Battery

[John612]

Should we disconnect the battery while connected to shore power?
I've heard it's hard on the battery to keep it connected all the time.

Thx
John

 

[droidguru]

This is what I normally do:

Turn the disconnect to off when you will be away from your camper significant period of time as in a two weeks or more, otherwise leave it on.

I can't back it up with an electronics lesson only to say I have had tremendous luck with batteries lasting more then the 5 year stated life span. That being said I check the fluid levels monthly (which I know is overkill) and always top them off when it is needed!

Good Luck and Happy Camping!

 

[Cate&Rob]

Hi John,

I would suggest that you leave the battery connected. If you disconnect it, everything that runs on 12V will be powered directly by the converter (battery charger). The converter is not designed to be a stand alone 12V power source, it is designed to be a battery charger. All the 12V things like lights, water pump and the controllers for the fridge, water heater and furnace should have a strong steady 12V supply from the deep cycle battery. The converter will put back whatever power is taken from the battery, at the proper rate.

Rob

 

[scott42blue]

All RVs in the below 500K bracket come with a low end 3 stage charger. No temperature sensing, higher float voltage and most max out around 65 amps. Key to battery life is keeping fluid topped off. Always use distilled water ( very cheap ) . A RV or boat can use 1/4 inch or more of fluid sitting on charger for 2 months. Enough to hurt battery performance a lot.
I would test battery disconnect. As mine in new 355 does not work. Easy to test. Turn disconnect off and see what works.
The only thing working should be CO detector and level jacks.
Scott

 

[scott42blue]

I will post what I find out after battery disconnect after I finish Splendide washer/dryer 210 XC install. Mine is set up for negative cut off, that reduces amp load on switch.

 

[Cate&Rob]

Hi Scott42blue,

You are right on with your advice on the importance of battery watering. This is really important if you actually deep cycle "deep cycle" batteries. I am interested in your comment about switching the negative side for reduced current load on the switch. Can you explain this further ? I have always been of the understanding that current in and out of the battery has to be equal.

Rob

 

[Canyonlight]

John--the guys have covered this well but one other thing is that w/o the battery power and if you would lose shore power the fridge fan cannot run and thus the fridge not function as it could for several hours with just battery power. Warm milk with your cookies is not good !

Dan

 

[TucsonJim]

Interesting anecdote. My son called yesterday and told me he was replacing his trailer battery after eight years! He has a typical three stage converter that he leaves plugged in all year. He doesn't have a disconnect switch. He tops off the water every month.

 

[John612]

Thanks a bunch for all your comments, sounds like I was given bum gouge and will make necessary course correction.
I will check battery water in the morning too.
Currently at Pollock Pines four nights between Sacramento and Lake Tahoe, plumb gorgeous and very quiet.
John

 

[droidguru]

I agree with the tips here as well. In my post above, I was referring to when I am not using my camper (it is sitting in storage with everything off). My camper is generally always connected to shore power even when in storage. If I'm using it I always have the battery connected. Should have clarified by asking a question before I answered.

Thanks to everyone else who picked up my slack!

 

[scott42blue]

Hi Scott42blue,

You are right on with your advice on the importance of battery watering. This is really important if you actually deep cycle "deep cycle" batteries. I am interested in your comment about switching the negative side for reduced current load on the switch. Can you explain this further ? I have always been of the understanding that current in and out of the battery has to be equal.

Rob

Rob
Main reason is on a car or RV the system will be grounded in as many as 10 or 20 places. The frame becomes a large conductor or wire. There are some issues with electric flow and protons but that part is above my pay grade. It was covered in ABYC class but I not the best person to explain it.
Layman's term would be if you jump start a car. Which cable gets warmer the positive or negative.
Scott

 

[JCR GD]

In my experience the negative is switched because there is usually only one cable coming off the Neg. side of the Batt. going to frame etc. and the Pos. side typically has several, so it makes more sense to have one cable to deal with on the switch.

 

[Cate&Rob]

We have wandered a fair ways from the original question on this post . . . but, good discussion.

Installing a disconnect switch on the negative side because it usually has fewer wires makes sense.

I am still thinking on the jumper cable analogy. Can't say that I have observed this . . . but can't say that I was every looking for it either. Resistance turns electric current into heat. I would suspect a poorer (higher resistance) connection on the positive side if there is heat being generated there.

Something related to this discussion is to ALWAYS disconnect the negative battery terminal before going near the positive one. The reason for this is that everything metal around the battery is likely grounded to that negative connection so there is no voltage difference between that end of the battery and anything you might bang the wrench into. If you go for the positive connection first and get the other end of the wrench jammed against the frame . . . you are in a very dangerous high current, high temperature, short circuit situation.

Rob

 

[John612]

Thanks Rob. My battery is maintenance free and appears to be sealed, so assuming I don't have to worry about checking water levels.
Before we start boondocking, plan on buying two six volt batteries.
Should I stay with maint free or go with ones where I need to check the water?

Thanks
John

 

[Dave and Monica]

I understand the reasoning but I know on my camper, the disconnect is on the positive side, not negative and I think that you'll find the same.

Dave

 

[Cate&Rob]

The positive side branches into circuits controlled by the OE "battery disconnect" and circuits that remain live.
I am thinking that another switch on the negative side would be an easy way to install a 100% disconnect of the battery.

Rob

 

[wingnut441]

I would also recommend using two 6 volt batteries combined to make 12 volts for you system. My 379FL killed my 12 volt deep cycle in just one weekend. I have no problem since doing this. I also use a Optima Battery Charger/Maintainer as well.