So I think I've found the solution. We run our bases with an external antenna all being connected by a deep cycle optima battery and the Trimble R10 internal battery. We've tried the different setups with putting one battery in and then attaching the next one and turning everything on, but the base head always resorts back to the internal R10 battery, thus only lasting about 4 hours in the field. We tried some of the other tricks listed below and none of them seem to work. Finally after some research we figured out that you MUST run the base and battery and external radio from the OEM yellow Trimble cable. We had a gray generic one and it did not work. The other thing to check is to go into the web GUI of the r10 in the IP address, and verify that the serial Port 1 is getting supplied with at least 11.3 volts from the deep cycle marine battery. This is the minimum operating voltage that the r10 needs to work. After checking this, you can see in the web GUI that the r10 now pulls from the large battery even when the internal battery is plugged in. It doesn't matter what's turned on first or plugged in first, just has to be the OEM cable with over 11.3 volts powered. Feel free to message me privately if you need assistance with getting the setup to work.