Since the mini DIN power is limited to 250ma, has anyone found a way to tap the battery to supply power to added electronics?
I'd prefer this over adding a secondary battery and separate charger
We have tried it and have a stably working system using a DC DC voltage converter directly off the battery. We have seen issues though where it will try to run the converter even when the 14-18v battery is at 4 volts so can extremely deep discharge the battery.
If you do this, I would suggest calculating your max current load you want to run and validating it won't over-tax the battery in an un-safe way or have significant spikes in power that will be a problem across the system.
Therefore, we introduced a buffer inbetween (OpenUPS or battery backup battery) to buffer it, clean things up better and allow the computer to function without the create being powered.
We also set up an automatic shutdown of the laptop if voltage becomes too low and "return to dock" commands after 15 minutes to make sure it re-charges itself as regularly as possible if not being actively used.
Additionally, we found that on the charger, when in trickle charge mode, the system does not actually test the voltage (Expects it to always be full), so the computer will discharge the battery and it won't turn the charger back on. You therefore have to pull it out of passive mode and then trigger it again (Back out then dock and charge) and it will correctly check the voltage and charge.
This is currently not a fully tested system, but have have tried it on multiple create 2's / NUC's / Laptops and have had the system recharging itself for 10+ days in a row while powering lidar, camera, NUC, create, etc.
If you try this, would love to hear how it goes for you and improvements you see as valuable.
Please also just be careful and have a fire extinguisher near-by. ;-)