Cheap charger mod

[Quaxo76]

Hi all,
I obtained a few days ago a very cheap, Chinese charger. I didn't like the cheap-ish look of it, so I measured the voltage and current supplied, and I found out that it was nowhere near the needed values/procedures for a Lipo cell. It actually overcharged the cells to over 4.56V. I disassembled it and saw that the circuit is a very simple regulator, with no ICs at all, and no safety measures.
Instead of throwing it away, I thought I'd try to save what was usable... mainly the chassis and the spring-loaded contacts. I simply soldered two wires to the spring contacts, and soldered a heavy-duty connector at the other end - the kind used for RC models; and now I just connect it to my professional charger that I use for the RC airplane. Now it automatically detects cell type, cell number (I can charge two 18350 together), and follows the correct charge cycle, also constantly displaying voltage, current and total mA that got into the battery...
(if anyone's interested, my charger is a iMax B6, good but cheap:http://www.hobbyking.com/hobbyking/store/__5548__IMAX_B6_Charger_Discharger_1_6_Cells_GENUINE_.html).

Cristian

 

[BShanahan14rulz]

IIRC, those were called the DSD chargers, because the brand of PSU was almost exclusively "DSD," whatever that is. I had one too, and now I use it either for a temporary 2x18650 series holder, or I hook up a resistor and use it to check Rinternal of my cells.

The DSD had what amounts to a very simple regulator chip (I suspect it was actually a cell protection chip, since it often terminated at 4.25V, but my charger regulator was sanded down), and minimal supporting components outputting to two paralleled bays.

You can find LTC4054 based circuit boards and knock-off equivalents on ebay for fairly cheap, these follow the Li Ion charging algorithm fairly well.
Review / Measurement: Charger module with TP4056 controller | BudgetLightForum.com < regarding a knockoff version TP4054 controller, note lack of reverse polarity protection. You can use with a 5V adapter or a USB cable.

Your option is much better, and would be the method of choice for those with multiple cell types who may already own a hobby charger. This is just a cheap option I remember seeing a while ago, figured your thread would be the perfect spot to drop this tidbit.