240z Alternator

[ta240]

Will the amp meter still register anything if you have a connection directly from the alt to the battery?

In my white Z the amp meter got fried so I replaced it with a volt meter before I did the alternator upgrades. In my orange Z I'm not up for ripping into it just yet to do something like that so I'm hesitant to move the high amp alt to the orange one. If the battery were ever to go dead in a parking lot that would be a lot of load to put on the wiring after jump starting it. With the alt trying to charge the battery on top of running everything else.

If you have direct wiring from the alt to the battery it makes sense to run add on accessories directly off the battery terminals, but with the stock setup wouldn't it actually be not the ideal setup as the amps have to make a complete trip from the alt through the interior of the car and back out to the battery. Putting a lot of wire between the alt and the accessory. And making it look like your battery is charging more than it is?

[Nissanman]

The ammeter is there to indicate what is happening to the battery.

If the meter reads in the negative, the battery is discharging into a load.

If it reads in the positive, the battery is being charged by the alternator.

Any direct connection from the battery to the alternator output, effectively shorts out the ammeter.

Therefore, the above two conditions are no longer indicated.

Normal operation with engine running etc. is a float voltage of ~13.8V, causing the ammeter to read just to the + side of zero.

To see the ammeter "dancing" is an indication of a wildly varying load and is demonstrating how effective the regulator and alternator are in compensating for that load.

As long as the battery gets a charge, all is well:classic:

[JimmyZ]

Restating ta240 and nissanman...

I think the Amp guage reads the amount of current not the force of it's flow. (Amps=current Volts=pressure of said current) Diverting the alt hot line would result in an inaccurate reading on the guage since it is not a volt guage on the 240. A volt guage would be better and not need the thick wire/lengthening of charging circuit. N-man you are right though. As long as it's charging who cares.

Don't know who's brilliant idea it was to run the wires as they did in this fashion. Think the 280's have volt meters so they must have figured it out by then.

The scary thing is that thick White with Red stripe running through the guage. It's handling all of the current. (From what I've seen) There is already enough going through it. My regulator malfunctioned and kept the field on (alt charging) which brought my charging volts to 16-17 volts. I caught a whiff of some wires getting hot and shut it down. Replaced the reg and no more fumes. Thank God. I did have bright lights while the alt was going nuts though:)

It would have been nice if the fusible link were still upstream. Might have averted the excitement if a proper fuse was used. I'll get around to replacing it someday.

Question for stock 240 fuse/link location.. (For authenticity/appearance sake)

The fusible link in question goes near the starter where the harness plugs into the White wire right?

[Nissanman]

The scary thing is that thick White with Red stripe running through the guage. It's handling all of the current. (From what I've seen)

The only current the ammeter doesn't display is that drawn by the starter.

Or at least, that is how it should be wired:ermm:

Choose your poison, ammeter/voltmeter, either is better than the alternator/charge lamp.

Don't be shy when it comes to fuseable links/maxi fuses etc.

They are a lot easier and cheaper to replace than wiring looms.

My '65 Fairlady has no protection whatsoever from the alternator o/p to the dash loom and ammeter.

The plan is to fit a maxi fuse [tucked under the alternator out of sight] to protect the whole deal.

Yes, the F/L goes at the starter, please replace it as a matter of urgency.

[Doesn't have to be an F/L, you can get maxi fuses now which are huge in current capacity.]

It will also protect the wiring if the battery is accidently connected frack to bunt:tapemouth

[ta240]

The scary thing is that thick White with Red stripe running through the guage. It's handling all of the current.

Yep, I found that out the hard way. On my white Z the fusable links were missing and I didn't know it. I was driving along when the car died and smoke started coming out the dash and filling the amp guage.

Had the car towed home and it turned out the alternator had shorted out and things heated up till the weak link (amp guage) gave out. I was very lucky it went before the wiring.

I replaced the amp part of the guage with a the volt part from a 280, bypassing the old amp guage connection. Added the fusable links and added a good sized wire with its own fusable link directly between the battery and the alt. Then proceded to add a fuseblock in the engine compartment which fed the headlights and other high draw items to take some of the load off the stock wiring.

I don't know if I want to do all that on the 'new' orange one so for now I'll leave the high amp alt off of it.

[Zs-ondabrain]

Just gonna throw this is, don't know what ya wanna do with it.....

When I first installed my headlight harness, the ammeter would kick over to the + side of the guage. It would go even further towards the + when I kicked in the foglights.

This told me that because the power was being drawn directly from the battery, while the alternator was pushing current into the amp meter, the flow was positive and showing so on the meter.

THEN, I added the ZX alternator and the effect was essentially the same. But then the power wire from the alt. started to overheat and melted the connector boot near the alternator. So I ran an 8 guage wire from the alternator to the starter. whiel keeping the opther Stock wire intact.

The meter no longer moves irradically when the lights, fog lights and amp is turned on (stereo) I'm guessing it's because I pretty much bypassed the meter by adding the 8 ga. wire directly to the starter which goes to the battery. It does move, ever so slightly, to the (-) if I turn everything on at once (stereo, lights, fog lights and fan) but the fan is the only thing on the fusebox side so go figure.

My harness's all but eliminate the major power draws from the fusebox so there is very little for the ammeter to justify moving any more.

FWIW

Dave.

[moritz55]

Dave - I'm interested in adding the 280ZX alternator and the Regulator Adapter (which I'd like to purchase from you). Can help clarify the 8 gauge wire you ran from the Alternator to the Starter?

Is the 8 gauge a HOT (RED) running from the Alternator Boot Terminal -- to the --> Starter HOT (Red) terminal?

Many thanks, Mark.

[sblake01]

My harness's all but eliminate the major power draws from the fusebox so there is very little for the ammeter to justify moving any more.

Dave, it sounds to me that with those upgrades a voltmeter would be more useful than an ammeter.

[Zs-ondabrain]

Sorry Mark, I never got notice of a post, must be a CZC glitch.

Anyways, YES, I ran and 8 gauge wire from the alternators (+) post, over to the harness, back to the starters (+) post. I also ran an inline 60 amp MAXI fuse for protection, in case of a short or something. Hey, it's a Z, anything could happen, as we've all dealt with or read about.

Dave.

[hd240z]

Dave, I presume you disconnected the original alternator wire when you added the 8 gage wire. Is that right?

[Zs-ondabrain]

When I addd the 8 gauge wire, it was as a back-up wire. so th original white wire is still there.

So roughly, because I added amperage to the system, I increase the wire size. If I had removed the original wire, ALL of the new amperage would be flowing thru the new one. SO adding wire and not removing the old is more of a "sharing" thing. I really don't care what my Amp meter says as long as I know the alternator is working, the battery is getting the voltage it needs and nothing is melting or over heating in the process.

I'm going to remove the clock, Add a White faced Volt meter in it's place, and look into building a "half and half" meter that has fuel level and water temp and then throw in a new oil pressure gauge. SO in essence, gauge 1 (on the left) will be oil pressure, gauge 2 will be fuel level and water temp and gauge 3 will be a volts meter.

I'll do the white face Tach and Speedo later on.

Dave

[hd240z]

Dave, I was thinking (and I know thats always dangerous) about the fuse in the 8 gage wire and what might result if "something" happened and blew the 60 amp fuse, then all the load would switch to the original wire and most likely burn it up. Would it make sense to install another fuse (40 amp?) in the original wire to protect it? I suppose it depends on the location of the problem, maybe the existing fuse panel or fuse link might protect the wire.

I like your plan to add a volt meter to the dash. It would look nice the way you describe it.