Dual Alternator on a desmogged 2F

[cruiserAUS]

Hi Tony,

If you add up the amp draw during a typical winter day in the nw (headlights, heater fan x2, rear window defog, windshield wipers, stereo) it's enough to cause a pretty good voltage drop at lower rpm...ie the stock 55amp alt can't keep the system at 14/14.5 volts. Everything electrical works better at 14.5v. If you add a second set of driving lights, especially for night wheeling where you're going slower, you're pushing the limits of the stock system even further.

In my opinion, the stock electrical system is just adequate, but if you add stuff it's no longer sufficient and needs an alternator upgrade.

Also, with a desmog, the space occupied by the smog pump is available to do something with. I have a jim-c pully, and that's a much easier/quicker way to replace the smog pump.

I went this route for four reasons: redundancy, to increase the reserve capacity of the electrical system, to see how it would work, and to document the results.

Do you want to sell the Jim C pulley.

 

[ntsqd]

Thinking about the "dueling alternators" potential issue, though Toby's explanation makes sense to me if it really bugs you then you could put a switch in the exciter wire for one of them and be able turn it off when the batteries are combined. That would defeat having two alts operating while actually winching. Do you make that many really long pulls?

 

[lovetoski]

Ok, time to finish up this thread. I got the wiring figured out and completed a couple of months ago, and have been testing it (aka just driving around) and all works fine.

One key question is why do this? The way I wired it up is to split loads between the two alternators. At idle, or lower rpm, with lights, fan, wipers, heaters, etc all running the amp output of the stock alt is insufficient to keep the volts at the optimum 14.5v. It just becomes worse as you add loads (additional lights, etc).

The headlight harness + additional lights are on the second alternator. Done this way, there are sufficient amps to keep everything electrical at the happy value of 14.5 volts. I've also wired things I'll use in camp to the second battery, so I can run it dead and still start the motor.

So, the reason to do this is: improved functionality, redundancy, replaces the smog pump.

However, the easier route would be to install a tundra alt, with a VSR or similar + a jim C pully. That would be way easier. Way easier.

Anyway, this works, I like it, and I enjoyed the puzzle in figuring it out.

Getting the sensing wire set up right was the biggest hurdle. I ended up using a relay, switched by the ignition. When the ignition is on, the sensing wired is connected to the secondary fuse box. When the ignition is off, the sensing wire is disconnected from the secondary fuse box. Without the relay the battery discharges through the sensing wire, causing the battery to go flat, and worse. The relay works perfect.

You'll also notice that I wired my winch to the secondary battery, and mounted the albright solenoid to the battery holddown.

Heree are some pics of the final result. Let me know if any questions.

 

[lovetoski]

Here's a better pic of how the albright ended up. The two loose wires (blue and yellow) will go the the external winch controller when I get it wired in. Currently I have only the in-cab controller wired in place.