Bosch range indication

Black Dog

Pedelecer
Jul 18, 2014
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Long post alert: a question about the reliability of the 'range' indication on the display of my wife's bike, a Raleigh Motus Low Step with Bosch drive. It seems to bear no relation to the battery status indicator. Key facts:

My bike is a Wisper 905 Classic with a 16Ah battery (592 Watt-hours, 37V) and has six power levels (six little LED lights on control unit) and four LEDs to show state of battery. My usual commute (27 miles round trip, hilly) is normally done on max power (6/6 lights) and when I get home I have two battery lights remaining, i.e. I have used about half the battery capacity. That implies a total range of about 50 miles, which is in line with the manufacturer's estimate.

The Motus has an 11Ah battery (400Wh, 36V) with four power levels (Eco, Tour, Sport, Turbo) and five segments to the battery status display. It also has a 'range' indication, which changes according to the power level you select. Eco, on a full battery, should be good for 70 miles or so, and less for the higher settings. Obviously, this figure reduces as you ride.

So on Tuesday I decided to use the Motus instead of my own, just out of curiosity. (It has a wider range of gears, which might help with some of the steep ascents I have to tackle.) I decided to use the Tour setting (2/4 and theoretically less than I am used to) in view of the smaller battery and my wish to get fitter. The range read 42 (full battery) when I set off, but to my horror by the time I had reached the top of the road, about half a mile away, it read 36, and then started to click downwards ominously. I switched to Eco after a while of this, using Sport and Turbo only for the steepest bits, and did probably half the miles with the thing turned off. When I got to work, very hot and sweaty, the range was reading 14 in Tour (just enough to get me home) and 24 in Eco. I used the assistance very little on the way home (I got a good sweat up again) and after 27 miles the range read 12 in Tour and 20 in Eco. The battery status indicator, however, showed three out of five bars, which is about half used. My estimation, based on the smaller battery size and the effort I put in, is that this is about right. The range indicator, however, says that in 27 miles, mostly off or on low settings, I have used the equivalent of 50 miles on Eco and 30 on Tour. So, do I believe the battery indicator or the range estimate? I don't expect the range figure to be 100% accurate (same as on a car, it's a guide), but the way it plummeted in the first couple of miles and then seemed to level off suggests that it is not something to rely on.

I'm taking it in again on Friday night, and will take the charger with me and give it a full charge at work. That way, I can use the assistance more without worrying about range. On the plus side, the experience shows that I am fitter than I was, and that doing the whole distance on an unassisted bike is not impossible. Also, the Raleigh rolls very well and without power feels like a heavy but smooth roadster, quite pleasant and easy to pedal along. When I ran out of juice on the Wisper, the remaining couple of miles were very hard work indeed. Possibly the drag of the hub motor? The Raleigh's crank drive is a dream, much more natural feeling than the hub drive on the Wisper, but then it's a lot more expensive too.

The Motus is clearly the better bike, and if this experiment had worked out I might have sold the Wisper and used my wife's bike full time (with her approval, of course) or even bought a crossbar Motus. But if I have to pedal it most of the time to conserve the battery I won't bother. Possibly relevant is that the bike was used a few times (40 miles total) last autumn and then put to bed over winter, with a couple of full charges while in storage as per the instructions. I put the charger on for about 12 hours before I used it this week and the system said the battery was full, but perhaps it needs a few charge/discharge cycles before it reaches peak efficiency. Any thoughts? Sorry for the long and rambling post!
 
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JamesW

Esteemed Pedelecer
Nov 17, 2014
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I test rode a moths 2 Weeks's ago with only 40k on the clock. What I noticed was that the range indicator seemed to change with assist level, amount of effort from me, and (most significantly) terrain. My guess (not having a Bosch bike yet) is that the range indicator helps you judge if you will make it based on the terrain ahead and the battery indicator is the true guide.

James
 

Wander

Esteemed Pedelecer
Aug 8, 2013
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I think the range indicator on the Bosch might base itself on the last mile / half mile or kilometer. i.e. it assumes that the rest of the journey will be as tough / easy as the last distance travelled and on the same terrain / speed / assist levels.
 

Martin@e-bikeshop

Esteemed Pedelecer
The range is based on the last km of riding.

This quote:
The range read 42 (full battery) when I set off, but to my horror by the time I had reached the top of the road
Implies that you live at the bottom of the road. So with that in mind, the initial range was calculated on your partner riding the bike home 'To the bottom of the road'.. Most likely downhill and possibly even coasting some of the way. (People naturally tend to slow down as they get closer to home ;))

You have then cycled back up the hill, hence why the range has changed. Again it is based on the last km of riding (so say approx 1/2 a mile).

If you want a more accurate reading (depending on what software you have installed on your particular unit) you can select the range function on the display, then hold 'Reset' this will then forget the last km of riding and base it on the battery capacity instead.

The above is assuming that you live at the bottom of a hill/road, or alike, judging by the wording you used.
 

Black Dog

Pedelecer
Jul 18, 2014
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You guys are dead right. The first half mile of my journey is uphill, moderately steep. The 'last km' thing explains why the apparent range dropped significantly when I got to the top, but only dropped gently afterwards. My car does the same with average mpg, although I am not sure how many of the last km it uses. I am using it again tomorrow night and I will take the charger just in case, but I will rely on the battery indicator rather than the range. In fact, I will turn the display to read something else so I am not panicking!

Martin, well Sherlocked. I am half way up a longish hill, a climb which needs a low gear on a normal bike. The first half mile is uphill, and you correctly guess that the previous half mile was my wife, who likes to coast a lot, riding down the same hill, with only 100m of uphill driveway to finish.

Very helpful gents, many thanks.
 
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Black Dog

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Jul 18, 2014
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Haha, even better. I have just checked this with my wife, and the last miles she did before we put it away for the winter was about three miles gentle downhill on the Brunel track at Neyland, at about 20 mph all the way. And then it travelled home on the back of the car. The bike obviously thought that the last km was easy, and in the future life would be good. All makes sense now. Cheers all.
 

JohnCade

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May 16, 2014
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I always think those things are a waste of time and definitely not to be relied on.
 

RobF

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Sep 22, 2012
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I always think those things are a waste of time and definitely not to be relied on.
Same here, I've never bothered with the range indicator.

Having done a lot of miles on Bosch bikes, I pretty much know what the range will be taking into account the conditions of the ride and how lazy I'm feeling.
 

Black Dog

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Jul 18, 2014
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OK, I have ridden in to work tonight (and brought the charger, Justin Case). The battery status is four bars out of five, so that should easily be enough to get me home again tomorrow. That, to be honest, is pretty much as I expected. Now that I understand how the range indicator works, it makes sense. When I left home, predicted range in Tour was 33 miles. Half way (6.5 miles in), it was predicting 36. Journey over, it is predicting 33 again. From what I can gather, it would only have any real use on a long journey on the flat in consistent conditions. Any hills or headwind for a significant distance will make it read something entirely different. I'm going to have the trip distance showing from now on, or elapsed time, or Radio 3, or something useful, and rely on the battery status for my range.

Thanks for explaining it all to an ebike noob.
 

stevenatleven

Pedelecer
Apr 18, 2011
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Thanks for posting this query as it has helped explain a similiar incident that my cycling partner experienced this week. She had covered 24 miles of a planned 50 mile round trip on her 11ah Bosch crank drive. When we turned into the wind and a bit of an incline to get to the cafe the range figure started to drop like you have described. On reaching the cafe her range on Eco was less than 14 miles but she still had 3 bars of her battery showing (out of 5).
The ride we were doing was round a loch and has a steamer service to the return point which she opted to take as she was convinced she would,nt get back.
I think in future we will disregard the estimates.
 

Croxden

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Jan 26, 2013
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I find the range forecast to be pretty accurate just before battery dies.
Bear that in mind.
 

Black Dog

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Jul 18, 2014
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Well, I cheerfully ride the Wisper and just rely on the battery status lights, and I'm going to do the same with the Motus. A range estimate that goes from 42 to 33 to 29 to 42 again in the space of a couple of miles is neither use not ornament. Steve, sorry you had your ride spoiled! Croxden, will remember that :)
 
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Sherman

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Oct 29, 2014
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I think the range indicator is handy. Over time you learn the range of the bike in different conditions. Which is valuable as conditions have huge impact on battery consumption.
 

Black Dog

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Jul 18, 2014
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Fair point. They key is learning how these things work, and then you understand what they are telling you. I didn't, but now I do. Pity the handbook wasn't as helpful as this forum :)
 
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Jimod

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Aug 9, 2010
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The ride we were doing was round a loch and has a steamer service to the return point which she opted to take as she was convinced she would,nt get back.
I think in future we will disregard the estimates.
Were you at Loch Katrine?
 

anotherkiwi

Esteemed Pedelecer
Jan 26, 2015
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My LCD battery gauge works kind of the same way. I have a long 4% hill climb and at the top I lose a bar which I get back after free wheeling down the other side.

I have run out of battery twice this week just before getting home but range is a solid 72-75 km which in my mind is very good for a 10.4 Amp battery in very hilly countryside. Yes, I have started dreaming of a 14 Amp battery... There is a cheap 100 € 8 Amp bottle battery on sale at BMS but it isn't compatible with my holder :(. It would have made a great spare/range extender.
 

Black Dog

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Jul 18, 2014
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My LCD battery gauge works kind of the same way. I have a long 4% hill climb and at the top I lose a bar which I get back after free wheeling down the other side.
I think that might be what they call 'voltage sag', where during of heavier use the battery voltage drops, losing you a bar on the gauge (or in my case an LED light), but which recovers as soon as you reduce the demand. I have four LED lights for my battery status, and after a long climb on the way to work it can go down to two out of four, but reads full (4/4) again by the time I have got there. The range indicator seems to be more intelligent than this, using the history of the last km travelled and a reading of the remaining battery capacity to predict likely range. Whether the predicted range takes account of voltage sag after a long climb or ignores it, I couldn't say.