Step-Down Buck Charging Board XL4015 ADJ Lithium Battery Charger Converter Module

[sam_sam_sam]

Will these units really do five amps

http://s.aliexpress.com/yUjqq6Rz

5A Max Step-Down Buck Charging Board XL4015 ADJ Lithium Battery Charger Converter Module DC-DC 0.8-30V To 5-32V 5A Step Down CC

[eccerr0r]

Re: Step-Down Buck Charging Board XL4015 ADJ Lithium Battery Charger Converter Module

Marginal IMHO, though probably will get there...pretty close. It will get quite hot but should just about do it...

[mariushm]

Re: Step-Down Buck Charging Board XL4015 ADJ Lithium Battery Charger Converter Module

Those don't really have anything to do with lithium battery charging, it's just a regular buck converter, a dc-dc converter.

No, as it is, it can't do 5A. Heatsinks would have to be applied. But it will also depend on your input and output ... the smaller the differential, the more efficient this will be... if you do 5v -> 4.2v then it will do... if you do 24v->4.2v ... tough.

It may do 3A continuously in any condition.

It's like cars have up to 100 miles an hour , up to 30 miles a gallon (or something like that)... basically you may not be able to do both at the same time

The board uses an XLSemi XL4015 switch IC, here's datasheet:

Datasheet says it can do 5A continuously, but it also says up to 96% efficient... so keep in mind the losses.

Page 6 will show you an efficiency vs current curve... for example with 12v in, 5v out and 5A the efficiency is around 87% with the optimum chosen components (which won't be the case as they use a cheap inductor that will work across the wide range of input voltage and output voltage, it's not picked for highest efficiency)
Anyway... 12v in, 5v out, 5A , let's say 85% efficiency.. 5v x 5A = 25w is 85% of drawn power, so heat produced is 25/85 * 15 = 4.4w

This 4.4w is not just on chip, it's chip, diode, inductor... but let's say 3w on chip.

If you look on page 4, you can see it says "Thermal Resistance (TO263-5L) (Junction to Ambient, No Heatsink, Free Air)" : 30c/w
This means for every watt of heat, the chip will hit 30c above ambient.
So if the ambient temperature is 25c in your house, 3w will raise temp. to 25+90c= 115c - the chip is rated for 125c and will probably limit itself before that.
The 30c/w is assuming there's something like 1 square inch of copper around the chip to dissipate heat into the circuit board but you can see the inductor and the diode are close to the chip also heating the board and raising the ambient temperature.


You also have a SS54 diode, which is rated for 5A peak, but you have to keep in mind that it derates if it goes above 90 degrees Celsius or thereabouts.
Here's datasheet: https://cdn.badcaps-static.com/pdfs/...17971f501f.pdf

Note how the example circuit on page 3 of the datasheet shows a mbrd1045g diode being used, which is a 45v 10A diode ... the board you link to uses a 40v 5A diode in a smaller package that will heat faster.

[redwire]

Re: Step-Down Buck Charging Board XL4015 ADJ Lithium Battery Charger Converter Module

chinese amps are different than American amps, although Ampère is a French mathematician and physicist.

At 5A output it is 87% efficient at best, so around 4W of heat dissipated in the IC for a tiny board. It has no thermal vias.
The Schottky rectifier and inductor also make heat. The parts running 80-120C at 5A.

It is basically a CV regulator with a CC op-amp added, so not a real battery charger. It has no smarts about that.

[sam_sam_sam]

Re: Step-Down Buck Charging Board XL4015 ADJ Lithium Battery Charger Converter Module

Here is a question that I have as you know that I have been working with the Ksger battery BMS protection board so I have battery protection board part

Will this unit control the current because the BMS protection board does not control current

This BMS board will put out as much current as you can give it this not going work

I need some kind current controller of some kind but I do want to use some big board profile controller with some really big heat sink

I have some current controller and that the problem that I have now

[sam_sam_sam]

Re: Step-Down Buck Charging Board XL4015 ADJ Lithium Battery Charger Converter Module

chinese amps are different than American amps, although Ampère is a French mathematician and physicist.

What is the difference between them please give an example

Thanks

[eccerr0r]

Re: Step-Down Buck Charging Board XL4015 ADJ Lithium Battery Charger Converter Module

1 Chinese amp is equal to 0.5 American amperes.

It was a sarcastic joke.