Range isn’t accurate

[Tubby G]

Evening all

Been having some fantastic rides on my EMTB since acquiring it just before Christmas last year. Absolutely loving the Bosch motor

One minor irritation I have noticed however is the range never seems to be accurate when fully charged. I keep the battery indoors and charge at room temperature. When putting into the bike and ready for a ride I’ve noticed that typically Eco mode states I have around 60 miles fully charged, but as I’m around 5-10 miles into the ride the range starts to increase. On the first few charges when brand new I was getting around 100 miles in Eco mode

Now it could be that I’m putting a room temperature battery into an outside temperature bike, and the last few weeks it has been below or around zero degrees C. I’d expect the range to decrease however into the ride, and start at maximum range available, and not state a lower range and increase during the ride

Anyone else notice this ?

 

[Rahr85]

My assumption was that it uses data from the trip computer and how much assistance you are using to calculate the range and that as you are not going off a fixed % of battery left the range is never going to be an exact figure unless you are riding at a steady speed on a constant gradient. It just assumes worst case scenario based on what has happened to that point rather than being overly optimistic.

 

[Doomanic]

Expected Bosch eBike Battery Range

This article explains the Bosch eBike systems battery range and how it continually calculates based on how and where you ride. It also details that all eBikes with Bosch systems will show different…

ebikesussex.com

 

[Jackware]

Do you increase the assistance towards the end of your rides?

As the system predicts the range from the power consumed in the last mile, this is my guess.

 

[Rahr85]

Today was my longest ride to date with the bike. It included some messing around at sherwood pines and a local "secret" location. First time i've got to the end with a range of 0 left. Mix of conditions/elevation/modes to get a good work out but not suffer up the steepest hills.

 

[Tubby G]

Do you increase the assistance towards the end of your rides?

As the system predicts the range from the power consumed in the last mile, this is my guess.

Yes! I go into full turbo mode in the last few miles as I know I have plenty of charge left so go for all out fun

 

[Jackware]

Yes! I go into full turbo mode in the last few miles as I know I have plenty of charge left so go for all out fun

So there's your answer, as you start off in eco, the computer recalculates based on the motors reduced assistance compared to how you finished the last miles of your previous outing.

 

[GrahamPaul]

Ah yes, the mythical and mysterious range calculation done by the Bosch motor software. Here's my predicted range after 25km on a ride in June last year...

 

[Hamina]

Ah yes, the mythical and mysterious range calculation done by the Bosch motor software. Here's my predicted range after 25km on a ride in June last year...

View attachment 50727

If you have ride 25km without even used a one pillar of battery then it sounds reasonable.

One could ask why you're riding electricbike in first place if you don't use the battery?

 

[GrahamPaul]

If you have ride 25km without even used a one pillar of battery then it sounds reasonable.

One could ask why you're riding electricbike in first place if you don't use the battery?

One could... maybe I just like the extra ballast for training

But the answer would be that there are two reasons:

1) The only way home is up a 2.5km climb with an average of 10%

2) The tracks around here have a lot of soft sand. (Fatbikes are popular, but see above).

I just can't face that climb home anymore...

 

[Hamina]

One could... maybe I just like the extra ballast for training

But the answer would be that there are two reasons:

1) The only way home is up a 2.5km climb with an average of 10%

2) The tracks around here have a lot of soft sand. (Fatbikes are popular, but see above).

I just can't face that climb home anymore...

Good points.

This is also the reason why the highly intelligent and with enormous calculation capacity equipped Purion can only give us the best available guesses on the range that's left. It doesn't understand what your about to do. It's kind of blind and deaf. It only sees what we have done during the last kilometers. I couldn't do any better guesses.

It's a different story if you commute 200 days a year same route and collect all available environment and traffic data to a database and make assumptions with supercomputer like weather forecasts.

 

[Hamina]

One note: It's interesting

One minor irritation I have noticed however is the range never seems to be accurate when fully charged. I keep the battery indoors and charge at room temperature. When putting into the bike and ready for a ride I’ve noticed that typically Eco mode states I have around 60 miles fully charged, but as I’m around 5-10 miles into the ride the range starts to increase. On the first few charges when brand new I was getting around 100 miles in Eco mode

Now it could be that I’m putting a room temperature battery into an outside temperature bike, and the last few weeks it has been below or around zero degrees C. I’d expect the range to decrease however into the ride, and start at maximum range available, and not state a lower range and increase during the ride

Anyone else notice this ?

I'm not a electric engineer, but the temperature affects the battery's capability to feed power.

What I've observed and what might be happening:
When you start riding in cold (-19'C) the battery starts getting colder first -> less power -> less range. As you continue riding the battery keeps pushing electric power to motor it also emits heat -> at some point the speed of temperature decrease starts getting slower and later on it's meets it's lowest point.

These all are just guesses as we don't know what variables the purion or the motor uses for the calculations. The battery temperature is available as it's shown in the Bosch service sheet that you get from for example when updating the firmware.

 

[GrahamPaul]

Good points.

This is also the reason why the highly intelligent and with enormous calculation capacity equipped Purion can only give us the best available guesses on the range that's left. It doesn't understand what your about to do. It's kind of blind and deaf. It only sees what we have done during the last kilometers. I couldn't do any better guesses.

It's a different story if you commute 200 days a year same route and collect all available environment and traffic data to a database and make assumptions with supercomputer like weather forecasts.

I ride very varied terrain a lot of the time (when not in lockdown ). What I've learned is that it's not worth having the range indicator display until I'm down to the last bar. When the estimated range is under 10km, and on the last bar, it's worth paying attention.

With 5 bars showing, it's a joke. One minute it will be over 200km, after 5km it could well be showing 30km, then another 5km later it'll be back over the hundred - and still with 5 bars showing. There lies range anxiety and madness. ?

 

[Hamina]

The Volspeed cheatbox shows battery % in addition to the range estimations in Purion. Same information is available in Kiox or Nyon and I think it's more valuable.

 

[Clubby]

Don’t get anything like that variation on my Purion. Usual drop when climbing or in emtb then back up when terrain flattens or goes down and back in eco. Found it pretty accurate as well, that’s gen4 with the first 85nm update.
GrahamPaul you must have some pretty big climbs and long descent to get that much variation or are you a constant mode switcher?