Thinking Of Installing A Battery-Disconnect Switch, Which One Is Best?

After all these years, I am considering installing battery-disconnect switches on both the chassis and house batteries.  I assume they are installed on the ground terminal.

You with experience with these, which design was most reliable?  Which type would you avoid and why?

I have been using a knife switch for almost 20 years on the chassis battery, never had a problem with it.   On the coach batteries, I just use the switch that PC installs.  For long term storage, I just disconnect the negative terminal on the coach batteries.  There's not enough room for a knife switch.

I used to remove the coach batteries for long term storage and keep them on a quality maintainer but with the Lifeline batteries I use now, they're fine just disconnecting the negative terminal.

Ron

Here is one I am considering. It was recommended from this forum.  Rated 250 amps continuous and 750 amps surge at 12 volts

https://www.homedepot.com/p/Battery-Doctor-Knife-Switch-for-Top-Post-Batteries-20138/202931972

Like donc13, I have brand new lifeline batteries.  Can’t wait to use them.  They should be remarkably better then my previous batteries of which one just died other on life support.

Ron S

In 2016 I had Kermit install this switch https://www.amazon.com/gp/product/B0070YEEI8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 in lieu of the relay based switch which was standard with Phoenix. We had this delivered to PC during our build.  I wanted to be 100% sure with the switch turned off the battery did not discharge due to known or unknown low current drain.  I also wanted to be able to disconnect my solar charging system which this switch allowed.


Last year I wired up a toad which required the battery being disconnected from the car electric system.  For this I installed a simple on off Blue Sea switch.


Both coach and toad Blue Sea switches have performed reliably.  After Kermit installed the reference Switch in 2016 I think he made this standard for 2017 and later models.  If I am correct that this is now standard, owners of newer coaches may have comments on reliability.

You can't go wrong with this one as long as you connect it tightly. $7 tops. I've had many over the years. This disconnects the ground by turning the green knob.

https://www.harborfreight.com/battery-disconnect-switch-97853.html?cid=paid_google|||97853&utm_source=google&utm_medium=cpc&utm_campaign=&utm_content=&gclid=Cj0KCQjw17n1BRDEARIsAFDHFezVmXT0PyiokqSIZ8JnD0EvydnzvqEWcgJxErBhMdJ78wV67X6MnGsaAkGwEALw_wcB

All boats have a battery disconnect switch. I would look at a marine switch if I were to install one. I’m sure the west marine website has a good listing of switches

Thank you all for your replies to-date.

I should have been more specific.  I am considering a battery post mounted disconnect switch for the chassis battery, and a screw terminal mounted disconnect switch on the house batteries.  I use the posts on my house batteries for easy-access external charging.  I no longer have a battery tray so the posts on my sealed AGM batteries are great for that as shown in this picture.


Panel mounted switches like fandj had installed during the construction of his rig, and those sold at West Marine would be ideal, but for me with my PC, that requires more installation effort than I am willing to consider at this time.

Are there any other battery mounted switches aside from the blade and dial type?  I worry the dial may come loose and the pivot on the blade will be an issue over time.  You know how it is......problems never surface at the right time, place, and circumstance.

Thank you all for your replies to-date.

I should have been more specific.  I am considering a battery post mounted disconnect switch for the chassis battery, and a screw terminal mounted disconnect switch on the house batteries.  I use the posts on my house batteries for easy-access external charging.  I no longer have a battery tray so the posts on my sealed AGM batteries are great for that as shown in this picture.


Panel mounted switches like fandj had installed during the construction of his rig, and those sold at West Marine would be ideal, but for me with my PC, that requires more installation effort than I am willing to consider at this time.

Are there any other battery mounted switches aside from the blade and dial type?  I worry the dial may come loose and the pivot on the blade will be an issue over time.  You know how it is......problems never surface at the right time, place, and circumstance.

Ron,

Sure, the pivots on the knife switch could break and the temper on the connection side (that the knife side slides into) could go bad so the knife no longer makes good contact.

Hugely unlikely though.  As I said, I have been using a knife switch on my chassis battery for about 20 years now (OK, 3 knife switches over 3 RV's) and have had zero problems.   Nor have I heard of anyone having problems.   Doesn't mean no one ever had a problem.

If you ever did have an issue with one, it's a 5 minute job to remove it and put the negative cable back directly on the battery.

The knife switch I mentioned below is out of stock.  The one at Walmart is out of stock.  What the heck!  I thought the run was on toilet paper!

Ron S

After all these years, I am considering installing battery-disconnect switches on both the chassis and house batteries.  I assume they are installed on the ground terminal.

You with experience with these, which design was most reliable?  Which type would you avoid and why?

That  is a REALLY good question !!

1st try: The one with the  green knob from Harbor Freight didn't work because the diameter of the post  is only 0.53”, too small for the Ford battery cable clamp.

2nd try: I bought a  knife switch , but the cast or sintered metal clamp was too small to fit over the (-) battery post and cracked when I tried to spread it.  Also the 2 screws that fasten the metal parts to the flimsy  plastic base were loose. I returned the POS to Autozone for a refund.

3rd try : I ordered this really clever design. It appears to be more robust than the flimsy knife switch, and looks promising because the perpendicular rotating post places the battery cable close to the (-) battery post with no twisting.

https://www.amazon.com/LotFancy-Battery-Disconnect-Switch-Trucks/dp/B07YFWCSYV

Updated

I have been using the same type disconnect 2 Lucky shows above for almost thirty years on various rigs and other vehicles and have never had a problem with them.  I started using this design so long ago that they were actually made in USA!

Paul

One more consideration for the chassis battery disconnect, when starting the engine, 100% of the amperage needed to turn over the engine must be carried by the switch.    In cold weather that amperage can easily exceed 500 amps until the engine actually starts.  Typically, that's only for 5 to 10 seconds.

So whatever switch you decide on, make sure it can carry that load without blowing out like an overloaded fuse.

So on the house batteries I would need Two disconnects being there are two ground cables?

I understand that there is and/or could be issues with the on board computer being turned off for an extended amount of time. Has any one had any issue with this? Or is this not a concern?

I understand that there is and/or could be issues with the on board computer being turned off for an extended amount of time. Has any one had any issue with this? Or is this not a concern?

I've always started (and if possible driven) any stowed vehicle at least once a month, for a variety of reasons. Most likely it is done partly to keep the "brains" awake. And remember to fire up the generator too as recommended, which is why you should use an all-season viscosity oil.