Which BMS? Agressively charging lower juice'd cells, more than "frying" less juice'd

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DRAH

New member
Joined
Mar 27, 2019
Messages
1
Hi,

I'm currently fiddling with a project where I trying to put some sort of a controller, BMS, charger together. In these my first attempts, I'm using the well known circuits before attempting more serious stuff.. The circuits I'm working with now, is the TP4056. The well known little Li-Ion charger, which comes in 2 editions. The one I have seen the most, is the one without the extra protection function. Actually I'm not quite sure how this works, so I've been avoiding these. Because, everywhere I've read about these, you are just told that the charger comes with a built-in protection!?!? Protection of over discharging? Because it can't be protection against overcharging, because TP4056 is exactly a charger which has been a success because it works well, and charges to 4.1V.

1. So please, please set me straight here. What does it do? Does it protect against discharging if you use the connections marked "B+" and "B-" ??

And if it's under-voltage it's protecting against, then what about circuits where several e.g. 18650's is put in parallel with a TP4056 each?? How would this be able to work. I've seen several attempts to do just that, and this is what I'm going to do too. Not quite, but similar basics...

And

2. If I want to use a single 18650 battery with the TP4056 without the extra protection, is it then OK if I connect the " 1S BMS " . One of the little mini BMS PCB's??


Hoping for some kind'ish words here ;)

KR
Dan
 

Korishan

Moderator
Joined
Jan 7, 2017
Messages
6,548
The TP4056 that has the built on protection circuit uses the DW01 dual mosfet. When connecting the cells/load correctly, the DW01 "should" disconnect the cell from the load during under-voltage conditions. I have not tested this as I don't have any of these styles, so I am not 100% sure of that.


image_eizddl.jpg


The one on the left is the standard non-protected charged. The one on the right has the DW01 in the upper right corner of the board.
 

Crimp Daddy

Member
Joined
Feb 21, 2018
Messages
961
Maybe ill ask this question first. What exactly are you trying to build?

If not exceeding a 1s pack design, you can use the TP4056 charger + a separate BMS board. If you are looking to use the TP4050 in series, then it would not work since they are not isolated. Parallel, no problem... increase cell count to cut current per cell, or increase TP4056 to increase charge rate.

There are many ways to accomplish the same result you could even consider using an adjustable DC-DC CC/CV power supply to charge.
 

Redpacket

Member
Joined
Feb 28, 2018
Messages
1,301
+1 like Crimp Daddy said, you can't use the TP4056 chargers in a battery pack, they're only suitable for single cells or a few paralleled cells
 
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