Fuse tap in 93 for second battery (1 Viewer)

[thehumaneraser]

Hey everyone.

I'm setting up a second battery in my 93 cruiser and I need to tap into a true ignition source for the isolator. I read a few things about tapping into a fuse and I think this is a better route to go than tapping into a wire. That said, I know basically nothing about electrical stuff. I busted out the multimeter and found a fuse that is live when the keys are in the car and not when the keys are out of the car but I have a couple basic questions before I tap it.

Apologies if these are stupid questions but I'm finding it hard to locate info online.

First, the fuse I found that's live is mysteriously labeled "Charge" and I can't seem to figure out what this is the fuse for. Is this one fine to tap? Also, I verified that it is dead when the keys are out of the car but when the keys are in, its showing only 0.75 volts. That seems really low. Why is that so low and is is that enough for the isolator? (Isolator instructions are super unhelpful here).

Other question is that I went to O'reilly and bought a piggyback fuse only to discover that the fuses in my cruiser are much bigger. Again, I'm a novice at electrical stuff, so I think it should be fine to switch out the factory fuse for a smaller one since the fuse is just meant to be a weak point in the circuit, but will this cause me any problems? The photo below shows the factory 7.5amp fuse compared to the mini 7.5amp fuse. Both are 7.5amps so its fine right? ...

Thanks in advance for the help!

 

[chap79]

Hey everyone.

I'm setting up a second battery in my 93 cruiser and I need to tap into a true ignition source for the isolator. I read a few things about tapping into a fuse and I think this is a better route to go than tapping into a wire. That said, I know basically nothing about electrical stuff. I busted out the multimeter and found a fuse that is live when the keys are in the car and not when the keys are out of the car but I have a couple basic questions before I tap it.

Apologies if these are stupid questions but I'm finding it hard to locate info online.

First, the fuse I found that's live is mysteriously labeled "Charge" and I can't seem to figure out what this is the fuse for. Is this one fine to tap? Also, I verified that it is dead when the keys are out of the car but when the keys are in, its showing only 0.75 volts. That seems really low. Why is that so low and is is that enough for the isolator? (Isolator instructions are super unhelpful here).
View attachment 2287542


Other question is that I went to O'reilly and bought a piggyback fuse only to discover that the fuses in my cruiser are much bigger. Again, I'm a novice at electrical stuff, so I think it should be fine to switch out the factory fuse for a smaller one since the fuse is just meant to be a weak point in the circuit, but will this cause me any problems? The photo below shows the factory 7.5amp fuse compared to the mini 7.5amp fuse. Both are 7.5amps so its fine right? ...
View attachment 2287543
View attachment 2287544

View attachment 2287545

Thanks in advance for the help!

What isolator did you purchase for your dual battery system? This will help us know if this circuit is required or not. Some systems require to be connected to the ignition circuit to be able to isolate the battery systems for highly sensitive electronics (sat/nav/life support). Also, the start/ignition circuit is not the same as the accessory on/run circuit.

 

[george_tlc]

IF you need to tap into Charge (this fuse is inline with the Alternator 'Charge/Light' output that goes to the dash to light up the Charge warning light), get the correct fuse adapter. The 80 uses ATC/ATO fuses. You don't want to muck with hacks - if you ever sell your 80, you will become the PO that the new owner will curse

cheers,
george.

 

[thehumaneraser]

I purchased a Stinger 80amp isolator from Amazon:

Stinger SGP38 80-AMP Battery Isolator and Relay


Thanks for the note about the fuses. I was trying to figure out what type they were so I could look for the right piggyback fuse and ATC/ATO is the magic information I needed. I'll go pick one of those up, thanks for the tip.

Also, after playing around with my multimeter a little bit I think I found a better fuse to tap in the main fusebox. Both of the headlight fuses are hot only when the keys are in the car. I'm not sure how I missed that before but those are reading at 12V so I think that'll be a better move than tapping the charge fuse.

Thanks for the info.