Battery Disconnect Switch

[WLC66]

Hi all - I was wondering if anyone had any thoughts on a good and easy to install battery disconnect switch? My TT suffers from the good ole Hummingbird parasitic drain (I'm guessing detector(s), but a dead battery is a dead battery) - going from a fully charged to virtually dead battery in about 18 hours. While I can always pull the battery, I've got limited storage at the house, and would prefer to keep it on the RV, but eliminate the draining issue. Thanks in advance for your thoughts!

[Mustang65]

Buy yourself a marine type disconnect switch and a 6" battery cable (BLACK) with a 3/8" lug on each end.
- Remove the main 30 amp fuse by the batteries.
- Remove the NEGATIVE battery cable from the frame ground bolt.
- Clean the area around the bolt hole
- Connect the new 6" battery cable to that frame bolt and tighten it into the frame
- Connect the other end of the 6" battery cable to the Marine disconnect switch.
- Mount the Marine disconnect switch to the frame
- Connect the battery's NEGATIVE cable to the other terminal in the Marine disconnect switch.
- Turn the switch off
- Install the main 30 amp fuse
- Check to see if everything in the TT is off (no power)
- Turn on the marine disconnect switch

Sit back and enjoy a nice cold beer. and send us a picture.

Project done!!
Total time for install less than 30 minutes

If your TT has a breakaway switch and it has a ground lead, connect that directly to the battery.

Don

My Registry

RVing with SOLAR

Something like this:

[01tundra]

This is the one I installed -

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

But I'm wondering if you don't either have a short somewhere or a bad battery. A battery with shorted plates can still show good on voltage.

I just measured the parasitic draw on our 17RK and it was 0.26 amps.

At 18 hrs this would equate to 4.68 AH

Are you sure something else isn't drawing power? I know the antenna booster will draw a little power and people sometimes forget to turn them off, but it's surely not that much of a draw.

Something else seems to be going on. I'd take the battery to a local auto parts store and have it tested, they will do the test for free.

[DanNJanice]

Originally Posted by 01tundra

This is the one I installed -

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

But I'm wondering if you don't either have a short somewhere or a bad battery. A battery with shorted plates can still show good on voltage.

I just measured the parasitic draw on our 17RK and it was 0.26 amps.

At 18 hrs this would equate to 4.68 AH

Are you sure something else isn't drawing power? I know the antenna booster will draw a little power and people sometimes forget to turn them off, but it's surely not that much of a draw.

Something else seems to be going on. I'd take the battery to a local auto parts store and have it tested, they will do the test for free.

What Tundra said ^^^
There is some parasitic draw, but it should not be that high. Put an amp meter in series with one of your battery cables battery (better yet, get a clamp on DC amp meter). Then start turning things off / pulling fuses until you find the culprit. Do you have an inverter that is being left on? What about lights inside passthroughs? Awning lights? Do you have a refrig that runs on 12VDC power? What about the trailer brakeaway switch, perhaps it has been pulled?
You are talking about several amps to draw down the battery that much in 18 hrs. Something is going on.

[WLC66]

Originally Posted by Mustang65

Buy yourself a marine type disconnect switch and a 6" battery cable (BLACK) with a 3/8" lug on each end.
- Remove the main 30 amp fuse by the batteries.
- Remove the NEGATIVE battery cable from the frame ground bolt.
- Clean the area around the bolt hole
- Connect the new 6" battery cable to that frame bolt and tighten it into the frame
- Connect the other end of the 6" battery cable to the Marine disconnect switch.
- Mount the Marine disconnect switch to the frame
- Connect the battery's NEGATIVE cable to the other terminal in the Marine disconnect switch.
- Turn the switch off
- Install the main 30 amp fuse
- Check to see if everything in the TT is off (no power)
- Turn on the marine disconnect switch

Sit back and enjoy a nice cold beer. and send us a picture.

Project done!!
Total time for install less than 30 minutes

If your TT has a breakaway switch and it has a ground lead, connect that directly to the battery.

Don

My Registry

RVing with SOLAR

Something like this:

Mustang65 - Thanks for the step-by-step and recommendations, I sincerely appreciate it!

[WLC66]

Originally Posted by 01tundra

This is the one I installed -

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

But I'm wondering if you don't either have a short somewhere or a bad battery. A battery with shorted plates can still show good on voltage.

I just measured the parasitic draw on our 17RK and it was 0.26 amps.

At 18 hrs this would equate to 4.68 AH

Are you sure something else isn't drawing power? I know the antenna booster will draw a little power and people sometimes forget to turn them off, but it's surely not that much of a draw.

Something else seems to be going on. I'd take the battery to a local auto parts store and have it tested, they will do the test for free.

01Tundra - As per your recommendation, I'm going to get the battery tested - I have the feeling I'm missing something, but better safe than sorry. I thought I had switched everything off, and then switched off the breakers just in case - but (assuming the battery is good) something is still pulling. I've got a few days to work it out before we head out again, and I'll check the antenna boost tomorrow. Thanks for the recommendations.

[WLC66]

Originally Posted by DanNJanice

What Tundra said ^^^
There is some parasitic draw, but it should not be that high. Put an amp meter in series with one of your battery cables battery (better yet, get a clamp on DC amp meter). Then start turning things off / pulling fuses until you find the culprit. Do you have an inverter that is being left on? What about lights inside passthroughs? Awning lights? Do you have a refrig that runs on 12VDC power? What about the trailer brakeaway switch, perhaps it has been pulled?
You are talking about several amps to draw down the battery that much in 18 hrs. Something is going on.

DanNJanice - Thanks for the list of potential culprits - I'll grab my meter and start doublechecking. I double checked the lights, but hadn't thought about the breakaway switch - thanks for the recommendations.

[01tundra]

Here's the meter I just purchased -

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[gypsmjim]

Originally Posted by Mustang65

Buy yourself a marine type disconnect switch and a 6" battery cable (BLACK) with a 3/8" lug on each end.
- Remove the main 30 amp fuse by the batteries.
- Remove the NEGATIVE battery cable from the frame ground bolt.
- Clean the area around the bolt hole
- Connect the new 6" battery cable to that frame bolt and tighten it into the frame
- Connect the other end of the 6" battery cable to the Marine disconnect switch.
- Mount the Marine disconnect switch to the frame
- Connect the battery's NEGATIVE cable to the other terminal in the Marine disconnect switch.
- Turn the switch off
- Install the main 30 amp fuse
- Check to see if everything in the TT is off (no power)
- Turn on the marine disconnect switch

Sit back and enjoy a nice cold beer. and send us a picture.

Project done!!
Total time for install less than 30 minutes

If your TT has a breakaway switch and it has a ground lead, connect that directly to the battery.

Don

My Registry

RVing with SOLAR

Something like this:

I did mine 2 years ago and have been happy ever since. At the time I did some research and the suggestions were to put it on the + line, not the ground. Any reason for the ground over the +?

[M&A]

The breakers are for AC only, and not DC.

As for disconnecting + vs. -, opinions vary; it's electrically and functionally the same. It's just that exposed - (negative) connections on the switch can't short against the frame or other exposed grounds like the positive might.

As stated before, a DC clamp on meter is a good tool. Know how to use it and note that the common inexpensive (~$10) AC clamp type is not accurate in this case.

[Mustang65]

Is there a single good reason for putting the disconnect switch on either side of the battery?

If you get down to the reason that a lot of installs are done on the negative side goes back to the backyard hotrod mechanics that removed the negative cable first to insure that they did not accidently short the positive terminal to ground while removing the positive terminal connection.

The reason that I recommend the negative is because of how easy it is to install the disconnect switch next to the ground bolt and just use a 6" battery cable to complete the wiring of the switch.

If someone wanted to do the positive terminal there would be no problem doing it that way.

Many years ago I remember a study that was being done to see if there was a difference in arching, if one cable was connected first or second.. the result that I remember was... no difference. I guess an Amp is an Amp.

Don

My Registry

RVing with SOLAR

[01tundra]

I cut my positive, added two lugs and installed the switch. No extra wire required for our TT since the positive lead was so long from the factory.

Been breaking the positive to winches on my trucks for years with no issues.

[WLC66]

So after recharging the battery (it tested fine), I took a run back to the TT to check for "operator issues" - refridgerator had been left on (as DanNJanice had guessed). Looks like I have a couple of items to add to my "shut off" list. Thanks to all for the assist!

[01tundra]

Originally Posted by WLC66

So after recharging the battery (it tested fine), I took a run back to the TT to check for "operator issues" - refridgerator had been left on (as DanNJanice had guessed). Looks like I have a couple of items to add to my "shut off" list. Thanks to all for the assist!

Left on propane correct?

Our refrigerator only draws 0.03 amps while on propane and the only other option for ours is to run on 120VAC.

So ours with just the refrigerator + parasitic draws 0.29 amps.

0.29 amps x 18 hrs = 5.22 AH's.

Sure there's not something else going on or do you also have a 12VDC option on your refrigerator?

[DanNJanice]

Originally Posted by WLC66

So after recharging the battery (it tested fine), I took a run back to the TT to check for "operator issues" - refridgerator had been left on (as DanNJanice had guessed). Looks like I have a couple of items to add to my "shut off" list. Thanks to all for the assist!

Glad you found it! I got bit by the trunk light switch in an old Dodge car. It had fallen out of the bracket so the trunk light was on all the time. Every few days the battery would be dead!
The battery disconnect is still a good idea. Batteries will discharge in a few weeks, with even small parasitic loads.

[WLC66]

My gut feeling is that there's still something else going on - besides me needing to work on actually shutting of what needs to be shut off. Although the disconnect will "fix" the drain while parked problem, I'm still going to give it the once over to see what's pulling amps. That much loss in such a short time seems weird to me - I'll update if I find anything new.

[WLC66]

All - just wanted to take a minute to thank everyone for their quick responses and helpful suggestions. Although finding a drained battery was a little frustrating, the forum's input and advice has really helped me to get to know my new RV. Thanks again!

[redsnapper]

Next purchase should be a battery "maintainer"
It's a very low input of power (1.5 amps) that keeps the batt (s) at full charge.
You will need a source of 110V household current to plug it in.

https://www.amazon.com/Schumacher-SE.../dp/B0009IBJAS

[norty1]

There are other things that have a parasitic draw like the LP/CO alarm.

[WLC66]

So I made a quick lunch and multimeter stop at the TT. There was a .56 amp pull with the charge line/slideout motor fuse in (w/other fuses pulled and everything switched off). If I pulled the 30amp charge line/slideout motor fuse, and reinserted the other fuses, draw drops to .02. Ideas?