Swapping out both house batteries - anything need to be disconnected?

[Thorne]

I've got a 2011 SMB Sprinter RB110S build, and will be replacing both old deep cycle house batteries with new 100 Ah AGMs, leaving the newer AGM starter battery in place.

Do I need to disconnect anything during this process, or can I just pull the cables off the old batteries and connect the new ones in the same pattern? I vaguely recall reading something about having to protect the solar charger but can't find the thread.

Thanks!

[86Scotty]

I can't imagine why it would be different than swapping batteries in anything else. Just don't let your positive cables touch frame or body if there is a solar panel connected. Shouldn't be a problem.

[BCam]

Based on your photo, your existing batteries are "Marine" batteries, which are dual purpose deep cycle/starting batteries. Are your new AGM batteries going to be the same or will they be "true deep cycle batteries"? True deep cycle batteries are a better choice for dedicated house batteries. They'll handle deep discharges much better than dual purpose batteries.

Note that any battery that contains cold cranking amps (CCA) in its specs isn't a true deep cycle battery and is a compromise between the two roles, starting and deep cycle.

[nyyankees588]

Technically speaking your change controller should always be connected to batteries when solar power is going through it. There is a chance that if the charge controller has nowhere to send the solar power, it can be fried. You can accomplish this by disconnecting the solar wires from the charge controller, flipping a breaker between the panels and charge controller (if one is installed), or simply covering the panels with towels/cardboard/something else.

That being said, I've not done the above steps 10-20 times and have yet to fry a charge controller.

[Scalf77]

One would expect that the power to run the controller comes from the battery, so if the design was good, input power from the controller wouldn't have any effect. If worried I would just cover up the panels.

-greg

[Thorne]

Thanks all, just wanted to make sure that the battery upgrade process doesn't make things worse rather than better.

[Tahosrfr]

Aren’t we supposed to just turn off the battery d/c switch then all good and safe?

[Scalf77]

Originally Posted by Tahosrfr

Aren’t we supposed to just turn off the battery d/c switch then all good and safe?

Sure if there was a battery disconnect switch? Something sportsmobile has never been big at. Also, a battery to DC fuse panel switch may just disconnect power to the fuse panel and do nothing about the Solar to battery connection.

-greg

[campIV]

I did add a DC breaker disconnect between both my solar panels and my house battery and the solar controller. That said, if I want to be extra cautious I just throw a moving pad over my solar panels before messing with the system.