I just bought my first diesel, a 96 Silverado 2500 6.5. Obviously it's 24v right?...hence the 2 batteries?

I bought this battery anti-theft/battery master switch, but I don't know how to properly connect it. It is an in-line connection that goes on the negative lead and has a screw type connector in the middle. A quarter turn will break the circuit, and you can even totaly remove the screw and take it with you so no one can use it. I have a couple concerns;

1)If I attach it to only one battery, will killing only one battery prevent a start? Do I need 2, one for each battery?

2)It has an amp rating of 100continous/600cranking....will that work on my system? Do I have to make sure my starter doesn't drain more than 100/600amps??

3)It says "Install the included HHM fuseholder with ATM-20 fuse for power by-pass to accomdate accessory equipment requiring continous power"...how do I wire this thing? I would like to still keep my alarm and potentially other plugged in gear powered, but still prevent a start. Does it mean I can only run 20amps thru the bypass total drain? I must also bring lots of 20a and bigger fuses

And as a side Q, I just want to make sure that its only the glow plugs and starter that require the 24v, but everything else is converted and powered by 12v? How does the alternator charge, same as a 12v system?

Excuse my poor electronic knowledge, but I'm trying to learn! Thanks

your truck is a 12 volt system. two batteries just equal more amperage for cranking.

Yes, the two batteries are connected to the electrical system in parallel, not in series. If both batteries were connected in series, you would have a 24 volt system.

The electrical system is a pair of 12 volt batteries connected in parallel, this results in 12 volts total voltage, but twice the current available with both batteries.

You will need two of these items, one for each battery, in order to function. You will need to disconnect both batteries with these devices in order to prevent starting. The fuses in each disconnect can be reduced to 10 amps each, though not necessary. 20 amp fuses will still blow immediately on starting attempts.

ok thanks.......so one battery is still enough to start? If my starter doesnt need 2 batteries then why have 2? I know it gives me more cranking amps, but do I really need them? What happens if I disable one?

If you jump in your diesel in -4 degree weather the glowplugs cycle and there may not be enough juice to glowplugs AND the starter.
Diesels are very high compression motors, it takes quite a bit of turning torque to start one. When temperatures get REAL cold available amperages from the batteries decreases.
It probably would start with just one, but, honestly, I think it's cheap insurance.

If you jump in your diesel in -4 degree weather the glowplugs cycle and there may not be enough juice to glowplugs AND the starter.
Diesels are very high compression motors, it takes quite a bit of turning torque to start one. When temperatures get REAL cold available amperages from the batteries decreases.
It probably would start with just one, but, honestly, I think it's cheap insurance.

I see. So even if I put one of these battery master switches on only one battery, chances are, unless its really cold, someone could still start it.

Outa curiosity then, why are most Toyota diesels 24v? In particular the HDJ81 and BJ60.

24v systems use half the amperage. It would be great if everything was 24v or even higher. then they could run smaller gauge wiring. but thry don't, not yet any ways. but I have heard rumors of higher voltages coming.

So is that how it works, the more voltage you have the less amps you'll need for the same load? I take it then that it's a lot easier to drain amps from a battery than it is volts? I'm just wondering what the advantage for higher voltage is. If you use higher voltage but less amps, is the voltage drain about the same as if you used less voltage and more amps and drained more amps?

Basically what drains easier, voltage or amps?

You always drain amps-- the volts go along for the ride. 12 volt battery will show a little over 12 when completely charged and a little under 12 when it is under charged!:)