Thanks for sharing your experience… can you be more specific, how many months do you think “a few” is?
Some explanation about overdischarge protection built into a battery, such as the one comes with your 2019 RRT-01:
When an overdischarge protection built into a battery is triggered, the battery will read 0 volts. Don’t worry, that tells you the protection circuit was triggered, at 2.5v
When a protected battery that has tripped the protection circuit, is put on a charger, or the built in charger on the battery, is plugged into a mini-USB cord, that resets the protection circuit and the battery will no longer read 0 volts. You can test it with a DMM after the battery has been on a charger for a few seconds, and you will see no less than 2.5 volts.
When a protection circuit is tripped, the 0 volts is not the internal voltage of the battery. The over discharge protection had turned off the battery circuit, to protect it.
recap, explanation
If you are using a protected battery, and while using the light it turns completely off, suddenly, that means the protection circuit is preventing the battery from being damaged by overdischarge. When the protection circuit is triggered, the battery reads 0 volts on a DMM. That resets when the battery is placed on a charger.
It is not necessary to use a special charger, plugging in the USB battery charger built into the battery that came with your 2019 RRT-01, will also reset the protection circuit and recharge.
thanks for letting me know
you are one of Three people that have expressed interest in a modded RRT-01
I will follow up when I feel competent, or, you can send a light to a modder, such as Vinh. I think his fee is $50 plus postage.