How much battery capacity is used for acceleration and?

[zener]

How much battery capacity is used for acceleration and for keeping the speed in average in a city enviroment?
Example: I accelerate with 60A till i am on my target speed where the consumtion is 20A in the ''city and around'' i have to stop about all 1000 meter.
How much from my battery capacity is used in average for acceleration and for keeping the speed ?

 

[imorton]

Have a look at this post…

http://endless-sphere.com/forums/viewtopic.php?f=2&t=55283#p823692

IAN

 

[zener]

No its not there.
I guess its about 50% for acceleration and 50% for holding speed. But its just a guess.

 

[imorton]

You might have noticed this info on the link i gave you.

A differing summation of watts required for a mountain bike to maintain various speeds.

*5mph = 22w
10mph = 68w
15mph = 163w
20mph = 333w
25mph = 601w
30mph = 993w
35mph = 1532w
40mph = 2247w
45mph = 3147w
50mph = 4280w
* from ebike.ca simulator

Now that is power (watts) need to maintain, so you would have to subtract the "power in" to get the numbers you are looking for.

I hope this helps, IAN…

 

[dogman dan]

I found that on a 15 mile commute, the normal route would average a stop every mile. If I took the downtown route, I couldn't even estimate the number of stops, some routes, a stop sign every block.

I would use about 20% more battery capacity to get home on the downtown route, but half the ride still the same few stops route. I would guess a complete non stop route might use as much as 30% less than a downtown city ride.

A great deal of that energy used is blown on the first 20 feet of each start. That's when your motor is making heat from 50% or more of the power. When I rode a semi fast wind motor, I had to pedal the first 20 feet, then throttle, or I would not make it home if I took the downtown route.

So your motor wind can make a huge difference. The greater efficiency of the start up of a slow wind motor is what has made me the slow wind motor kook on this forum. If you have a city commute, a semi fast wind motor like a yes 1000w kit is not the ideal choice. A slightly slower wind like a clyte HT or magic pie will work better in stop and go. So will a mac 10t work nicer in stop and go than a fast dd. But a mac 8t will not be as nice as a 10t.

You don't need a crazy slow motor for city riding, but choosing one that is not on the fast end of the spectrum is the thing to do. On the other hand, if your ride is short, so what if it uses a lot of power? Town and back for me is 30 miles, so I need to care about efficiency.

 

[Cephalotus]

This diagram shows a short trip with a reprogrammed BionX system (no speed limit, battery current limited to 20A, regen current limited to 7,5A) and some inner city stop&go traffic. No hills.

Ignore the voltage drop at around 7:20, I hit a pothole at 30km/h and the battery contacts came lose.

You can see the short peaks in power and the amount of regen (quite limited at those high speeds, it's much more significant when limiting the system to motor assist below 30km/). Typically a BionX supports up to 30A at 48V which translates to 1300W+. This is for a legal European "250W" system, btw....

You see the high power consumption when accelerating and this includes a driver that adds some amount of his own power (a bit limited today, because I'm ill)

 

[cal3thousand]

It's JUST like driving a car, 2 things use your 'fuel' the more you are on them: throttle & brake.

The throttle is obvious since it is the "gas", but not so obvious to everyone is that the brake lever converts kinetic energy to heat, which is another energy loss.

So, do your best to cruise to a stop at lights and signs. ESPECIALLY stop signs since they don't change color and you can't "time" them. I'm off the throttle and coasting to most stop signs. By the time I get there, I have seen all the traffic that is entering and exiting the intersection. And most times, I just do a slow yielding 'roll' until I find my window and blast through it. That is the most efficient way to handle stop signs. If I'm good, I don't even have to touch the brake and I save my momentum/battery.

At SOME stoplights (on my legal bike), I will coast up to it and NOT pass the cars sitting in queue (if I feel that we will all make it through one light; if too much traffic, I lane-split). If I "time" it correctly, I will be pulling up on the rear of the pack on a coast as they pull away and we will accelerate as a pack. I save a lot of juice in those situations and get the benefit of being safer. Cagers don't get pissed by having to pass you before the next light and you end up catching them anyways. Also, if you are going in a "pack" through the 3 or 4 lane intersection, you are pretty much guaranteed not to get left-crossed as the cars on your left act as blockers. Just don't go too late behind the last car in the pack, or the left-cross is open again.

 

[dogman dan]

I do that a lot too, try to time the lights. One light, I have a downhill run to it, then an uphill once through. If' its red, I will slow or even stop while on the downhill, then when it turns green, I get to hit the bottom at speed, and that works a lot better than an uphill start from the actual light.

But you get that opportunity one light per ride. Downtown, you are just screwed, the side streets have a stop sign every block. So just roll through them right? Well, it's in the houses, so there's that damn bush on every corner. Or a wall, so you are very close to stopped the first chance to see you have.

If you are having issues with range, pedal the first 10-20 feet from the stops, and then ease on the throttle. Along with coasting up to each stop.

Beating the slow motor horse some more, I just swapped out my 5304 for a 5305 on my cargo bike. Much less amp spike on the starts now. The 5305 is comparable in rpm with a 9 continent 2807. Not that slow really at all. But it's not a fast one like a 5303. Or semi fast like the yes 1000w kit.

 

[Lebowski]

This diagram shows a short trip with a reprogrammed BionX system (no speed limit, battery current limited to 20A, regen current limited to 7,5A) and some inner city stop&go traffic. No hills.

Ignore the voltage drop at around 7:20, I hit a pothole at 30km/h and the battery contacts came lose.

You can see the short peaks in power and the amount of regen (quite limited at those high speeds, it's much more significant when limiting the system to motor assist below 30km/). Typically a BionX supports up to 30A at 48V which translates to 1300W+. This is for a legal European "250W" system, btw....

You see the high power consumption when accelerating and this includes a driver that adds some amount of his own power (a bit limited today, because I'm ill)

Can you somehow integrate the current so we can see the accumulated Ah for your trip ? If not please send me the data and i'll try to process it.
The integrated curve would allow us to see the amount of Ah used for aceeleration and constant speed, and also how many Ah you get back from regen...

 

[Cephalotus]

Can you somehow integrate the current so we can see the accumulated Ah for your trip ? If not please send me the data and i'll try to process it.
The integrated curve would allow us to see the amount of Ah used for aceeleration and constant speed, and also how many Ah you get back from regen...

I do have some other diagrams incl. Wh for assist / regen from other trips. See attachments. I usually do not use a lot of motor power so those diagrams may not be so helpful for the fast e-bike plans with little human power input that are discussed here.

I now also own a legal speed pedelec with a Bionx SL motor in 28" wheels (max. assist speed on the flat is around 42km/h), but didn't made any data logging with that bike yet.

 

[amberwolf]

I don't know exactly how much capacity is used for each part, but as a general rule of thumb if I have a lot of full stops / starts, I will get significanlty worse Wh/mile than if I am cruising around without having to stop much.


As an example, my work commute of ~2.2 miles each way has at least a dozen complete stops and starts, on average, for traffic lights, etc. I get a typical Wh/mile of 29-32 on that, either direction, under various conditions.

However, on another much longer 20-25 mile total route I do every so often, which only has a stop about every mile or so (occasionally on hte half mile as well) I get a tyipcal Wh/mile of 20-24, about 2/3 of the above.

On an ~10 mile (each way) ride along hte canal path, where there are no stops but there are fairly steep but short "hills" on the underpasses to the roads the path crosses, every ~1.5 miles, I can get as low as 19-20/mile, average, if there is no wind--but because it is a long stretch of straight unobstructed path for many miles, almost directly along the most common wind direction corridor for this part of the city, there is almost always wind and becuase of timing of trips and wind direction changes during the day, I'm almost always riding against hte wind, which makes it closer to 25-30Wh/mile again, depending on the wind speed.


All are with no pedalling, cruising at just under 20MPH, acceleration as hard as I can, 40A 12FET controller, 9C 2806 26" front, ~350lbs bike+rider/etc, almost completely flat terrain.

 

[Chalo]

How much battery capacity is used for acceleration and for keeping the speed in average in a city enviroment?

You have presented a serious case of "insufficient data".

The answer you seek is a function of stops per mile, average incline, gross power output, motor efficiency/speed curve, riding style, pedal assist, and cruise speed, along with who knows how many other factors. There's probably no generalization you could make that would hold true for even a single standardized model of commercial e-bike used in different places by different riders, let alone the DIY hodgepodge we have here.

If you want to know what you personally are getting, measure it.

 

[dnmun]

yep, just read it on the ammeter. hills are the worst imo. you can always slow start but hills eat juice fast.

 

[999zip999]

Fat ass and hills.