Fantastic battery?!

[sjpt]

2. The meter readings aren't very linear, though saying that the KT ones are a bit better at giving a better idea of range left. The only way of knowing battery level is an lcd with voltage read out or the use of a watt meter to shoe ah/wh usage.

Are the meter readings linear in voltage (which is non-linear in capacity remaining because of the nature of the battery discharge)? Or not even linear in voltage?

An lcd with more precise voltage read out would give more information than the 5 bar voltage range; but would still suffer from the nonlinear discharge and the effect of load on voltage so need careful interpretation. A watt meter would clearly be able to be much more accurate.

With our 13ah 36v Samsung cells battery on the tandem we typically see a two bar drop on the meter between gentle 12mph pedalling on the flat on PAS 2, and moderate hill at 8mph on PAS3. We usually recharge when the meter gets to 3 bars on the flat, 1 bar on the hills. Not sure what it would be like on the hills if we let it get down to 1 bar on the flat.

 

[Nealh]

With our 13ah 36v Samsung cells battery on the tandem we typically see a two bar drop on the meter between gentle 12mph pedalling on the flat on PAS 2, and moderate hill at 8mph on PAS3. We usually recharge when the meter gets to 3 bars on the flat, 1 bar on the hills. Not sure what it would be like on the hills if we let it get down to 1 bar on the flat.

This is voltage sag and is normal with the 3 bars, the Samsung 13ah will use the very mediocre 26F cell. One to avoid in the future unless you parallel 10 together.
The latter of indicated one bar doesdepend on the cells used some will hit lvc on a hill if high current is asked of it, others will cope.
My Panny PF cells cope nicely at lower voltage on hills, at 35- 36v they sag a little with current demand but don't hit LVC.

 

[vfr400]

2) KING METER INDICATIONS - Why did my meter still say FULL after 30 miles? This seems to contradict all the reducing voltage graphs etc that you are all talking about?

The 4 bars are might be divided into 4 equal steps or they might be set at arbitrary voltages, like mine. I think mine are something like 39v, 37v, 35v and 33V. The first step from 42v to 39v is a bit bigger because batteries drop to 41v very quickly before stabilizing into a steady ramp down, as you can see in the graphs.

So, I ride for 30 miles while the voltage drops from 42v to 39v, then the first segment goes out, then I ride another 20 miles and the second segment goes out, 15 for the third and 10 for the fourth when my battery is at 33v. At that point, if I try to take any significant power from it, the voltage sag drops it to the cut-off point. I can limp for a maybe a couple of miles with the power turned right down, but the ramp has already turned down much steeper, so there is very little left.

 

[sjpt]

Interesting. From battery performance graphs you and other have posted (*) it looks as if 33v really is near the battery dead point. I've never dared get it so it was down to the last bar when riding without much load. We are getting much lower mileage then you say even at mostly PAS2 of 5; but it is a tandem and 13aH battery, and not working ourselves that hard. And as Nealh says, probably not the best cells in that battery.

(*) https://www.pedelecs.co.uk/forum/threads/is-the-extra-5-amps-chewing-up-my-range.35664/#post-520066