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Battery disconnect?

R

ramdough

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Anyone have an aftermarket battery disconnect that can disconnect both 12v and 24v at the same time? I have been doing a lot of work where I keep unscrewing the batteries and am interested in an easy solution. I could just buy two disconnects, but would rather have one.

Anyone ever see one?


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simp5782

simp5782

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All you need to do is run the ground thru the disconnect. This drops the ground from the truck to the batteries. No ground no drain on batteries.

Cole harsee has several disconnects
 
chucky

chucky

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simp5782 said:
All you need to do is run the ground thru the disconnect. This drops the ground from the truck to the batteries. No ground no drain on batteries.

Cole harsee has several disconnects
Click to expand...
I was planing on useing one of the 3 way turn disconect on amazon when i wire my slave cable post back to my batteries so one pos.12v 2nd pos. off 3rd pos 24v so i could take or give a charge from 12 or 24 what ever was available for me or to me !
 
chucky

chucky

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ramdough said:
Anyone have an aftermarket battery disconnect that can disconnect both 12v and 24v at the same time? I have been doing a lot of work where I keep unscrewing the batteries and am interested in an easy solution. I could just buy two disconnects, but would rather have one.

Anyone ever see one?


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Click to expand...
marine battery disconect on amazon 4 or 5 diferant brands
 
R

ramdough

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simp5782 said:
All you need to do is run the ground thru the disconnect. This drops the ground from the truck to the batteries. No ground no drain on batteries.

Cole harsee has several disconnects
Click to expand...
Thanks!!!!!

So the 12v is from the first bank to ground not across the other battery?

I must be overthinking things.


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Ronmar

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Yep, both 12 and 24 are referenced to ground, so a single disconnect on the ground lead will isolate both voltages... whichever way you go, the one on the 24v lead or ground needs to be large enough to handle peak current flow to the starter...
 
T

tennmogger

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Then 12v becomes a reference, with 12v high current between anything 12v, and anything 24v.. If you work on circuits where 12v bus and 24v busses are close together, you can still experence a catastrophic short. Like working behind the dash, or the polarity protection box. Still best to disconnect the batt terminals.
 
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Ronmar

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True, the 12v lead is the neg terminal of the 12-24 set of batts... I didn’t catch that in the OP’s question. for maint work it would be better to disconnect both 12 and 24.

played around with the instrunment shunt today. If the spec I found is correct 100MV across the shunt = 1000A. Connected a MV meter and pressed the start inhibit button. Measured peaks between 15 and 26MV or 150-260A of current draw while cranking...
 
R

ramdough

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Ronmar said:
True, the 12v lead is the neg terminal of the 12-24 set of batts... I didn’t catch that in the OP’s question. for maint work it would be better to disconnect both 12 and 24.

played around with the instrunment shunt today. If the spec I found is correct 100MV across the shunt = 1000A. Connected a MV meter and pressed the start inhibit button. Measured peaks between 15 and 26MV or 150-260A of current draw while cranking...
Click to expand...
How about welding? I have been disconnecting both terminals for welding. Is that necessary?

Thanks!


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TechnoWeenie

TechnoWeenie

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Welding is basically shorting out the batteries.

You don't wanna do that.. They can and do explode.

The only time I'd ever consider welding with batteries is if they were a great distance away, not near or in my truck, completely disconnected from the truck, NOT needed to start the truck, and the repair I needed to effect would either cost more than the truck, or be needed to save my life.

When it comes to FERs (Field Expedient Repair) you do what you have to do to get yourself safe, but if it's a situation that can be solved by a wrecker, or a friend, then call in that lifeline.

It's not a bad capability to have, but you do it because you have no other choice and it can save your life, NOT because you want to or you think it's cool to show off what you can do.

If you plan on welding, pick up a small 2kw genset for $200, and one of those cheap 120V welders for another $200, and you're set.
 
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tennmogger

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The "two bank disconnect" still leaves a high current short available between 12 and 24 positives.

Batteries can and do output hundreds of amps every time the truck starts. Working on typical field repairs and shop welding is usually around 100 amps or less. The batteries don't mind a bit. My Ready Welder purrs on a 24v Unimog or LMTV. FWIW.
 
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Ronmar

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Yea, the batteries don’t care about the welding, in fact, a pair of batteries can weld just about anything on the truck for 30-45 minutes:) It is the weld current finding it’s way thru a ground loop and thru something more vital like engine and transmission ECU’s that can be an issue. So disconnecting batts and keeping the welder ground lead as close to the weld as practical is the best practice...
 
coachgeo

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sounds like your stuck with KISS aka- two battery disconnects on each of the main 12v and 24v mounted near each other, and of the same type. drill a hole in the switch arms... run rope or? (any non conductive something??) thru them with stops properly placed so if you tug on it one way it disconnects both.... the other way...... it re-connects both.... or just swing two switches when needed instead of trying to be all fancy lol.
 
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scabskunk

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I think this is the unit i got. Don't feel like pulling batteries out to check model number.

Pro Installer 400A Double Pole Battery Switch - MC10

A powerful new generation battery switch with outstanding performance and features for both the installer and end user. Three mounting options: surface, rear panel, and front panel mounting, plus optimized cable access makes installation a breeze. Pro Installer switches set the new benchmark...
www.bepmarine.com
video of where i put the switch. Added a box on the side of battery/air tray and have the switch access inside the box to keep it out of the way. There is also ones that have a remote switch setup if you want to hide a switch in a the cab and have a disconnect in the battery tray. https://www.bepmarine.com/en/p/720-MDO/Remote-Opered-Btery-Switch-with
 
coachgeo

coachgeo

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scabskunk said:
I think this is the unit i got. Don't feel like pulling batteries out to check model number.

Pro Installer 400A Double Pole Battery Switch - MC10

A powerful new generation battery switch with outstanding performance and features for both the installer and end user. Three mounting options: surface, rear panel, and front panel mounting, plus optimized cable access makes installation a breeze. Pro Installer switches set the new benchmark...
www.bepmarine.com
video of where i put the switch. Added a box on the side of battery/air tray and have the switch access inside the box to keep it out of the way. There is also ones that have a remote switch setup if you want to hide a switch in a the cab and have a disconnect in the battery tray. https://www.bepmarine.com/en/p/720-MDO/Remote-Opered-Btery-Switch-with
Click to expand...
did you wire it like this set up... does it disconnect both 12v and 24v positives?
 
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