Charging a 48v eBike battery with 13 1s chargers?

Batteries, Chargers, and Battery Management Systems.
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redilast   1 kW

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Charging a 48v eBike battery with 13 1s chargers?

Post by redilast » Jun 02 2017 12:49am

I think this topic has been discussed before, but its a very difficult topic to search for on the forums.

I'm thinking about my next eBike battery build, maybe using no BMS, but instead charging the 13s pack with 13 individual Li-ion charging PCB's which normally run off 5v. So basically I'd run a lead from each battery + and - to the + and - of the charging board PCB and it would treat that cell or cell group as if it were an individual 3.7v Li-ion and not a 48v pack. This way there is no need for balancing with bleed resistors and no need to have a circuit board hooked up with parasitic drain that could one day kill the pack. A fuse would be used for shorts/overcurrent situations and some battery cell loggers would be used to monitor each cell groups voltage.

Any problems you foresee with this type of setup besides there being quite a few wires/connections?

Any links or sources to those that have done this type of setup before?

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amberwolf   100 GW

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Re: Charging a 48v eBike battery with 13 1s chargers?

Post by amberwolf » Jun 02 2017 2:00am

redilast wrote:So basically I'd run a lead from each battery + and - to the + and - of the charging board PCB and it would treat that cell or cell group as if it were an individual 3.7v Li-ion and not a 48v pack.
Yes, but the individual chargers must be designed as isolated, meaning that none of hte output wires connect to any of the input wires.

Quite a few things have one of the input wires connected to one of the outputs (usually neutral/ground/negative). As soon as you connect non-isolated stuff across cells, you instantly short out the cells, with damaging (or even catastrophic) results.


This way there is no need for balancing with bleed resistors and no need to have a circuit board hooked up with parasitic drain that could one day kill the pack.
You might still want to only plug the chargers in when actually charging, as their output stages might not be completely drain-free.



There's more info in a few of the threads in this search
https://endless-sphere.com/forums/searc ... mit=Search
but there's lots of irrelevant ones too. :(

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Overclocker   1 kW

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Re: Charging a 48v eBike battery with 13 1s chargers?

Post by Overclocker » Jun 02 2017 3:50am

i was thinking of doing the same but only for pseudo-balancing. because this scheme doesn't let you detect a cell that's starting to go bad since they're all charged up to 4.2v everytime

the boards are super cheap. you could buy 2 dozen of them and bin them for accuracy

999zip999   100 GW

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Re: Charging a 48v eBike battery with 13 1s chargers?

Post by 999zip999 » Jun 02 2017 1:49pm

How many ampere hours are these cells is is a big enough battery for an e-bike.

mark5   100 kW

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Re: Charging a 48v eBike battery with 13 1s chargers?

Post by mark5 » Jun 02 2017 2:20pm

redilast wrote:I think this topic has been discussed before, but its a very difficult topic to search for on the forums.
...
Any links or sources to those that have done this type of setup before?
Here's a good thread. Don't know whether the pictures in the thread are still there, especially xyster's setup, because they don't show on my pc.

-- THE SINGLE CELL CHARGER POST -- by Doctorbass
https://endless-sphere.com/forums/viewt ... =14&t=2586

Xyster's X5 pictures
https://endless-sphere.com/forums/viewt ... 7&start=30
https://endless-sphere.com/forums/viewt ... 7&start=38
Last edited by mark5 on Jun 02 2017 2:49pm, edited 1 time in total.

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fechter   100 GW

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Re: Charging a 48v eBike battery with 13 1s chargers?

Post by fechter » Jun 02 2017 2:40pm

Each charger needs to be isolated. Little dc-dc converters running off a common supply won't work unless they are isolated.

I think a lot of Xyster's posts fell victim to the auto-prune feature before it was turned off.

His setup looked like this:
Chargers.JPG
Chargers.JPG (117.9 KiB) Viewed 665 times
"One test is worth a thousand opinions"

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Overclocker   1 kW

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Re: Charging a 48v eBike battery with 13 1s chargers?

Post by Overclocker » Jul 18 2017 11:15am

Image

any updates on this project. i went ahead an got six of these 5v 2a wall warts, and twelve tp4056 boards

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Re: Charging a 48v eBike battery with 13 1s chargers?

Post by fourbanger » Jan 10 2018 12:00pm


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