Battery Disconect Switch

SoundGuy wrote:
... all because the user chose to install a dual battery disconnect switch.

Sam Spade wrote:
And ALL a waste of time and money.
Discharging only one at a time accomplishes exactly NOTHING.
Charging only one at a time, likewise.

100% incorrect. Run dual 12 volt batteries in parallel and the pair will run down to 50% discharge together, leaving the RV owner stranded without any more battery reserve to fall back on if he wants to preserve the long term durability of the batts by not drawing down beyond that 50% threshold. OTOH, running one down to 50%, then switching over to the 2nd fresh battery not only allows the RV owner to continue camping but offers the opportunity to then recharge the first battery, say by genset, so that once the 2nd battery is down to 50% the first will be ready for service again ... a repeatable cycle for as long as the RV owner may want.

A dual battery switch also offers the choice to run one battery at a time so you're not caught dead in the water without a paddle as just described OR run both together whenever the task at hand may be to power an inverter that in turn is powering a high draw device such as a toaster or coffee maker without excessive voltage drop that could otherwise cause the inverter to go into alarm mode and shut down.

P.S. This ain't my first trip to the Rodeo. I've been in the electronics industry for 50+ years.

Funny about that - 45 yrs in the televison production business as a technical supervisor. You ain't the only one with an electronics background, Sammy. :W