What battery to run

[ggzilla]

This is why it is not charging:

With the meter set to 20DCV, the key on and the testor red on the top of the T and the black on the battery NEG I get nothing. Same with the stem.

Your procedure is correct (if you are measuring the harness T-connections and not the alternator T-connections), but you don't have 12V at the wire ends. Therefore it won't charge.

 

Yes, the S wire needs 12V. In a GM "1-wire" it is connected that way internally. In Most GMs it is connected via the wiring harness. Ditto for a Datsun IR setup. So you can either do it by jumping wires, or just connect it directly. If it makes you feel any better you can connect it to IGN 12V (say to the Ballast Resistor). The IR has diodes so it won't run down the battery. External Voltage Regulators don't work the same way. That's why the Yellow wire is used for a different purpose with the original setup.

 

With the L wire plugged in , the CHG light should light up with key on, engine off (does your charge light say "IGN"?). If that does not work, the wiring is not correct. Any chance you have an intermittent wiring issue, sometimes it acts differently?

 

Try this:

* Connect S to BAT

* Start engine. It will be at 12v about

* Jump L to battery for a few seconds. Voltage should jump up to about 16V at 1200 RPM.

[boxboy]

This is why it is not charging:

 

Your procedure is correct (if you are measuring the harness T-connections and not the alternator T-connections), but you don't have 12V at the wire ends. Therefore it won't charge.

 

I tried measuring at the T right out of the alternator and got nothing, so why would there be anything down stream? Again, my problem is that it is charging TOO MUCH.

 

 

Yes, the S wire needs 12V. In a GM "1-wire" it is connected that way internally. In Most GMs it is connected via the wiring harness. Ditto for a Datsun IR setup. So you can either do it by jumping wires, or just connect it directly. If it makes you feel any better you can connect it to IGN 12V (say to the Ballast Resistor). The IR has diodes so it won't run down the battery. External Voltage Regulators don't work the same way. That's why the Yellow wire is used for a different purpose with the original setup.

 

So I will go and wire my S (Y) to the post and run a temporary wire to the WR in the harness. I want to stay away from getting the Restistor and stuff involved because I am only half understanding this as it is.

 

With the L wire plugged in , the CHG light should light up with key on, engine off (does your charge light say "IGN"?). If that does not work, the wiring is not correct. Any chance you have an intermittent wiring issue, sometimes it acts differently?

 

Previously I had the S to the BATT post on the alt and when I went to turn on the key I had no light, but when I plugged it back in to the Y on the harness I did have light. (I can't say for sure what the dash light says at this point, but it is either ALT or IGN I believe. I'll check)

 

Try this:

* Connect S to BAT

* Start engine. It will be at 12v about

* Jump L to battery for a few seconds. Voltage should jump up to about 16V at 1200 RPM.

 

You want me to jump L to the POS or NEG of the batt?

 

For now I need to go reinstall the alt

[ggzilla]

Let me double-check

[ggzilla]

Jump L to Battery + (or to alternator BAT terminal). It should go to over 13.2 at 1200 RPM. It should not go over 15.7, since it is internally regulated.

 

You could also use your test light between S terminal and battery POS. With engine off, test light should be on. With engine running, test light might flash once, but should go out.

 

All this test does is bypass your harness wiring.

[ggzilla]

nissan Factory Service Manual schematic for internally-regulated alternator

 

notice it shows S terminal connected to BAT terminal

 

 

From 1980 Datsun 210 FSM with LR150 unit

The 1995 Nissan 1200 wiring diagram shows the same thing with LR135 unit (the small one).

[boxboy]

ggzilla, my profoundest apologies for not just listening to you in the first place. I ran the S to the BATT as I had done previously, but this time instead of running the black and white wire from the harness to the WR wire from the IGN light (yes it does say IGN) I ran a new wire bypassing the harness completely. BINGO! I had about 12.4V at idle and revved the crap out of it and never got above 14.65 V. Then I loaded it up and still above 14.5V no sweat. The J13 idles at about 450 rpms, so it takes a little rev to get the light off at start up. I may bump it up a bit to 6 or 700 and see if that helps keep me above 12.5 at idle. But I am done, finally.

 

So now I get to thinking that it is quite possible that I never had a problem with the VR or the other ALT, but simply a bad wire between the two. That sucks, because I could have saved $60 , kept it original, and saved countless hours of fretting. But then again I learned a lot, and have better charging now. I might have had this problem since I bought the truck and didn't know it. My IGN light would blink once in a while and speed up with my RPM's. Someone on here told me it was no big deal. I guess perhaps it might have been.

 

Thanks again man, I can't say it enough. I was about to give in. But if my Datsun never does, how can I, right?

[ggzilla]

Glad to hear it's working. And you didn't give up!

 

At idle, it's not supposed to charge fully, as long as the light goes out it is OK. Although with headlights on at idle, the light will probably glow dimly. The factory service manual says that is OK as long as the 1100-1200 RPM voltages are correct (as yours are).

[DanielC]

The idle should be a little higher, 600 to 700 RPM or so.

An alternator has a maximum RPM it can run. The size difference between the crankshaft pulley, and the alternator pulley determines how fast the alternator turns at maximum rpm. A v8 engine in a car normally turns about 5000 RPM max, so the alternator can be ran faster at all speeds on those engines. On a small four cylinder engine, the alternator has to be driven slower, so it does not overspeed at high engine RPM. Because of that, the alternator turn too slow at idle engine speed to put out a lot of current. If your idle is really slow, the alternator may stop putting out current altogether.

 

Check for a current draw going out the wire connected from the battery, to the alternator "S" terminal, with the engine off. As it was pointed out, some alternators do not draw current on this wire with a stopped engine. But other alternators may draw a current. It depends on how the internal regulator inside the alternator was designed, and wired.

[XXL]

Maybe I should have said this, but I am not looking for the latest and greatest. Just a decent option that fits. I am running stock J13 so I don't need a ton of cranking amps. Thanks all for the input.

 

Well, the Bi-Mart "84 month" battery (looks like you bought it May 2012) may be about to croak.  We got a cold spell the other day and now the truck doesn't want to crank.  It lags real hard when I first hit the key, then may or may not spin enough to start the truck... if it does spin over enough from the initial stopped position, it speeds up and starts... it sounds a lot like it's not giving me enough current to turn over a completely stopped motor.  I've checked alternator and am seeing 15.8 volts once the exciter energized after you blip the throttle (it's the one-wire alternator that you installed).  I've buzzed both battery cables and they have zero resistance across them, and they have clean and tight connections... so I'm going with battery at the moment.  This is my dd, so I need to make sure it starts when I hit the key.

 

BTW, what you bought was a "Bi-Mart by Exide" part number #5684, with 590 CCA at 0°.  Bi-Mart's website says that's a bad part number, as does Exide, but Bi-Mart does offer an 84 month battery with 590 CCA... so who knows what it is.  Dimensions are very odd... it's 10L x 6.6W x 9.25H... which doesn't conform to any BCI group number I'm aware of.  *sigh*

 

Edit:  I spoke with Exide.  They said the Bi-Mart part numbers have changed, but that the old part number (above) was pretty easy... it's a BCI group 56, and it's an 84 month battery = #5684.  Group 56 dimensions are consistent, so...

[XXL]

I thought I would do a write up of this process. I took pictures along the way and I want to make sure I have done it right. Let me know if there are errors.

 

 

 

 

 

 

 

Problem has returned.  Here's how the truck was delivered to me approx 3 years and 19k miles ago...

 

 

... including cut yellow wire.  It's been working fine (as far as I know) for some time, but last night I had to push start it in a store parking lot  :crying:  ... I put a charger on it overnight and fancy Schumacher charger now says it's 100% at 13.4 volts.  When I start the truck, fancy Schumacher charger tells me alternator output is zero.  I haven't yet checked that by any other means, but it's consistent with the fact that battery was dead.  However... NOT consistent with fact that I was able to push start the truck and drive it 2 miles home with (very dim) headlights... since, if the battery was dead, I'd have been running off the alternator.  OR... maybe battery was simply too dead to spin the big amp starter, but good enough to feed the distributor for the trip home.

 

In any case, the alternator bearing has, since the day I got the truck, had a kind of squall sound to it... like maybe too much side load from the belt on a cheap bearing.  Replacing the alternator might be worth it if only to get rid of that noise (if, indeed, it's actually coming from there).  Anyway... I was hoping to figure out the part number for the alternator boxboy used, but didn't see it in the thread.  I'd like to make a swap as painless as possible since I'm old and tired, and this is my daily driver.

 

Any input on this would be appreciated.

[datzenmike]

What year and vehicle??? Where are you? This info would help if in your profile. North American Datsuns are familiar but if from someplace else they may have different parts.

 

 

S and L terminals are usually internal regulated alternators. 

 

The cut yellow wire would be a good place to start. Yellow usually goes to the positive side of the battery. Looks like it fell off that blue connector on the positive output post on the alternator right below/beside it

[zed1]

If you want to have the alternator rebuilt locally, then take it to:

Auto Electric Systems Inc

11361 Emerald Street

Dallas, TX 75229

(972) 241-2077

 

They have rebuilt my 240Z, PL520, and L60 starters and alternators over the past 25 years.

Keith

[XXL]

What year and vehicle??? Where are you? This info would help if in your profile. North American Datsuns are familiar but if from someplace else they may have different parts.

 

 

S and L terminals are usually internal regulated alternators. 

 

The cut yellow wire would be a good place to start. Yellow usually goes to the positive side of the battery. Looks like it fell off that blue connector on the positive output post on the alternator right below/beside it

 

I didn't figure I needed to reintroduce the vehicle, since it's the topic of this 4 year old thread, where a PO detailed his battery issue, then his alternator issue and replacement.  But... it's a 1968 520 with J13.  Alternator is a Hitachi one-wire unit (self-exciting).  

 

And that yellow wire has been EXACTLY as pictured since I bought the truck (see my introduction thread here-- http://community.ratsun.net/topic/51431-new-520-owner/, and specifically the last pic in this post-- http://community.ratsun.net/topic/51431-new-520-owner/?p=872930 ).  That wire has never been connected to anything since at least 2013, and I have put about 19k miles on it during that time.  If that wire was supposed to be connected to something, it seems like I'd have found out by now.  :hmm: ... but that S wire is what would be used to excite the unit if it weren't self-exciting... right?

 

If you want to have the alternator rebuilt locally, then take it to:

Auto Electric Systems Inc

11361 Emerald Street

Dallas, TX 75229

(972) 241-2077

 

 

Thanks for the pointer... I actually moved out of the area at EOY.  I re-re-re-scanned this thread in hopes of finding a Hitachi part number so I could just order up a 1:1 replacement, but may have to actually remove it and carry it to a parts house to match up.  Sadly, it's a one-belt system, so I can't drive it after I take the unit off (which is what I did for a few days while I had the starter rebuilt last fall).  

[wayno]

I think that the wire that looks like it has fallen off is the "BAT" wire, the main dull yellowish wire, but if I were you, I would remove the positive battery connection before touching that wire if it has indeed fallen off, as it is a hot wire all the time and could cause a fire if it touches ground, if you look real close it doesn't look like anything is connected to that blue electrical connector in the photo.

Remember, that wire is HOT all the time, disconnect the positive battery cable before messing with that wire.

[XXL]

Thanks, wayno.  You're seeing a bad camera angle.  There is a blue insulated ring terminal on the battery output lug of the alternator... again, it was there, wireless, since day one.  The yellow wire is just a tiny pigtail, and is incapable of reaching the ring terminal.  And, as I stated before, it has been that way for the 3 years I've been driving the truck on a daily basis.  

 

At this point, I have confirmed that the alternator isn't putting out a charge.  I pulled the battery wire off the post (and I got rid of the empty blue ring so we can put that to rest... BTW, it wasn't even crimped, so it never had any wire in it.  I'm guessing boxboy or someone after him just used it as a "washer" for the nut) and with the engine running at 2500 RPM, found a bouncy 0.00 - 0.71 volts coming out of the alternator.  This was truck running completely off battery, with alternator electrically isolated from the battery.  It should have been putting out a solid 13-14 volts.  Also, that squall sound I mentioned earlier seems to definitely be coming from the alternator... and the bracket sleeves that boxboy made (see his pictures on post #57 here-- http://community.ratsun.net/topic/43454-what-battery-to-run/?p=691104) are not holding the back of the alternator very solidly.  The bolt he inserted is tight against the shoulder where the threads end, but it's not tight to the alternator (the shims he made aren't long enough).  So... again, need to find an alternator and do the swap.  And since it looks like I'm going to have to rework the bracket changes he made anyway, there's less reason for me to find an identical alternator.  Though... I've visually identified it with Google's help.  It looks like a Hitachi LR series (such as the  LR135-58B), which is a 35 amp unit originally fitted to a number of farm tractors.  However, I have not found any indication as to whether this part number actually is a one-wire unit, or if whoever supplied it to O'Reilley (boxboy's post says that's where he bought it) converted it to one-wire, or if there's another part number to look for.  Also... 35 amp seems pretty wimpy, even for this little truck.

 

 

[XXL]

Oops. Forgot to check the input lead to the alternator. It only had 2 volts on it. When I bypassed the connection and fed it a solid 12v, the alternator immediately kicked in, producing a charge. So... aside from the loose mounting bracket and squall noise from the alternator, it is indeed capable of charging. Now... to figure out why theinput wire only has ~2 volts on it. I traced it from alternator plug back to a rectangular plug with 8 or so pins, on the right fender, just ahead of the fusebox... about where the original regulator probably used to be. I'll check out the schematic for that white/red wire tomorrow to see where it comes from... still not sure how it would only be seeing v unless there's a bad relay in front of it somewhere (???).

[XXL]

For anyone interested, the saga continues...

 

I'm starting to think that whatever was wrong for boxboy 4 years ago is still a problem today.  Here's what I did...

 

 

 

The above connector, which is just forward of the firewall, contains a white/red wire (bottom front wire in picture).  That wire heads off into the wiring harness, and the schematic I have for the truck just sends that off into oblivion as well (tracing it on the schematic shows some possible relationship with the instrument panel itself... hmmm).  In the picture above, that white/red wire has 12v switched on it.  When I plug the connector back in (see single pin connector with green wire in background), that wire drops to a paltry 0.nn volts (near zero, but not zero)  edit:  The reason for the voltage fluctuation is that it's not 12v switched... it's a light bulb... which is sucking up everything to try to light itself, and so it's drawing a circuit through the bulb... which will pull WAY too much current through those flimsy traces on the IP circuit board.  That green wire is what runs around and connects to the alternator's "L" connector (see pic in post #85).  When these are connected, and I start the truck, the alternator DOES NOT produce output.  When I start the car with the connector disconnected (the alternator, of course, also DOES NOT produce output), but I can alligator clip from that green wire directly to the fuse box voltage and it does energize the alternator, which immediately produces output.  The only drawback to this alligator clip workaround is that I can't shut off the truck... when I turn off the key, the engine continues running... until I pull my alligator clip from the fuse box.

 

 

So... after tracing the white/red wire on the schematic (I know I've jumped across circuits with my red line above... that's the way it was wired by boxboy or whoever... the white/black of the alternator becomes white/red at that plug), it appears that someone is expecting the lightbulb on the dash to actually feed enough current to energize the alternator.  That may well be why I had gauge problems last summer, which included replacing the PCB (the old one had a burned/repaired trace on it).

 

What a mess.

 

Here's a video step through of the above... https://youtu.be/gtCMstuA1ag

[XXL]

I have made a few wiring changes to (temporarily) get it going again... I'm using the switched fusebox tab to feed a relay, which breaks B+ with the key.  This now gets me charging and able to turn off the truck with the key.  I'm still very interested in figuring out why it was wired the way it was (through the IP cluster), and how it should be wired "factory" (obviously, bypassing the nonexistent external relay).  I'm need to figure out which wire in that 8-pin plug that used to feed the external regulator is a better source for energizing the alternator... I'll keep researching.  I've seen a few references on the board, but if anyone has more info on the external regulator pin out, I'd appreciate it.

[Charlie69]

I had such a hacked up harness in my 66 520 and I was adding 720 heater, AC, alternator, L20B automatic, power windows and doors locks, and electric fuel pump that I am modding a 1980 720 L20B automatic harness which did not have the power windows and doors locks, and electric fuel pump.  I am adding those circuits from a later model 720 harness.  This ended up being so involved that I ended up drawing a new wiring diagram.

 

[XXL]

I had such a hacked up harness in my 66 520 and I was adding 720 heater, AC, alternator, L20B automatic, power windows and doors locks, and electric fuel pump that I am modding a 1980 720 L20B automatic harness which did not have the power windows and doors locks, and electric fuel pump.  I am adding those circuits from a later model 720 harness.  This ended up being so involved that I ended up drawing a new wiring diagram.

 

 

Nice.

 

If/when I get a burst of energy, I'm going to go ahead a swap in a Delco 10si alternator and be done with all this nonsense.  I'm sure I'll have to fab brackets from scratch to make it work, but it will then be mostly bullet proof and I can clean up the wiring.  If/when that happens, I may take your cue and draw up an updated wiring diagram for the next guy.

[XXL]

Truck has been working fine for almost 2 weeks (*knock, knock*).  However, every time I start the truck I get a nasty belt squeal.  What's odd about that is that I didn't touch the belt... I mean I literally did not even touch it, so it seems odd that it would suddenly slip on startup.  Rather (and my engineering brain is kicking in), I suspect it is because now the alternator is actually charging any time it spins, even at > 0 RPM... so when I first start the truck, the alternator is slightly harder to turn because it's already created an electrical field, and thus the was-always-nearly-slippy belt is now slippy.  I'll live with it until I get another burst of energy.