Still Another House Battery Maintenance Question

[tlundell]

I know there have been a number of threads regarding house battery maintenance and I apologize if one has addressed my specific questions.. I have a 2015 Interstate Grand Tour which, due to space limitations at home, I store at an indoor facility off-site. Unfortunately, the storage facility is not able to provide shore power for all of the 100+ RV's stored there, so my AI is without a power source (including solar) for two weeks or so at a time between our trips. Of course, I shut off the main power switch when it goes in, but I do understand that there are several vampires drawing down on the batteries. My questions are: 1) is it feasible to install an easily accessible battery disconnect (like the "kill switch" sometimes used as an anti-theft device on autos)?, and 2) is their consequence or damage to the AI having no house power for weeks at a time? Thanks for your thoughts.

[Ron_CA]

I am not sure that you will be able to eliminate all electrical draws. I think it will damage your house batteries without being connected for 2 weeks.

[Protagonist]

One draw that you cannot shut off is the BIM. It has to be powered all the time, monitoring the charge states of the house and chassis systems, so that it can tell whether to connect or disconnect them from each other.

[nrgtrakr]

Only two weeks with no charging? Why is that a concern? A disconnect at the battery terminal will eliminate any draw on the battery (effectively it would not be hooked up to anything).

[tlundell]

I guess the ultimate question, then, is whether the storage situation I describe is destined inevitably to ruin the batteries, given the apparent consensus from other threads that an "unplugged" AI will quite quickly run the batteries down to zero without some other source of power (i.e., solar, generator, engine running, etc). Is that correct?

[nrgtrakr]

How does a disconnected battery discharge? I would love to know.

When I left the USA for an overseas assignment, my Father offered to let me store my car at his place since it had very few miles. He put it up on blocks, started it, poured oil down the carburator until it choked, disconnected the battery and covered the tires.

The original assignment of 2 years ended up being 6. When I got home, I gave it a tune up, checked the battery with a hydrometer, topped off the battery water (the plates were still submerged) and it started right up.

Maybe I'm magic ...

[Protagonist]

Originally Posted by nrgtrakr

Only two weeks with no charging? Why is that a concern? A disconnect at the battery terminal will eliminate any draw on the battery (effectively it would not be hooked up to anything).

If it was a trailer where the battery box is readily accessible, that would be fine. But in an Interstate with rear sofa, all but a few require you to disassemble the sofa to reach the batteries (not kidding, you have to take it apart before you can even open the battery box). And to make it more fun, the electricity has to work in order to disassemble the sofa, because you can't recline it without power, and you have to recline it halfway through the process in order to unbolt the seat bottom. And as others have noted, there are components that wouldn't like being disconnected, including anything with a computer chip and volatile memory.

Originally Posted by nrgtrakr

How does a disconnected battery discharge? I would love to know.

All batteries self-discharge. The best 12v batteries only discharge about 2% per month, but 5% per month is more typical. As long as batteries depend on a chemical reaction, they'll always self-discharge; you can't turn chemical reactions on and off with a switch.

[tlundell]

[responding to ngrtrakr] No, the consensus seems to be that there are enough draws on the house batteries, even with the "house power" switched off that the batteries are going to be drawn down below the recommended minimum voltage in a matter of days without some source of charging power. That was the basis for my original question about effecting a total disconnect of the battery, as ngrtrakr describes. Manually disconnecting the house batteries (by pulling one of the leads off the terminal, for example) is not practical in an AI as the battery compartment is not easily accessible. Therefor the question about a "kill switch" or inline disconnect.

[avanti]

Just get one of these:



https://www.bluesea.com/products/770..._-_12V_DC_500A

and connect it between the positive battery terminal an everything else. This will totally isolate your battery and can be controlled from anywhere in the coach. It draws no power whether off or on. Your battery will last many, many months.

[nrgtrakr]

Originally Posted by avanti

Just get one of these:



https://www.bluesea.com/products/770..._-_12V_DC_500A

and connect it between the positive battery terminal an everything else. This will totally isolate your battery and can be controlled from anywhere in the coach. It draws no power whether off or on. Your battery will last many, many months.

There ya go ...

[73shark]

Originally Posted by avanti

It draws no power whether off or on.

What size batteries does it use then?

[nrgtrakr]

Protagonist, having never experienced it before and on your comment I went looking ... it appears that even some of the greatest minds of science do not fully understand the battery self discharge effect.

[Sebtown]

Would 2 battery disconnects work? One for the house, the other for the chassis thus totally isolating the BIM? Sort of a poor man's "bluesea"

[Titus]

Batteries are not as hard to get to as Protegonist says on newer lounge models - can open the compartment from the rear. But still not fun and easy to do a total disconnect. I have put a second disconnect switch - on the large + cable going to the Magnum. So after switching the two house battery switchs 'off' and disconnecting the chassis battery at the accelerator pedal, all that is left (I think) is the BIM and solar controller. Not sure how much each of them draws. I would put a kill switch on each of them too - if I knew for sure which wires to put them on.

[lewster]

Originally Posted by Titus

Batteries are not as hard to get to as Protegonist says on newer lounge models - can open the compartment from the rear. But still not fun and easy to do a total disconnect. I have put a second disconnect switch - on the large + cable going to the Magnum. So after switching the two house battery switchs 'off' and disconnecting the chassis battery at the accelerator pedal, all that is left (I think) is the BIM and solar controller. Not sure how much each of them draws. I would put a kill switch on each of them too - if I knew for sure which wires to put them on.

Hopefully you placed the inverter disconnect between the inverter and the inverter fuse. The fuse should be first in the positive inverter cable, then the disconnect, then the inverter.

It is also a good idea to upgrade the inverter fuse from the small 150 amp plate fuse to a class T inverter fuse of the same rating. A class T fuse has a circuit interrupt rating approaching 100 times the rating, or in this case 15,000 transient amps. The fuse Airstream provides, even though it has the same rating, has an interrupt rating of only 3000 to 5000 amps. Huge difference if you get a shorted cell in a battery and the cable becomes the conduit for the huge amperage capacity of a shorted battery!!!! I only use class T fuses in my inverter installations.

[hamiltonmj]

Reaching my batteries is easy in my 2013 AI. Open the back doors and look to the right. There is a black box with about 4 to 6 screws. This is the battery box. Undo these screws and pull the cover off then you can slide the batteries out far enough to see them. Airstream says not to let the batteries discharge more than 80%. To keep this from happening now as I am in the same situation is that I have a Honda EU200i that i run to keep the battery from discharging too much...I had to buy two new batteries several weeks ago and the Airstream dealer installed Duracell batteries. I complained to AS and the the Dealer...hopefully I will get Lifeline's installed again and not Duracell...PS with the inverter off and house power off I lose 5% of battery life per 24 hours....