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Charging Problem


Dat521sun

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Merry Christmas/Happy Holidays everyone. I have a stock 1972 Datsun 521 with minor mods (petronix electronic ignition and Weber carb) A few months ago, my alternator died. I replaced it, since then, the truck is not charging. I have replace the alternator 3 times, the voltage regulator twice, clean the fuse box, replaced the fuse box, added a new fuse box to replace stock fuse box, removed and cleaned the gauge unit/speedometer, the wires at the passanger side under the glove compartment. I have read your post and have done everything, I need help... Battery under warranty and after 10 swaps at autozone, they won't give me another one 😱. Any suggestions

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10 minutes ago, wayno said:

You say you cleaned the instrument cluster, so the light comes on when you turn the key on, correct?

Does the light stay on or get any dimmer after you start the engine? 

I forgot to mention that both lights(oil and ign) comes on when you turn the key and you start the truck and they both turn off also, the water gauge stop working (fuel gauge does work). 

Ign light was on when the first alternator died, went back to normal after replacing alternator. 

Edited by Dat521sun
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OK, I have been thru this years ago, I replaced the alternator and the regulator a few times but my light would be half on all the time, I took the truck to the auto parts store and they tested it and even though the light was half on it was charging, the problem with this is when it quit charging I didn't know it because the light was still half on.

In the end I decided that the stuff they sold back then and the stuff they sell today is crap, an OEM used alternator/regulator is a way better part than a new one bought at any of these auto parts stores, also I am not sure these guys at these stores or online know the difference between internally regulated alternators and externally regulated alternators, I had to give up on my truck as I could not fix it and neither could they, so I went with an externally regulated alternator from a 1980 thru 1982 Datsun 720 and I made my own mount bracket to lower it so it would fit properly, I used the wire going to the light in the dash, but the rest of the wires I made myself,

There is a way to jumper the plug going to the regulator to use your wiring you have, but in the end even that would not work for me, there was something wrong with my wiring.

wiring-diagram-IR.jpg

There are also smaller internally regulated alternators out there that put way more out on other vehicles, personally I would look into them if I were you and give up on the stock system the 521 had.

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12 minutes ago, wayno said:

OK, I have been thru this years ago, I replaced the alternator and the regulator a few times but my light would be half on all the time, I took the truck to the auto parts store and they tested it and even though the light was half on it was charging, the problem with this is when it quit charging I didn't know it because the light was still half on.

In the end I decided that the stuff they sold back then and the stuff they sell today is crap, an OEM used alternator/regulator is a way better part than a new one bought at any of these auto parts stores, also I am not sure these guys at these stores or online know the difference between internally regulated alternators and externally regulated alternators, I had to give up on my truck as I could not fix it and neither could they, so I went with an externally regulated alternator from a 1980 thru 1982 Datsun 720 and I made my own mount bracket to lower it so it would fit properly, I used the wire going to the light in the dash, but the rest of the wires I made myself,

There is a way to jumper the plug going to the regulator to use your wiring you have, but in the end even that would not work for me, there was something wrong with my wiring.

wiring-diagram-IR.jpg

There are also smaller internally regulated alternators out there that put way more out on other vehicles, personally I would look into them if I were you and give up on the stock system the 521 had.

Thanks Wayno, I've been looking at internal regulated alternators, mostly for a direct /OEM fit. I have pics from other members here that have done it, where they explain how to bypass the voltage regulator. 

 

It just frustrating, truck runs good, just right now is running on battery, that I have to charge every 4 days. 

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You see that is the thing, I got so frustrated with mine also, the only way I could tell it was not charging was when the modern radio started cutting out from not having enough voltage to work properly, the 521 wiring harness is a weird one, as I could pull every fuse and the engine would keep right on running till I turned the key off.

Like I said I finally gave up and moved on to an internally regulated alternator, I believe the 1981/82 Datsun 720 alternator and alternator mount is the one you need if you go that route, that mount lowers the alternator about an inch so the larger alternator will fit and not hit the idler arm when the engine is under heavy load circumstances, but again there are other more modern internally regulated alternators that are smaller and put out more amps that others have used with success.

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19 minutes ago, wayno said:

You see that is the thing, I got so frustrated with mine also, the only way I could tell it was not charging was when the modern radio started cutting out from not having enough voltage to work properly, the 521 wiring harness is a weird one, as I could pull every fuse and the engine would keep right on running till I turned the key off.

Like I said I finally gave up and moved on to an internally regulated alternator, I believe the 1981/82 Datsun 720 alternator and alternator mount is the one you need if you go that route, that mount lowers the alternator about an inch so the larger alternator will fit and not hit the idler arm when the engine is under heavy load circumstances, but again there are other more modern internally regulated alternators that are smaller and put out more amps that others have used with success.

😂 True, I have everything unplog and truck kept running. I noticed with new fuse box, everything is brighter but battery died faster. I'll look and research at a 720 alternator. 

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17 minutes ago, datzenmike said:

The '78-'79 620 alternator is internally regulated and small like the 521 but only 35 or 36 amp output. Myself I'd rather have a 720 higher 50 amp output one for sure.

Thanks Mike, I read other options here somewhere, like Daniel's Dragon is running a Pathfinder alternator, wonder what year

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wish I would have caught this sooner

a 521 charging system is simple

Did you get the alternators checked????  do it aty least 2 different places as those guys are not good as they say. and load test it

The Napa Volt regs made in USA suck and don't last long

most autozone and O reiley Altwnator don't last more than 9months if that now.

 

ON 521s always ck the fusebox and connections and clean as most of my proplems are right there.

 

You have a 72 so be careful as if you get a newer type alt you need to disconnect the elelctric choke otherwise your battery will die when you jumper those wires when you convert. I use the old Volt Reg connector and just jumper the wires there in case you go back to a stock VR and alternator

I went with a stock POWER SELECT alternator from Rockauto.com and they are new manufactured ones and going on my 3rd year.(this is a bolt in) NO mods

 

I use a Innova battery /alt checker that plugs in the cig lighter. and they work well. I see if I charging as Im driving and putting loads on there and can see if it goes bad immediately. Or acting funning. The IGnition light coming on is way too late in most cases.

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5 hours ago, banzai510(hainz) said:

wish I would have caught this sooner

a 521 charging system is simple

Did you get the alternators checked????  do it aty least 2 different places as those guys are not good as they say. and load test it

The Napa Volt regs made in USA suck and don't last long

most autozone and O reiley Altwnator don't last more than 9months if that now.

 

ON 521s always ck the fusebox and connections and clean as most of my proplems are right there.

 

You have a 72 so be careful as if you get a newer type alt you need to disconnect the elelctric choke otherwise your battery will die when you jumper those wires when you convert. I use the old Volt Reg connector and just jumper the wires there in case you go back to a stock VR and alternator

I went with a stock POWER SELECT alternator from Rockauto.com and they are new manufactured ones and going on my 3rd year.(this is a bolt in) NO mods

 

I use a Innova battery /alt checker that plugs in the cig lighter. and they work well. I see if I charging as Im driving and putting loads on there and can see if it goes bad immediately. Or acting funning. The IGnition light coming on is way too late in most cases.

Thanks Hainz, my carb is manual choke. I got the new voltage regulator from Carquest, read in one post that you mention they were pretty good. I replaced the fuse box with the same one DanielC used on his 521

 

wJ2u7se.jpg

 

The new alternator is slightly different (from old one), new one has an extra plug or connector.

 

dCPpO9q.jpg

 

Do you know what plugs here? 

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2 hours ago, wayno said:

OK, so you changed out the fuse block, now I am suspecting that maybe you may have wired it wrong and the regulator is not getting the power it needs to work properly or it is getting power that it is not supposed to, wiring can be tricky.

The fuse box was replaced as a last resort, after the 3rd alternator

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9 hours ago, Dat521sun said:

Thanks Hainz, my carb is manual choke. I got the new voltage regulator from Carquest, read in one post that you mention they were pretty good. I replaced the fuse box with the same one DanielC used on his 521

 

wJ2u7se.jpg

 

The new alternator is slightly different (from old one), new one has an extra plug or connector.

 

dCPpO9q.jpg

 

Do you know what plugs here? 

I have wondered about that damn connection point a few times.... 

I have no idea what it's for but I do know you dont want to connect anything to it..

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1 hour ago, Crashtd420 said:

So is that the alternator your trying to use right now?

Are you using a voltage regulator with it?

 

I see the L on the back... doesnt that mean its internally regulated?

 

It would have F N on the back if externally regulated..... 

 

That's the one is installed, should I bypass the voltage regulator to see if it start charging? 

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9 minutes ago, Crashtd420 said:

What did you ask for when you got that altenator?

What vehicle?

I asker for an alternator for a 1972 Datsun 521 (Nissan 521 in their systems) I remember when installed, the first voltage regulator popped/smoked, so I replaced it. After that, I replaced alternator 2 more times and VR once since it haven't charged. 

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15 minutes ago, Crashtd420 said:

You should double check the part ... if it is internally regulated than yes you should be bypassing the external regulator.... 

In their system said it was external regulated, but now a days, you can't trust their systems. I remember 25 years ago, back in Puerto Rico, the guys working at the parts store, were mechanics and knew their stuff, and if part was wrong 😅 

Edited by Dat521sun
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Just now, Dat521sun said:

In their system said it was external regulated, but now a days, you can't trust their systems. I remember 25 years ago, back in Puerto Rico, the guys working at the parts store, where always mechanics and knew their stuff, and if part was wrong 😅 

I know what you mean... if you ask for motor mounts they sell you ones for a 720 that aren't even close to correct.....

It's not a bad thing if the altenator is internally regulated,  they seem to work better.... 

I would try bypassing the regulator...

Also if yours had an electric choke that needs to be rewired too or the relay will always be on....

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6 minutes ago, Crashtd420 said:

I could be wrong but it does sound like they are giving you the wrong altenator....

What store did you get it from?

Do you know the part number they were selling you?

 

Autozone. My old carb was weird, it was manual choke, but without the cord. The PO owner vent the throttle cable so truck always idle high, I had to pull the accelerator pedal with my toes. I replaced the carb, and it was electric, a few months after that, first alternator died. 2 weeks ago, I replaced the carb with a manual choke 

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