Cheap chargers, and balancing ?

Batteries, Chargers, and Battery Management Systems.
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rick (nova scotia)   10 mW

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Cheap chargers, and balancing ?

Post by rick (nova scotia) » Jan 25 2016 8:58pm

Best title I could think of.

Question is; is one of those cheap chargers that typically come with kits, having only a red light (while charging) / green light (when full charged) are the cells balanced when the green light comes on ? or should one leave it plugged in when the green light comes on ? at least some of the time...or once in a while ?

Reason I ask is I got NO documentation what so ever with the ready made E-bike, just a 20 dollar generic charger with a red, and green light.

Thanks,
Rick

Syonyk   10 kW

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Re: Cheap chargers, and balancing ?

Post by Syonyk » Jan 25 2016 9:07pm

You probably don't have a balancing BMS at that price point...

But often, it takes a while to balance after the green light comes on.

A $20 charger probably shouldn't be left unattended, though...
Battery packs, Sunkko Welders, and more. http://syonyk.blogspot.com/

rick (nova scotia)   10 mW

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Re: Cheap chargers, and balancing ?

Post by rick (nova scotia) » Jan 25 2016 9:58pm

Thanks _______ for the reply. (sorry for the blanks, but after hitting post I can't see that info)
I do wish the manufacturer would have left at least "some" instruction ? Ridiculous really.
I do believe the battery does have a BMS, although I admit that is blind faith, but supposedly a good samsung batt. Biktrix Stunner.

rick (nova scotia)   10 mW

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Re: Cheap chargers, and balancing ?

Post by rick (nova scotia) » Feb 01 2016 11:12pm

Thanks again Syonyk, I think I agree with with some time left on green---at least some of the time ?.
For a more basic of question, yet important of one I would have expected a tiny bit more of explanation.

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dogman dan   100 GW

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Re: Cheap chargers, and balancing ?

Post by dogman dan » Feb 02 2016 7:06am

You'll need a voltmeter to have the slightest clue what the pack is doing.

Charger plugged into battery, voltmeter on the plug you'd discharge through.

If the pack charges to full voltage for your cell count, then starts dropping slowly after the light goes green, that's the packs bms discharging high cells to balance it. If the charger eventually turns itself back on, it's still balancing. It won't be easy to catch the charger truning back on, it will only be red again for a few sedonds.
But you can see that it happened by the next morning, because eventually the pack will fill to that same voltage, and then it won't drop. That's balanced.

If the thing drops, but never eventually holds its full voltage, your charger is just turning off completely when it stops. Some chargers do that, won't restart themselves. To make it balance, wait for the bms to do it's discharging. Then unplug the charger from the battery, and plug back in again. If that doesn't start the charger, go ride around the block, then restart the charger. Repeat until the pack holds the full voltage. You are manually restarting the charger, to keep topping up the low cells. Each time, the high cells will fill fast, and then the bms will discharge them. In the process, eventually the lower cells get fuller.

Bear in mind, if the voltage drops instantly when the charger stops, that's not the bms. That is just cells that can't take a full charge. As a battery ages, it will not hold the full charge anymore. It's the slower drop in voltage that is the bms balancing the pack by discharging a few high charge cells.

rick (nova scotia)   10 mW

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Re: Cheap chargers, and balancing ?

Post by rick (nova scotia) » Feb 02 2016 9:07am

THANK YOU VERY MUCH Mr. Dogman.

That is what I was looking for, I appreciate the time you took to explain it well.
I have a volt meter, and know the charger puts out 41.8, will monitor, and know for sure what is going on.

Rick.

Too cold to ride here now...but soon.

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