Before. And not only set, but a fix afterward - with a bit of glue or something like that. Voltage set should not be incidentally changed.
MAX745 is a Buck convertor. You should supply it with higher voltage (it accept up to 24V). It will regulate it itself. Current limiter in external poser supply also doesn't needed - MAX745 provides its own.
How much of current you plan to get? 3S4P configuration assumed charging with 4*C current, I think it will be much close to 4A (btw it's a maximum current, supported by MAX745. Not sure for rest of circuit on PCB from AliExpress )
Yes
It is question about rated capacity of accumulator and charging current. For 1P configuration charging current should be set to accumulator rated capacity (example: 1A for 1000mA/h accumulator). For 3P it should be 3 times more. If your charging current is less then charging time will increase proportionally. If current is bigger you probably blown up your accumulator.
Ouh. AliExpress is a VERY unreliable source of accumulators. About 99% if them here is a fake.
> If this refers to capacity units (Coloumb)
Yes, it is capacity units, but not Coulombs but Amper*Hours (for LiIon commonly used milliAmper*Hours)
This is not a 'charging indicator' This is CC/CV indicator. Charging considered done when charging current drops below 1/10 of preset of current. Not shure that module has appropriate circuit.
Charging interface: Red LED indicator,when charing is Red,Fully charged light is out.
Check the voltage. If it 16.8 than it normal - module moved to CV mode
If you supply it with 20V it also quite normal - they try to balance accumulators and turned on
MAX datasheet says about 'status' output -
An open-drain MOSFET sinks current when in current-regulation mode, and is high impedance when in voltage-regulation mode. Connect STATUS to VL through a 1kΩ to 100kΩ pullup resistor. STATUS can also drive an LED for visual indication of regulation mode (see MAX745 EV kit). Leave STATUS floating if not used
There is no other status indicators. PCB do not contains any other IC except MAX.
So seller just do not know what he sell (as usual)
Before. And not only set, but a fix afterward - with a bit of glue or something like that. Voltage set should not be incidentally changed.
So, just to make sure I understand correctly. I connect my external power supply to In+ and In- of the Max745 module with let's say 20V and with a DMM I check the voltage on the Bat+ and Bat- side of the module and I adjust it to 16.8V with Vset, while the module is not yet wired to the battery pack, correct?
MAX745 is a Buck convertor. You should supply it with higher voltage (it accept up to 24V). It will regulate it itself. Current limiter in external poser supply also doesn't needed - MAX745 provides its own.
How much of current you plan to get? 3S4P configuration assumed charging with 4*C current, I think it will be much close to 4A (btw it's a maximum current, supported by MAX745. Not sure for rest of circuit on PCB from AliExpress )
Hi,
If you do not know the specs on the batteries how could you know the maximum charging current?
The max charging current varies widely for Li-ion batteries, from maybe 300 milliamps to 20 amps, so how could you know the max for the cells you have. Even then if they are not from a reputable source the specs can even be bogus.
If they are the 18500 on the low end is usually around 500ma to 700ma, up to 20 amps or maybe higher. I've personally delt with the 700ma and up types. If you do not know, then 700ma is probably a good limit for the current during charging.
Charging is one of the most dangerous modes for these batteries so it has to be done with extra care. Making a pack with cells in series/parallel also requires that each battery cell has built in BMS protection so that each cell can monitor it's own charge regimen.
For initial testing you should probably have the pack outdoors and test for overheating with a thermometer. If anything goes too wrong it quickly turns into a disaster.
Hi,
If you do not know the specs on the batteries how could you know the maximum charging current?
The max charging current varies widely for Li-ion batteries, from maybe 300 milliamps to 20 amps, so how could you know the max for the cells you have. Even then if they are not from a reputable source the specs can even be bogus.
If they are the 18500 on the low end is usually around 500ma to 700ma, up to 20 amps or maybe higher. I've personally delt with the 700ma and up types. If you do not know, then 700ma is probably a good limit for the current during charging.
Charging is one of the most dangerous modes for these batteries so it has to be done with extra care. Making a pack with cells in series/parallel also requires that each battery cell has built in BMS protection so that each cell can monitor it's own charge regimen.
For initial testing you should probably have the pack outdoors and test for overheating with a thermometer. If anything goes too wrong it quickly turns into a disaster.
I am aware of the dangers of charging these batteries. If you read my 1st post you see I have a BMS to help with protection for over/under voltage and current scenarios and also for shorts.
Of course that this is not 100% safe and that there is still the chance for problems, but that's inherent to anything related with electricity, generally speaking!
Ok, I'll take that value of 700mA as a reference. Also, if 400mA can charge this battery pack in like a few hours, I'm good with it. Don't need super fast charging, also because of safety concerns I rather to take longer to charge the battery pack safelly, than to charge it faster but risking fires or explosions, etc!
Yeah, I know, I'm aware of the dangers. I've seens quite a few really bad situations regarding Li-Ion Batteries catching on fire an even exploding. And how hard is to deal with the fire.
But a warn is never too much and I'm not more concerned about using this pack of batteries where I wanted to use them. I'll have to think a bit more about if I really want to use it where I wanted to use it, which was in the trunk of my car to feed a survaillance system I was building to my car!