days ago I did this project like the pic which is a DIY for 4*18650 OR 6*18650 (NOW I MADE 4 AND LET`S STICK TO IT) Sony vtc5a charger 3.7 v with new tp4056 with protection (copied from one youtube channel I don't own this pic) and please I want to do it parallel like this, it already soldered
the problem
is how to balance the four batteries because they must be balanced and the protection in the tp4056 is against the low voltage drop so when the voltage would drop the circuit will stop charging. And really use already build charging balancer like IMAX6 and that would be totally dumped and would not consider as a solution because of the whole thing is a challenge between me and a friend of mine to DIY one of corse not from 0 to 100 but not already done. I'm thinking that if I soldered one PCB between the TP4056 for each battery (LIKE ONE OF THEY GUY HERE IN THE WEBSITE DID) but I don't know if that would work?????
Hm? Not sure why they must be balanced unless you’re hot-plugging cells and and out of the bank. Ie, you won’t want to plug a fully-charged cell into the pack when the pack’s almost depleted, nor a nearly-depleted cell when the pack is fully charged.
If they’re all soldered into place, you can “equalise” the charge slowly via resistor to limit current, then hardwire it in once done. At that point, they’ll all charge/discharge exactly equally (eg, all cells at 3.942V).
And PTCs don’t open up like fuses. They’re commonly(?) called “constant-wattage devices”. Ie, as they heat up, they’ll limit current to maximum “safe” levels. Eg, a stalled wiper-motor on a car won’t have 14V across nearly a dead short of a stalled DC motor, but would limit the current to slightly more than a moderately-loaded motor to keep it from burning out and taking the car’s electrical system with it (or at least keep it from popping fuses).
Plus, PTCs do have a certain minimum resistance which you’ll have to factor in. Even a fractional-ohm inserted in series with each cell will limit current by quite a bit.
at the first thanks for ur kind answer well I did get it but may I bother u to give me a drawing for what u say to get it 100 right and where to put the resistor on the plan I know that it must be somewhere between the battery and the tp4056 but how ???? look I have the new tp4056 that already have an out+/- circuit and I think that u may tell me that I need to wire it with the resistor but that out +/- is for charging protection when the voltage become lower than 3v it would stop charging and transfer the power to the output.
If you wish to connect 4 cells in parallel to create one big 4p CELL or Pack, then it is good practice for the voltage of each cell to be fairly equal before making the connection. This is done to avoid sparks and arcing and high current flow between cells at unequal voltage.
In order to equalize the cells, a power resistor can be used to drain the higher voltage cells down to that of the lowest cell. A 40 to 100 Ohm resistor rated at 1 to 5W could be used to connect between cell + and - to drain the voltage.
Once the 4p Pack is created and the cells are balanced, then one TP4056 board could be used to charge the “CELL”. No need for 4 boards, i doubt it could even be done that way.
Assuming you soldered the 4 cells in parallel: By soldering the 4 cells in parallel to one pack, you created “one big cell”. The problem is that the four TP4056 are probably interfering with each other if you connect them in parallel.
You either could use just one TP4056 to charge the pack (like kennybobby said), or you could use a different chip to charge the pack at a higher current.
thanks for ur replay I want to tell u that every battery is 35A 3.7 v and 3000mAh so one tp4056 won’t be enough because I tried it before it would take centuries to charge them but where to but my problem that is where to put the resistor because I’m new in this field and may I bother u to draw one explanation to me please and I would be thankful.
do u mean that I need to connect the resistor in between the out +/- of the board and the battery ???
To charge 4 series cell, i think u need to boost the voltage
Wire the cell parallel is another solution, but i wont recommend
Because what if there is a full 4.2V cell in slot 1, and you add near dead 3.2V cell in slot 2, the current will run From 4.2V cell to 3.2V cell, and WONT BE LIMITED, until the voltage of 2 cell is same
A bleed resistor is a temporary connection that you make on each cell individually with a jumper wires.
This would be for a balancing operation done before making any connections to other cells or boards.
With your drawing using the diodes then you don’t need to do the resistor balance since no current can flow from one cell to another. i don’t know if you intend to use your pack with the diodes in place, but if so then they must be sized to handle your maximum current draw plus some margin.
i think one tp board could be used to charge all 4 in about 10 hours << centuries.
I just asked about parallel charging (with a hobby charger) and I got this answer from a respected member/
I also saw some YT video where a guy put different state of charged batteries in parallel and measured the current and it was nothing to be too concerned about. I’l have to search for the video though. I think it’s the guy that rebuild a VW hippie van to run on recycled 18650 batteries.
how much this bleed resistor must be???
where exactly i need to put it in between the cell and the board or after the board I’m really new in this field. sorry but pls explain it to me how it must be with the resistor pls pls
As TA mentioned, every cell should not be different much in voltage(0.5v)
Typical IR of ncr18650b is about 55 mili ohm, so the current if there is difference is:i=v/r=0.5/(0.055*2)=4.5A, this current will slow decrease to 0 when there is no difference in voltage
If the difference is high(4.2-3.2=1), the current will be nearly 10A
This gets worse if the cells are not ncr18650B but IMR high drain battery
Yes, but the peak current of 10A will only be for second or so after that the current will go down drastically. I’m not saying it’s the way to go but if you design it your self you know how to handle it so I don’t really see a problem with it. It’s not like he’s going to put it on the market or something. This is how I’m going to parallel charge 8to12 cells. I won’t be lending my setup out to anyone, if they need to borrow a charger they can use my opus or xtar chargers.