5a lithium charger modules

[vinceroger69]

Hi i have one of these modules
https://www.aliexpress.com/item/5A-L...72e6cd557ef8dc
youtube video of it
https://www.youtube.com/watch?v=sGYP...t=83s&index=19
my question is i need too add a protection diode as if you turn off the power too the module before disconnecting the battery on charge it blows the unit up as mentioned in the video comments, what diode do you guys recommend i add to stop this from happening thanks

[sam_sam_sam]

Re: 5a lithium charger modules

The diode is used in case you hook up the power supply the wrong way on the battery
This would be a good idea to put one in series from the battery to the power supply
If you do not want this to happen

If just take the power supply away from the the battery would cause it to fry the board then it is not designed correctly and I would not want to use it if this is the case

[eccerr0r]

Re: 5a lithium charger modules

Usually one would add a diode with anode on the output of the switching element and cathode to the input of the switching element to protect it. Why it wasn't designed with one baffles me, this would be a serious design defect.

[vinceroger69]

Re: 5a lithium charger modules

The diode is used in case you hook up the power supply the wrong way on the battery
This would be a good idea to put one in series from the battery to the power supply
If you do not want this to happen

If just take the power supply away from the the battery would cause it to fry the board then it is not designed correctly and I would not want to use it if this is the case

Thanks for the reply what diode would you recommend i use? i was thinking of putting like you say one in series too protect the module in case of a power cut etc

[sam_sam_sam]

Re: 5a lithium charger modules

It depends on what amperage you are going to use this at
If you are going to use this at one amp then you could use a 1N4004

Just remember to adjust the voltage after the diode

[vinceroger69]

Re: 5a lithium charger modules

It depends on what amperage you are going to use this at
If you are going to use this at one amp then you could use a 1N4004

Just remember to adjust the voltage after the diode

thanks and ok i have some of those what about 2 amp?

[sam_sam_sam]

Re: 5a lithium charger modules

1N-something

[eccerr0r]

Re: 5a lithium charger modules

1n5402

[vinceroger69]

Re: 5a lithium charger modules

1n5402

thanks i have some of them i will give the unit a try

[eccerr0r]

Re: 5a lithium charger modules

Whoops... someone said 2 amps so I gave a 3 amp diode. But the design requirement was 5A ...?

[vinceroger69]

Re: 5a lithium charger modules

yes designed too run at 5 amp max you can set the charging amps manually i was concerned after reading the comments people saying if there was a power cut or you disconnect the power too the unit first the module blows up as no protection it does also say this in the add but does not tell you what diode to add so if this was your unit what diode would you use?

[eccerr0r]

Re: 5a lithium charger modules

I'd reverse engineer the board a bit and use the cheap 1N4001 to protect the chip instead of just adding a series diode...

[vinceroger69]

Re: 5a lithium charger modules

i will take some good clear pictures of the unit and maybe you can help me modify it if you dont mind

[budm]

Re: 5a lithium charger modules

Can you read the P/N of the IC?
Once you find the spec sheet of the IC, it will probably has the application circuits that is more likely to be used by these boards manufacturer. It may also have some caution about the circuit protection.

[redwire]

Re: 5a lithium charger modules

Those modules use XL4015 buck-converter (step down) IC, rated 5A but those are chinese amps... so derate by 1/2 for actual use Some of these modules have tiny diodes, others have large heatsinks.

Charging a battery, you get backfeed into the IC if input power is removed.
It has a P-ch MOSFET inside so it should have a built-in substrate diode and not blow up if connected to a battery.
There is a current spike when you connect only a battery at the output of the buck converter (with no input power).
The input capacitors get charged, and maybe this is what damages the IC.

You can add a series Schottky blocking diode at the output. Like SS54, SB540, or junkbox parts from a PC power supply.
That diode will also make heat, several watts worth (5A*0.4V=2W) and best to have some heatsink if you are going for 5A.

The diode will make the exact charging voltage mushy due to its voltage drop, so the IC feedback trimpot might be moved to monitor battery voltage after the new diode.

TI Design Trade-offs for Switch-Mode Battery Chargers fig. 17-19 show the situation.

[vinceroger69]

Re: 5a lithium charger modules

Thanks for the input guys i will update this thread with pictures asap many thanks

[vinceroger69]

Re: 5a lithium charger modules

pictures the ics used are
XLSEMI
XL4015E1
72441

LM358
8AK
SSM 158

[eccerr0r]

Re: 5a lithium charger modules

Now I'm a bit confused what the proper diode is, but I think despite it being more sensitive than what a 1N4001 can handle, it should be just fine.

I think all you need is:

[vinceroger69]

Re: 5a lithium charger modules

Now I'm a bit confused what the proper diode is, but I think despite it being more sensitive than what a 1N4001 can handle, it should be just fine.

I think all you need is:

would a IN4007 be ok i have some UF4007 too if not will look on part boards

[eccerr0r]

Re: 5a lithium charger modules

I was wondering if some schottky diode was needed here or not versus a higher voltage 1n4007, but this should do instead of the 1n4001.