2nd Gen Non-Engine/Transmission Battery disconnect

[M Barnett]

Would a 55 amp disconnect be big enough, or should it be bigger?

Thanks

Michael

 

[me4osu]

try this

Of course you would need one for each battery.



Eastwood battery disconnect

 

[klenger]

55 amps, ... NOT!

 

[Ncostello]

Try this...

Our fire trucks with dual batteries use a Cole Hersee M-750 dual battery master disconnect switch. Choose #1, #2 or both batteries plus an OFF position. Its good for 500 amp intermittant and 300 continuous. The other truck has 5 batteries with a single on-off master switch for all of them combined.



OR check out ColeHersee.com. They have master disconnect switches under battery accessories from 125A to 2000A.



And they have selenoids, relays, fuses, accessories plus a thousand other heavy duty items. These are not your radio shack switches commonly found.



Hope it helps. Surely you will find one to fit your needs.

 

[MCummings]

Each of my batteries in my truck are good for 750 Cold Cranking Amps.



55 Amp disconnect? Slightly underated.



Merrick Cummings Jr

 

[kluther]

how about a perko switch from a boat?

 

[M Barnett]

Thanks for the replys fellows. I don't know how to find out how many amps the switch should be. I want to put it in line between the starter and battery. And Ncostello, I discovered I did buy a Cole Hersee battery disconnect switch. Didn't know it because it came from napa in a echlin box, but Cole Hersee made it. Going to their web site, looks like it is 175 amp continous. Any electricians out there tell me if its big enough?

Thanks

Michael

 

[Chipstien]

If a continuous rating is the same with automotive as it is with electrical then continuous means it will work for three hours or more without being shut off. Considering that this application is intermittant, I would say it should work. However... . Don't hold me accountable if it catches fire.

 

[Deezul1]

I think the starter draws something like 300amps but once you are running with nothing on its prolly 10-15 amps then starts going up for AC and headlights those are the big amp draw and those are maybe 15-20 amps or so. Harbour Frieght and some auto parts houses have a disconnect that goes on the battery post and the cable attaches to the disconnect and there is a green knob that you unscrew to disconnect. It turns easily by hand and can be removed to prevent theft. I have one on each battery and they have worked well and also had them on 2 other trucks. They run about $10 at Harbour Frieght.

 

[rubberneck]

I put a flaming river battery disconnect on my truck. It sure makes it sweet when working on the truck. takes a whole 1/2 second to disconnect the batteries. I got it from summit. The units are only 60 bucks and are well worth it. I believe it is rated at 250 amps continuous and 2500 amps intermittent. I made a billet aluminum battery hold down for the driver side battery that incorporates the disconnect switch. I run the power for both batteries through the one switch

 

[ddutil]

Michael, take a look at the cables: in my truck they look like AWG 2, which is the size of a small house's electrical main (125 amps).



50 amps will sooner or later turn into a toaster. 100 amps continuous would be my low-end figure, and I'd rather go with the next bigger one. Face it: you own a heavy-duty pickup



A too small setup will not only heat and eventually toast, it will also lower the voltage to your circuits (starter and lights).



Dan

 

[M Barnett]

ddutil and the rest of you fellows, thanks for the help. I made a mistake and thought the switch I bought was a 50 amp, but it is 175 continous so I think it will be ok. I am going to mount it to the floor right under the front of the seat which won't be far from the starter. Its a big switch, almost teacup size, 3/8" terminals with a big chrome lever like a fuel switch. I want it for the theft protection and also to shut down the electricial system in case of a short. I don't live far from the Mexican border and pickups can sure come up missing here. I guess the next thing i have to figure out is small voltage going to the clock to keep it going when the switch is deactivated.

Michael

 

[Deezul1]

There is a device that plugs into the cigarette lighter that takes a 9 volt batterey that is used to maintain radio presets and clock settings when changing batteries. It can be bought at most auto supply stores and isnt expensive.

 

[M Barnett]

Thanks for that Deezul 1, I didn't know there was such a thing! I will get one soon.

Michael

 

[B.G. Smith]

Switch

M Barnett, the free running amp load for the starter is 200 amps, cranking amps is 450-700. That 175 amp switch will leave you undone some cold morning. bg

 

[M Barnett]

Darn, B. G. , just when I thought I had it made. The biggest one they have is 2,000 amp. Maybe i should just get one of those.

Michael

 

[Bill Lins]

Originally posted by M Barnett

The biggest one they have is 2,000 amp. Michael

That oughta do it!

 

[illflem]

I might be wrong but isn't the load rating for when flipping the switch? When flipping under load the switch will arc, that's where the problem lies. I would think if you only flip the switch with no load you'd be fine. If you just put the switch in the cable going to the starter all other electrical functions will still work except the starter and pull up voltage for a 12 valve shutdown solenoid. The rest of the electrical system besides the starter grabs it's power right next to the battery.

 

[Ncostello]

Our fire trucks use a 500 int, 300 cont for dual batteries (1000 CCA class 8D). The have worked for 15 years without failure and will see more amps than any pickup ever will. The lights are 60 amp total, the pump primer is 100 amp when running, the 3 radios are 30 amps total and on and on with all the equipment chargers and electronic gauges. Many times all this is going at once. Something like 200 continuous would be more than enough for any truck.