rb20det alternator in 240z

[zzzzed]

hi guys. I am just trying to nut out my alternator wiring. Does the white wire with red stripe that goes to the charge light get wired to the amp gauge seeing that the 240z does not have a charge light? I am having heaps of trouble trying to sort out whit wire goes where I cant find the correct wire in the engine bay that goes to the amp gauge

 

[Mr Camouflage]

Hi Mick

 

Maybe the 280z alternator swap instructions might be of help? Same concept - going from externally regulated to internally regulated alt.

 

http://www.atlanticz.ca/zclub/techtips/alternatorswap/index.html

[zzzzed]

Cheers mate. Ill check it out tomorrow when my tired brain can focus

[nizm0zed]

I have a RB30 alternator bolted to the side of my motor. It should be almost identical to the RB20 unit.

I have the fat white white straight to battery (as per usual) and the field sense wire runs through a diode and connects to the fat white wire.

Ala 1 wire alternator 

Once revs get over 2000rpm it starts to self excite and charging occurs as it should.

If you didnt want to do it that way, the field sense wire does require a small load on it, like a lightbulb.

I have read about a racer that connected it through his room lamp, so it'd stay on until the engine started.

If you dont have the load or the diode on it it'll keep the engine running when you turn the key off.

 

Now, as for the amp gauge, i ripped mine out long ago, so im going off rusty memory here...

Do you still have the shunt? or is that 260z only?

The main fat wire to the battery goes through the amp gauge, that way the gauge will read how much power the alternator puts out.

You shouldnt need to change anything in that regard in your setup.

 

edit:

This site helped me get my head around it somewhat.

http://mightymo.org/Proj_OneWire.html

[zzzzed]

Thanx guys all the wires are where they are ment to be exept 1.

The wire I am not sure about it the thiink white wire with a red tracer on the two wire plug on the side of the alternator. Where does that one go?

[Zedman240®]

When I had the RB25DE in my 240, I kept the RB alternator too. I remember keeping the original plug that goes into the alternator and made a plug in loom to adapt the 240Z wiring to suit the alternator. A diode had to be soldered onto one of the wires. I'll try to find the info..

[dat240z]

When I had the RB25DE in my 240, I kept the RB alternator too. I remember keeping the original plug that goes into the alternator and made a plug in loom to adapt the 240Z wiring to suit the alternator. A diode had to be soldered onto one of the wires. I'll try to find the info..

 

Correct. I did it the opposite though. I used the stock L24 alternator and bolted it onto my RB25det. No probs.

 

Also be careful of your amp guage getting really hot really quickly with the RB gear.... Ive disconnected mine (needle sits in middle of guage which is halfway). Otherwise you will see the amps bouncing at the top end of the guage followed by smell and smoke.... Disconnect it

[zzzzed]

Ok so I won't worry about the amp gauge maybe I will get an auto meter fuel gauge and get rid of the amp gauge all toggeather.

[dat240z]

Yeah mate, no need. I did the autometer ultralite tacho/speedo (direct fit). Then bought a white face kit for 3 stock guages as they are too hard to replace and still keep all info and neatness i think. I then painted needles fluro red to match autometre and youd struggle to tell them apart now. Just dont hook up the amp guage. Everything else is almost bolt on/hook up. Even the stock L24 oil sender and temp sender connect to the rb and let u retain original guages......

[Zedman240®]

A 260Z Volt / fuel gauge is what I'm planning to swap mine with...the amp shunt is a major bottle neck in the electric circuit in a  240Z.

[jamo240]

Hey zzzed.

 

Standard 240Z alternator wiring sees the alternator output go to the amp meter via the fuse panel thru a white/red cable. From the amp meter the cable changes color to white. The white cable then goes to the starter motor battery terminal via a fusible link. The way the charging circuit is configured, when the alternator is charging, the current flows to the electrical system via the fuse panel without going through the amp meter. So essentially, a +ve current output is showing the current flow to the battery....the actual alternator output is higher than this, as the current to the electrical system is in addition to this. When the alternator is failing to charge, full current flow to the electrical system goes via the amp meter, hence you are seeing total current flow from the battery.

 

The reason is that you are interested in current flow to and from the battery...not total flow through the system, as this is not important to understanding whether your battery will go flat...it's a very cool circuit configuration...i don't know why people get rid of it!

 

In my case, even starting with a very flat battery that will barely start the engine, my amp meter shows around 40A current flow to the battery, and there is no smoke or smel from the meterl. Current flow gradually subsides over time until the battery is charged. This is how you know your battery is charged...the alternator is now supplying power to the electrical system as required, but you will only see a small positive current, showing your battery is now charged.

 

This is how i configured my circuits in my installation:

 

Alternator output: Connected white/red cable through an 80A fusible link to existing white/red alternator output circuit.

 

Field excitation: Connected Black/white 'IG' cable through a diode to RB field terminal (light green cable). The diode prevents alternator output (once engine is running) from being fed back to ignition circuit which can prevent the engine turning off even after you key off. This is necessary as the standard 240Z voltage regulator is not there any more to perform this function.

 

Battery condition sensing: Take the white cable that goes to the 'A' terminal on the 240Z voltage regulator and connect to the RB sense terminal (red cable). This white cable is actually wired in parallel to the starter motor battery cable, and so is an accurate point to sense battery condition at.

 

Amp meters are a cool thing, and come from the halcyon days of sports cars. If you understand what they are measuring, they give you a very good indication of the state of both the battery and charging condition. Most people didn't understand what they were showing however, hence by 260Z they introduced volt meters to make life easier (simply give it a green zone between 12.5-14V, and people are happy campers if the needle is there). This was still too much for many to understand or care about, so lamps were introduced to complete the dumbing down process such that you didn't need to understand anything other than if the lamp is on when the engine is running there's a problem. For the mental pygmies who found that too confusing, we have now progressed to the 'check engine' warning to make it clear that action is required!

 

There is no need to install charge indication lamps to make the system function. As explained above, these were only introduced in cars without either amp or volt meters, and hence show whether the alternator is charging (the lamp stays illuminated if the alternator is not charging). If you have an amp meter, there is no need for a lamp!

 

Hope this helps.

 

Cheers

 

 

Jamo

 

 

 

[zzzzed]

Thanx mate that explains a lot