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Explain to me how my batteries are going to kill each other if they're not connected together when I park the truck. Even if I was missing a chunk of a plate and my #1 battery goes dead, I pop the hood and connect the 2nd one and jump myself basically. If I want, I can completely disconnect the first battery by simply disconnecting the negative cable from it.
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I misspoke, I knew you didn't leave your batteries connected all the time yet I pretended as if they were. Before I had the Ford solenoid in there I used to just use one jumper cable between the positive terminals to get the extra cranking power. I have 20' 2 gauge jumper cables. It's amazing the difference between even 2 gauge and 4 gauge, that's why I always push 2 gauge stuff now.
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Your schematic is interesting though. I didn't say I haven't considered an isolator, but the setups that are rated for the 140 amps my alternator is going to put out are few and far between, and expensive.
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I second that. Of the isolators I've found it seems you pay about a buck per amp. The nice thing is that the higher end ones are solid state and are better at current limiting instead of like the old or cheap ones with a self-resetting circuit breaker and the current limiting is a bit redneck or non-existent.
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Could you email me a better quality version of that schematic if you've got one available? Either that or contact me on AIM and transfer it to me. I'm always open to suggestions and this one isn't a bad one if done right.
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Here's a bitmap that is much better (but ten times larger).
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I agree on the solder/heat shrink stuff. If I had a dime for every corroded rat's nest I've had to fix, I would be so rich I'd retire at age 20, especially when I used to work on boats. Who knew a cheap crimp on connector would corrode in salt water? I now use solder and shrink tube almost exclusively. My soldering gun is going to get pretty warm when I do my TBI swap, trust me!
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You sound just like me. /forums/images/graemlins/grin.gif The only thing that sucks more than laying on your back under the dash with the brake pedal in your temple is doing it twice because you didn't solder it the first time.
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Ok now reading into your schematic, it appears that your isolator acomplishes two things for you:
1. allows you to ensure that both batteries charge all of the time, whether you're using number two or not.
2. allows you to switch on number two without getting out of the cab.
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Yeap and yeap.
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So, as long as I hook up my 2nd battery once in a while to ensure that it's charged, I don't have anything to worry about, except that if my alternator crapped out while I was driving somewhere, I'd have two dead batteries instead of one because number two is hooked up when I'm going down the road.
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Yeap. If I end up with a dead alternator the truck will tell me by the voltage gauge going down to around 11. I turn all the accessories off and I've gone 4 hours with my headlights on with the one battery. If I needed to, I could then run off the second battery. But when I stopped the battery was still charged enough to start my truck so I don't think you'll have that problem anyway. I think it's a battery going bad (plate falling off and shorting) that is the problem which you don't have to worry about.
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However, in your case, once that Ford solenoid is energized, you've got the exact same circuit I've got (electrically speaking).
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Yeap. The Ford solenoid is only used so I can operate the winch (which I don't have) or jumpstart myself without monkeying around. I plan on having a quick disconnect (which I don't have a source for) easily accessible front and rear.
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So, the only advantage is when the 2nd battery isn't connected through that solenoid, it can still recieve charge, and because of the diode, no worries about one battery killing the other?
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Yeap. See, I run my electric fans off the auxilary battery. Out in the woods, those fans could kill a battery in short order. In fact, it has on two occassions.
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Isn't the 40 amp relay going to be a problem there though? The alternator is capable of putting out 140 amps, and that relay is only rated for 40. I realize that no battery is going to charge at a 140 amp rate, but the potential is there, isn't it? Is that really a safe setup, having a 40 amp isolator where the alternator can put out nearly four times that?
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Actually, the circuit breaker will blow before the fuse or the relay does. The circuit breaker is self-resetting. I have blown fuses before, but they're those crappy little mini-ATO fuses that corrode and then create heat. Wal-mart only had mini-ATO fuse holders at the time when I did this. Someday I'll put a regular ATO fuse holder in. My isolator has no current limiting capabilities (or maybe it does, I don't remember which one I put under the hood) so under normal conditions the circuit breaker just blows.
Ideally, you'd want to have an isolator rated for more than your alternator can deliver. However, you should never have a battery needing that much current to charge it because it'll ruin a lead-acid battery. So therefore, you'd only need the isolator to provide the current for the loads. If you need more than say 50 amps, why wouldn't you just connect the two batteries together until you didn't have that load anymore? An isolator (a solid state one) offers resistance and heat to a system. If I had a high load (say more than 50 amps) I'd run it off the main battery so as to avoid the resistance of the rest of the system.
I'd never run a winch through an isolator anyways. You want peak voltage to operate the winch so you have less current flowing. Ideally, you'd run with the motor on which the alternator tries to push 13.8 volts and two batteries trying to deliver 12.6 volts. The load requirements (say 400amps near stall for a 5 horse series wound motor) will suck around the 90 amps that a 100 amp 12SI alternator can deliver at idle and then another 100 amps out of the main battery. It'd then suck the remaining current out of the other battery due to voltage equalization.
