I have built a battery charging unit for my robot as shown in the figure below. After plugging in the adapter, the converter module gets really hot after a few minutes, I don't really understand why the converter module overheats. Is there something wrong with my work? Is there an alternative module that I can use instead of the LM-2596 and solve my problem?

Thank you!

enter image description here

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    \$\begingroup\$ The LM2596 is a discrete component. What is the circuit it is connected to? How much current is your battery charger drawing? \$\endgroup\$
    – vir
    Commented Oct 14, 2022 at 21:50
  • \$\begingroup\$ I don't know how much current it exactly draws, I only know the charger draws a maximum of 3A.The hx-2s charger module : usa.banggood.com/… \$\endgroup\$ Commented Oct 14, 2022 at 21:55
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    \$\begingroup\$ You're running it at 100% rated power, I would expect it to get hot. What specific part of the converter module is getting hot? \$\endgroup\$
    – vir
    Commented Oct 14, 2022 at 21:57
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    \$\begingroup\$ Your charging unit needs a proper LiIon battery charger. The HX-2S-02 is just a BMS. You batteries will not survive this mistreatment for very long. \$\endgroup\$
    – StarCat
    Commented Oct 15, 2022 at 9:19
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    \$\begingroup\$ Please stop what you are doing and get yourself a li-ion charger instead before you have a fire or fiery explosion. \$\endgroup\$
    – winny
    Commented Oct 15, 2022 at 10:39

1 Answer 1


You are short circuiting the buck module into the lithium battery which is dangerous. Mishandled batteries may become unstable and burst into fire and explode, so stop immediately what you are doint.

You have no lithium charger in the circuit.

What you think as a charger is not a charger but a battery management system and protection board, a BMS.

And a BMS is not a charger.

  • \$\begingroup\$ Thank you @justme! Could you please look at this link: amazon hx-2s The image says the P- & P+ can be used for charging, What shall I do? Is there any component I use to charge batteries? \$\endgroup\$ Commented Oct 15, 2022 at 11:38
  • \$\begingroup\$ I have just researched the XL-4015, Is it ok if I connect the XL-4015 directly to the batteries? – \$\endgroup\$ Commented Oct 15, 2022 at 11:48
  • \$\begingroup\$ The Amazon link is correct, P- and P+ can be used for charging. With a lithium charger, obviously. XL-4015 is a buck converter chip, it is not a lithium charger chip. It is not OK to charge lithiums with anything else than a device intended to charge lithiums, safely. \$\endgroup\$
    – Justme
    Commented Oct 15, 2022 at 12:32
  • \$\begingroup\$ Please check Link, There is a LED to show the battery charge situation, Is it still improper to use it as a battery charger? So why do they design that module like this? \$\endgroup\$ Commented Oct 15, 2022 at 13:10
  • \$\begingroup\$ @masoudkhanlo These are SMPS DC-DC supplies, not really chargers for Li-ion batteries, although these have a current limit adjustable and because there do not have, at least, a "voltage limit supervisor" ... \$\endgroup\$
    – Antonio51
    Commented Oct 15, 2022 at 13:39

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