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

redilast

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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?
 
redilast said:
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/search.php?keywords=single+cell+charg*&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
but there's lots of irrelevant ones too. :(
 
redilast said:
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/viewtopic.php?f=14&t=2586

Xyster's X5 pictures
https://endless-sphere.com/forums/viewtopic.php?f=6&t=147&start=30
https://endless-sphere.com/forums/viewtopic.php?f=6&t=147&start=38
 
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
 
BsvsZhF.jpg


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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