Powering Nano via a T6845-C step-up power supply / charger

Hello,

I am using a T6845-C based charger / power supply to run my Nano project. The device is like this one:

While receiving power from an external USB charger, the T6845 charges a 18650 3.7V Ultrafire battery. That goes well.

The T6845 5V output is connected to my Nano´s VIN pin. That works well while the external USB charger is connected.

When I disconnect the USB charger, the T6845 output drops to 4V. That, of course, drives the Nano crazy and it resets itself every few seconds.

The drop to 4V also happens if the Nano board is not connected to the T6845 output.

Is this normal and expected behavior from the T6845-C? I thought it would deliver 5V all the time to the Nano, while the battery lasted.

Any ideas? Thanks in advance!

Pablo

It may be that the module is behaving as it's supposed to. This is a "powerbank" module, and they typically require a certain minimum current draw to continue to operate at full voltage. If your Arduino doesn't draw that much current, the module will shut down in some way. Here's an older thread on a similar module:

Powerbanks are designed to charge another battery, like your phone's battery. When they detect that charging has completed (when charging current falls below a certain level), they shut down so as to preserve their own battery life. This feature is called auto-off. You really need something that isn't a powerbank, something that is always-on. Here's one that isn't a powerbank:

And here's a video on why it may not be safe to use:

Or, you can rig up your Arduino so it will periodically sink some extra current and keep the powerbank alive. Of course that kinda defeats the purpose of battery power, but it will probably work.

I´ve found out that T6845-based step-up chargers require a min of 60 mA of load in the system they power, in order to avoid the drop in the output voltage.

Has anyone had any experience in this matter? Any easy way to avoid or overcome this, without adding a lot of LEDs to my circuit? :slight_smile: I have around 25/30 mA as idle current of my Nano based system.

Regards!

ShermanP:
It may be that the module is behaving as it's supposed to. This is a "powerbank" module, and they typically require a certain minimum current draw to continue to operate at full voltage. If your Arduino doesn't draw that much current, the module will shut down in some way. Here's an older thread on a similar module:

https://forum.arduino.cc/index.php?topic=549855.0

Thanks ShermanP, I have read that post and learned some about these step-up chargers. I´m trying to find a way to pump some current load in my circuit every few seconds in order to prevent shut down but at the same time do not over charge the system, reducing the battery autonomy.

Saludos!