Battery cutoff switch

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Battery cutoff switch

Postby Tom&Shelly » Sat Jan 20, 2018 3:02 pm

For those who charge their camper battery from both the TV while driving, and also shore power via a converter (such as in the PD4045) when camping, and have a battery cutoff switch, do you wire your switch to cut off the battery from both possible sources, just the converter, or some other way? I can see the argument for either way, as the TV can be taken off line simply by unplugging the trailer cable. But someone like me might forget how I'd wired it.

Also, connecting the TV battery to the camper battery via the auxiliary wire in the cable (with 30 A fuses at either end), it appears the converter would charge the TV battery as well as the camper battery if one were at a site with shore power, and left the trailer cable plugged into the TV. Any issues with that? I recognize it's not the best thing to keep both batteries in parallel for too long (more than a few days), but, of course, they are connected in parallel for the duration of a drive, with the TV's alternator charging both. How about leaving the batteries connected overnight?

Thank you for your thoughts.

Tom
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Re: Battery cutoff switch

Postby John61CT » Sat Jan 20, 2018 7:36 pm

If by TV battery you mean a House bank separate from the Starter batt, the former can /should be operated together with the trailer's House bank, as long as properly heavy gauge wires connect the two.

If you mean Starter, that should be connected to House only when a charge source is active, usually via a combiner (VSR, ACR) .

A bank of any size should have a master cutoff switch easy to reach in an emergency, ideally close to the batt positive. Also a fuse sized to protect the wiring.
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Re: Battery cutoff switch

Postby tony.latham » Sat Jan 20, 2018 8:17 pm

When I turn my Tacoma off, it disconnects the trailer. I've got a master switch that turns the camper battery off, but I find myself only using it to reset my amp meter to zero.

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Re: Battery cutoff switch

Postby Dale M. » Sun Jan 21, 2018 8:51 am

A lot will depend on how TV is wired... On my Chevy PU (2005) the 12 volts to trailer connector is ON (hot) all the time... I envision modifying the wiring with a relay to cut it off when engine is off.....

Some vehicles as noted above the power to connector cuts off when engine is off by design...

When I wired my Jeep, I made it on/off as same as ignition... So when I shut down engine it disconnects CWT (Charge While Towing) ...

IT will depend on how manufacturer of TV or persons that added CWT wired vehicle...

MY thought is if you have CWT cutoff on TV ignition you are "golden"... IF not, simply have relay added that is controlled by ignition and there is nothing to remember or forget....

There is noting wrong with batteries in parallel as long as they are basically same type and of same physical condition... In industries like telecommunications we run battery strings in parallel "forever" (but all batteries are matched) and its as common as the sun rising every day...

Also consider disconnect option if you have to charge a battery for "break away" control of electric brakes on trailer...

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Re: Battery cutoff switch

Postby Socal Tom » Sun Jan 21, 2018 9:11 am

Tom&Shelly wrote:For those who charge their camper battery from both the TV while driving, and also shore power via a converter (such as in the PD4045) when camping, and have a battery cutoff switch, do you wire your switch to cut off the battery from both possible sources, just the converter, or some other way? I can see the argument for either way, as the TV can be taken off line simply by unplugging the trailer cable. But someone like me might forget how I'd wired it.

Also, connecting the TV battery to the camper battery via the auxiliary wire in the cable (with 30 A fuses at either end), it appears the converter would charge the TV battery as well as the camper battery if one were at a site with shore power, and left the trailer cable plugged into the TV. Any issues with that? I recognize it's not the best thing to keep both batteries in parallel for too long (more than a few days), but, of course, they are connected in parallel for the duration of a drive, with the TV's alternator charging both. How about leaving the batteries connected overnight?

Thank you for your thoughts.

Tom

You can disconnect your TRailer battery by unplugging from the TV, so unless it’s automatic, I don’t see value there. You essentially disconnect from the converter when it’s not plugged into shore power, so not much value there. There is value in disconnecting the battery entirely, in case of storage or some sort of fault.


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Re: Battery cutoff switch

Postby Tom&Shelly » Sun Jan 21, 2018 12:11 pm

Thank you for the good advice folks.

I was wondering about why I'd want a cut-off switch in the first place, when yesterday, right after posting, while replacing the battery in my Jeep, it came to me in a flash! :frightened: Actually, it wasn't until I thought about it later that I figured out the advantage of the cut-off switch, but there was a literal (small) spark as I connected the ground. Something in the Jeep must have charged up when the wire first made contact, and it sparked a little until I was able to secure the connection. Well, it's a new sealed battery and so no damage, but if I had a cut-off switch, that problem wouldn't happen.

For the teardrop, we're planning to build a fairly fancy tongue box that will include a battery box, and then the PD 4045 and electrical connections next to it. If I put the cut-off switch just outside of the battery box, I can turn it off to swap batteries, then close the battery box before turning the switch back on. Keeps the sparks and the hydrogen gas away from each other! :)

Our TV will be my wife's Jeep Wrangler, with just a starting battery, no extra deep cycle batteries to help out the tear drop. We are thinking of paying our mechanic to install a seven pin connector, and will ask about setting it up so the auxiliary is not connected when the ignition is off. That sounds like the best solution for us, in case we forget to disconnect while plugging into shore power.

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Re: Battery cutoff switch

Postby Socal Tom » Sun Jan 21, 2018 1:07 pm

Tom, the factory jeep 7 pin harness is available on amazon https://smile.amazon.com/gp/product/B00 ... UTF8&psc=1

The instructions are set up for the layman to perform the installation. It even has the provisions for a trailer brake system. All the wires, mounts etc are there. That's what I did, by the time you buy all the parts you are just about at that price anyhow.
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Re: Battery cutoff switch

Postby John61CT » Sun Jan 21, 2018 1:44 pm

Yes the main point of the cutoff switch is safety, during maintenance or in an emergency.

Truly ensuring isolation from consumers during storage is another, so then you only need compensate for the self-discharge rate.
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Re: Battery cutoff switch

Postby Tom&Shelly » Sun Jan 21, 2018 7:27 pm

Socal Tom wrote:Tom, the factory jeep 7 pin harness is available on amazon https://smile.amazon.com/gp/product/B00 ... UTF8&psc=1

The instructions are set up for the layman to perform the installation. It even has the provisions for a trailer brake system. All the wires, mounts etc are there. That's what I did, by the time you buy all the parts you are just about at that price anyhow.
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Thank you Tom. I just ordered it. Shelly thinks she wants us to try installing it ourselves, which means she gets to crawl around and I'll hand her tools, and stay out of the way. After all, it is her Jeep! :)

If we balk on that plan, we can always give it to our mechanic and avoid any mark-up from him buying the parts. We also have a Tekonsha 90195 brake controller we plan to install.

Tom
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Re: Battery cutoff switch

Postby S. Heisley » Sun Jan 21, 2018 8:54 pm

Some electrical items may continue to drain the battery even when they are turned off. Also, having a battery disconnect will prevent drains from possible shorts. A battery disconnect can be especially helpful when the trailer is in storage. If done right, a battery disconnect may also help protect your controller, if you have one. However, it all depends on how you have everything wired and connected. Many things are possible. Check the way each item that you are wiring works. ...My two cents worth. (And, of course, always protect with fuses.)
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Re: Battery cutoff switch

Postby Dale M. » Mon Jan 22, 2018 9:56 am

Even with buying the JEEP/MOPAR 7 pin harness kit, I would suggest that you add disconnect relay for the 12 volts to the TD if harness does not have one....

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Re: Battery cutoff switch

Postby Dale M. » Mon Jan 22, 2018 10:04 am

S. Heisley wrote:Some electrical items may continue to drain the battery even when they are turned off. Also, having a battery disconnect will prevent drains from possible shorts. A battery disconnect can be especially helpful when the trailer is in storage. If done right, a battery disconnect may also help protect your controller, if you have one. However, it all depends on how you have everything wired and connected. Many things are possible. Check the way each item that you are wiring works. ...My two cents worth. (And, of course, always protect with fuses.)


Yeah... We worry about our power grid and generation power in future but we still have products that use power to stay alive (when off) so they can be turned on by a remote control, then there is the "night light" on television (VISIO) and the items that have that silly LED that is on sucking electricity just to let you know it plugged in and alive... How did we survive with out all those little LEDs glowing at us in the dark...Sure each one is very tiny, but think of the MILLIONS and MILLIONS doing it....

Oh well end of rant, and yes there are items the draw power even when turned off...

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Re: Battery cutoff switch

Postby Tom&Shelly » Mon Jan 22, 2018 6:48 pm

Dale M. wrote:Even with buying the JEEP/MOPAR 7 pin harness kit, I would suggest that you add disconnect relay for the 12 volts to the TD if harness does not have one....

Dale


Yes, I agree that is a very good idea, and we will add a disconnect relay, if one isn't already included.

On the subject of unnecessary power suckers: We plan to install USB ports for charging our phones--the type that run off of 12 vdc, but are made to use a modern household switch plate. They only seem to come with LEDs. Shelly doesn't like that much light while trying to sleep, so I took one apart and cut one of the wires to the LED. Was afraid it was part of a voltage regulator circuit, or something, but, no, the thing seems to work fine without an LED. Not without collateral damage, however. I will have to use 5 minute epoxy to put the back of the plastic box back on, the snapping mechanisms evidently weren't meant to be undone by the consumer.

They have some electronics to turn the 12 vdc to 5 vdc (that's what USB ports have), and I need to check and see if the circuit (sans LED) draws current when nothing is plugged in.

At least those particular USB ports are fairly quiet around AM radios. I also bought some of the circular kind that fit in the holes for cigarette lighters, and they are (electrically) noisy as all get out!

Tom
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Re: Battery cutoff switch

Postby bdosborn » Mon Jan 22, 2018 9:01 pm

I've had great luck with a Yandina combiner. It's not that expensive and it's been working in our trailer since 2010 or so.
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http://www.yandina.com/c100InfoR3.htm

It combines when either the trailer is charging (solar or battery charger) or the truck is charging. Disconnects when the trailer is running on batteries. It's also little so it doesn't take up nearly as much room as most combiners do.

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Re: Battery cutoff switch

Postby John61CT » Mon Jan 22, 2018 9:30 pm

Yes she actually invented the product category, all her products are excellent, unparalleled warranty and support.
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