Range calculation....am I doing this correctly .

[JW1980]

Hi everyone.

I recently wrote a post asking for some help with a newly purchased second hand E bike.

It turned out one of the three batteries was no good so I have replaced that one like for like.

All seems ok but I am trying to wirk out the correct range of the bike.

Just wondered if someone could confirm I am doing it right or could correct me if not?

So here is what I have done.

1/ Take the power of the motor and devide that by the battery voltage to give me the current consumed by the motor.

2/ Take the Ah rating of the batteries and divide the current cosumed by it. This should give me the total running time.

3/ Take this running time and multiply it by the running speed to give me the maximum distance.

I have assumed a couple of things here.

a) the throttle is fully open to running at max speed / motor power.

b) there is no pedalling so running purly on the batteries.

I guess, if I have done this correctly then the real figure will be slighly less due to efficiency of the motor and other external influences etc..

Thanks in advance everyone.

Best regards

Jonathan

 

[ColinJ]

It sounds about right, but why don't you just ride it and see how far you can go on a full charge?

 

[JW1980]

Hi ColinJ,

Thanks for responding.

My reasin is to check that everthing is working Correctly and I am getting what I should out of it.

My problem is there does not seem to be a whole lot of information about this model on the net and it did not come with any

 

[fossyant]

Add in variances for hills, traffic light stops, wind, weight and you'll be bob on.

PS if you decide to ride it to see, do it in a circular route, just incase you've got a walk back home.

 

[ColinJ]

Hi ColinJ,

Thanks for responding.

My reasin is to check that everthing is working Correctly and I am getting what I should out of it.

My problem is there does not seem to be a whole lot of information about this model on the net and it did not come with any

Ah, ok.

As fossy suggests, even if all is well, the range will probably be a bit less than you expect, but at least you have a reasonable idea from your calculations.

 

[DaveReading]

if you decide to ride it to see, do it in a circular route, just incase you've got a walk back home.

And try to plan your route so that it's all downhill.

 

[JW1980]

Thanks fossyant,

Thats a good idea

 

[JW1980]

Thanks ColinJ

 

[JW1980]

Thanks DaveReading

I will try that too.

 

[JW1980]

Hi everyone,

I have just thought of another question but not sure if there is a simple answer to it.

I wanted to ask. Is there a way to estimate how much the distance travelled will be increased by pedalling as well?

 

[ColinJ]

Ah, well that is one thing that you CAN find out by just doing it!

Without a powermeter to measure how much work you are putting in, I can't see how you could calculate how much difference it would make.

Actually, if you know what kind of speed you can do on a conventional bike then you could get an idea of your power output. If you could put in about half as much power as the motor, then you would extend the bike's range by about 50%.

Play around with THIS BIKE CALCULATOR to come up with a power figure for yourself.

 

[snorri]

All seems ok but I am trying to wirk out the correct range of the bike.

I do wonder if it is worthwhile spending much time trying to estimate the range by calculation, there are so many variables as to make the calculation little more than a guesstimate. e.g. gradients, surface rolling resistance, load carried on bike, undulations on different routes, battery ageing, wind speeds and direction.
Even the cycle manufacturers claimed range could be considerably different to the actual on the road range. I'm thinking of some car manufacturers claimed fuel consumption figures which have been proved to be rather misleading.

 

[JW1980]

Thanks ColinJ.

I will gove that a go.

 

[JW1980]

Hi Snorri,

My car certainly does not to what is says in paper.

I am really just trying to work out if the bike is working as it should because I don't have any paperwork or manuals with it and finding anyting on like is proving to be difficult

 

[fossyant]

It will go as far as you can pedal it if you don't press the go button.