Just been on a 15 mile ride on my folding bike with a 36V 10Ah battery and KT controller / display, it is showing half full battery on the KT display, when I measure the voltage with a multimeter it is showing 38.9V
Are the KT controllers slightly pessimistic as far as battery level ?
- Thread starter Peter.Bridge
- Start date
I've never noticed anything special. It probably depends on your battery too. I know when mine goes down to two bars, I haven't got much left. You know that you can display the actual battery voltage by a short press of the power button to schange the bottom line of the display from total distance to trip distance to battery voltage?
You need to adjust your P5 setting. There is a formula that says the voltage when the last bar disappears on your LCD is something like LVC voltage setting + (P5 setting/3.77) but I have never found this really helpful. I think I set P5 =12 for mine (36V battery) but its not something I worry too much about as I spent most of my life driving older cars/vans with dodgy fuel gauges. I tend to hit the center button twice at the end of a journey to read the actual voltage if I am concerned about running out of juice.
Good point. P5 is basically a damping factor for the battery display. If you set it too low, the display goes up and down every time you open the throttle. If you set it too high, it still shows your battery empty after you charged it until you've ridden half way up your street. They give recommended settings for different voltage battery in the manual. The mid point for 36v is about 10, and about 13 for 48v.
One thing I can recall for certain is that the LVC voltage setting (C12) also has a bearing. In my case its set to the default value of 30v. I can remember setting it higher once to 31V and this scaled up all the other levels on the display. My battery normally starts to show empty at around 33.3v (under load) and this seems to loosely correspond to the formula. ( P5 = 12 and LVC = 30, the battery shows empty at 30v + 12/3.77 = 33.2 volts). I did not pursue this any further.
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I'm a relative newcomer to the KT system, so still exploring all the configurable options. I have never paid much attention to the 'fuel bar' display, preferring to look at the voltage displayed instead. Out of interest, I just checked my readings after an 18 mile ride.
48 volt 12Ah battery - initial reading of 53.8 volts on my multimeter.
After my ride:
KT LCD3 display showed 51.7 volts, multimeter showed 51.2 volts (I'm pretty sure the multimeter is correct).
The fuel bar showed 75% charge
My P5 value is set to 15, I'll try saneagles suggested value of 13 to see if that helps accuracy.
I have the C12 LVC set to 7 (40 +1.5)
I really like that the KT display can show voltage and watts used in real-time. It's interesting to see how much voltage drop there is when climbing steep hills and watching the watts required shoot right up.
I've been playing around with quite a few of the KT settings. For example, switching between current control and speed control with P3 value has been a great way way of comparing the two different power delivery methods.
I found in speed control mode that setting the C14 value to '3' - strong assist, gives quite a linear progression across the 5 power levels. The watt meter showed roughly 120 / 220 / 340 / 470 / 740.
I can understand why many of the contributors to this forum recommend the KT controllers, as they can be configured to suit individual preferences.
48 volt 12Ah battery - initial reading of 53.8 volts on my multimeter.
After my ride:
KT LCD3 display showed 51.7 volts, multimeter showed 51.2 volts (I'm pretty sure the multimeter is correct).
The fuel bar showed 75% charge
My P5 value is set to 15, I'll try saneagles suggested value of 13 to see if that helps accuracy.
I have the C12 LVC set to 7 (40 +1.5)
I really like that the KT display can show voltage and watts used in real-time. It's interesting to see how much voltage drop there is when climbing steep hills and watching the watts required shoot right up.
I've been playing around with quite a few of the KT settings. For example, switching between current control and speed control with P3 value has been a great way way of comparing the two different power delivery methods.
I found in speed control mode that setting the C14 value to '3' - strong assist, gives quite a linear progression across the 5 power levels. The watt meter showed roughly 120 / 220 / 340 / 470 / 740.
I can understand why many of the contributors to this forum recommend the KT controllers, as they can be configured to suit individual preferences.
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P5 doesn't really affect the accurancy. Instead, it's the time to change the battery display. If the number is too high, there's a delay in it updating. If it's the number is too low, it dances aboutwith how much power you take.
Do you remember the old car fuel guages that went up when your turned left, down when you turned right, down when you went uphill, and up when you went downhill? Now they have electronic damping in them so that doesn't happen. That's what P5 looks after.
When attempting to understand the meaning of the various KT controller settings I trawled through this forum and Endless Sphere and from my notes made at the time, wrote down my understanding of C12 settings.
As can be seen from the extract below (for which I can't quote the ultimate source), C12 basically adjusts the controler's Low Voltage Cut-off point up or down in 0.5v steps from it's default value.
If others have a different understanding then please post here so we can all learn - thanks.
As can be seen from the extract below (for which I can't quote the ultimate source), C12 basically adjusts the controler's Low Voltage Cut-off point up or down in 0.5v steps from it's default value.
If others have a different understanding then please post here so we can all learn - thanks.
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I like the LCD3's because it's easier to view in sunlight, has bigger letters and the all important thermometer so I know the temperature inside the case. I wish KT allowed tire diameter in mm instead of the presets.
I mostly go by voltage and miles, as I know my range. It's nice to see the LCD3 battery icon full, but when it drops a bar, I'm at 49V, about half charge, and the rest of the bars drop quickly. I always want to be going home before I reach that level.
On my ebikes that don't have KT displays/controllers, I put on voltmeters, All are hard to see in sunlight, but I can eventually see what they say.
It would be nice to know wind speed. I knew a golfer with a hand held instrument for that. Gave direction and speed. Another guy had a optical scope that was reputed to detect a white golf ball hidden in shrubbery. That didn't work, but the wind meter was cool.
,
.
I mostly go by voltage and miles, as I know my range. It's nice to see the LCD3 battery icon full, but when it drops a bar, I'm at 49V, about half charge, and the rest of the bars drop quickly. I always want to be going home before I reach that level.
On my ebikes that don't have KT displays/controllers, I put on voltmeters, All are hard to see in sunlight, but I can eventually see what they say.
It would be nice to know wind speed. I knew a golfer with a hand held instrument for that. Gave direction and speed. Another guy had a optical scope that was reputed to detect a white golf ball hidden in shrubbery. That didn't work, but the wind meter was cool.
,
.
Yes it is the same as I have always understood it to mean.
The C12 though is unlikely ever to come in to play with modern BMS will overide it unless one has a battery BMS that is programmed to a much lower LVC .
It is a back up LVC should a BMS fail but should that happen one expects the battery will cut out .
C12 maybe slightly useful for those who ride without a BMS but then one is risking early battery issues.
I have a very limited understanding of the electronic side of e-bikes, but the KT LVC settings have seemed a bit too low to me. I suspect that Nealh is correct in that the battery BMS will intervene before the KT LVC level is reached.
I originally had a Lishui controller on the bike and I wonder what the LVC setting was on that system? I can't check as it's not possible to tinker with or interrogate the Lishui controller settings unfortunately.
It's supposed to be the other way round. The controller should cut first. Battery BMSs are usually set a bit low - typically around 2.9v per cell, but by the time the cells go that low, they have very little charge left, which can send some much lower if you don't charge immediately, and it's not good for them charging at normal rate when they're that low. I always set my controllers to 3.1v or 3.2v per cell to be kinder to the battery.
Voltage sag in the battery will trip the controller LVC before its actual cutoff. You can get a little relief by adjusting C12. Might get you an extra mile or two. Sag is worse on smaller capacity batteries, so your results will vary,
The advice above comes from the German forum. You could try it out to see does it work .
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