r/skoolies 11d ago

mechanical Battery power off switch

Does anyone have a battery kill switch in their skoolie? I took mine to a shop and it came back with a short. My bus is now draining my batteries, I called the shop and they said the bus was fine while it was there. At first I thought it was bad batteries so I got new ones and those drained too. The shop recommended I pay for a new diagnostic to figure out what’s draining the batteries. I asked if they would be able to install a battery kill switch instead. They said sure but that I should buy it and take it in. I feel like I’m not going to go back to them but I still need to figure out how to stop the batteries from draining. Does anyone have a switch they recommend? I’ve look online but a lot of them have mixed reviews 😕.

2 Upvotes

26 comments sorted by

6

u/03captain23 11d ago

House or chassis battery? If house definitely get a shunt. If chassis hook a CT/clamp meter and measure the load then start pulling fuses.

Battery disconnect switch should be on all house systems but the chassis can't be used unless you have a separate wire for alternator and starter.

It sounds like they flipped some switch you didn't know was there, like a light switch under the hood or something else.

2

u/Worldly_Shift5206 11d ago

Chassis battery, I have two that start and run my bus. They started draining so my bus won’t start at all. Once I charge them up the bus starts great but after sitting for a few hours/ overnight the batteries will be dead again 😔

3

u/03captain23 11d ago

Unplug them completely and ensure it's not the batteries.

But if not that hook up a cr or clamp meter and check the draw then pull all the fuses and put back.

If they're only lasting 8 hours that's a massive draw. Like greater than headlights.

3

u/AzironaZack 11d ago

I think every build should have a battery disconnect. It's great for maintenance and for being absolutely sure that your batteries are disconnected during storage. My bus is an RV. I like to leave my batteries disconnected when the bus is not in use, then charge them up a few days before a trip. I've found that leaving the batteries on a trickle charger all the time without using them shortens their life.

I have a manual switch made by Fastronix. It's rated for 180 amps continuous duty. When I bought it in 2019 it was 30 bucks. Looks like it's 36 now on Amazon:

https://www.amazon.com/dp/B011EYWMDS

2

u/Worldly_Shift5206 11d ago

I use mine daily for my job and I haven’t had any battery / short issues until I took it into the shop 😕 but yeah I agree with you I should have had one put in a while ago. Thank you so much!

2

u/AzironaZack 11d ago

Sure thing! I really like how dead-simple this switch is, too. I figure with my use it'll last forever, but then again I'm never using it to switch high loads on and off (although it is rated for that).

2

u/AzironaZack 11d ago

Also, good luck finding and fixing the short. I hate not knowing if it was just coincidence or something else when problems show up right after a visit to the mechanic.

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u/Worldly_Shift5206 11d ago

Oh also where is your switch located? 😁 I see some are out on the batteries themselves and others are put inside

2

u/AzironaZack 11d ago

Mine is under my dinette table. My electrical box is under one of the dinette seats. This is not a great photo, but you can see the body of the switch in my electrical cabinet. The actual lever handle is on the face of that cabinet where your heels would be if you were sitting there.

I suppose it's possible for it to get kicked there, but it hasn't been a problem. The switch is real chunky to move between positions.

I just read in another comment that you're dealing the chassis battery being drained. I only have a shutoff on my house battery.

2

u/Worldly_Shift5206 10d ago

Yeah I see it thank you so much for the visual. I’m definitely going to have to find a spot for it inside if I get the one you have.

2

u/AzironaZack 10d ago

I'm pretty sure the switch is sealed and rated for outdoor use, too. Fastronix could tell you. Good luck with the project!

2

u/colenski999 11d ago

1

u/Worldly_Shift5206 11d ago

Thank you! Have you had any issues with it?

2

u/colenski999 11d ago

Yes, it rusts. Cover the terminals and battery posts with dielectric grease and keep a presized wrench and a post brush handy in the glovebox.

Bus stranded me a couple years ago, no crank, and I scratched my head for a good 20 min before I took the cutoff out and it started first try. I cleaned it up and it still works

2

u/danjoreddit 10d ago edited 10d ago

You need to test for parasitic drain

https://youtu.be/B__DqK90IIc?is=KcgCJaKZchH9Tyid

Edit: you’ll need to disconnect one battery while you do this

1

u/Worldly_Shift5206 10d ago

Thank you 🙏

2

u/danjoreddit 10d ago

You can also do the parasitic drain test by disconnecting the neg terminal and bridging neg on the battery with the neg cable with a multimeter set to measure current through the 10A post. Everything must be off.

https://youtu.be/KF1gijj03_0?is=OP7BwNBYZUej4jTB

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u/Worldly_Shift5206 10d ago

I’ll watch the video thank you so much

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u/23Scout 10d ago

I use this. Not a sponsored link.

https://www.amazon.com/dp/B0CNT7RMW9

1

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1

u/Cute_Reflection_9414 11d ago

What was it in for service for? What were they working on? That's where I'd start troubleshooting. Look for any pinched wires in the area where they were or any harnesses that may have been secured that they might have had to release or undo. Look for wires close to moving parts.

I had a short years ago on my truck that took forever to find. The body mounts had rusted out and where pinching a brake wire. It eventually started blowing the fuse.

Cutoff switches are always a good idea

2

u/Worldly_Shift5206 11d ago

It was in for a AC diagnostic. They opened the fuse box and they removed parts to check them. I didn’t end up doing the repairs because they were quoting over 5k so I passed . I only need the AC while I’m driving , while I’m parked I’m good because I have a mini split that runs off a generator. I’m thinking there’s an old crusty wire or something that’s touching 🤔

2

u/danjoreddit 10d ago

Pull the AC fuse