Ninebot mini pro will not turn on

[Cindy59]

I have 2 ninebot mini pros that have not been turned on in about a 6 months.  They are stored in our house.  Neither one will turn on at all now.  I plugged the battery charger in and the light on the charger pack stayed green.  Left plugged in overnight just in case, but still will not turn on this morning.  Any ideas to correct this issue are greatly appreciated

[fred_dot_u]

Not specific to this type of scooter, but I had a similar problem with a couple of Airwheel S8s. It's likely the batteries have dropped voltage to the point where the charger will not engage. I had to remove the battery pack (not a simple process with an S8) and charge the cells with an external balancing charger of the radio control type.

It's necessary to unwrap the heat shrink in which your pack is probably enclosed. My pack has foam panels to absorb shock attached to the heat shrink, so I sliced carefully along one edge to enable me to re-wrap when the process was complete.

If you slice your pack and test each set of cells with a digital multimeter, you may find more than one of them has dropped to a too-low value. The absolute bottom voltage for a typical lithium cell is 3.0v, but none of my cells had gone below 3.8v. The total voltage of my pack with all the combined low cells must have been too low, or the battery management system (BMS) had decided that the disparity between cells was too great to allow the charger to engage.

The BMS is supposed to maintain a balance during charge, but I suspect that it just didn't work properly. When sitting idle, as you describe, the cells can be depleted by the BMS pulling small currents.

[FreeRide]

There is a thread on here with more details, on how you might be able to revive the battery especially if it has only been 3 months.

First easy thing to try is to remove the battery from the segway, 4 screws on the bottom.

Then plug it into the charger for 24 hrs while it is removed from the Segway.  you may also try unplugging it after 8 hours and replugging it in. and again after 16hrs.  especially if the charger light is staying green.  If you do get the charger to turn red, leave it plugged in until the light on the bottom of the battery is no longer blinking red, but green.  It should go from blinking red, solid green, then blinking green.  At that point you can put it back into the segway.

If the above does not work, look for some thread on here on how to revive the battery once it is removed, by connecting a couple wires to you charger and to the batter directly, not through the charge port. [ Be sure to understand the risks involved in this type of operation ]

Sorry I have not been on here for a while and don't have the thread handy.

Edited May 23, 2021 by FreeRide

[Cindy59]

Thanks for the help.  Got the batteries revived

[Chriull]

3 minutes ago, Cindy59 said:

Thanks for the help.  Got the batteries revived

 

On 5/14/2021 at 11:44 PM, FreeRide said:

If the above does not work, look for some thread on here on how to revive the battery once it is removed, by connecting a couple wires to you charger and to the batter directly, not through the charge port.

FYI: @Cindy59- if you followed the advice to revive the battery by charging it by circumventing the charge protection circuitry be aware that this means that the  battery pack has an increased fire hazard risk!

@FreeRide- one should rethink about publishing and pointing people to potential unsafe practices, without at least mentioning the risk. Li Ion fires are no fun.

[FreeRide]

On 5/17/2021 at 10:23 AM, Chriull said:@FreeRide- one should rethink about publishing and pointing people to potential unsafe practices, without at least mentioning the risk. Li Ion fires are no fun.

Hopefully the main articles or threads about the battery reviving techniques properly explain the risks and how one can take precautions.  That is where that information belongs.  

[MetricUSA]

Don't ever leave batteries unattended that long... They self discharge and ruin batteries, charge up to 90% charge every month or two at most...