Which indicates distance you can travel

 

36V not this

20Ah means what ?

or

750 Wh I assume this ?

 

 

Thanks

Yes - so a 36V * 20Ah battery would store 720Wh of energy - the more Wh the further you can go (everything else being equal !)

Wh (which is Ah * V) is indeed the measure of capacity that controls range. Of course there are lots of other variables. Also, if the battery doesn't have very good ability to deliver current then it will suffer voltage sag under load (eg up hills), that might mean even though there is capacity left it will cut out to save killing the battery. That could limit the effective range, especially if there is a big up hill fairly close to your destination; quite likely that the battery gets tired exactly as you need it most when you are tired; uphill at the end of a ride.

Which indicates distance you can travel

 

36V not this

20Ah means what ?

or

750 Wh I assume this ?

 

 

Thanks

They're both the same thing. 36v x 20Ah = 720wh.

If you want the most accurate measurement of range, usage and capacity, you should get a wattmeter, which will not only show you the watt-hours used and remaining, but it'll give you a good understanding of how your bike works and how much battery you use in different circumstances.

Thank you

One can roughly estimate range by dividing the wh by wh usage and how you ride.

If one rides often above the speed cut off then usage can be in 5 -7wh per mile range, if one rides in low power mode a lot ( ie a current control controller) then one can expect to use 8 - 12 wh per mile . If using a higher assist then anything up to 20wh per mile may be used also applies to riding with a high assist cut off.

One can roughly estimate range by dividing the wh by wh usage and how you ride.

If one rides often above the speed cut off then usage can be in 5 -7wh per mile range, if one rides in low power mode a lot ( ie a current control controller) then one can expect to use 8 - 12 wh per mile . If using a higher assist then anything up to 20wh per mile may be used also applies to riding with a high assist cut off.

So potentially that is another advantage of using a controller with power based assist levels rather than speed based assist levels ? They are more efficient, if you are adding quite a bit of pedalling effort ?

So potentially that is another advantage of using a controller with power based assist levels rather than speed based assist levels ? They are more efficient, if you are adding quite a bit of pedalling effort ?

 

Yes .

Most crappy speed controllers give max current more of the time until the speed threshold for the power level is reached , the power based current controllers can be more efficient depending on the power it supplies . The KT's for instance put out approx. 13% of the max power in PAS1, others like woosh set this to 40% in the lishui's. More importantly though is riding above the cut off to increase range just as riding with the battery switched off.

 

My long rides are 160km on a nice sunny, using a 36v battery and 48v one used independently of each other. 36v PF in the triangle and a homemade 13s 7p PF in a rear bag /rack top pannier, mostly all the journey in PAS 1 except for some PAS4/5 climbing up out of Ovingdean on the way home . I usually still arrive back at home with 30 - 40% of total wh available.

[mention=40353]Saracen[/mention] - in the longer term if you had some means of measuring how many watt hours you used/consume for your different rides then you will over time get to know how much power you are using for your different riding scenarios.

 

Once you know this and the capacity of your battery, you'll become quite good at working out your range.

 

I don't have a watt meter on my bike but back in the bike shed I have a home built rig that;

(a) measures how many watt hours I have to put back into the battery to get back to the fully charged state (having started with a fully charged battery of course) and then log the miles done, type of terrain etc. to obtain the watt hours per mile figure mentioned by Neal in post #6

(b) I can also discharge the battery into a dummy load to measure the capacity in watt hours.

 

These measurements aren't overly accurate but over time have been enough for me to be confident in what range I'll get for any particular ride - so no range anxiety for me lol.

I can pretty much get 8- 10wh out of my riding so can quite easily use 10wh as my guide for range. For my 6ah 12s 2p of HG2's I can eke out 30 miles from 264 wh's, typically though one doesn't get 6ah as one can't ride or discharge at 0.2c.

I do have a watt meter, no idea what it means LOL

 

The watt meter /gauge shows simply how much power (watts) the controller is out putting it won't tell you how many wh is being use or has been used for that one needs an anmeter type watt gauge that uses a shunt on the main power feeds.

 

d8veh's handy little watt meter mod.

Latest Cheap Wattmeter | Pedelecs - Electric Bike Community

I do have a watt meter, no idea what it means LOL

 

[ATTACH type=full" alt="Image1.jpg]55278[/ATTACH]

It's a meter that shows watts rather than a wattmeter. A wattmeter shows present watts, cumulative watt-hours, current, max current, amp-hours and things like that, so you can measure the capacity of your battery for each type of ride you do, then during those rides you can see how much of the battery you've used and calculate or estimate how much further you can go.

I see it's been a while since you've posted, but I just wanted to ask—has anyone noticed if your estimated range changes much depending on cold weather or wind? I’ve been tracking mine and it seems to drop way more than I expected when the temperature drops or there’s a strong headwind. Wondering what kind of difference others are seeing in real-world riding compared to what the display says.

 

This phenomenon of loss of range in cold weather, is a feature of pretty much all battery systems. A lithium battery is a chemically driven device ,and the reactions inside the cells in which lithium ions move across the electrically insulating separator depend on temperature for efficient movement of ions. When temperatures are low, the process works more slowly.

 

When you connect the battery terminals to a load, lithium ions move across the battery from anode to cathode. They change the electric charge on the anode and cathode and this makes electrons flow through the terminals from the anode (the negative terminal) to the other side passing through the motor load.

 

This is what we want when we use a battery and electric motor. The rate of flow changes according to the temperature, and the total amount of flow changes too, so all electric vehicles with batteries see a loss of maximum power and range in colder weather. A cold battery will see voltage sag on a hill climb which probably would not happen in warmer weather.

 

My smaller bike, which has a nominal 8.5 Ahr battery (about 300 watt hours) showed a noticeable drop off in range during the winter, even though it was quite new. When summer came around again, and the temperature was about twenty centigrade, I noticed that the first voltage led out of four on the simple display unit, went out after 9.5 miles, on upward slopes, whereas in winter it went out at about 7 miles.

 

This is a rough and ready test, but it shows the tendency which affects all of our batteries. Range is affected in the same way, because the battery system is working less well at lower temperatures. Like most chemical processes, temperature variations affect performance.

 

As for wind - a solely human powered cyclist will notice head winds. It is simple physics, you are pushing against a strong air flow. This will obviously influence top speed and battery range too.

 

 

 

https://letstalkscience.ca/educational-resources/stem-explained/how-does-a-lithium-ion-battery-work

 

Cold temperatures also affect the rate at which a battery can be charged.

 

The internal resistance of the battery rises in low temperatures making it resistant to the charge.

 

You should not attempt to charge a battery that is at low temperatures around zero. Bring it inside and let it warm up slowly to room temperature.

Edited September 19, 2025Sep 19 by Tony1951

Wind is a big factor to overcome esp a head wind , so yes it can reduce range quite a bit.

Cold will also not help range .

I see it's been a while since you've posted, but I just wanted to ask—has anyone noticed if your estimated range changes much depending on cold weather or wind? I’ve been tracking mine and it seems to drop way more than I expected when the temperature drops or there’s a strong headwind. Wondering what kind of difference others are seeing in real-world riding compared to what the display says.

That's a very good question. There are 3 parts to the answer:

Your battery

It's generally accepted the batteries don't give so much capacity in the winter, but I think that the effect is much less than what most people think, though that does depend on individual circumstances. The reason I say that is because batteries have their own central heating system. You can feel some get noticeably warm both when charging and discharging. The inner cells are surrounded by other cells that are also warming up, so they won't be able to lose their heat, and even the ones on the outside are well insulated by the still air around them and the plastic case and often foam rubber. When they do a test of a single cell in the lab, the metal case is directly in contact with the cold air, but it's nothing like that for the cells inside a battery.

 

You.

It's very well know amongst athletes that your body becomes much less efficient when cold. There have been all sorts of tests done to try to quantify that, but I'd be surprised if you could make a definitive rule. Imagine if you're only pedalling half as hard in the winter as you do in the summer. That would make a profound effect on your range.

 

Wind

That's simple physics. Wind resistance increases with the cube of its relative velocity. Depending on the wind speed and direction, it can sap anywhere from zero to all the power you and the bike make. Winds are generally stronger in the winter than the summer, so that would make an overall difference in range. Also, the heavier clothing you wear in the winter increases your coefficient of drag. Also, the extra mass of winter clothing also affects your range, assuming that your ride is not 100% flat. The hillier it is, the more the affect of mass.

 

To summarise, my gut feeling is that the effect of winter temperatures on your own efficiency, along with your heavier mass and larger coefficient of drag have a more substantial effect on range than the affect of temperature on the battery. Ultimately, it makes little difference why, as long as you understand that you can't go as far in the winter as summer.

If you look at https://www.bosch-ebike.com/en/service/range-assistant you get a very good idea of how range changes with conditions. It's for Bosch bikes, but the differences are similar whatever the system. If you interpret things like the motor type carefully you can even get a reasonable idea of range on non-Bosch bikes,

 

You'll also see how quickly changing from perfect conditions (the 'up to' quoted by so many adverts) to even reasonably OK normal conditions easily drops the range to 1/2, or even 1/3.

Edited September 19, 2025Sep 19 by sjpt

Dont discount the extra effort/work involved in wearing weatherproof clobber, not so significant alone but compounded with everything else cold weather entails ....

It'll be different for different systems, and also degree of rider involvement.

 

I notice a bit of cold related effect, but I have a torque sensor mid-drive, so maximum current is far lower than a hub drive in high assist because I can use the gears to give me and the motor an easy time. Lower current means less voltage sag, and therefore more usable battery capacity before the low voltage cutout kicks in.

 

I know how far I want to go, so I can manage my consumption by slowing down and using lower assist levels to make sure I get there.

 

Headwinds do add a lot of load: aerodynamics of a cyclist are rubbish, which is why our speeds are so low. Add even 10mph of wind when we're only trying to do 15mph, it's a big effect. Slowing down is the best strategy to maintain range: power required goes up with the cube of the relative windspeed, so just a few mph less can halve power requirement.

 

Worst case will be a speed control bike trying to maintain 15mph on a cold day in a head wind. For that kind of bike, just choose a lower target speed in those conditions.

 

Current control and torque sensor systems adapt semi-automatically to changing conditions.

If you look at https://www.bosch-ebike.com/en/service/range-assistant you get a very good idea of how range changes with conditions. It's for Bosch bikes, but the differences are similar whatever the system. If you interpret things like the motor type carefully you can even get a reasonable idea of range on non-Bosch bikes,

 

Just had a look at that, configuring it to my Bosch per' CX/625wh.

After 3 years of use i can confirm it is pretty accurate.

So using their filters- turbo, mainly in a city riding, so asphalt, all year weather, weights etc puts my range at about 40miles(Reality is im getting 36-38miles)

 

I've another ebike- hub motor/380wh but has no way of recording speed/time/distance. I should get a simple cyclocomputer and use trip distance to gauge what kind of range im getting across my usual riding/routes.

Just had a look at that, configuring it to my Bosch per' CX/625wh.

After 3 years of use i can confirm it is pretty accurate.

So using their filters- turbo, mainly in a city riding, so asphalt, all year weather, weights etc puts my range at about 40miles(Reality is im getting 36-38miles)

 

I've another ebike- hub motor/380wh but has no way of recording speed/time/distance. I should get a simple cyclocomputer and use trip distance to gauge what kind of range im getting across my usual riding/routes.

Is that quite hilly ? 36-38 miles of tarmac city riding (I'm presuming with 25km/h motor assist limit ) from a 625Wh battery seems a bit on the low side ?

Is that quite hilly ? 36-38 miles of tarmac city riding (I'm presuming with 25km/h motor assist limit ) from a 625Wh battery seems a bit on the low side ?

That'll be the Turbo setting!

That'll be the Turbo setting!

I was thinking the Turbo setting would be like a speed based control on a hub bike with a cadence sensor, that it would give full power until you hit the speed limit for that level, but as you approach 15.5 mph the power supplied by the motor would reduce. I know it very much varies based on rider weight and terrain, but on my Woosh conversion kit with 720Wh battery over undulating but not really hilly terrain, I did 43 miles (there and back to Northallerton) and I had 1/3 of the battery left

 

 

I guess one difference is city cycling is likely a lot more stop / start

Don't forget the Bosh is TS so in Turbo it will be giving full beans current wise what that is not sure if any one knows, though 20 - 22a has been suggested as some say the newer motors can out put 800w.

I was thinking the Turbo setting would be like a speed based control on a hub bike with a cadence sensor, that it would give full power until you hit the speed limit for that level, but as you approach 15.5 mph the power supplied by the motor would reduce. I know it very much varies based on rider weight and terrain, but on my Woosh conversion kit with 720Wh battery over undulating but not really hilly terrain, I did 43 miles (there and back to Northallerton) and I had 1/3 of the battery left

[ATTACH type=full" alt="IMG-20230610-WA0001.jpg]64417[/ATTACH]

 

 

I guess one difference is city cycling is likely a lot more stop / start

The big brands' torque sensor bikes are way more sophisticated than the bottom bracket torque sensors used with hub motors and the TSDZn models. They are designed for and manage with ease the delicacy needed on rough offroad terrain. Fundamental to that is a fast responding, accurately proportional algorithm which in most settings on most models is a fixed % of the rider's input. The highest torque models give 400% of rider input, which means a city rider on flat roads can maintain 25km/h all the time. Hence substantial impact on range. And of course lovely to ride with bionic legs, but overkill for shopping and commuting!