>>Your statement "the solenoid itself tales precious electricity when you may need it most." is not factual. Very little current is use to engage the relay/solenoid, surely not enough to affect the winch.<<

I see you as saying that it's not factual, than state "very little current". I see any current draw as a loss.


>>If it were me I'd switch off the main battery while winching. This way you will not spike the alternator or other electronic in the truck that's connect to the main battery. But that's just me and that's why I run a hydraulic winch.<<

OK, you see the solenoids, or the winch motor as a possible reason for a voltage spike? What asbout the starter that we use to start our cars? It is practically the same setup as a winch. Now, if I were concerned sbout spikes, I would rather have 2 batteries in parralell to help absorb & buffer them.

I attend the IBEX convention every year. I attend the ABYC electrical, electronic & communications certification seminars each year. For the 9 years I have been attending, the use of multiple battery banks has been discouraged by the ABYC. I have only installed 1 2 bank system in a boat in all of this time:

60' Morgan outhouse with 2-18 AGM battery banks. The only reason was that there were 2 heart interface inverters synced to provide 240V & they charged their respective banks. That was the owner of the boat yard's boat. It has multiple wind gens & solar panels.
When charging off of the alternator, the power feeds 1 bank with an ACRs (automatic charging relay) to automatically feed the other bank, Gen & engine start batteries. ACR's do all of the work & save energy as compared to diode isolators. You set the on/off points, hysterisys & feed bank. Also, they can be wired for remote paralell operation.

I want you to understand, I am not trying to be argumentitive, but hear from old timers about using dual banks & manually switching them. I draw it out for them as a water resivoir & after explaining it all, they usually understand.
Again: just for battery life, using 1 bank of 2 batteries gets 1/2 the depth of discharge & 1/2 the discharge cycles as compared to 2 banks of 1 batteries.
That leasd to longer battery life & allows the batteries to pull longer & deeper.

Ed