How to keep USB battery power flowing?

[rea5245]

I'm plugging a USB device into a USB battery pack. After a minute or so, the battery stops supplying power.

I've tried two different battery packs, both bought from Amazon a while back, and neither is still being sold.

The device is a USB to 12V "cigarette lighter" converter (https://www.amazon.com/dp/B093KXL19S). After a short while, it loses power, even if I haven't put a load on the 12V side.

If I plug the converter into a USB AC adapter, it stays powered on indefinitely.

Is this a problem of the converter not doing any power negotiation? It seems inconceivable that the battery packs would require it; I would expect them to happily provide 5V and at least 1.5A forever.

Any thoughts?

Thank you.

[ledtester]

You may need a "power bank keep-alive" circuit:

https://www.eevblog.com/forum/beginners/defeat-powerbank-auto-shutdown/msg3884138/#msg3884138

[rea5245]

You may need a "power bank keep-alive" circuit:

Thank you.

I can't add a "keep alive" circuit in my application - everything needs to be off-the-shelf. But if that's just the way these battery packs work, I'll need to let the user(s) know they have to "wake up" the battery.

Thanks.

[tooki]

You can get power banks with a low-current mode that won’t shut off. I have one from Anker like that. You hold the button for a few seconds till one of the LEDs changes color. I use that to charge my Bluetooth earphones, which don’t draw enough current to keep most power banks alive

[tooki]

Is this a problem of the converter not doing any power negotiation?

No.

It seems inconceivable that the battery packs would require it

Well, it is necessary for USB-PD charging at higher voltages. Most decent power banks use “smart” ICs that can detect and negotiate with all the major standards, including the older proprietary standards that predate USB-PD, so that every device can charge as fast as possible.

I would expect them to happily provide 5V and at least 1.5A forever.

And they would if you were drawing 1.5A. But you’re not drawing 1.5A and that’s precisely the issue: power banks have power-saving auto-shutoff circuits that look at current draw on the port. If it’s below some threshold value for long enough time, it shuts off. Small devices — like your 12V boost converter without a load — are below that threshold so the power bank shuts off.