Lazy Daze Owners' Group

Lazy Daze Forums => Lazy Daze Technical => Topic started by: HiLola on April 17, 2025, 02:22:39 pm

Title: Battery Disconnect Switch
Post by: HiLola on April 17, 2025, 02:22:39 pm
So I received the new battery switch and would like to install it but have a question first.  To do this in an electrically safe manner, will turning off the lithium batteries (using the switch on top of the batteries) and pulling the fuse for solar input do the trick? Obviously, I won’t be hooked up to shore power or running the generator.
Title: Re: Battery Disconnect Switch
Post by: Andy Baird on April 17, 2025, 03:43:19 pm
As long as you remove all sources of power (e.g., batteries and solar charging controller), you should be fine. If you have any doubts, use a multimeter to verify that the 12 VDC system is dead.
Title: Re: Battery Disconnect Switch
Post by: Larry W on April 17, 2025, 05:14:38 pm
So I received the new battery switch and would like to install it but have a question first.  To do this in an electrically safe manner, will turning off the lithium batteries (using the switch on top of the batteries) and pulling the fuse for solar input do the trick? Obviously, I won’t be hooked up to shore power or running the generator.

Where are you planning on installing the switch? 
If on top of the battery as it was originally, I would cover all the battery terminals. One false slip could produce a lot of damage and possibly harm to yourself.
Lithium batteries can produce a huge amount of amperage for short durations.

Larry
Title: Re: Battery Disconnect Switch
Post by: jor on April 17, 2025, 06:16:13 pm
Quote
I would cover all the battery terminals.

Second that. You can just throw a rug or something over the batteries.
jor
Title: Re: Battery Disconnect Switch
Post by: HiLola on April 17, 2025, 09:24:38 pm
Where are you planning on installing the switch? 
If on top of the battery as it was originally, I would cover all the battery terminals. One false slip could produce a lot of damage and possibly harm to yourself.
Lithium batteries can produce a huge amount of amperage for short durations.

Larry

Good suggestions. I need to pull the RV out of its parking location to access the battery compartment to take a look-see. Any suggestions for a mounting location?
Title: Re: Battery Disconnect Switch
Post by: Keith S on April 18, 2025, 10:15:03 am
I connected my switch on the negative cable, next to the batteries in the (original) battery box to minimize cable length. In the photo, it’s at the upper left. You can just see the red handle, and the label stating which direction is ON and OFF.

Title: Re: Battery Disconnect Switch
Post by: HiLola on April 18, 2025, 10:26:29 am
Nice install, Keith!  Are you able to access the switch easily?
Title: Re: Battery Disconnect Switch
Post by: Keith S on April 18, 2025, 11:18:13 am
Actually, yes. The ON and OFF legends on the switch body are hard to read, so I added the labels you can see for CW and CCW.
Title: Re: Battery Disconnect Switch
Post by: StevenJill on April 19, 2025, 07:54:33 am
Although it was probably over priced, I bought the one Lazy Daze sold about 5 years ago that gets wedged between the two batteries, so mounting was easy.
Title: Re: Battery Disconnect Switch
Post by: HiLola on April 19, 2025, 09:50:19 am
Although it was probably over priced, I bought the one Lazy Daze sold about 5 years ago that gets wedged between the two batteries, so mounting was easy.

Hi Steve. I also have the factory disconnect switch but I’m told it’s no longer appropriate with my recent lithium battery and 2K watt inverter installation so an upgrade was suggested.
Title: Re: Battery Disconnect Switch
Post by: HiLola on May 03, 2025, 03:15:22 pm
I am attempting to swap out the factory battery disconnect switch with a Blue Sea unit. The new unit has connections labeled “input” and “output” but the old switch does not. Which cable needs to go where? Would input be coming from the batteries? Hopefully these photos help.
Title: Re: Battery Disconnect Switch
Post by: Larry W on May 03, 2025, 03:45:27 pm
I am attempting to swap out the factory battery disconnect switch with a Blue Sea unit. The new unit has connections labeled “input” and “output” but the old switch does not. Which cable needs to go where? Would input be coming from the batteries? Hopefully these photos help.

The ‘input’ connects to the battery, and the ‘output ‘ goes to the coach.

Larry
Title: Re: Battery Disconnect Switch
Post by: HiLola on May 03, 2025, 03:48:33 pm
The ‘input’ connects to the battery, and the ‘output ‘ goes to the coach.

Thank you, Larry! Just out of curiosity, what would happen if the cables were reversed? Would the switch just work backwards or would the smoke be let out?   :o
Title: Re: Battery Disconnect Switch
Post by: HiLola on May 03, 2025, 05:11:59 pm
Success, and all the smoke stayed in!  👍👍 The cable above the switch is a bit longer than needed so I should probably shorten it to make it look pretty. And, I don’t like the way all the terminals are connected on a single post.

Anyone need a factory battery disconnect switch in good condition? Just pay shipping and it’s yours!
Title: Re: Battery Disconnect Switch
Post by: StevenJill on May 04, 2025, 08:06:37 am
Thank you, Larry! Just out of curiosity, what would happen if the cables were reversed? Would the switch just work backwards or would the smoke be let out?   :o
Unless I am missing something, besides the fact that I am not Larry LOL.  It would work the same, unless it has a light on it or something. It probably has to do with the internals, the live side is probably less exposed for safety, but off would still be off and on still on.
Title: Re: Battery Disconnect Switch
Post by: Larry W on May 04, 2025, 11:53:00 am
Unless I am missing something, it would work the same.

Yes, it’s an on-off switch, and it doesn’t matter which way the switch is connected. If a switch is labeled, it’s best to wire it the way indicated to prevent future confusion.
You now have a sealed battery switch that is rated to carry the amperage that your inverter draws.

Larry
Title: Re: Battery Disconnect Switch
Post by: Andy Baird on May 04, 2025, 12:21:24 pm
I've always been puzzled by Blue Sea labeling SPST switch terminals "Input" and "Output." Electrically, this makes no sense. I'd love to see an authoritative explanation.
Title: Re: Battery Disconnect Switch
Post by: Steve TK on May 04, 2025, 09:29:55 pm
I think FEED and LOAD might have been a better choice for the labeling - not that it matters electrically.

Steve
Title: Re: Battery Disconnect Switch
Post by: Andy Baird on May 04, 2025, 09:59:56 pm
I have to disagree, Steve. That would be just as misleading as INPUT and OUTPUT. There's no reason for any labeling. When have you ever seen any other SPST switch labeled as if it had polarity?
Title: Re: Battery Disconnect Switch
Post by: Keith S on May 04, 2025, 10:13:17 pm
One connotation of “input” or “supply” or “source” is to make it explicitly clear to some unfamiliar future maintainer which side is always energized whether the switch is ON or OFF. Of course, from an electrical circuit standpoint, it makes no difference.
Title: Re: Battery Disconnect Switch
Post by: Andy Baird on May 05, 2025, 11:15:57 am
"One connotation of 'input' or 'supply' or 'source' is to make it explicitly clear to some unfamiliar future maintainer which side is always energized"

That's a point. It can be useful to know that. And that's probably why Blue Sea labels the battery switch terminals that way. Thanks for clearing that up, Keith!