A two battery ride

[RobF]

I made first use of my second battery in a ride on the C2C path from Sunderland to Annfield Plain in County Durham.

It's a long grind up hill from Washington onwards, not steep, but the incline goes on for miles - they used two locomotives on this stretch when it was a railway line.

Add a head wind, and the result was I all but flattened the battery on the way out.

It's only 21 miles, so it shows what a huge impact conditions have on power consumption.

The climbing will have the most impact, but I wonder how much juice I would use on a warm day with no wind.

I did a couple of 45 mile rides on one battery last summer.

Range is the most common question I'm asked and it's the one with the most complex answer.

 

[peerjay56]

I made first use of my second battery in a ride on the C2C path from Sunderland to Annfield Plain in County Durham.

It's a long grind up hill from Washington onwards, not steep, but the incline goes on for miles - they used two locomotives on this stretch when it was a railway line.

Add a head wind, and the result was I all but flattened the battery on the way out.

It's only 21 miles, so it shows what a huge impact conditions have on power consumption.

The climbing will have the most impact, but I wonder how much juice I would use on a warm day with no wind.

I did a couple of 45 mile rides on one battery last summer.

Range is the most common question I'm asked and it's the one with the most complex answer.

It would be an interesting run to do on a nice warm day; you will certainly get better performance from the battery because the higher ambient temperature will improve the battery chemistry. The headwinds are another matter - they effectively increase your weight/load. I dare say there is a formula that would tell you what effect a certain windspeed has in terms of that extra load, and it's probably exponential!

 

[VictoryV]

It would be an interesting run to do on a nice warm day; you will certainly get better performance from the battery because the higher ambient temperature will improve the battery chemistry. The headwinds are another matter - they effectively increase your weight/load. I dare say there is a formula that would tell you what effect a certain windspeed has in terms of that extra load, and it's probably exponential!

Its a "square Law" i.e if you have a twice as strong headwind than usual, then the resistance is 4 times what it would have been before. If 3 times higher than usual, then it will be 9 times higher than before - it follows from the formula for "drag coefficient" - 1/2 drag coefficent x area x speed squared

 

[Deleted member 4366]

Temperature doesn't make much difference. In theory it can, but in practice, the battery warms itself up, so is not the same as the ambient temperature.

In my experience, wind can make a massive difference in a single direction. On my 15 mile commute, consumption to work varied between 1aH and 6aH depending on the strength and direction, but for the return journey it varied between 6aH and 12AH because what you lost in one direction, you gained in the other,sonot so much variation, but if there was no wind, consumption both ways would be around 9aH or less. With the wind how it's been recently, I've sometimes had to pedal hard down steep hills with the motor on, where normally, I'd be free-wheeling at 24mph.

Riding on the flat with no wind takes hardly any energy, especially at speeds below 12mph, but a one mile 8% hill can take 2aH or more from your battery.

 

[peerjay56]

Temperature doesn't make much difference. In theory it can, but in practice, the battery warms itself up, so is not the same as the ambient temperature.

Not so. I've got four years of operating a fleet of segways in varying temperatures, and both duration and available power are significantly affected on cold days. 'Normal' performance tends to be reached on days when the temperature is around 15C or higher. You might argue that doesn't apply to ebikes, but I don't see how. It also makes a mockery of the insulating covers that Martin sells.