Aliexpress Disputes

[Handlebars]

A few reasons for the spark are a battery with no BMS or an inexpensive BMS.
Another would be that the switch on the battery is ON or was recently ON and there is some residual current in the BMS. To drain this just turn the bike ON with the battery OFF and the display will use it up in a few seconds. Leave the battery switch OFF while you plug in the charger.
Same goes for the charger... If it is plugged in or was recently plugged in with no load there can be some residual voltage present. Not necessary but if you wanted to dissipate it you could short the connector or connect it to a voltage meter with the charger unpluged.
All these are exacerbated by the cheap 5.5mm plug.
Correct procedure to plug in your charger....
Plug the charger in to the battery with the battery switch OFF
Plug the charger into your house electric.
If it doesn't start to charge, cycle the battery power switch ON

Thank you for the comprehensive explanations about the chargers - and the bikes, for that matter.

 

[Gionnirocket]

The original charger ("SANS" brand) that came with the bike doesn't create sparking under any conditions so far.

Since you have a new charger, you may have done something a little different than usual and possibly one of the things I mentioned above. In any case as long as you follow the instructions there is nothing to be concerned about. You may want to check the voltage output with a meter.
If I remember correctly you purchased a slightly larger amp output? If so this would facilitate quicker charging if you still desire that. In the end do what ever you are comfortable with but SANS is a generic Chinese charger as well.

Edit: after a quick search seems they may be a bit more of a reputable company.

SANS

Wuxi Sans Electronic Co.,Ltd. is a professional leader China , manufacturer with high quality and reasonable price. Welcome to contact us

en.wxsans.com

 

[Handlebars]

Since you have a new charger, you may have done something a little different than usual and possibly one of the things I mentioned above. In any case as long as you follow the instructions there is nothing to be concerned about. You may want to check the voltage output with a meter.
If I remember correctly you purchased a slightly larger amp output? If so this would facilitate quicker charging if you still desire that. In the end do what ever you are comfortable with but SANS is a generic Chinese charger as well.

Edit: after a quick search seems they may be a bit more of a reputable company.

SANS

Wuxi Sans Electronic Co.,Ltd. is a professional leader China , manufacturer with high quality and reasonable price. Welcome to contact us

en.wxsans.com

I bought a 1A charger for slow charging (hoping for longer battery life).

 

[Gionnirocket]

I bought a 1A charger for slow charging (hoping for longer battery life).

2 amp is already slow charging. At a certain point there is no additional benefit. If it happens to be a more stable power supply it might do a better job of topping off the battery and allowing for more time to balance.. if not, then I guess you have yourself a rediculously slow back up

 

[ki11a]

Yep battery’s will always degrade when charging and using them. You can control the degradation point to a certain degree but after certain points it’s moot.

 

[Allroads]

I purchased my second battery 48v14.5ah integrated on Alibaba. Arrived into Canada within 5 weeks with a damaged box. Battery end cover was cracked and damaged. They sent me a new cover in 10 days. Also I was not charged any broker, duty or GST fees.
I also purchased a Tektro Dorado 4 piston brake kit in July. Arrived complete within 2 weeks, no duties or any additional charges. Both items were purchased during this Covid time frame. Their overall service is highly rated on my behalf. If you do your due diligence one can be successful.