Building a modular lithium ion battery charger

[Shawn McCarty February 14, 2017 at 1:18 pm Post count: 0]

#12710 Reply |

I want to build a lithium ion battery charger that is modular. The goal is to use small buck converters like the DROK 25W 3A Adjustable DC-DC Converter. I’d wire them in parallel with one power source, and charge each cell with one charger set to 4.2 volts.

Will this work or do the chargers need to have separate power supplies?

thanks,

Shawn
batteryblocs

[DrokKeymaster February 15, 2017 at 9:09 am Post count: 2971]

#12728 Reply |

Hello Shawn McCarty,
Thank you for writing in.
We are not sure which converter you plan to use. It’s hard to confirm the item with the item title you offer.
And in order to avoid mistake, could you please draw a wiring diagram to show your plan?
If you don’t know how upload picture here ,you can send it to service#droking dot com ( please replace # with @)
Look forward to your reply.
Best regards.

[Greg Griffes April 6, 2017 at 2:13 am Post count: 0]

#14719 Reply |

Hi, I want to do the same thing, charge two 18650 Lion cells so I purchased the Step-down Constant Current & Voltage Converter 4-38V to 1.25-36V 12V/24V Buck Voltage Regulator 5A 75W High Power LED Constant Current Driver Module for Lithium Battery Electromobile Charging. Thank you for providing advice on how to set the current limit on the device. I am wondering if you know what current limit should be set for an 18650 type lithium Ion battery.

From what I’ve read, Lion cells need to be charged individually not in parallel. This is because if one cell is highly discharged and the other cell is charged, there is an imbalance in voltage and one of the cells can get damaged. Therefore, I recommend using a separate charger for each cell, however, many manufacturers of 18650 battery chargers don’t do cell balancing; so, I could be wrong. Some batteries have protection built in, some don’t.

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