% of battery power left to use.

[Eightbikes]

After a ride out on my Bafang powered Raleigh I normally check the voltage using a multi meter before charging the battery. I can then work out the watt hours consumed during the ride. On Sunday I rode 51.5 miles and consumed 310 watt hrs of my 15amp hour 36v battery. Total climbing was around 4250ft. The table attached may help others to work out watt hrs per mile

 

[Bikes4two]

That's an interesting table - do you know what make battery the table refers to as 18650 cells can have quite different discharge curves?

The other factor to weave in is the BMS cutoff voltage which could see you not being able to go lower than around 32v (for 10s).

 

[Eightbikes]

I don't know what battery make it refers to, I haven't ever discharged my battery to below 35volts so no idea what the voltage the BMS will cut off power. I found the table by searching on Google. I'll attempt to discharge the battery till it stops in the next couple of rides, if I take my spare I'll be ok

 

[Bikes4two]

I look forward to reading about your observations. I've spent quite a bit of time trying to work out voltage versus power available - so far all I know for sure is that running in (BMS) bypass mode I get more range out of my battery which for my cheap Chinese 10Ah bottle battery is around 40-45 miles in ECO mode (TSDZ2) and that at 36v ish the battery is about half spent).

 

[guerney]

That table is pretty much on the money, I hit a low battery cutoff that's set in the controller at 31%, at about the voltage on that table (36v battery, LG MH-1 cells) - which is when I hear strange noises coming from the motor as power sputters out. I avoid such low battery, but sometimes on very long journeys it can't be helped.

 

[Nealh]

Voltage reduction and % used isn't linear as that tale shows so working out wh usage is a guestimate, ones needs a watt meter wired in to get a more accurate picture.

 

[passionate off roader]

I don't have a percentage readout, just bars.

One thing I've noticed is that when in motion, the LED indicator tends to give a lower reading than is available in reality. For example a week or two back I had forgotten to re-charge the battery, so was only on 2 bars when I started out to work (6 miles both ways). I knew that on the return journey I'd be down to nil, and on personal power only. Starting back, I was still on 1.5 bars, but within 2 miles of home, the bars disappeared completely, but there was still power available and was able to complete the journey home on battery power.

After I returned home, as I was about to re-charge, I switched the indicator on, to see one bar still showing.

 

[Nealh]

Battery indicator bars are wholly unsatisfactory way to gauge battery % remaining, they will always go up and own like a yoyo depending on voltage sag. The best one can get from bars or led's is that the range may be within 25% of an estimated voltage. With four bars one can take a guess that each bar is aprrox. 25% of voltage remaining but as best is only a very poor and rough guestimate.