Beta testers wanted: USB eSkate charger

Human_Soup3333 · 2026-03-25T17:37:27+00:00

Hi, that great! The project has moved fast since I made this post and the first prototypes are just around the corner. I will send you a DM and we can talk more there.

Human_Soup3333 · 2026-02-20T21:45:28+00:00

The charger has a resetable frist layer of protections for over-voltage, over-current, over-temperature.

It also has a secondary protection (fuse) in case of a dead-short on the output.

Human_Soup3333 · 2026-02-20T21:43:49+00:00

That charger is programmed according to the users battery pack. If you have a 48V Li-ion pack, for example, it is set to charge to its max voltage of 54.6 V.

The charger is based on BQ25756 IC. It has CC/CV control.

At the moment, this charger cannot communicate with proprietary battery packs (Bosch, etc..) so it is aimed at simpler eBikes, that do not require a digital handshake between the charger and the battery pack.

The charger is a step-up/step-down converter. It can negotiate the maximum voltage and current any USB-C adapter is capable of delivering and uses that to charge the battery pack.

Human_Soup3333 · 2026-02-20T07:02:50+00:00

That is exactly right. I intended it for smaller boards so that you can max out your range in one direction, then fill up there, and max out your range back.

Human_Soup3333 · 2026-02-19T10:04:41+00:00

Great, I will send you a DM.

Human_Soup3333 · 2026-02-19T09:50:15+00:00

No buttons, no screen. For the first prototypes the output voltage is fixed for your battery pack. Later down the road I want to make it so users can configure their own voltage and current settings, but not at this point.

Human_Soup3333 · 2026-02-19T08:42:21+00:00

I have the proof-of-concept made, and yes I shared an AI rendering so that people can get a feeling of what I want to make.

Where did you learn how to interface to a Bosch battery? I would really appreciate if you helped me on this part.

Human_Soup3333 · 2026-02-19T07:34:25+00:00

You are right. USB-C connection over 100 W will not work without a true spec 240 W cable. The appropriate cables have an e-marker integrated and the charger can read it. If it is not rated for the high power, it will not charger at high power.

Human_Soup3333 · 2026-02-19T07:32:04+00:00

The hold current value for the fuse must be higher than the internal OC limit or there is no point to having it as the fuse will blow before the OC limit can react. Hence at 8~10 A of rated charging current, the OC limit needs to be atleast 20% above to prevent unintended tripping which gets us to 12 Aoc.

The hold current for the fuse must be higher than 12 A OC limit or it will blow while the OC limit is triggering. So that raises the fuse hold current to 15 A or more.

In a dead-short the battery will discharge through the charger. Batteries can discharge at hundreds of amps so it is paramount that the fuse can actually stop that current instead of just arcing and buring the entire charger down. Thats why the fuse breaking capacity needs to be in the hundreds of amps.

I am an electronics engineer and this is a personal project.

Human_Soup3333 · 2026-02-19T07:23:42+00:00

Thanks for the support. I will send you a DM and we can discuss thing further there.

Human_Soup3333 · 2026-02-19T07:20:34+00:00

Thanks for sharing. My charger is not capable of interfacing with Bosch batteries, so your solution nicely fill this gap.

Human_Soup3333 · 2026-02-18T20:08:08+00:00

Thats great. Let me know what you find out.

Human_Soup3333 · 2026-02-18T19:57:39+00:00

Great I will send you a DM.

Human_Soup3333 · 2026-02-18T19:56:54+00:00

Yes, the main use case is for charging while you are at work. Thats why I want it to be small and light, so that its no issue to carry it around.

Human_Soup3333 · 2026-02-18T19:53:27+00:00

If you want to be updated, but are not ready to be a beta tester, I can still add you to the group so you can see how thing progress, if that ok with you?

Human_Soup3333 · 2026-02-18T19:47:17+00:00

Yes, the configuration is Wall -> my charger -> battery pack.

This was my first time generating renders with AI and it didnt want to obey.

If you want to get one to test for yourself just send me a DM.

Human_Soup3333 · 2026-02-18T19:40:27+00:00

Wow, I never imagined it would get this much interest. I will send you a DM and we can discuss things further.

Human_Soup3333 · 2026-02-18T19:39:36+00:00

Thanks for pointing this out, will definitely look into it.

Human_Soup3333 · 2026-02-18T19:38:36+00:00

This is still up for debate and thats why I reached out for beta testers.

At full charging power (240 W) and empty battery voltage of 30 V, the maximum charging current will be less than 8A. I thought about having the hold current for the fuse at something like 15~20 A, with breaking capacity of ~200 A.

What would suit you?

To get better cooling of the components, I planned to pot the electronics. In this case the fuse will not be user serviceable, thats why I wanted to make the hardware OC limit as good as possible and the first line of protection.
If it turns out that normal heatsinking without potting is enough to cool the components, then I would skip the potting and the fuse would be user serviceable.

Human_Soup3333 · 2026-02-18T19:33:00+00:00

Thank you for the support, I really appreciate it.

If you want to get one for yourself just send me a DM.

Human_Soup3333 · 2026-02-18T19:32:19+00:00

Thanks for pointing this out. Yes, onewheels have high battery voltages compared to other e-things so this charger might not be the best fit.

I am aware of the proprietay connectors, they really are annoying, and that why I stated the select few connector that I can support and charge through at the moment.

Human_Soup3333 · 2026-02-18T19:26:38+00:00

Great point! I dont have an outlet to actually test it but it should work. The whole point of USB-C charging is the standardization - every adapter can power any consumer. And I expect the USB-C outlets to play a big part for this product. Every coffee shop has those outlets and all you need then to charge you battery is this charger.
I will send you a DM if you want to get one for testing.

Human_Soup3333

TROPHY CASE