Best way to climb a hill for battery/motor health

[emjay]

OK, possibly a silly question, but I'm going to go ahead anyway

There's one big hill that I have to climb on my commute, and I always wonder what the best setting is to climb it, from the point of view of not stressing my battery/motor. My vague understanding is that the motor likes to be near its maximum speed range, so I should crank up the assistance level to full and climb it as fast as I can, right? Even though that will briefly cause a very high current draw from my battery and controller.

If my reasoning is wrong here, please let me know!

 

[Peter Thornton]

I crank it up to full, that's why I bought an electric bike!

 

[Woosh]

There's one big hill that I have to climb on my commute, and I always wonder what the best setting is to climb it, from the point of view of not stressing my battery/motor.

if you bike has a crank drive motor, use a low gear and keep the cadence as high as you can.
If your bike has a geared hub motor, use maximum assist and try to climb as quickly as you can.
If you have a direct drive, just take a few deep breaths before the hill.

 

[anotherkiwi]

Woosh beat me to it. But with a crank drive you can also up the assistance level and use a higher gear and... pedal harder. You decide how much work you do.

I now am much slower on the 2.8 km climb back from the station because I change down and stay seated. When I had the hub motor I learnt how to climb at just under the cut off and that required some effort.

 

[Wisper Bikes]

If you have a hub drive with a torque sensor the bike will perform well in any gear, the more pressure you put on the pedals the higher the assist level will be. Simply ride up the hill in the gear and to the cadence that suits you best, if you do need more assistance go to a higher assist setting. The bike will do the work for you.

 

[Gubbins]

Here is my two peneth and I have tried all ways, including killing myself in a low power mode but its just like the range question.. It doesnt really have a difintive answer so you will get many differening opinions.
I look at the power meter on my Bosch head unit and try not to let it get too high, by ballancing mode, effort and speed to try to acheive the best road speed with the lowest power output (acording to the head unit).
My reasonings are that the higher the guage goes the more juice I am using, the higher the gear the more effort is needed and the more I give the more the motor will give so blasting up in a high gear in Turbo using a lot of effort uses more than a more ballanced climb in a lower mode at a higher candence. You could argue that climbing fast uses more but does it quicker so perhaps uses les power, and the more you put in the less battery you will use but in my experiments this only aplies when you are riding close to or at the cutoff, below which if you give more then the motor gives more.. isnt that how it works?
One of the things I like about MTB mode is that on a hill when the bike is automatically applying Sport or Turbo and the power guage goes up to the top, I can back off, change down a couple of gears spinning faster and, depending on the hill, it will drop back a mode and the power guage will come down a bit.
The experts will probably produce some complicated graphs to say otherwise but unless you understand what you are looking at its all a bit meaningless.
I am surrounded by big hills and have had 5 years of trying different methods and ride differently depending on how far I intemd going, and you will also discover that those who get further than most of us on a charge are either fit enough to push the bike past or near to the cut off for longer and ride all but the steepest of hills in eco, or dont really know what a hill actually looks like.

 

[anotherkiwi]

I had to postpone last Fridays ride because the weather window I had went away and today there is snow on one of the three mountain passes I want to cross ... In any case I want to see how many Wh I use on 760 metres climbing and 48 km when riding as economically as possible.

 

[Jimod]

I crank it up to full, that's why I bought an electric bike!

I agree totally. I see no point in buying an electric bike and then me struggling up a hill. Full power for me.

 

[Gubbins]

I agree totally. I see no point in buying an electric bike and then me struggling up a hill. Full power for me.

Yes me too, but I dont go more than 25 miles at one go, but if you want to plan a longer ride economy needs to be considered..

 

[emjay]

Thanks all for your replies, my bike is a hub gear with PAS sensor so max assist it is. It's a very short hill so I think unlikely to affect range much, just wanted to make sure I wasn't stressing the bike unnecessarily.

 

[PatH]

Full power all the way for me, the 250w power limit means the actual motor will never really be approaching burnout, and Li-Ion batteries are good at providing peak amps consistently and are designed for this.

More demanding are big hill starts, as you push off the battery will be providing a lot of juice and the copper windings will be heating until you are moving.

I've seen a video of a guy rebuilding an ION hub motor, there really isn't much to the motor, and the problem was simply corrosion on the power connectors. Lack of use probably (it was in Dutch language).

So ride it anyway way you like, but ride it.

 

[Gubbins]

Been for a hilly ride out with the Cobi display set to a screen showing Cadence, HR and Power (including motor support) with all three showing actual over average and are colour coded green, Amber, Red (see Screenshot).
What I found interesting was with the gradient increasing how the power meter went Red as it moved above 200 Watts and by changing down a gear and continuing on at a higher Cadence the power came down significantly.
Changing back up and down to see what it showed sort of made me think could I use this as a Battery management tool on a longer ride?

 

[PatH]

Changing down through the gears is also about maintaining peak human power efficiency, if you are in too high a gear up a hill then some of the energy will be wasted.

In cycling parlance it's called spinning, my daily route is one big incline with 3 or 4 others of varying gradient, I'll be changing gear maybe 4 or 5 times a minute to maintain a fairly fast cadence (pedal rotation speed).

 

[Gubbins]

Changing down through the gears is also about maintaining peak human power efficiency, if you are in too high a gear up a hill then some of the energy will be wasted.

In cycling parlance it's called spinning, my daily route is one big incline with 3 or 4 others of varying gradient, I'll be changing gear maybe 4 or 5 times a minute to maintain a fairly fast cadence (pedal rotation speed).

What do you call fairly fast?

 

[PatH]

100 to 120 rotations a minute?

Or more than one rotation a second.

 

[Gubbins]

100 to 120 rotations a minute?

Or more than one rotation a second.

Well, since finding the Bosch cadence output on my display and purchasing a Garmin one for the Yamaha I find that my Ideal cadence on the Bosch MTB is around 75 to 80 and on the Yamaha Road bike its more like 80 to 90 which I assume is down to the different riding positions, but on either bike anything that needs hard work from me gets me down into the 60's.
Until recently I was blissfully unaware of any of this.

 

[PatH]

Depends on speed and conditions too of course, if climbing on a mountain bike and off road then lower cadence will be a necessity, I'm usually on the road and spinning along at 16 mph, or down to 13mph for the big hill.

On the flat I don't care and will happily cruise using hardly any rotation!

 

[trouty]

my story
I was in the Vinsgau area of Italy September last year with a group of far fitter guys than me so had the Trek powerfly bosch system
towards the end of the week we had a climb of 6000 ft in about 10 miles
The first 3000 feet I rode with the non ebike lads and then turboed the last 3000 feet giving it my all this emptied a 500 battery ( had a spare in the backpack ) .

2 days later we did the same climb and I rode up with the guys on normal bikes and only needed eco to ride with them used only half the bars on the readout .
so speed eats battery IMHO

 

[PatH]

What a ridiculous statement and totally absurd.

 

[GLJoe]

Well, since finding the Bosch cadence output on my display and purchasing a Garmin one for the Yamaha I find that my Ideal cadence on the Bosch MTB is around 75 to 80 and on the Yamaha Road bike its more like 80 to 90 which I assume is down to the different riding positions, but on either bike anything that needs hard work from me gets me down into the 60's.
Until recently I was blissfully unaware of any of this.

Hmmm. I assume you are talking about the cadence that YOU as a cyclist are happiest at?
I ask, because if you have a normal yamaha PW motored bike, then once you get up in the 90RPM range, you are getting very little assistance from the motor. Its most powerful at around 75RPM, but virtually useless over 100RPM.
The Bosch (especially CX) will go higher.
Sounds like you need to swap motors around