Battery indicator shows empty after short distance

[Deleted member 25121]

Is the display still showing empty after a short journey even though you replaced the battery connectors?

 

[johneb]

Is the display still showing empty after a short journey even though you replaced the battery connectors?

Yes, it does for a while after I stop, then goes back to showing full (ie, all bars reappear). The battery LEDs still show full.

 

[vfr400]

Did you tighten the motor connections, like I suggested?

 

[Deleted member 25121]

Yes, it does for a while after I stop, then goes back to showing full (ie, all bars reappear). The battery LEDs still show full.

On Tuesday you were saying that after charging the battery you had a test ride. "The starting voltage was 53.6v on the display, confirmed with my voltmeter. Rode for around 1 mile on flat and gentle incline, using level 2 assist. The battery level indicator on the top of the display was showing full until I stopped, when all the bars promptly disappeared. The voltage was down to 52.8v. "
I presume that things are unchanged even after you've replaced and tightened the connectors.
The drop of voltage from 52.9V to 52.8V is small and shouldn't cause all the bars to disappear. The battery appears to be OK and I wonder if there's a problem with the electronics behind the display that senses the battery voltage.
Try turning the bike on and keep it powered up for a while, say 5 to 10 minutes, while occasionally turning the pedals. There would be little drain on the battery and if the bars disappear it would point to a problem with the display.
Also try having a short ride and stopping very gently, if the bars are still showing it would indicate a had connection somewhere (maybe you were stopping quickly previously and the jolts causes a connection problem).

 

[vfr400]

The battery wire goes into the LCD carrying the battery voltage. A line is taken off through a voltage divider that cuts it down to around 2.5v (i.e. divided by 20) directly to the CPU. The CPU uses that to calculate the battery voltage using an A to D converter. It can then use that info to send instructions to the LCD battery segment display and the voltage display simultaneously. You can't have one high and the other low because the instruction comes from the same source. The only exception is when the LCD is dual or multi-voltage and gets confused by which battery you have, i.e. it could misinterpret a fully-charged 36v battery as a depleted 48v one. That would show, say 42V on the voltage display and no segments on the segment display. It won't change instantaneously from one to the other. It only decides which you have when the battery is switched on. OP's display is 36v/48v (worth checking on the back if it says 36v/48v/60v or anything else) in which case it can't assume that you're using a battery of higher voltage to show it discharged.

The only other anomalous battery voltage representation I've seen is when P5 is set to a high number, which can make a big delay in the display showing the correct information, like you came home last night with a run down battery, switched off and charged up overnight, then when you set off in the morning, your display still shows empty for a minute or so, then suddenly jumps up.

 

[Deleted member 25121]

johneb - were your voltage readings taken off the display or a DVM (I'd assumed the latter)?

 

[johneb]

Did you tighten the motor connections, like I suggested?

Yes - it appeared ok, but separated it and re-seated just to be sure.

 

[johneb]

johneb - were your voltage readings taken off the display or a DVM (I'd assumed the latter)?

I took the initial reading with my DVM. When the display gave an identical reading, I assumed that it was functioning correctly, so the end reading was just from the display.

 

[Deleted member 25121]

I took the initial reading with my DVM. When the display gave an identical reading, I assumed that it was functioning correctly, so the end reading was just from the display.

In that case ignore my last suggestions and follow those from vfr400 regarding the P5 setting.
There's still a small possibility that the bar display or its driver circuity is faulty but it's odd that it only shows up when you stop.

 

[johneb]

The battery wire goes into the LCD carrying the battery voltage. A line is taken off through a voltage divider that cuts it down to around 2.5v (i.e. divided by 20) directly to the CPU. The CPU uses that to calculate the battery voltage using an A to D converter. It can then use that info to send instructions to the LCD battery segment display and the voltage display simultaneously. You can't have one high and the other low because the instruction comes from the same source. The only exception is when the LCD is dual or multi-voltage and gets confused by which battery you have, i.e. it could misinterpret a fully-charged 36v battery as a depleted 48v one. That would show, say 42V on the voltage display and no segments on the segment display. It won't change instantaneously from one to the other. It only decides which you have when the battery is switched on. OP's display is 36v/48v (worth checking on the back if it says 36v/48v/60v or anything else) in which case it can't assume that you're using a battery of higher voltage to show it discharged.

The only other anomalous battery voltage representation I've seen is when P5 is set to a high number, which can make a big delay in the display showing the correct information, like you came home last night with a run down battery, switched off and charged up overnight, then when you set off in the morning, your display still shows empty for a minute or so, then suddenly jumps up.

The display and controller are both dual voltage 36/48v. The motor is 36v and the battery 48v. As you previously suggested, I plan to dabble with P5 over the next few days. I was extremely careful making all the connections, as it's the first time I've ventured into anything like this, but think I'll go back and re-make them all, just to eliminate that as a potential factor.