18650 USB Chargers. Same time recharge and power question.

Just wonder is there 18650 USB Chargers that allow discharge to phone and charge 18650 at the same time?

Reason I am asking - I am trying to setup cache battery on my bicycle to store energy and in the same time power phone / light.

I did multiple tests for below charger but unfortunately it only allows charge or discharge one at a time. Just wonder if it can be modified to allow same time charge/power cycle.

Also I tested below charger but it is behaving strangely when trying same time charge/power.
Every second it drops and restores output power when plugged in. I wonder if it can be fixed?

Much Tanks!

I’m not sure what in HKJ’s web site but it may be worth a look.

Tested this:

While charging it from a wall charger; it charged a cellphone (quite slow, though) and, later, powered a USB fan. Seem to work fine. But it’s only a 2x18650s. Maybe you could ask fasttech whether their other 4x or 6x ruinovo chargers work as well.

Side note: The 2xLEDs don’t work while being charged.

This box will do both simultaneously according to PyTech. We had a discussion about it on the fasttech forum. I've only just received mine and haven't had time to test it yet with my solar panels.


The ML-102 will also work, though it is maybe not ideal for bicycle mounting without a mod of some kind to stop the 18650 rattling out. (Rubber band or tape?)


It is obviously very difficult to know what is in these generic boxes in terms of circuitry but I have a box that looks identical to the white one in first post. I got it from Cottonpickers at CPFmarketplace with some solar panels. He fitted a socket for me to plug a voltmeter into. I am quite sure that mine will accept input and output simultaneously as I've monitored the voltage when doing exactly this.

But I guess the internals of yours may be different.

Just wondering how you are testing the charging?

Your post is brief and you are a new member so we really don't know how much you know about these topics. The following comments are not meant to be patronising.

Did you try using a proper USB wall-wart or are you actually testing with whatever setup you have on the bike. I have only ever used the mini-USB input on my box and not the pin-type input.

Also, may be a silly question but are you using a regular bicycle generator for input? Keep in mind that a lot of the older types designed for regular incan bulbs actually output an AC signal, not DC. Have you checked this?


Suppose you are talking to me, gadabout? Yeah I don’t post much here, but been lurking like a fair bit since mid last year. Thought I had covered most of the salient details, but since you asked, here’s some more details:

Input supply: Nokia 5V/550mA microSD wall charger.
Output load 1: HTC Desire Z.
Output load 2: USB fan.

I forgot to add that the charging indicater on the USB charger went from roughly 75% to 100% while I had USB fan connected. It was just a quick and dirty test but let me know what else you need to know.

PS: Last time I had a dynamo on my bike, the light emitter was filament-based (ie: LEDs weren’t made yet) :slight_smile:

Hi Purple

Umm... actually I was talking to "sametime" - in the original post he mentioned

I am trying to setup cache battery on my bicycle to store energy and in the same time power phone / light

The way I read that was as if he was trying to use the bike generator to charge his 18650 box. Otherwise I'm not sure why he would be wanting to charge/discharge at the same time while on the bike? That's why I commented that his post was not entirely clear.

Thanks for the info on the RUINOVO unit though. That's another one that might be handy for me at some point.

@sametime, further to my post #2 and #5 - the USB charger appears to switch to discharge-only after the batteries are fully charged.

Let me run it on the USB fan load for a day or so, and I will get back to you.

@gadabout, sorry about the confusion. But with the latest “discharge-only when fully charged” issue, I hope it doesn’t end up another dead-end for sametime.

MRsDNF* - I checked HKJ’s web site but no same time charge / discharge info there *purple – Much Thanks on Ruinovo 102 link and thank you to trying setup test for discharge-only mode after the batteries are fully charged.
@gadabout – Vogue 4*18650 looks great. Please keep posted on test results…
For my tests I use below 2A wall USB charger + phone & mp3 as load. For white 4 batteries charger I tested both mini-USB and 3.5mm inputs. Charge immediately stops when plugged in any inputs.

For bicycle dynamo I plan to use e-werk or build rectifier with USB to get DC 5v 1A out.

further to post #7, I am glad (and embarrassed) to report that it was a false alarm. There was an intermittent contact problem with the multi-way AC adapter that the Nokia wall charger was plugged into.

With the wall charger plugged in properly, the charging indicator LEDs on the Ruinovo is ALWAYS enabled whatever the battery condition. But runs cool even when fully charged (ie: no overcharging).

In summary, I think this unit should suit your “discharge while charging” requirement.

Let me know if you need me to do any other test.

I don’t know the answer to your question, but I have that power pack on the top coming any day in the mail now. I harvested 12 Sony 18650s and I’m excited to see how well that power pack recharges our electronics!