Range and boost

[Swissrider]

I’ve just done the biggest ride so far on my rise H30 using the battery extender. It was 45 km and about 1000 m of ascent. All of this was done in boost at the highest level of support - (my excuse is I was riding with people on full fat bikes]. When I got back I had 7% left, which I guess is 7% of the main battery, and of course the extender was completely empty. One of the guys with me, who was on a Levo had 10% left - 10% of a 700 W battery which is a Lot more than battery, which is quite a lot more than 7% of a 450w battery). The other rider with me had about 30% battery left on his new Rocky Mountain altitude. One of the things that interested me was looking at the assist level on my Garmin edge (using the Orbea Rise toolbox app) which most of the time uphill was around 60%. However, if I slow down the cadence, The assist level would go up, as high as 90%. I thought one got maximum support at higher cadences. But this did not seem to be what was showing on the edge computer. I don’t even know what it percentage support actually means, but it does seem odd that assist seems to be higher at lower cadence’s cadences rather than higher ones since Orbea says motor produces most power at high cadences. Can anybody explain this?

 

[ebsocalmtb]

You had 7% of your total battery capacity remaining. IE, 7% of the main battery + range extender battery. Once the range extender is hooked up, the bike reports total capacity of both.

Wattage or power provided by the rider, is calculated by P = F * V. Or Power = force * velocity. Velocity, in this case is cadence. You can increase power by increasing force (leg effort) or increasing velocity (cadence). If you are keeping leg effort the same, which most ebikers are doing... you are increasing power as you turn over the cranks faster. '

Regarding the assist and power output. That's the nature of how motors and by extension ebike motors work. The bike will consume the most amps, and put out the most assist power at a slower cadence where it can apply 350% of the work you are putting in.

In this case, even though your leg effort feels the same at a slow cadence vs a faster one, you are spinning faster and are likely putting out just enough power where the motor is maxed out and is not providing 3.5 x the power you are outputting. In this case, since the ep8rs maxes out at 350w, all you have to put in to max it out is 100 watts.

The ep8rs is nearly as hungry as a full power motor. If you want it to be efficient, don't let it chug you along at 15-18mph on flat ground. That's when you switch it to trail or eco and put in more leg effort. This is how I maximize the range, if I am trying to do so.

There is some additional nuance to how all of this works, specifically on the ep8rs and the firmware that orbea has developed in conjunction with shimano. The max assist levels you will see on the ep8rs are more or less 85-90%. It seems in the process of modifying the firmware, they did not re-scale the assist percentages for the limiters they put on it. As far as the cadence tuning on the ep8rs, that has to do with a 3 phase ac motor pulse width modulation tactic called near field weakening. They have basically fed in more (or some, I'm not totally sure how much the standard ep8 is even using this) near field weakening to allow the motor to continue to output power past it's technical optimum which for motors of this style, is usually around 60ish rpm from the cranks. I am not sure what motor RPM this works out to, but from my experience working with similar 3 phase motors, I'm guessing that's around 4k rpm or so and orbea is likely adding another 1k to that by using near field weaking within the firmware.

 

[Swissrider]

Many thanks for comprehensive explanation. I’m not sure I understood everything but I think I (and maybe others!) have got the gist of it. I think there is a bit of confusion (caused by Orbea) by giving the impression that not only will the motor react to rider input by increasing power but also it works better at higher cadences. But actually what’s happening is the rider is putting in more effort relative to what the motor is putting in. Thus one goes faster and can cover more distance. So, what Orbea should say is that at higher cadences range will be greater as rider is doing more. I expected the Rise not to produce much power at low cadences and some tests seem to confirm this. However, to my (pleasant) surprise, it almost feels like the opposite. If one one wants a work out and to get maximum range, spin those pedals. However, if one is feeling tired or lazy, just reduce the cadence and let the bike do more of the work. One caveat; if riding with others on full fats, there’s no choice but to pedal like mad!

 

[LeeS69]

I have felt like pedalling at 60rpm I get minor support but spin up, without putting lots of effort in, and the boost increases noticeably.... This is climbing though, if you're on the flat I'm not sure of the difference...

 

[mike_kelly]

There is something called "maximum power transfer". Two devices will transfer maximum power when they both are running at their "favorite" speed. THe motor has it's favorite speed and when you are pedaling at a cadence that is closer to the motors favorate spped the transfer of power is the most efficient. The motor does not like slow low speed high torque situations. It likes faster cadence. It is just like a non-powered bike when the hill gets too steep you shift into lower gear because your body does not like really high torque pedaling. It prefers spinning just like the motor. So if you shift, just like you always have before, so that the gear is appropriate for the climb, the motor will be more efficient.

 

[hind-corners]

Cadence makes a huge different as well others things related to you riding style. I ride lot with full fats (630 and 700wh) and often I have 30+% more battery left on rides. My Rise H has been tuned to output 500w on profile 2 boost but I rarely use it.

 

[Swissrider]

Cadence makes a huge different as well others things related to you riding style. I ride lot with full fats (630 and 700wh) and often I have 30+% more battery left on rides. My Rise H has been tuned to output 500w on profile 2 boost but I rarely use it.

Not sure what you mean by bike been tuned it 500w on profile 2 boost. E-TUBE project just has torque settings for each mode in each profile, but no option to change power in watts. According to Orbea Default in boost profile 2 is max power of 60nm and nominal power output of 250w so how do you get 500w?

 

[hind-corners]

Not sure what you mean by bike been tuned it 500w on profile 2 boost. E-TUBE project just has torque settings for each mode in each profile, but no option to change power in watts. According to Orbea Default in boost profile 2 is max power of 60nm and nominal power output of 250w so how do you get 500w?

Lets just put it this way: How many watts does the ep8 RS put out?

Theoretically you will lose warranty and I don’t encourage you to do it but its possible. Also its good to keep in mind most probably Orbea has not tested their batteries with this setup.