USB - C connector purely for charging a battery

Question

I'm looking for an ultra slim charging connector to attach to a li-ion battery pack. All I need are positive and negative pins. I have read that USB C supports up to 5A current. If I get a product like this:

https://www.globalsources.com/gsol/I/USB-C-connector/p/sm/1164613438.htm#1164613438

And something similar for the socket end and if I solder positive and negative of the battery to VBUS and GND of the socket and positive and negative of the charger to same pins of the plug... will I be able to charge my battery at about 2A?

I know it seems stupid to try use a data/power connector purely for charging but I can't find a 2 way power connector close to its compactness.

Thanks in advance!

Answer 1

Yes, Type-C connectors, in a standard way, do support currents up to 5A. In standard way the connector uses 4 contacts for ground, and 4 contacts for VBUS, making it at 1.25A per contact. So you need to make sure that your design (on PCB and on cable side) uses all (4+4) pins. You can use more contacts if you need more current, but I would advise against it, to avoid port destruction in case if someone decided to plug your cable into their laptop/phone.

However, if you plan on productizing your charger (and device), a simple two-wire power connection will be technically illegal from Type-C standard. In Type-C standard the VBUS must not be present on wires until the cable is plugged into a Type-C receptacle. To achieve this you will need at least one (thin) signal wire in your charger cable. This wire should be connected to one of CC pins and have a 10k pull-up to +5V. Your device receptacle, in turn, must have two 5.1k resistors to GND on each CC1 and CC2 pins of your receptacle.

Your charger side should sense the voltage level on CC wire, and turn VBUS on only when it senses the voltage drop on it (due to 5.1k pull down after connect). A simple analog comparator with right threshold and a high-side power switch (or just a power P-FET) will do the job. In this arrangement your charger (with Type-C cable) will be fully compliant and won't harm any other Type-C user devices.

Answer 2

With what you described, as long as the USB C connector is connected to some type of battery charger, you should be able to use it. Just connect the positive voltage and common ground of the USB C connector to the charging IC. But I would take it one step further and consider getting a Power Delivery Module. This allows you to supply power to the battery charge via a USB-A to USB-C cable, but also allows you to use a higher input voltage if you are using a USB-C to USB-C charger. If your charger is some type of buck/buck-boost converter, then this would be beneficial since you will be able to charge your batteries faster (if they aren't already at the max charging current) at a higher voltage, usually ranging from 5V to 20V. Using this module, you will be able to get the 5A max current output. You can not get that with a normal USB C connector, so you would need some type of Power Delivery module.

Answer 3

Variations of this questions are asked very often on here: to draw high currents over USB-C from a USB-C power supply, it's not enough for your device to have a USB-C plug. It needs to talk the rather complicated USB-PD protocol with the power charger. So, it's not that easy.

If you really just need a cable to transport power, barrel connectors are cheaper and smaller (at least in one direction). There's a lot of two- or four-contact rectangular connectors ("MOLEX pin header") that are pretty common, too.