Voltage oscillation when charging

PjKahut

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Hi
I got a Accolmile Cola Bear 750w with a 48V 17.5Ah battery, it comes with standard 2amps charger.
As many others do i purchased a generic 4 amp charger for shorter charge time.
When I plugged it into the bike i saw a flash and heard a bang, quickly unpluging it again.
Then got the multi meter out to check for correct voltage, and it was spot on 48 V.
When I checked the original 2 amp charger I got a changing, oscillating reading, all over the place. (it works and charges the battery)
Simply cannot find any thing like that on this forum or on utube.
Anyone out there with any knowledge regarding this?
Thanks
Ps. video clip was too large to upload.
 

HumanPerson

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Hi
I got a Accolmile Cola Bear 750w with a 48V 17.5 battery, it comes with standard 2amps charger.
As many others do i purchased a generic 4 amp charger for shorter charge time.
When I plugged it into the bike i saw a flash and heard a bang, quickly unpluging it again.
Then got the multi meter out to check for correct voltage, and it was spot on 48 V.
When I checked the original 2 amp charger I got a changing, occilating reading, all over the place. (it works and charges the battery)
Simply cannot find any thing like that on this forum or on utube.
Anyone out there with any knowledge regarding this?
Thanks
Ps. video clip was to large to upload.

where did the flash and bang come from the battery or ther charger?

when i check voltage from my chargers, it is all over the place as well, but they all work as intended.
 

PjKahut

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where did the flash and bang come from the battery or ther charger?

when i check voltage from my chargers, it is all over the place as well, but they all work as intended.
Hi.
The spark came when inserting the charger plug into the battery, the connection point between the two.
"when i check voltage from my chargers, it is all over the place as well, but they all work as intended."
It seems like there are different charger "behavior" The ones i have seen on utube are all static voltage whereas yours and mine are fluctuating.
How come there's no talk about this anywhere especially when purchasing aftermarket chargers???
Did manage to make a utube video showing the difference between a static charger and a fluctuating charger (while unplugged from the battery)
 

Hoggdoc

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Have you used your meter to check the voltage that the charging plug on the battery it should show full battery voltage in most cases? I had a similar situation and it popped the fuse on the charging line. I didn't discover that until I open the battery found the fuse and tested it. Replacing the fuse brought the battery pack back to life.

Also that spark took out the charger. I think that's what's happened to the charger that showing Fluctuating output.
 

PjKahut

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Have you used your meter to check the voltage that the charging plug on the battery it should show full battery voltage in most cases? I had a similar situation and it popped the fuse on the charging line. I didn't discover that until I open the battery found the fuse and tested it. Replacing the fuse brought the battery pack back to life.

Also that spark took out the charger. I think that's what's happened to the charger that showing Fluctuating output.
thanks for that Hoggdoc.
The battery is fine, it drives the bike and takes the charge from the original (fluctuating) charger, so no battery trouble.
And no original charger trouble either, it charges the battery fine,
The trouble is with the new 4amp 48v charger, its the one that somehow is incompatible with the 48v battery, sparking when I insert the charge pin into the battery.
So whats the difference between the 2 chargers??? the original fluctuate the voltage whereas the new 4amp voltage stays steady.
It seems the battery is made to only accept the fluctuating voltage charge, and does not tolerate the steady voltage of the 4amp charger :unsure:
Question is, are there 2 different ways to charge a battery, or rather is a battery made to accept a certain type of charging (fluctuating or steady)
 

HumanPerson

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I have 1 charger, from China, 58.8 volt charger.
That 1 charger had the wires wrong. And they were Brown and Blue.
So Check the wires and what they are give that a try and tell us what ya seen
 

PjKahut

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Thanks HP
Everything about this is weird.
The 4amp charger I just bought actually works as one would expect (the reading is steady and constant) so I won't mess it up by opening it, as I intend to send it back as it incompatible with my battery.
I will just forget about the whole charge abit faster and stick with the bike supplied 2amp charger.
Still a fecking head scratching mystery to me.
Ah, well.
Could email the bike company about it, although they might invalidate the warranty, better not.
 

Nelson37

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Li-ion batteries are supposed to be charged with a CC-CV method. Constant Current, Constant Voltage. Charge begins with a steady amperage and changing voltage, which gradually ramps up to the full 4.2V per cell times number of series strings. When voltage hits this number, it remains constant while the amperage gradually ramps down.

Definitely should not have had sparks and bang. Wiring for the output pins is not at all consistent, different companies do it different ways. Then there is the near non-existent chinese quality control.

When you got the 48V reading, that is NOT correct for a fully charged "48V" battery, or charger either - note you did not specify which you checked - should be 50.4, 12S X 4.2, or possibly 54.6, 13S X 4.2, which is usually referred to as "52V", while 14S X 4.2 gives 58.8 and is described with a variety of trade names.

You MUST know your series count, and also chemistry, as LifePO4 and LTO have very different per-cell voltages.

Nobody talks about Lithium Titanate (LTO) cells but they are damn near indestructible. Lower voltage, higher weight but they will take extreme amounts of abuse.
 
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