Welcome to the forum
@Miket351
The most common way of connecting is using an Anderson plug to the battery with its own controller.
You can still do it this way and monitor using the drifter by running the negative to the shunt instead of directly to the battery.
Hello
@Miket351,
Welcome again to this forum. There are lots of different ideas on what you are saying. Some are satisfactory, but not really as efficient, whilst some are the optimum but need more work and adjustments and sometimes you may lose your flexibility. No doubt you have read a lot of the postings on this thread and so it depends on what you see as most important. To answer your questions in order (as I see it):
1.
@Bellbirdweb is quite correct. That is the easy way and simple, AND you still have the flexibility of using the portable panel for other purposes - charge tug battery etc.. However, that means that there is likely to be some conflict between the different controllers in controlling charge voltage and float level.
@mikerezny put out a excellent explanation in an earlier post of what "could" happen but as yet, I have NOT been able to test/prove out this method fully. Still seeking really professional technical advice on this. I do know that connecting two controllers in series or parallel is far from ideal although some members on this forum have found it okay??
2. Confirmed that connecting portable panel to existing controller (bypassing panel controller) is the most efficient and your Drifter panel will provide proper readouts. But not all that difficult. With an Anderson plug at side of van, connect the appropriate wires from portable panel (bypass the panel controller) in parallel (onto the same terminals on Drifter) Pos on POS and NEG on NEG. Both panels would need to have bypass diodes for proper operation if one set of panels is shaded. Later if you are looking for more power from your panels, a step up to a MPPT controller and connecting both panels in SERIES is the ultimate.
3. Definitely NOT RECOMMENDED. Flat pin plug is for use from your tug to SETEC and not the way to go at all. In all cases, a solar controller must be used to control solar panel current and charging to your battery. Failure to do so WILL end up damaging your battery/ies as there is NO control on panel voltage (usually about 18 to 20 volts) and no control on charging even if battery is fully charged. 12 volt batteries do not like 18 or so volts going into them for long periods especially when fully charged. They get very hot and bothered about it!!!!
Hope this answers all your questions and gives you all the options. Good luck whichever way you go. Cheers