acknowledged base Paul, due to the hybrid nature with the rider's unknown ability playing such a big part.

Hub motor bikes will generally need at least a 37 volt 14 Ah battery to cope with 40 miles.

The crank drive 26 volt Panasonic system will need at least the new 12 Ah battery for most riders, but the 18 Ah to be quite sure. That said, when ridden for economy by a capable rider, even the 10 Ah can be sufficient.
.

 

[NRG]

As Flecc points out there's no base to work from and only practical experience will give you and idea of what range you will achieve. From my own experience using a 250W hub powered bike I can get anywhere between 8 and 14Wh / Mile depending on speed, route etc.

I regularly ride over the same route and to get 8Wh my average speed drops to just below 13mph, on the same route and averaging 16mph I use 14Wh / mile or more giving me a range of 55 to 32 miles approx. from my 444Wh battery. You can see the difference in range is quite large given the small increase in average speed.

 

[Deleted member 4366]

I reckon that most 36v bikes with a battery of at least 10aH should achieve that as long as you're prepared to put a bit of effort into your pedalling and there aren't too many steep hills. However, I don't think you'll go as fast as you have asked. 14mph average would be nearer the mark unless you already ride a bike regularly. If you're fit and can pedal hard, I would say virtually all bikes would manage it. I don't know about 24v or 26v bikes because I haven't tried one. I do my 30 mile (return) commute on between 2 and 3 amp hours. I'm not particularly fit and weigh 98kg (was 105). My journey only has slight hills apart from one 2 mile continuous steepish hill just before I get home, which takes about 1.2 aH to climb. Most of the rest of the way, I'm pedalling faster than the electric assist speed, for which no power is used. If it's windy, it slows me to below the assist limit, so I use about 2 aH extra one way and less the other. My bike's a cheapo Chinese one, so I guess other bikes would be better (maybe). I hope this gives you some insight into battery requirements. It's going to be different for everyone depending on their journey and the wind. Some people have to keep stopping and starting. I don't.

 

[galactico]

thanks for the info. its a 36 mile round trip if i cycle to work and wish to do it more often as i will need to sell a kidney to keep putting fuel in the car. i manage the trip without assistance but i would prefer it to be a little easier so i can keep cycling every day. at least i have some base info to go from now. a 36v battery with 10aH will be a good start. i didnt want to shell out for a battery that will only last 15 miles. will the motor effect the draw much between a 350w and 500w?

thanks

 

[tangent]

On my Giant Lafree, upgraded to an 8 speed hub, my energy consumption varies between 60Wh and 85Wh over a 7.5 mile commute. For me the difference seems to be almost entirely dictated by wind direction and strength. The 60Wh being achieved with a strong wind behind me. The opposite for 85Wh. Tiredness comes into it a bit as well - I use more energy as the days progress from Monday to Friday.

From personal experience if I was buying another Panasonic based bike I would go for the 18Ah battery if I needed to do 40 miles between charges.