Self balancing charger idea: diy using tp4056

[whatever]

I've found the tp4056 boards extremely useful for charging individual 18650 cells, there are two version so of this board, a basic one, and a better one with a couple of chips on it, the more complex board is much better and they are extremely cheap ( around $50c aud per board).
Here is my idea:
use a multitude of these small boards to charge individual cells which are in series, that way each cell will reach same voltage when charged, no need for balancing, it should self balance. Has anyone already tried this idea or suggested this method for a self balancing charger?
outline of how its setup:
I envisage each cell is permanently connected to its own tp4056 charger, they run on 5v generally. So a 5v power source is required with enough amps to satisfy how ever many of the small charger boards are connected.........in my case it would be 14s pack, so 14 lots of tp4056 required, at 1amp each board that 14amps at 5v, I would imagine plenty of atx computer power supplies would handle that many amps.
potential issues:
the only thing i'm really worried about is some interaction bewteen cells and the charger, making the charger cut off, I use atx power supplies alot and do find using two chargers together sometimes there is some interaction probably since each charger is using same ground via the atx supply.
The max current will be one amp per cell so not suitable for large ahr batteries, but most smaller ebike batteries should be ok, I charge my 24v packs at 1 amp and its fast enough. Some youtube videos do show you can increase the current a bit but some heatsinking of the chips required.
There might be other unforseen issues I'm not aware of.
If anyone has any experience using these boards in this manner please chyme in, I would be surprised if no-one has tried it.
basic picture of the idea below just showing 3 cells but could work for any number of cells in series
Last comment: it would be extremely cheap charger also if this idea works.

 

[whatever]

so reply to myself after searching forum is yup it has been done, and the earthing is a problem between cells/chargers, oh well, was fun idea while it lasted.....i'm guessing a simple diode pn each tp4056 wont fix the earthing issue.

 

[fechter]

Right. Each charger board needs to be isolated from the source to prevent a short. If you had an isolated dc-dc converter for each one, it could work but this could get expensive. I remember one guy that used a separate AC wall wart for each cell and that worked but it was a real spaghetti pile of wires.

 

[leffex]

so reply to myself after searching forum is yup it has been done, and the earthing is a problem between cells/chargers, oh well, was fun idea while it lasted.....i'm guessing a simple diode pn each tp4056 wont fix the earthing issue.

yes it was. I guess I had the thought one day in the past as well but no time to investigate and the next day forgotten from history...

What I could second is to bulk charge. Charge a battery directly with the correct voltage charger or another one that has a higher amp output if that is needed and from time to time. Once a week, once a month do a balance charge to get everything back in order and to spot for error if that would ever occur.

 

[amberwolf]

To use these boards for each series cell or cell group, you would need an electrically isolated power supply for each board. If there are 14 cells or cell groups, you need 14 boards and 14 PSUs, and every PSU has to be electrically isolated on it's output from it's input (no electrical connection from DC + or - to AC neutral, hot, or ground).

 

[whatever]

well you guys wont believe this, just did a quick google search for "tp4056 series cells"
and bingo, one video shows the solution, its using a very cheap isolated 5v supply for each cell, but those isolated supplies are
powered by one big 5v supply of course, the component is B0505S-1W it costs about same as a tp4056 but still it makes a very nice
cheap self balancing charger.
here is the video:
tp4056 as series charger
aaarrrggghhh I just read some posts on that video and these units since only 1 watt, means only 200mA of current, very low, hence the resistor mod on the tp4056 to 5k to lower current..............damn........will be too slow......

 

[DogDipstick]

DO NOT DO THIS AT ALL.

READS THE DWO1 Datasheet. The " 1" in the name means ONE CELL ONLY!!!

https://cdn.sparkfun.com/assets/learn_tutorials/2/5/1/DW01-P_DataSheet_V10.pdf

Putting tp4056 chips in series is what destroys batteries and starts fires.. at leaat this is what happened to the Hovorboard battery recalls.

Here is an electrical expert on the forum telling you WHY you should NEVER do this and WHY the failure creates a "Cascade failure" of serious danger.

Gooodness da just buy a real charger.

Circuit analysis of a cheap BMS, and why you shouldn't use one

Hello folks, I am an embedded systems engineer. I design and program all kinds of electronics, as a hobby and a profession. Electronics from realtime control units that run constantly for years at a time, to "simple" electronics like BMS boards. Battery Management Systems are safe and...

endless-sphere.com

Hello folks, I am an embedded systems engineer. I design and program all kinds of electronics, as a hobby and a profession. Electronics from realtime control units that run constantly for years at a time, to "simple" electronics like BMS boards.

This is a very unsafe design for 3 reasons:

1. Each of the protection chips (DW01A) is separate, there is no cooperation. Meaning: one chip could fail, due to ESD, water droplet, etc. Then that cell group is completely unprotected, opening up the possibility that the cell group could become overcharged and explode unexpectedly! With a 2-wire monolithic design, if one part fails, due to ESD, etc, the output FETs are turned off PERMANENTLY. This is much safer, as charge can no longer flow in or out. Crisis averted, while also alerting the user of the failure.

2. For exactly this reason, the manufacturer states clearly that the DW01 is a 1S ONLY protection chip. Using them as a 4S, 10S, 14S, etc is NOT RECOMMENDED because of this safety hazard! That's what the "01" in DW01 stands for! Here is the datasheet confirming my claim: http://www.kexin.com.cn/pdf/DW01.PDF

3. The protection and balancing chips are separate, leading to a condition where the balance chip fails, and the cell group is no longer able to bleed overcharge anymore. This is less dangerous, but still a design flaw stemming from using a 1S protection chip incorrectly. Proper multi-cell chips will perform balancing as well as protection.

 

[whatever]

thankyou doggy dipstic, I did read a comment on one youtube chanel that mentioned this but went into no more detail, consider this idea cancelled!