Should batteries be disconnected when on shore power?

Our coach (signature) has its original IOTA charger/converter. I'm gonna guess it is neither pricey nor particularly smart. Yet, even with that, we can camp a couple months in one place and not loose water from our single 12V "deep cycle" Wally World battery. Working theory is that there's enough 12V draw while actually camping to keep things from getting out of hand. I don't know what would happen if the coach was simply parked, NOT in use, for that amount of time. For that reason, I turn the battery switch OFF when parked at home but plugged to shore power. I only have to add water about annually.

korbe wrote:
When I first got my 6-volt T105's I watched them closely while connected to shore power. I found they overcharged even with my 3-stage converter. So I installed a disconnect switch and now when I plan on being on shore power for more than a couple days, I disconnect them. Everything still works just fine. And that is how my system works. Every system works a little bit different and to monitor your battery situation is always a good start.

Since the bulk charging specification of a T-105 is 14.8V, you must be having a converter malfunction to overcharge them.

Also, if a battery is left with no charge present, it is sulfating. It can be argued just how severe that is and what effect it has on batteries when intermittent charging is in place but it does remove some battery longevity (compared to the other situation,i.e. always having charge voltage present).

A drop in electrolyte level is customary and, if not excessive, does not mean batteries are being "overcharged".

Pipeman wrote:
My batteries are shut off via a cut off switch, when I'm hooked up to shore power.

If you are offering this as advice to others......it is bad advice, in general. There is NO good reason to do that. And there are several reasons NOT to do that.

You have been lucky; that does not prove that it's good practice.
The system was not designed to be used that way.

There is no reason to disconnect your batteries.
Mine have been hooked up for 11 years.

06Fargo wrote:
My rvs have Intellipower something or other converter chargers with fancy battery charging...

Or do the batteries provide a "cushion" for starting 12v furnace motors etc.?

Details are important. "Something or other" just won't cut it for a question like this.

And I don't understand that second question. Typically things like furnace motors run off 12 V which comes ONLY from the batteries when shore power is not connected.

If you are camping on shore power, the converter will be at 13.6v. That would be too high a voltage for warm temperatures, and you will slowly lose some "water."

You could adjust for that by disconnecting the batteries and reconnecting, but that is not really good for them either. Batteries will last a long time anyway if you keep an eye on their water level. Some batteries also like an occasional deep cycle to keep them in good shape.

If you are on shore power and not using 12v things as when camping, the voltage will drop to 13.2v. That is good for floating battery maintenance at 77F, but too low if it is cold out.

That PD converter will give them a shot of 14.4 every so often while doing 13.2, which will help some in the winter.

IMO just leave the rig plugged in and let the "fancy" converter take care of the batteries. But do keep an eye on things. Trust but verify.

Doesn't your owner's manual answer this question? Mine says to keep a battery connected even when on shore power. Have not boiled a battery in ten years with cheap original equipment converters. I do top them off with distilled water every few months after continuous use. Don't know how long the batteries will last as I trade trailers every few years.

When I first got my 6-volt T105's I watched them closely while connected to shore power. I found they overcharged even with my 3-stage converter. So I installed a disconnect switch and now when I plan on being on shore power for more than a couple days, I disconnect them. Everything still works just fine. And that is how my system works. Every system works a little bit different and to monitor your battery situation is always a good start.

If the batteries are on shore power for long periods they may start boiling out the fluids. I check mine every couple of weeks here...

Having a smart mode charger (that works) will help reduce the possibility of the batteries boiling out on you...

Post your model number of the converter/charger being used...

I am using the Progressive Dynamics PD9260C unit here and do not see any boiling out of fluids when on shore power for long periods of time. Out of habit I still check my batteries just in case...

My batteries lasted good from 2009 to mid 2016 when I have scaled back alot of my camping... I am in the process of upgrading my battery bank now with new batteries and more capacity.

Roy Ken

Thanks for your replies