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Old 08-14-2018, 11:42 PM   #1
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Name: David
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Battery disconnect

Hi, I am D-Robbie. I have a new 17 ft Casita Freedom Deluxe. As I have had problems with my battery running down while not in use I want to install a disconnect switch. Not much room in battery cubicle. Any good ideas?
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Old 08-15-2018, 12:01 AM   #2
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Welcome to FGRV David. I added a battery disconnect from Little House Customs. It's the plug version without the key they carry and is all in the battery box. You're probably draining the battery from the CO monitor as it's hard wired and always drawing power. Way easier than pulling the battery out enough to remove a cable too .
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Old 08-15-2018, 12:07 AM   #3
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Yes, and a small solar trickle charger cannot keep up. The only space in the box for the switch is between the battery and the cubicle door.
Thanks for your comment.
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Old 08-15-2018, 12:11 AM   #4
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if you dig into the right (street side) rear bench, you'll find the other side of the battery box, and on the side of it is a automatic 30A circuit breaker, the battery is connected to this, and the other side of the breaker goes to the power converter thats under the side dinette bench. (at least thats where these are on my Casita 16, I assume a 17 is similar).

I would mount a disconnect switch on the side of the bench, under the rear bed, disconnect the big heavy black wire that goes from that circuit breaker to the power module, and instead connect it to one side of a battery disconnect switch, then run a new 10 ga. black wire from the other side of the disconnect switch back to that circuit breaker where you lifted the other wire off..

https://www.campingworld.com/single-...connect-switch
https://www.amazon.com/BATTERY-CUTOF.../dp/B003BQLZ36
https://www.amazon.com/dp/B07413JWLD

etc etc. I don't like the ones with removable keys as thats just something else to get lost.
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Old 08-15-2018, 12:12 AM   #5
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a 10W solar battery tender should be fine for keeping the battery fully charged if its already charged when you park.

me, I just leave my trailer plugged into an extension cord.
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Old 08-15-2018, 01:15 AM   #6
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Quote:
Originally Posted by D-Robbie View Post
Yes, and a small solar trickle charger cannot keep up. The only space in the box for the switch is between the battery and the cubicle door.
Thanks for your comment.
Exactly why I went with the plug and not the swt.
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Old 08-15-2018, 05:29 AM   #7
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Until you get your battery switch you can pull the fuse for the propane alarm.
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Old 08-15-2018, 08:49 AM   #8
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Auto batteries put out a lot of current when they are starting the car. But our trailers never have huge loads, especially with LED lights. Probably the most amps are when the TV is charging the battery during a trip. I bought a 25 amp toggle switch from an auto parts store, extended wires from the positive battery lead, and mounted it on the partition next to the bed. That way it's easy to use and away from the nasty battery gases. You can also add voltage and current meters like I did if you want to get fancy.
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Old 08-15-2018, 09:53 AM   #9
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If you only want to know where to mount the switch I can’t help much. I do like the idea of the switch in the camper instead of outside where it is subject to corrosion, weather and vandals. I also suggest that it be easy to reach (but not where children will switch the battery off without you knowing it). Yesterday I moved my switch from under the bench hatch to inside the “Porta-potty” storage area because it was often a pain for me to move things around, lift the cushions and access the hatch. Now I can open one door and use the switch.

More notes that you probably already know about:

Check your converter manual to ensure the system will function properly without a battery attached to it. Some converter designs require the battery to be attached.

Positive or negative side? There is much debate and it usually makes little difference in a small RV. But if things are wired straight to the battery on the positive side, and they use a common or frame ground elsewhere (not at the battery), and if you want these things off when the switch is off, then the ground side makes sense. I wont debate this anymore since like I said, in a small camper it usually is OK either way.

But if you do use the negative / ground side and use a shunt for monitoring the battery, then it should be on the load side of the shunt so that the battery monitor can continue to monitor the battery when the switch and loads are off. The battery monitor does still use a few milliamps, and of course the battery will self-discharge, so you still need to charge it occasional and/or use a battery tender type of maintenance charger.

Also consider solar if you have it, or might get it in the future. I would (and did) wire it so that, when the switch is off, it still allows the battery to be charged. In other words the switch disconnects the loads but not the solar charger. The charger is connected at the load side of the shunt, but before the switch, so that the TriMetric can record the solar charging current.

Are there any other things that should still be powered when the switch is off? Obviously, a break-away switch for example should not be wired upstream of the switch (and should be wired straight to the battery).

Kudos for your decision to add the switch. It not only helps to manage your power use, and extend the life of the battery, it is also a good safety device.

This is what I ended up with, using the ground side to disconnect the trailer's 12 loads (the same polarity one should disconnect first when disconnecting the battery at the battery posts). All trailer loads run off the buss bars.
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Old 08-15-2018, 10:00 AM   #10
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Just run out to your local NAPA or AutoZone parts house and get yourself a battery cut-off switch. Easy enough to mount it on a chunk of 1/8" flat bar bent into an "L". Drill a few mounting holes for the switch and the wingnut and you're good to go. And I never remove the "key" handle because there's no real need to do so. Just leave it in where it belongs.
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Old 08-15-2018, 11:12 AM   #11
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Battery disconnect

Looks like a plan! Thanks.
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Old 08-15-2018, 02:52 PM   #12
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I agree w/casitas Gregg
I did exactly the same installation... very easy
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Old 08-15-2018, 03:15 PM   #13
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A couple of easy solutions to battery depletion when not in use. If you can plug in the trailer and let the converter keep the battery charged. If you can't do that the best thing is to remove the battery and connect to a Battery Minder, Battery Keeper, or so other like device.

One of the problems with flooded cell batteries is that they will self discharge. Even with a cut off switch you could still find your battery dead.
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Old 08-15-2018, 03:26 PM   #14
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Quote:
Originally Posted by Byron Kinnaman View Post
A couple of easy solutions to battery depletion when not in use. If you can plug in the trailer and let the converter keep the battery charged. If you can't do that the best thing is to remove the battery and connect to a Battery Minder, Battery Keeper, or so other like device.

One of the problems with flooded cell batteries is that they will self discharge. Even with a cut off switch you could still find your battery dead.
Unless you've upgraded to a 4-stage "smart charger", your old 3-stage converter charger will gladly fry your battery in short order.
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Old 08-15-2018, 03:43 PM   #15
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Originally Posted by Casita Greg View Post
Unless you've upgraded to a 4-stage "smart charger", your old 3-stage converter charger will gladly fry your battery in short order.

I don't use but have an American 20 amp converter and when I was using it the battery was never overcharged. It all depends on a number variables. Making general statements is generally not totally correct.
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Old 08-15-2018, 03:45 PM   #16
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Quote:
Originally Posted by Casita Greg View Post
Unless you've upgraded to a 4-stage "smart charger", your old 3-stage converter charger will gladly fry your battery in short order.
Have to say that depends on the charger. The one that came with my WFCO converter/power station is only a 3 stage, and it maintains the batteries fairly well. We leave the trailer plugged in when stored with no issues.
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Old 08-15-2018, 04:20 PM   #17
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Have to say that depends on the charger. The one that came with my WFCO converter/power station is only a 3 stage, and it maintains the batteries fairly well. We leave the trailer plugged in when stored with no issues.
I must agree. Every charger or converter has it's own charging profile. Some shut off charging at a pretty low voltage thus never reaching the over charge point. Others just keep on charging. I called Amercian to find out what the charging profile was and I was told that it stops charging when the battery gets to 12.2 volts. That's a bit low, however many people seem to thing it needs to keep charging until over 14 volts. This could be a problem. Not only do we have different charging profiles but each brand of battery has a different point at which over charging occurs.

There's too many variables to insure everything will be alright. Something like a battery minder, battery tender are trickle charges and are probably incapable of overcharging.
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Old 08-16-2018, 02:07 PM   #18
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12.2V is a 80% discharged battery at rest. no WAY the charger stops there. trickle chargers run a constant 13.6-13.8V, while 3+ phase chargers use an absorption phase of 14.2-14.4V for an hour or so then drop the voltage to the 13.6V or so maintenance state.

btw, 3 stage chargers are smart chargers too... the old dumb chargers were '1 stage', basically current limited with a max voltage of about 13.8, so you sort of get 2 stages, initially you get max current while the voltage rises til the voltage hits that max, then with the voltage at the max the current drops til its nearly zero and then there they sit.
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Old 08-16-2018, 02:32 PM   #19
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12.2V is a 80% discharged battery at rest. no WAY the charger stops there. trickle chargers run a constant 13.6-13.8V, while 3+ phase chargers use an absorption phase of 14.2-14.4V for an hour or so then drop the voltage to the 13.6V or so maintenance state.

btw, 3 stage chargers are smart chargers too... the old dumb chargers were '1 stage', basically current limited with a max voltage of about 13.8, so you sort of get 2 stages, initially you get max current while the voltage rises til the voltage hits that max, then with the voltage at the max the current drops til its nearly zero and then there they sit.
Here we go making generalizations without knowledge.
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Old 08-16-2018, 02:40 PM   #20
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Here we go making generalizations without knowledge.
care to clarify where I was wrong? I've been working with electronics, including battery charging systems for 40+ years.

the 4th stage on a 4-stage charger is an 'equalization' phase, to be used ONLY on wet cells.
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