House Battery on or off when unable to charge?

[smithie]

Hi all,

Quick question. I've done my best to find an answer to this one in the forums, but no luck so far. I have a 2010 SMB with no solar and no easy access to shore power outside of longer trips that I will mostly be street parking during the week. I will be able to drive it at least once or twice a week to keep batteries active and not fully discharged between the longer trips.

My question is, is it best to just turn the house battery completely off via the kill switch when I'm not using the van, and then turn it back on when I'm able to drive it around and give the house batery some charge, or, should I simply leave the house battery "always on" rather than regularly turning it on and off again once a week?

Thanks for the help!

[arctictraveller]

There will always be some form of parasitic draw on the house batteries when they are turned on. The draw may be very minimal, or somewhat more. Eventually, that draw and the natural discharge rate of the battery will deplete it. Depending on how much draw there is, that could take a week, or months. With minimum load (0.5A say) a good battery should last weeks between recharge drives, so turning off the battery wouldn't make any difference. If there is a larger parasitic load (inverters for example consume amp hours anytime they are on, even when they are not being used) turning off the switch may be worth while. Without a battery monitor though, you can only estimate and learn from experience what the loads are and how long you can go between recharges. At a minimum, you need a volt meter to start keeping track of your usage.

[smithie]

Fantastic - thanks for your reply. This is an older battery, and there is definitely some parasitic draw as well as a lowered ability to hold a full charge in general, so, I just wanted to make sure that turning the house on and off on a regular basis wouldn't actually do more harm than good in terms of trying to get the most out of what this battery has left!

[Jeffrey]

Tell me about your 'kill switch'. I don't think I have one in my 2007 SMB.

[smithie]

No idea when they introduced it. My catalog is dated 8/09, and it describes the switch as an Option (O) called the Auxiliary Battery Disconnect Switch. In my RB-50, it's a larger yellow quarter turn switch on the outside of the rear couch panel (near the house fuses). SMB describes this switch as a built in alternative to disconnecting the negative terminal by hand when trying to prevent parasitic battery drain.

[HK33FAN]

With out solar and or shore power you are going to draw 1-2 amp hours just powering your carbon monoxide and gas detectors (if so equipped) . You probably have newer equipment than my 07RB, but the base load+ parasitic draws can take my 200 amp hour batter down to 70/% in as little as one day, two days with only a 1 amp draw. I would turn off the Isolator when not in use and not plugged in. Regular discharging to 50% or lower will quickly shorten the life of your battery.

I have installed 2x100 watt grape solar panels and have plenty of dc power for long periods of parking and or boon docking in Nevada. During a month long trip through Montana and Canada the solar could not keep up in October due to snow, clouds and shade from trees. I supplemented the solar by running a 2000watt generator when camped for more than 3 days at a time. Batteries would be topped off in 1-3 hours depending on depth of discharge. I would just put it 20ft away and charge while making breakfast. Ryobi has a new 900 watt propane generator that is crazy quiet and could be fed from the house tank. I will be experimenting with this generator in the fall.

Depending on how much sunshine you get, a portable 30-50watt solar panel batter tender would be plenty for long term parking.