Those batteries were a nice idea, but the implementation is poor. The output voltage is very near 9V, but the capacity is very likely exaggerated and the batteries will likely self-discharge in a month or two. I bought 10-20 of them and am dissatisfied.

Also, they have switching noise that the NiCd batteries you currently have don't.

If you're doing that, I'd indicate that on the schematic so others don't comment on the non-standard values. The closest 5% value to 500 is 511.

My use case requires voltage, but not a ton of actual power. The device is indoor and lives next to a power outlet. I plan to leave it plugged in when not in use, and I plan to use it for few hours at a time.

As far as switching noise goes, I suppose the best bet would be to throw a decently sized capacitor across the rails, no?

I'll update the resistor value, thanks for helping me look like I know what I'm doing!

 

The device is indoor and lives next to a power outlet. I plan to leave it plugged in when not in use, and I plan to use it for few hours at a time.

The 9V Li-ion batteries will discharge whether or not they're powering anything. The ones I have go from fully charged to fully discharged in less than 2 months.

 

The 9V Li-ion batteries will discharge whether or not they're powering anything. The ones I have go from fully charged to fully discharged in less than 2 months.

To clarify - I have a little usb power board that takes a 9v barrel connector. The cells will be plugged in and charging when not in use. Self-discharge shouldn't be a huge issue for me

 

To clarify - I have a little usb power board that takes a 9v barrel connector. The cells will be plugged in and charging when not in use. Self-discharge shouldn't be a huge issue for me

Those 9V batteries have a USB connector for charging. The output terminals are only for output. Even if you have the outputs connected to a 9V source, the internal regulator will still be operating from the Li-ion batteries. If the output and the 9V supply weren't the same voltage, that could be an issue.

 

Those 9V batteries have a USB connector for charging. The output terminals are only for output. Even if you have the outputs connected to a 9V source, the internal regulator will still be operating from the Li-ion batteries. If the output and the 9V supply weren't the same voltage, that could be an issue.

I'll be using the usb-c inputs on the batteries to charge them and the terminals will only be for output. The board I described takes 9v wall wart power and sends out 5v over usb-a. It came with my breadboard so i figured i'll just use it!