Alternator question

[kamikaZeS30]

If you have a 240Z then THERE IS NO WIRE GOING FROM THE ALT TO THE BATT without passing through the AMP gauge and ALL of the factory wiring FIRST. If you connect stereo equipment or big fans to your BATT +post then you are going through every inch of factory wire, every cruddy splice, and the AMP gauge shunt, BEFORE you get power to your ADD-ON stereo/fans/etc. DO NOT CONNECT stuff to your BATT+ post until you eliminate the AMP gauge and bond the factory power wires together in the 2 places I describe.

 

Let me see if I understand what you're saying: all I would need to do from this point is disconnect the shunt, then remove the two power wires from the back of the gauge, replace with heavier gauge wires, but they will terminate at the firewall. These wires should then be connected from the alternator and the battery positive from this point and then I would run my stereo-power and electric fan power from this distribution, with a final smaller gauge wire running into the rest of the harness?

 

That sounds simple enough, but I am having trouble visualizing it. I will see if I can find my Hayne's manual diagram...

[bjhines]

The published wiring diagram is not exactly what they did in practice. The fuse panel is all wrong. There are 2 large white(one with a red stripe) wires behind your gauge. The shunt is part of that gauge.

 

Remove the gauge.

Connect the 2 large existing wires behind the gauge.

Unwrap your harness near the firewall and out to the alternator, you will find those 2 wires.

Attach a junction block to your firewall where you have plenty of room.

Make a new alternator wire, make a new BATT wire,

Connect all 4 to the junction block

 

Use fusable links, properly terminate connections, and make sure you add any power circuits at the junction block.

 

There are many unused wires that run to the external regulator plug. You need to get rid of those. Make new wires according to your alternator.

Edited December 6, 2010 by bjhines

[kamikaZeS30]

Yeah, I see what you're saying, now.

 

The diagram I have shows the primary cables going to the starter, but then there are other wires going from the alt to the fuse block and then to the AMP gauge. But, I don't remember anything going from the fuse block to the gauge inside the car.

 

Was there maybe a difference in how they were wired from the factory between the series ones and the series twos?

[bjhines]

I think the diagram was never intended to be a true representation. It is just enough to do a little troubleshooting and that's it. There are DOZENS of mistakes in that diagram. There are a lot of things entirely left out as well.

 

I purchased a laminated, large format, color print, wiring diagram that someone did on Ebay. That was a complete waste of money. The person who did that only copied the factory ~representation~, along with all of it's mistakes.

 

I sat down one weekend to make a TRUE TO LIFE wiring diagram. I had unwrapped 2 harnesses from 1972 and 1973. I got part way into the project and decided that I would never gain anything from it for the time it would take. I really cannot fix the original diagram, I would need to start from scratch and completely reorganize the entire layout.

Edited December 6, 2010 by bjhines

[Wilson_WWSC]

So if I'm reading this correctly, hooking things up to the battery increases voltage drop (more wiring) than to the alternator? What should I have hooked up to the battery (starter, amplifier wire)? How do I hook other electronics up to the alternator, such as power for HID's (I have relays to turn on with the 240z harness)?

[bjhines]

The harness was designed in 1968, to use no more than 45 AMPs. Everything about the original electrical system is inappropriate for modern electrical devices. The external regulators are noisey, unstable, wiring has gone bad, etc. The original alternator is heavy and weak compared to todays versions. The whole idea of an AMMETER as a useful gauge is antique and misleading. Anything you add to the electrical system is going to make the AMMETER less accurate.

 

I outlined my method for fixing these problems in the previous posts. You need to get rid of the AMMETER and re-route your power distribution accordingly. This will isolate the original harness and all of it's weaknesses.

 

If you are hooking things up to the battery posts then you are only creating more problems. The battery+ is the furthest from the alternator in the original power distribution circuit. The battery does not run ANYTHING in your car when the engine is running. The battery is just another drain on the alternator. Anyone who thinks the Battery will somehow buffer power draw is completely wrong. The battery makes the power problems WORSE on the harness and alternator when you hook things up at the BATT +post.

[Wilson_WWSC]

Thank bjhines, your info is very useful.

 

This is my current situation:

I'm pretty sure it is the stock alternator.

The right terminal is "A" and the left terminal is "E."

 

From w = v x a, my HID's pull about 12 amps if I have all 4 on. I have a deck installed, nothing fancy, something you would find anywhere.

 

So this is what I want to do: replace the alternator with a higher amperage one, probably a 3 wire GM model (around 100 amps). What I want to know is: can I attach the factory wire loom AND a wire from the alternator directly to the battery? In the case of the stock alternator, what I would be suggesting is keeping the factory wire on "A" and then adding a new wire from "A" directly to the Battery + terminal. If this were to work, would I add a terminal block for accessories off the battery or "A" on the alternator? Would this method bypass the factory loom for the accessories to pull enough power without setting wires on fire?

 

If this doesn't work, then I will go with what bjhines has suggested, but I am a visual learner, and I can't seem to picture the set up you suggested here:

"You can remove the AMP gauge and connect the two heavy gauge wires using a brass bolt and nut(insulate the connection when done). Then connect the Factory BATT and ALT wires near the firewall and make all power-circuit branches at the firewall distribution block.

ie. New ALT wire(with fuseable link 6g), New BATT wire(with fuseable link 6g), Factory ALT wire(w/fuseable link 10g), Factory BATT wire(w/FL 10g), Additional power wires(fused individually), etc(fused ind)."

 

Can you or someone make a simple cartoon of this set up (besides the connecting of the 2 ammeter wires)?

 

Keep in mind that I will be doing this with a new GM 3 wire alternator. I have not figured out how to wire one of those yet.

 

Again, thank you to all for the help. I don't think I could have done so much on my Z without the help of the HybridZ community.

Here's a pic of my car as it is now:

[Wilson_WWSC]

Thank bjhines, your info is very useful.

 

This is my current situation:

I'm pretty sure it is the stock alternator.

The right terminal is "A" and the left terminal is "E."

 

From w = v x a, my HID's pull about 12 amps if I have all 4 on. I have a deck installed, nothing fancy, something you would find anywhere.

 

So this is what I want to do: replace the alternator with a higher amperage one, probably a 3 wire GM model (around 100 amps). What I want to know is: can I attach the factory wire loom AND a wire from the alternator directly to the battery? In the case of the stock alternator, what I would be suggesting is keeping the factory wire on "A" and then adding a new wire from "A" directly to the Battery + terminal. If this were to work, would I add a terminal block for accessories off the battery or "A" on the alternator? Would this method bypass the factory loom for the accessories to pull enough power without setting wires on fire?

 

If this doesn't work, then I will go with what bjhines has suggested, but I am a visual learner, and I can't seem to picture the set up you suggested here:

"You can remove the AMP gauge and connect the two heavy gauge wires using a brass bolt and nut(insulate the connection when done). Then connect the Factory BATT and ALT wires near the firewall and make all power-circuit branches at the firewall distribution block.

ie. New ALT wire(with fuseable link 6g), New BATT wire(with fuseable link 6g), Factory ALT wire(w/fuseable link 10g), Factory BATT wire(w/FL 10g), Additional power wires(fused individually), etc(fused ind)."

 

Can you or someone make a simple cartoon of this set up (besides the connecting of the 2 ammeter wires)?

 

Keep in mind that I will be doing this with a new GM 3 wire alternator. I have not figured out how to wire one of those yet.

 

Again, thank you to all for the help. I don't think I could have done so much on my Z without the help of the HybridZ community.

Here's a couple pics of my car as it is now:

[rejracer]

Also, unless I'm completely retarded, how would upping your alternator's amperage rating start fires unless you actually put that kind of load on it? Not to mention you'd have to eliminate any kind of circuit protection like fuses.

 

Wire components in for the worst case scenario, rather than what you want it to be. If you have a dead battery, and you start it up, and then increase the rpm, then the alternator will be charging at full tilt for x minutes.

 

 

If you are hooking things up to the battery posts then you are only creating more problems. The battery+ is the furthest from the alternator in the original power distribution circuit. The battery does not run ANYTHING in your car when the engine is running. The battery is just another drain on the alternator. Anyone who thinks the Battery will somehow buffer power draw is completely wrong. The battery makes the power problems WORSE on the harness and alternator when you hook things up at the BATT +post.

The battery will "buffer" power draw once voltage drops below it's stable charge state (roughly 12.5 volts). So it's not stable voltage by any means. Also with the factory wiring harness the voltage at the device using the power will be lower than 12.5 due to the losses in the harness. Everything BJhines is saying I agree with, except I would add the one detail on the buffer bit. I will say that if someone is running old school technology (carb, points distributor) then the voltage is not much of a concern, assuming dimming lights and slow fans don't bother you. If you are running a modern computer controlled fuel / spark system then the stock system is not adequate.

 

I think what is really needed is an accurate diagram, (which I think I created in the below thread) so one can easily track the power path from the alternator to whatever device you are concerned with.

 

 

BJhines,

I just completed my 240z charging system upgrade consisting of a 200 amp alternator, heavy duty battery cable assemblies, Aux Power Posts, circuit breakers, and eventually Volt meter. I can tell you are not a neophyte in the ways of the electron, so would like your input on my setup. I created the diagrams based on the 72 / 73 FSM. So far the FSM is accurate in the engine bay, up to the firewall. When I go for the Voltage gauge install, this will tell me how accurate the FSM diagrams are from the firewall to the Ammeter and fuse block. My plan so far is to cut out as much of the old white / white red going to the ammeter as possible.

[kamikaZeS30]

What I ultimately ended up doing is similar to what bj was saying. However, I still need to find a distribution block that fits my needs. Right now everything is running off of BATT+, but I divorced the electrical system from the alternator and it and the battery are connected directly. Running off BATT+ as a temporary "I need to drive the car" solution. So far nothing seems fishy, in fact, my lights are brighter, stereo seems to be getting the juice it needs and the voltmeter indicates that I have very little voltage loss (14~15 when alternator is on, 12~13 when disengaged-- it's "seeing" the voltage towards the end of the harness, away from source).

[zdlite]

I really like that MADD electrical site. They have a lot of good information and ideas.

 

Also want to echo what BJ is saying about 240’s. I did basically what he is saying but want to add a couple of ideas. First buy a fused distribution block and second a voltmeter from a 280Z attaches right to the back of the 240Z front bezel.

 

Car stereo places sell fused distribution blocks that are perfect for what is being done. They allow you to attach a 4 gauge cable from the alternator to the distribution block. You then have up to 4 fused circuits to wire the rest of the car. Some of them even have built in digital voltmeters, how cool is that for a quick under hood check?

 

http://www.hifisoundconnection.com/Shop/Control/fp/tcat/28049/SFV/30046

 

I have an 85 amp Denso alternator. I put a 4 fuse block up near the radiator and connected it to the alternator with a 4 gauge wire and 85 amp in line fuse. On the back side I used a 40 amp fuse in one of the fuse lines to route a 10 gauge wire to the battery, I hooked the two power wires from the two sides of the fuse box to the second fuse (I forget what amps I used there, either 20 or 40), then used the third fuse to power the electric fan.

 

Instead of using a brass nut to connect the ammeter wires together I spliced, soldered and heat shrinked a connection.

 

The 280 voltmeter has a charge indicator light. I hooked that to the Denso alternator. I then hooked the voltage sensing wire into the fuse box. The voltmeter and charge light give positive indication of the charging system health. They both came in handy when my car threw a belt the other day. Kept me from overheating it.

Edited May 6, 2011 by zdlite