i tested this module and yes indeed it only goes up to 1 amp. TP4056 module with protection buy Kiev Odessa Kharkov Ukraine
this one i did not, but maybe it will go upto 3amps. https://www.roboelements.com/product/1s-2a-bms-li-ion-battery-protection-board-with-nickel-strip/
Well, testing one thing and not the other thing, isn't much of a test...
How did you test it?
The Rds(on).
and what load? Can you explain the test circuit?
with some load resistor. i can assure you that it only allowed 1 amp.
If you haven't measured both modules, you haven't proven anything.
Rds(on) should big or small to allow more current?
okay i will test them both again.
see this module https://www.ebay.ca/itm/313623573217 . it has 2 mosfet and OC is 5.2amp. so that means 2 mosfet increased the OC value?
Yes, they have put the MOSFETs in parallel. That would cut the on resistance in half, and double the current protection trip point.
Small.
Look up Ohm's law. The protection triggers at around 150mV (+/- 30mV). This voltage develops over the RDSon of the MOSFET. Following Ohm's law, if you want more current to develop that same 150mV potential, would you need to increase or decrease RDSon?
@anon57585045 that r2 resistor is also parallel with the mosfet, so why changing that value won't change the OC limit?
It is not in parallel with the MOSFET main current conduction path. It is in the gate circuit which is high impedance, and is not affected directly by current between the drain and source.
Edit - sorry not the gate circuit. But the resistor is not connected across the drain/source of the MOSFET. That is where current is sensed.
i meant serial.
It's also not in series with the mosfet. Look at the schematic again. R2 is a reverse voltage protection for the input of an internal opamp within the chip. It says so pretty clearly in the datasheet. Its value does not play a significant role in setting the current protection.
so what i understood is that, those 2 module should the be using different mosfet to get different OC, right?
I'm wondering now, are you just trying to understand, or are you trying to reason yourself out of the problematic situation?
What is your final goal?
It's far more likely that the vendor/supplier is a liar, copy and pasted the information, and/or has no clue about electronics really...
I'm not completely sure which "those modules" you are referring to, though, as I think we've discussed 3 so far...
to build a protection circuit that can handle 2A. it's a part of bigger circuit. I don't want to experiment, i want a circuit that already works.
I will test this 2 and come back with some answer.
