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Charge X8 with 5A charger, safe?


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1 hour ago, Johey said:

As I received my KS16 today, I also got a powerful charger of 5A. My question is, can I use this charger for the X8, or will it charge too fast for the battery?

I wouldn't suggest it; AFAIK, X8 has 170Wh or 132Wh battery, so either 2.9Ah or 2.2Ah cells, no parallel packs. Lithium-ion (non-LiPo) cells shouldn't be charged above 1C (ie. faster than in one hour from empty to full), or simply, at an amperage larger than the amphour-rating of the cells (so 2.9Ah = 2.9A max, 2.2Ah = 2.2A max). It will stress the cells and the BMS may not be designed for that large charging current. Do you know how most of the Hoverboard-fires started? During charging... ;)  Although, to be fair, probably it was an overvoltage issue rather than too fast charging, but anyway... :P

With multiple paralleled packs, the charging current is divided between the packs (unless there's a daisy-chain configuration), so the charging current per series of cells is total charging current / number of parallel packs.

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I absolutely agree with @esaj, it is, indeed, recommended not to exceed 0.5C I.e. 1.45 Amps on a 2.9Ah cell. Note the 5A charger is fine on the KingSong, with its large battery 5amps is still below 0.5C and it is known the wiring, plugs and BMS can support it.

NASA did some testing of Panasonic 2.9Ah cells it makes interesting reading here: https://batteryworkshop.msfc.nasa.gov/presentations/Perf_Safe_Test_Panasonic_Li-Ion_NCR_18650_Cells_JRead.pdf

If you skip to the last page summary they have this to say: 

  • The cell capacity degrades significantly over the course of 200 cycles especially at the 1C charge and discharge rates at room temperature. This capacity degradation is exacerbated at lower temperatures (-10oC) 

In fact they found that after charging and discharging at 1C (2.9 Amps) at room temperature the capacity had halved within 170 charges.

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1 hour ago, Jason McNeil said:

@Johey, I usually include this statement in the post-sales literature for the KS16s:

"Please also note that the fast-charger is designed for the King Song 840Wh Wheel ONLY. Using this with other Wheels may result in permanent damage or even the risk of fire."

@Johey, Jason is very right to include this statement , its not just a statement. I have had many close calls related to chargers and batteries when the thing was on the verge if burning or blowing up. Need to be very careful. Just 2 weeks ago, something happened to the battery management system in gotway 2 i was riding ( possibly has to do with my plugging in the 5A kingsing charger) where the battery was getting super hot to the point that the shrink wrap started turning brown. Thank god i ooened the wheel and looked. 

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