Ok.. I have purchased my new double core radiator, my taurus fan, and my delta controller. See Houlster's thread for details on what I intend to do with it all.

http://www.4x4wire.com/forums/showflat.php?Cat=&Board=UBB86&Number=746041

My questions come in with the wiring of this and other aftermarket accessories (in a minute). I was under the impression that a high amp draw item such as this would need a higher amp alternator to operate it (I currently run the stock 50 amp unit) along with AC, lights, blowers, etc. So I purchased a ford 3g alternator remanned to 200 amp capacity (I like to be sure, ok??) and will do the alternator mod like Phil and Richard did here.

http://www.4x4wire.com/forums/showflat.php?Cat=&Board=UBB86&Number=613359

My question comes from seeing the instructions for the delta fan controller. It shows wiring the fan controller directly to the positive and negative battery terminal. In this configuration, how will the higher amp alternator be powering the fan during normal use? If I were to add other accessories could I simply come off of the positive battery terminal as well? Would the alternator power the items "through" the battery somehow? I was thinking that I would need to slip into the existing wiring to set these types of things up?
Thanks for helping to clarify this for me.

JD

The battery powers all in your electrical system. The alternator just keeps the battery charged as needed. It does not matter if you hook directly to the alternator, the battery or through the fuse box. There is only one electical system. 12v is 12v. ground is ground.

The delta fan controller you wire directly to the battery because it's a high draw item. Same as the starter and how you'd wire a winch too. The controller has short protection built into itself so there is no fuse, fusible link or circuit breaker in it's power wires.

BTW, you won't need anywhere near 200 amps. Your 50 amp alt will probably keep up with the demand fine most of the time. In normal use, the fan's only gonna draw maybe 10 to 15 amps, and probably nothing at higher speeds. Maybe if you're over-heating so the fan's at full power, at night with the lights on, stereo blasting, in the rain with wipers going, etc. That's one of the nicer things about the controller, it only sends enough power to the fan to keep the motor cool. With the full shroud and double row radiator, I wouldn't expect it to need full power very often.

I think upgrading the alt is a good idea (50a is a bit small), but realize the alt will only put out the amps that the vehicle is drawing. When you exceed the alt's limit, the battery fills the gap, then charges back up when the load drops below the alt's max output.




Yes, but I'm not a real fan of running a bunch of wires directly to the battery. It gets messy and confusing as heck after 6 months and you don't remember what wire is what. It's much cleaner to get an aux fuse block. Run that to the battery through a fusible link, then hook your accessories to the fuses in that. If you go with junkyard parts, you can find small blocks with fuses and relays as well for higher loads. Draw a diagram of your fuse block and update it with what fuse goes to what as you add stuff and it makes it easier for future maintenance.




This is only a suggestion. I've wired in an aux fuse/relay block from a junkyard (TJ I think. this block is nice because even though it's big, it's filled with small removable sections for fuses, relays or fuse/relay combo that you can pull out rather than use the whole thing). I've got power to it from the battery, and also a power wire that comes on with the ignition, and another that comes on with the charge relay so it's powered only when the engine is running.

When I need to add an accessory, I can use an empty fuse and/or relay to power it either all the time, with the ignition or the charge relay depending on which power wire I use to trip the relay.

--Dan

BTW, are you replacing your stock alt? How are you planning on handling the charge relay? You can make it still work with a 2nd relay, but you need to dive into your stock fuse box and move some wires around. Not a big deal. I touched on it in Randii's thread you linked to above but I'll post more details later.

--Dan

I was going to go the same route as Phil at the bottom of this quote.. I could just leave the stock alt in place too, making 250 amps available.. I can put a converter and power strip in the bed of the truck and go camping with a big screen TV and DVD player!!

JD

I could just leave the stock alt in place too, making 250 amps available..

You can't do that as it just does not work like that.

See HERE for starters.

The shorter story is that running dual alternators is close to impossible. Not totally impossible, but very close.

Michael

great info. Thanks for the link. I think I will just run the new alternator solo. It should more than meet my needs. Photos and progress reports as I get into this (after I get home in a few months). Thanks again.

JD

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This doesn't sound like the best idea. While this does work, it kinda doesn't either. The output from the alternator goes to batt positive. If you splice the charge relay into that, you're energizing it *all* the time. Even with the truck off. The charge relay no longer comes on just when the engine is running.

This means:
The charge light won't come on (ever).
In case of an accident, a dead engine won't stop the fuel pump.
The battery will go dead if parked long enough (okay, a long time maybe).

And, Phil's wiring must be slightly different than mhy '94 Amigo. On mine, doing this would result in things like the fuel pump running *all* the time, air regulator powered all the time and everything else the charge relay kicks off being powered all the time. These obviously can't be happening for him so you should really study the wiring diagrams for your truck to see what will happen. You could even test it now with your current alternator in place and put in a jumper from the alt output like he did.


To do it like this you should use a really BIG diode. Cut the main power line from alt to battery and install the diode so juice goes from alt to battery, but can't go the other way. When you splice in the wire for the charge relay, do it between the diode and alternator so it can't get power from the battery, only from the alternator. This is is a pretty good way to go, but you need diodes rated for at least the max amperage of your alt and this can be big, expensive and/or hard to come by. Maybe you could scavenge the rectivier diodes from another alt...???

Secondly, does your alt use a separate battery sense wire? That will need to be run to battery to sense battery voltage. A lot of alternators (most GM and our Isuzu one as well) have a separate pin for battery sense, but it just taps into the the alt output to the battery at the wiring connector for the alternator. With the diode in place, it'll no longer work. You'll need to re-route this so it connects between the battery and diode so it can sense battery voltage. Some alts have this connection internal. If that's the case, you're screwed or will have to do surgery on your alt.

--Dan