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#1 herrods

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Posted 31 October 2009 - 08:36 AM

I've done a search but found nobody with a similar issue to mine.

260z will start from a jump start, and after disconnection run for about 3 minutes and cark it, voltage meter gets right down to 6v when this happens.

Battery is holding 11.5v off and 11v on, alternator pushing out 10.8v.  I just pulled the alternator and the external regulator out and the electrician replaced the rectifier in the alternator.

obviously I have to go back down and ask him what he did/failed to do, but where does one purchase a new regulator.  mine is an ingram external regulator same as toecutters (from previous thread pic.)

any ideas? or ways to rule things out wld be handy (what happens if I unplug the regulator and run it, (there is a big sign sayign dont do this so i assume its bad...))



#2 Zedman240®

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Posted 31 October 2009 - 10:19 AM

Sounds to me your Regulator has failed. Reason the engine dies is because the car is running off the battery instead of the alternator. If the alternator can't supply enough power, the engine gets that power from the next available supply (battery), after that is gone...engine stops! A battery with nothing running/being used should be around 12.5. With the engine cranking, go no lower than 11.0V and with the engine running with most accessories on, be around 13.8V. Most auto shops should carry those regulators...or go to a wrecker that have warranties for the cheapest option.

#3 dazzed

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Posted 01 November 2009 - 10:36 AM

if there are ever any charging issues in a early zed never rebuild ,, upgrade ,,, alternator output is way to low waste of money playing with the 40 amp alternator ,  do you have a charge light in your volt gauge if so does it glow when the ignition is on, if not put a new globe ,,the globe circuit is part of the charging system if it is blown alternator will not charge , very rare for regulators to pack up , battery should be fully charged ,  an alternator will not charge the battery fully , unlike a generator generates its own current alternator wont , how old is the battery??? keep it simple

#4 pauly_adams

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Posted 01 November 2009 - 01:29 PM

i had the same problem it turned out that my alternator had been rebuilt and i put an external regulator on long story short when it was rebuilt it had a internal regulator installled, since taking it off i have had no problems.


cheers pauly 


#5 tbscobraZ

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Posted 01 November 2009 - 05:23 PM

I have the same problem and after searching around it's a poor grounding problem [for me anyway] probably worth looking at.

#6 dazzed

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Posted 01 November 2009 - 10:07 PM

generally speaking the zed electrics are very reliable  just like toyotas, but where getting a bit old in the tooth now , and most people have powerfull headlamps , high power stereo, electronic ignition, and if you still have points well just trying to fire the unleaded fuel requires a bigger demand from the ignition system, on my 240 i deleted the amp gauge and fitted a bosch or bocsh, 80 amp alternator with built in reg and a 260z volt gauge with a light in it , piss of the amp gauge its a fuse drags pwr just to pass current through it thats how it gauges the amps draw and on top of that you have this pissy 35 amp alternator that wouldnt pull a greasy stick outa dogs arse , dont piss fart around spending megga bucks on your retifyer , when you should be rectifying the problem,

#7 Add

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Posted 05 November 2009 - 09:40 PM

I am sorry if this is thread jacking but I have been having a similar problem. When checking the negative terminal from the battery its earthed to the gear box. However, after checking the old man's ute it goes Battery ->Body -> Gearbox. Could someone please advise on what the grounding should be? Or is this correct.

Thanks in advance,
Ad

#8 Scoota G

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Posted 06 November 2009 - 09:16 AM

I have three seperate earth's to the engine (one near the distributor one at the gearbox and one at the rocker cover) and one to the Chassis.

#9 Zedman240®

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Posted 06 November 2009 - 03:27 PM

You can never have too many earths. Think of electricity flowing like a highway. You can't have a 4 lane road heading out and a coblestone laneway for inbound traffic; Both have to be as good as each other.

#10 herrods

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Posted 08 November 2009 - 10:19 AM

**update**

I managed to "rectify" the problem for the track day, but it has since packed in the towel again.

It seems my charge system has a mass comedy of errors in one hit.

The core of the problem was a "centripital short" inside the alternator, which was of course found last, and the fault of the auto electrician who fixed it the first time round.

So the order of proceedings was the centripital short was causing an overvoltage making the reg kick in which stressed the reg and blew tyhe fuse inside the reg

regulator problem solved

because the fuse in the reg was tripping over anbd over, we decided to check the grounding.  The wiring in one section of my loom had undergone some weathering making the ground dodgy and rusted (split insulation) so we fixed the wiring by replacing all the main power and ground wires to the battery, starter motor, alternator and in and out of the fusible link as we foudn all of them to have splits int he insulation and some rust getting in to the copper

Wiring Issues Fixed

After this it would provide good voltage, but after a bit of RPM or heavy load at low RPM it would re-blow the fuse int eh regulator, which is the point where we had the alternator re pulled apart and the short was found.

5:30pm on melbourne cup day the day before my track day, problem solved with a warning that the alternator probably wouldn tlas the full day at the track

Turns out the alternator did manage to last the full day at the track, and then failed about 2km from home

Its off the the electricians to be rewired with a new higher powered bosch alternator with internal regulator.

Dave

#11 RB30X

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Posted 29 December 2009 - 02:29 PM

I've got a seperate charging issue which I thought I'd tag onto this thread.

I've just installed a spare alternator from a 280ZX with a 'voltage reg' (black plastic cover thing on the back of the alternator) onto my L24. With a full battery 12.4ish volts, when the engine is running the alternator is spitting out 16.5-17.5 Volts depending on revs which weren't really that high. The only load on the battery would be the coil and fuel pump, nothing else. If I pull out the two wire Tee harness plug at the back the volts drop down to normal but it obviously means the battery isn't charging though. The engine revs also slow down if this plug is in and rpms increase again when the plug is pulled out.
Do these symptoms indicate the voltage regulator is stuffed??

#12 Zedman240®

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Posted 29 December 2009 - 04:42 PM

Have you removed/unplugged the original regulator that's mounted on the side of the engine bay? You can't have two regulators running together.

Here are some instructions on how to install a 280ZX alternator in a zed with an external reg:

Converting to an internal regulator alternator

Question: I would like to know if anyone has converted from the external
regulated alternator to an internal. What wiring did you change?

Answer: First a little background: The 60 amp internal regulator alternator was used on the '78 280Z and then the non-turbo 280ZX. I have also seen it on the '78-'85 810/Maxima and the '81-'85 720 pickup trucks. It is marked "LR160" on the case. There was also a 70 amp version (marked LR170) that was used on the 280ZX turbo's.

[Note: It looks like the '84-'86 non-turbo 300ZX 70 amp alternator could be used as well, but the wiring connectors are different, so get (i.e., cut it off) the corresponding engine harness connectors as well if you get one of these alternators. I'll write this up this conversion later.]

Because I don't like to give instructions without some explanation of what you are doing (it makes troubleshooting easier), I will start by describing the internally regulated alternator's electrical connections:

1. An "L" connection which goes to a "switched" 12V supply. By this I mean a 12V source that is active only when the ignition switch is in the ON position. I use the mnemonic "L" for "lamp", the alternator warning lamp (if used) is in series with this connection. This terminal also supplies the "excitation" current to the alternator field winding at engine turn on, allowing the alternator to begin producing voltage as the engine is ramping up to idle speed. Once the alternator rotor is turning fast enough, it generates it's own supply for the field winding and the current in the "L" connection stops flowing. The warning lamp (if used) goes out.

2. An "S" connection which goes as close to the positive terminal of the battery as physically possible. The "S" connection "senses" the battery voltage and this is the voltage that the regulator is tying to control. This connection has a high impedance, so it only draws only micro amps from the battery, so it can be left connected without fear of battery discharging.

The "L" and "S" connections are in the plug connector on the rear

of the alternator that looks like the capital letter "T". The top

of the "T" is the "S", and the other part of the "T" is the "L". Or

in crude ASCII art:

                        "S"

                    ...............

                    :  -------  :

                    :....  |  ....:

                        :  |  :

                        :  |  : "L"

                        :.....:


3. An "A" terminal, which is the output of the alternator, which also is connected to the positive terminal of the battery. This connector carries the charging current. Because of the high currents this wire must carry, it is a low gauge wire, which means it has a large cross sectional area. For safety reasons, a fusible link should be in series with this connector. The "A" terminal is the insulated threaded stud on the rear of the alternator.

Of course, someone may ask: "Why do you need two separate (the "S" and the "A") connections between the battery and alternator?". It is because of the fact that even large wires have some resistance, and therefore there will be a voltage drop between the alternator and the battery when the battery is being charged. If the regulator sensed the alternator output (which is higher in voltage) and not the battery terminal, the result would be undercharging of the battery. Now there are alternators which work this way, but they need a fairly large diameter charging wire to reduce the voltage drop. The separate "S" connection is a much better method of regulation.

4. There is a "P" terminal on the 280ZX turbo alternator (but have also seen it on a few of the non-turbo 280ZX alternators). There is not a corresponding connector on the engine harness to mate with the "P" terminal, even on the turbo 280ZX's. So, the "P" terminal is not used/needed.

5. Finally, there is a ground connection on the alternator, although the case is a pretty good ground connection to the engine block.

Now, the following procedure only applies to the 240Z. The 260Z has electrical connections between the regulator and the interlock module and the electric fuel pump, so it's more difficult to convert to an internally regulated alternator, but I have a procedure for it as well. Please email me directly if anyone is interested. I have not looked into converting a 280Z, but I would think that it would be possible as well.

1. Disconnect the battery.

2. Unplug the external regulator and note the color code of the wires that are on the regulator connector of the engine wiring harness. You will be connecting some of these wires together, so get another plug from a junked regulator or cut the one off your old regulator. Now the wire colors I will be referring to are on the regulator connector of the engine wiring harness. This is because although the regulator wire colors match the engine harness with the stock regulator, I've noticed that some aftermarket regulators have a different wire color code.

3. Connect the white wire to the yellow wire. This connects the battery to the "S" input.

4. Connect the black with a white stripe wire to the white with black stripe wire. This connects the "L" terminal to a switched 12V.

5. Disconnect and unbolt your old alternator. Bolt up the new alternator. Depending on what particular internally regulated alternator you use (I've seen different pulley sizes), you might need a different length belt.

6. At the alternator, connect the white with red stripe wire of the engine wiring harness to the threaded stud (the "A" terminal) on the alternator. This connection provides the charging current for the battery. Connect the black ground wire to the alternator. Don't forget to include any bypass, or filter capacitor. Plug the two-pin "T" connector into the alternator.

7. Re-connect the battery and start the engine. With a good digital voltmeter measure the voltage directly across the battery terminals. This is the charging voltage. It should be 14.7V +/- 0.3V, but this voltage is a function of the ambient temperature and the state of charge of the battery. If the voltage reading is not correct, then re-check your wiring. More than 15.0V indicates that the "S" connection may not be connected correctly.

SPECIAL NOTE:

I had this problem and thought I'd share the solution. Many thanks to Ken Osman and Steve Golik who provided the solution:

When an internally regulated alternator is put into an early Z and the external regulator is removed, you often have the problem that the car will not shut off when the key is turned off.

You have to put a diode in series on the wire that goes to the "L" terminal on the back of the alternator. The "L" terminal is the bottom contact on the "T" shaped connector.

You have to connect the cathode of the diode (identified by a stripe on that end of the diode) to the "L" terminal and the anode (other end of the diode) to the wire that previously went to the "L" terminal. In my case (71 240Z) this was a white with black stripe wire. This prevents the "L" terminal current from feeding back into the ignition circuit when the key is turned off.

The diode I used was a 1N5402, other people have used a 1N5400 or a 1N5062. Easy fix to a vexing problem.

Side note: when I fixed this I connected the Yellow wire in the harness which leads to the alt to the "S" terminal (top of the "T" connector) on the alt - PO had spliced white/black wire into both the "L" and "S" terminals - my under hood light started working. WHOOOHOOOO!

Damian
71 L28 now shuts off with the key!

#13 RB30X

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Posted 29 December 2009 - 05:11 PM

Thanks but, could you go over that one more time????

I'll get up early and read that tomorrow. ;D

#14 herrods

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Posted 29 December 2009 - 05:41 PM

I had that same issue with mine.

What would happen is that the alternator would put out somewhere between 16 and 18 volts, and after a bit of revving, drop the current all together by blowing the fuse in the regulator.

I took the alternator to the alternator fixit man, and he pulled it apart and diagnosed it as a "centripital fault"

What this apparently means is that the alternator waws being spun too fast.  The original alternator could not keep up with my new 2.9L engine revving out to 7500 all the time.

Your alternator could also have said centyripital fault but not be so far gone as to blow the regulators apart yet.

thats my 2c worth

#15 RB30X

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Posted 30 December 2009 - 09:10 AM

Mine is putting out those volts at a fast idle though, not high rpm???

OK, I've spent the day in the shed with litres of sweat dripping off every hour but I kept telling myself, I love Datsuns ;)
I tried Nzeders advice, I hooked up an external voltage reg which came with the 240 but don't know what model it is actually from. Still getting too high voltage to the battery.
Can anyone tell me if this 280zx alt has a built in voltage reg?
Posted Image
And this is the one originally on the 240.
Posted Image

What would be really handy, if anyone could scan or link a wiring diagram for a 280zx that i could compare to the 240/260z manual to look for differences.

cheers



#16 Ben

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Posted 30 December 2009 - 09:15 PM

REgarding high voltage at high rpm's - get an under-drive pulley
:)

Regarding the images above - yes it looks like an internally regulated alt. to me.

Note regarding the (rather good) tutorial above - the ADM 260Z doesn't have the seatbelt interlock system mentioned, so that isn't a variable in the upgrade process.

Long story short; - S to battery, L to lamp (ideally with diode, but a decent lamp will do the same job) insulated post to battery via fusible link. IGN is black with white stripe, and it should all fall together.
:)

Any excess wires in the old external reg harness can just be left unplugged.

#17 RB30X

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Posted 31 December 2009 - 04:24 PM

OK problem solved.

Both of my alternators required external regulators, so I asked an auto electrical parts store to recommend a generic external regulator.

A BOSCH RE55 was the answer.
Posted Image

Now how do they work??, I've drawn up a diagram to help anyone attempting the same job I've just done. Makes sense really, starting from scratch without all these extra wires.

Posted Image

The reg has two pins in a tee, like the alternator does (see pic) The D+ pin gets a feed from the battery when the ignition is on only (otherwise it would drain the battery with engine off), this voltage is feed into the regulator which determines how much charge the battery needs, and regulates the voltage coming out of the DF pin. This can "regulate" from 0-12V determined by battery requirements. This "regulated voltage 'excites' the coil in the alternator via the F pin, determining how much charge comes out of the A pin which directly feeds the battery.

Hope that makes sense.
Cheers

#18 zedachyia

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Posted 26 March 2010 - 07:50 AM

i just recently came in posession of a 280zx turbo that has a charging issue. I can charge the battery, and run it for a few minutes, and it dies, and wont restart. I have installed two alternators in it, and it still does the same thing.
I cant find any wires that are grounding out, theres only one ground that isnt hooked up, but i dont know if that is the only problem.
Could someone please give me info on how i can go about finding where i am getting the instant battery drain from? I am at a complete loss with this.

#19 Zedman240®

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Posted 26 March 2010 - 09:36 AM

Start with a process of elimination; have you checked if the alternator is charging? Is it puting out at least 13.8V? Have you checked the battery's health? Also measure the current drain with a multi-meter if it is a drain.

#20 zedachyia

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Posted 27 March 2010 - 12:41 AM

Thank you Zedman240, I will try that today. I am trying to take the current alternator out, which by the way, is not alot of fun, and we are going to take it in and see if it is even charging.
If that isnt the problem, I will have to trace down every wire and see if there might be one grounding out somewhere. (Happy freakin Joy)
Also, do you know a cheap place i can get replacement chrome for the fenders? It seems that the previous owner let all of it just start falling off.
Thank you,
Zedachyia




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