There are hundreds.
Google "18650 battery charger". You will see from 1 battery up to to 8 at a time.
And incorrect, it's just "Aye, Captain". They only say "Aye Aye Captain" in bad movies!
No sign of a USB input socket.
It won't, the authoritative thread is on this forum.
Yes, those will be ok, but you need to get them tested for how much capacity is left.
If the TP4056 isn't being used to charge the 18650's when the batteries are run down and not connected to the circuit then they are not needed. If you want the TP4056 to re-charge the batteries, you need a bit more circuit than what you show. For this project, just drop the TP4056 and get a proper charger. The batteries connected to the MT068 will work fine.
This is what it looks like now. I am wondering if there is need of tp4056 for battery over-discharge protection. i was also wondering that if i should replace the 2 caps(100µF 25V) across the servos and instead place one 1000µF 25V cap across the buck converter in the very start.
@jim-p @PaulRB @sonofcy Could you check if anything is amiss ?
Any and all suggestions are deeply appreciated.
That chip doesn't have over-discharge protection.
Some modules that have a tp4056 chip also have an over-discharge protection chip, but not all.
The over-discharge protection chips are available as separate modules, and you definitely need one to protect you batteries. But with 2 batteries, you need one designed for 2 batteries. Or maybe you can use 2 single battery protection circuits.
I can't see any other problems with your circuit.
Only use batteries that are fully protected, that way you don't need to worry about over charge and over discharge.
wondering that if i should replace the 2 caps(100µF 25V) across the servos and instead place one 1000µF 25V cap across the buck converter in the very start.
No, leave as is.
I would also include an on/off switch to save battery power.
Do you have a multimeter/ DMM?
I found these three on the net. Could you check which would be best for the project.
- 2S 7.4V 18650 lithium 8.4V lithium battery protection board
- 2S 2 strings 8.4V lithium battery protection board
- 2S 7.4V 8.4V lithium battery protection board
I think second one might be better as it is small and is easy to fit.
What does that mean, batteries that are fully protected. Idk what it means.
Will do.
I do.
When you buy batteries only buy those that are fully protected.
It means that they include circuits inside that will prevent over discharge and over charge.
Well, I harvested mine from an old laptop. There is a BMS in it but it's for 6 batteries and I don't have a single clue about to use it.
Are they still good?
Well, I am still finding that multimeter of mine. I don't remember where I had put it. I'll check it soon enough. Though the laptop's problem wasn't the battery. So I have every reason to believe that they would be alright other than they have not been used for over a year.
Li-ion batteries don't last forever. Eventually they won't fully charge, hold a charge or provide the rated current.
If the laptop was 5 years or more older, I'd buy new batteries.
That means the batteries are unprotected if you didn't also harvest the BMS. It's a fairly simple job to use only 1 of the 6.
I think you need to understand the difference between protected and NOT protected.
One is safe if handled properly, the other is a bomb waiting to go off at the slightest provocation.
My suggestion is to dispose of the laptop batteries at a lithium battery disposal site. At the very least put them in a steel can and get them out of your house.
Given that they are unprotected cells, it is extremely dangerous to connect them in parallel.
Seems ok, they all seem ok to me.
I would use one of those tp4056 boards to charge your batteries and when you do that for the first time, do it outdoors (on a dry day) in a place where nothing can catch fire, like on a concrete surface. And warn anyone around to stay away from it.
The problem with li-ion batteries is that they can be damaged by over-discharging, over-charging, over-heating, being dropped.... and they might look absolutely fine, and still seem to work ok. But when you recharge them, that's when the danger arrises. They can burst, spray hot chemicals, catch fire and even explode.
So take care of yourself and others!
Well, I will be joining them in series, I have updated my schematic a little.
So, can we use the BMS for two cells. It was being used for 6 cells before....
The one you said was okay has overcharge protection as well so does that mean it works the same as tp4056 but with 2 cells in series together?
2S 2 strings 8.4V lithium battery protection board
Under the wiring instructions, it is mentioned that:-
- P+ is connected to the positive electrode of the charge/discharge terminal (common to the charge terminal/discharge terminal)
- P- Connect the negative electrode of the charge/discharge terminal (common to the charge terminal/discharge terminal)
So does that mean I don't need the tp4056 if I have this module?
Only if 2 < 6.