UPDATE: Video Demo is here:

The chip is HT3582DM and not 3852DM sorry for the typo.

I bought this 18650 Li-Ion Battery Charger for about PHP 35, it is very cheap because it is broken. I can smell something inside, like a component burned or exploded.

The unit is dirty, the AC Pin are rusted.

I only bought it because I do not have any 18650 battery holder, and if I can make this charger work then I will have another charger.

The sticker label of the charger appears to be in Spanish language and it does not make any sense, there are also three screws, one of them is rusted too but I can still use it.

The isolation from AC mains’ is not good, there is not fuse/in-rush resistor, only a half-wave rectifier is used instead of a bridge rectifier and the parts used are all cheap and low quality. It is better to use a good quality AC-DC Switching PSU and connect it to the IC chip for safety.

The unhealty smell is coming from the NPN Power Transistor 13001, it appears to be an overcurrent/short circuit? The zener diode 4.7V appears to be damaged too. Luckily, no other components appear to be damaged. The board is very dirty, there are some dead ants in it and some soil.

The IC

The datasheet of the HOTCHIP HT3582DM is on Chinese and I have to use a Chinese to English Translator.
Here are some useful information from the datasheet:

- The HT3582DM is an internal reference voltage constrol chip universal charger with automatic battery polarity, short circuit protection, over temperature protection (of the chip).

-- Maximum charge current is 300~350 mA
-- Support for 0V rechargeable battery
-- Normal mode for three lights' and two lights mode or colorful lights mode.
-- No Load Voltage Minimum 4.15V, Typical 4.23V and Maximum is 4.30V
-- Saturation Voltage, Minimum 4.17V, Typical 4.25V and Max 4.32V

Pin 1 is the Battery Negative
Pin 2 is the Light 3
Pin 3 is the Light 2
Pin 4 is the Light 1
Pin 5 is the SW pin, function selection
Pin 6 is the GND
Pin 7 is the Battery Positive
Pin 8 is the Vdd (5~8 +Vin)

I have also reverse engineered the schematic of this device and you can download it below:

The Philips AC/DC Adapter as my DC PSU for the HT3582DM instead of the broken one.

I applied +5.9V (from a Good Quality Philips AC/DC Adapter) to the Vdd and GND and the Green LED lit up.

I desoldered some parts but ended up destroying some.

I soldered wire to the Vcc, GND, the B+ and to a inline fuse holder to and from the B- to add some overcurrent protection, just in case if the chip fails.

I can now use it to charge my batteries, including the dead ‘0V’ ones

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