KS16 battery level proportional to voltage under load

[RenaissanceMan]

Over the weekend I explored the Steinhuder Meer area. Below is a graph of the actual voltage over time as well as the KS16 battery level, both measured by @JumpMaster's nice android WheelLog app, version 1.1.4. It seems the battery level values are measured in 1/6 intervals. I also looks like the battery level is proportional to actual voltage.

If this observation were true this means that the so-called battery level of KS16 is not an indicator of remaining battery capacity or energy measured in Ampere x hours or Watts x hours as the name suggests but an instantaneous, discrete measure of voltage under load, which has been argued to be the proper indicator for predictions on euc endurance in this forum.

It also implies that Kingsong decided that - agnostic of the actual battery capacity (1p, 2p, 4p) - below a voltage under load of 58.7V it is (especially for the 1p case) not safe anymore to request that extra power boost required to e.g. safely negotiate a bump or evade another moving object, while with a 4p pack instead of an 1p, all other things being equal, it still takes four times the mileage (without any speed limit) to get down to those 58.7V, and after that four times the mileage of a 1p pack to reach limp home mode, albeit at the reduced maximum speed of 25km/h.

Assuming 66.2V as 100%, 58.7V as the 50% barrier, then 51V would be 0%, no usable energy left anymore, or 3.19V per cell, which is not too conservative (and of course, depends on the battery type).

I reached the battery level 50% mark after riding for (true) 31km with a maximum speed of 26km/h (FW v1.18 unlocked, 828Wh, KS16 with 17kg, rider's weight incl. clothing and backpack about 88kg, all on flat terrain, asphalt or gravel, with plenty of accelerating and breaking actions, for practice and for fun).

Taking into consideration the ever looming, unpredictable and with increasing speed potentiating risks like rapidly changing road conditions or inattentive and/or inconsiderate fellow riders to me the speed limit setting in FW v1.20 seems a fair compromise between speed junky dare devils and "sensible" riders as well as between 1p and 4p users. The "loss" of energy due to the limitation in FW v1.20 that otherwise could be converted into unlimited speeding of course depends on the pack size, battery type, road conditions, weight and driving style, but on the lower end with a heavy rider, going uphill and with 1p battery pack there is probably not much left to lose.

I hope I got all this correct in the attempt to better understand the limits and capabilities of my precious; if not battery "chief amateur" @esaj will surely be able to put things right ;-)

 

 

[JumpMaster]

Yes you're correct in that the battery level is an instantaneous measurement.  I am on firmware 1.20 and when the battery is close to 50% (say 52%) going up hill or accelerating makes the voltage drop and lowers the battery % to under 50% kicking in the speed restrictions.

Interestingly  KingSong call 0% less then 50.0V and Gotway calls it at 52.90V. I guess the pack sizes are different.

The equations for battery % are.

KingSong
Battery % = ((Voltage - 50.0)*100) / 16

Gotway
Battery % = ((Voltage - 52.9)*100) / 13

[esaj]

18 hours ago, RenaissanceMan said:

If this observation were true this means that the so-called battery level of KS16 is not an indicator of remaining battery capacity or energy measured in Ampere x hours or Watts x hours as the name suggests but an instantaneous, discrete measure of voltage under load, which has been argued to be the proper indicator for predictions on euc endurance in this forum.

As far as I know, all the wheels measure the remaining battery capacity based on the battery voltage. And the voltage will drop / raise according to the amperes being pulled from (acceleration/hill climbing) / pushed into (braking, going downhill) the batteries, and of course depends also on the remaining charge.