Hoverboard Batteries


Fall 2002

    This fall my Go-Ped® Hoverboard™quit working properly. It had no power when the throttle trigger was pulled. When I first opened it, I found that the connectors were melted where the wires were crimped. I thought that this might be the cause of the problems. You can see the pictures of the disassembly below. The cause of the melted connection is the heat generated by the current flowing through the wire/connector interface. I replaced the wires and connectors and reassembled the scooter but was still having problems.




    Upon reassembly I found that I was still having trouble. If I accelerated quickly the motor would stop moving and just growl. If I accelerated very slowly with no load the scooter would seem to operate normally. I was stumped, so I recorded this video and sent it to my friends at Patmont Motor Werks (Go-Ped® ).


HOVERBOARD MOVIE
Windows Media 8 (1.82MB)

    After my friends took a look at the video they recommended that I measure the voltage across the batteries. When I did this I got the following results. You can see that the individual measured readings for the batteries adds up to the total voltage in each case. Battery four (closest to the speed controller board in series) seems to be causing all of the problems. The total voltage goes from 24 V to 13 V just because battery four is going from 6 V to -5 V. My friend said that it is very common for battery four to go bad.

Voltage Readings

  Rapid Acceleration (No Load) Slow Acceleration (No Load)
Battery One 6 V 6 V
Battery Two 6 V 6 V
Battery Three 6 V 6 V
Battery Four -5 V 6 V
Total Voltage 13 V 24 V

    I spoke with my grandfather who is an electrical expert. We were discussing batteries and the possible causes of failure. The four batteries are in series, so the current while charging and discharging and the voltage across each battery should be consistent. The only cause for repeated failure of battery four is some kind of external physical condition. When the scooter is not in use it is typically leaning to the left. This is the only attribute I can think of. All batteries, as they age, form sediments in the electrolyte fluid. I tried shaking the batteries and turning them over for a few days to shake up any sediments, but that did not seem to work. We will be draining the battery and examining its contents in the near future to test our hypothesis.

Spring 2004

     I got a new set of batteries for my Hoverboard for about $56 including shipping from www.batterymart.com . I got four of these: http://www.batterymart.com/battery.mv?p=SLA-6V12-F2 They are generic, but I asked them for data sheets (see below) over the phone and all of the power characteristics are the same. They also told me that "a lead-acid battery is a lead-acid battery" and that they were all pretty much the same. I also learned from a friend that used to build solar cars that these batteries, because they are in series, should be rotated often. He said that the voltage swing mentioned above is very common with rechargeable lead-acid batteries wired in series. This is because the internal resistance of each battery is cumulative in the charging circuit, limiting the available charging voltage of the batteries downstream in the series rendering these downstream batteries ineffective contributors. I have been riding around again for about a month now and have already rotated them once and everything is going fine.

     I also saw that Go-Ped is beta testing their new electric.


FILES

Specifications on Yuasa NPX-50 batteries (.jpg)

Specifications on Litton Poly-Scientific motor (.pdf)

Specifications on Universal 6120 Battery (.pdf)


LINKS

www.goped.com
www.batterymart.com

www.batterymart.com/battery.mv?p=SLA-6V12-F2

 

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