Battery Keeps Dying out on me!!!

[Mini-L320]

Got my alternator to Autozone and Passed the test. Battery is New. When I start the car and keep it at 2000 RPM's the voltage on the battery reads 13.XX Volts. and when Idle goes back down to 12.XX. So I know that both the alternator and Battery are in good Shape. AS i leave the car overnight and go to start it back up next day its turns over then it just dies(The battery) after like 2 seconds of holding the switch to start. What do you guys think? Im guessing I have a bad Voltage Regulator.

 

(I put the XX cause I forgot what the exact #'s were)

[datzenmike]

Seems like a low charge when running. Is the fan belt tight? Is the voltage regulator solidly mounted and grounded?

 

Disconnect the battery over night see if it's the same.

Disconnect the two wire plug to the alternator over night see if it's the same. Could have a bad diode.

Disconnect the regulator over night see if it's the same.

[Mini-L320]

Seems like a low charge when running. Is the fan belt tight? Is the voltage regulator solidly mounted and grounded?

 

Disconnect the battery over night see if it's the same.

Disconnect the two wire plug to the alternator over night see if it's the same. Could have a bad diode.

Disconnect the regulator over night see if it's the same.

 

Fan belt is not tight nor loose. Its in the perfect adjustment.

Yes Voltage regulator is mounted and grounded tight and perfect. the other day I heard a Buzz coming out of it :huh: and thats what caught my attention to this problem.

[thisismatt]

Sounds like a parasitic draw when the ignition is off.

[Mini-L320]

I have the belt tight enough so when I spin the fan pulley that the crankshaft also turns with it

[I'm BLUE]

I have the belt tight enough so when I spin the fan pulley that the crankshaft also turns with it

 

you must be one strong mo-fo :lol: ^^^

 

I will agree with thisismatt as well ^^^^

[datsunaholic]

you must be one strong mo-fo :lol: ^^^

 

 

 

I'm not strong and I can turn the engine over via the fan. Very slowly. But usually the belt slips (too tight, you burn out the water pump bearing).

[fivetenguy]

I had this problem on my 620 a month ago. You are going to need a test light for this procedure. My problem was a bad voltage regulator. Please correct me if I'm wrong experts. Disconnect the negative lead on your battery. Connect your aligator clip from your test light to the negative cable. Now connect your test light to the negative terminal on your battery. If you are drawing current the bulb will light in the tester. Leave it like this and disconnect your voltage regulator. If the light goes out this is your culprit. If not move on to the next thing, your alternator. If the light is still on then you will have to go to your fuse box and pull one fuse at a time until the light goes away. Then you can see what is tide in that particular circuit. The tricky thing about this is that if there are numerous circuits drawing current, the light might not go out, but it should dim out a little. Hope this works.

[Mini-L320]

you must be one strong mo-fo :lol: ^^^

 

I will agree with thisismatt as well ^^^^

 

Yes I do eat my Wheaties every morning :D hehe.

 

I've check google about parasitic draw and it makes alot of sense, they show you how to test it properly so I will check tommarrow and let you guys know how it goes.

[I'm BLUE]

I'm not strong and I can turn the engine over via the fan. Very slowly. But usually the belt slips (too tight, you burn out the water pump bearing).

 

^^^ yeah I can too ;) ,,, I thought it was funny that he could "spin or hit" the fan ,,, as a result turn the crankshaft/water-pump :lol:

[Mini-L320]

I had this problem on my 620 a month ago. You are going to need a test light for this procedure. My problem was a bad voltage regulator. Please correct me if I'm wrong experts. Disconnect the negative lead on your battery. Connect your aligator clip from your test light to the negative cable. Now connect your test light to the negative terminal on your battery. If you are drawing current the bulb will light in the tester. Leave it like this and disconnect your voltage regulator. If the light goes out this is your culprit. If not move on to the next thing, your alternator. If the light is still on then you will have to go to your fuse box and pull one fuse at a time until the light goes away. Then you can see what is tide in that particular circuit. The tricky thing about this is that if there are numerous circuits drawing current, the light might not go out, but it should dim out a little. Hope this works.

 

Thanks alot. Hmm You brought up a Bad Voltage Regulator?. Mine just started to make a Buzzin noise a few days ago and noticed it like 2 days ago. I will do that test and see what happens. Was your Voltage regulator making a Buzzin Sound?

[Mini-L320]

^^^ yeah I can too ;) ,,, I thought it was funny that he could "spin or hit" the fan ,,, as a result turn the crankshaft/water-pump :lol:

 

Well once the crank makes its way to the COmpression stroke thats when the belt usually slips a bit, thats when it gets harder to spin it by hand with out it slipping :D

[ggzilla]

NOT GOOD

 

When I start the car and keep it at 2000 RPM's the voltage on the battery reads 13.XX Volts.

 

That won't keep your battery charged. At 68 degrees, the a valid charge is 14.2 to 15.2 volts.

[Mini-L320]

NOT GOOD

 

 

 

That won't keep your battery charged. At 68 degrees, the a valid charge is 14.2 to 15.2 volts.

 

I think 15.2 is a bit over kill dont you think. theres a reason why thay call a 12 Volt battery a "12 Volt" because when not in use a battery reads 12.5 by itself but when car on it reads 13.6 Volts. usually when a battery is fully charged it only reads 12.4-12.6 by itself.

We are talking about a Tiny 1.5ltr with a 50 amp alternator right? Not a Cummins Diesel Engine with a 120 Amp Alternator

[thisismatt]

I think 15.2 is a bit over kill dont you think. theres a reason why thay call a 12 Volt battery a "12 Volt" because when not in use a battery reads 12.5 by itself but when car on it reads 13.6 Volts. usually when a battery is fully charged it only reads 12.4-12.6 by itself.

We are talking about a Tiny 1.5ltr with a 50 amp alternator right? Not a Cummins Diesel Engine with a 120 Amp Alternator

I don't know what engine displacement or alternator current output really has to do with anything, but upper 13's are fine for normal charging and over 14.4~14.5 is excessive and not good for a lead acid battery either.

[ggzilla]

I got it right out of the Datsun repair manual.

What's the source for your statements?

[Mini-L320]

I don't know what engine displacement or alternator current output really has to do with anything, but upper 13's are fine for normal charging and over 14.4~14.5 is excessive and not good for a lead acid battery either.

 

Im all confused :huh: . I just said previously that I had the car running at a steady 2000 RPM's and the battery was reading 13.6

Now is that good or bad. Cause ggzilla said is no Good.

And when I shut the car off battery reads 12.37, so that is telling me that my alternator is working and charging the battery properly,

Yes or no?

[ggzilla]

the battery was reading 13.6

 

13.XX is no good.

13.6 is charging the battery just enough if the battery is healthy. The voltage needed to charge a lead-acid battery varies by temp, with 13.5 V optimum when the temp is something over 100 degrees. At colder temps higher voltages are needed. This is basic lead-acid chemistry and hasn't changed in the last 100 years for traditional car batteries. Advanced AGM batteries like some Optimas take different chargiing voltages.

 

AS i leave the car overnight and go to start it back up next day its turns over then it just dies(The battery) after like 2 seconds of holding the switch to start.

Given the 13.6 volts, the voltage regulator is fine as far as regulating (though it still may have a leak in the lamp circuit or somthing). Alternator output is fine. Sounds like you got something draining charge from the battery overnight.

 

Do this test as Mike said: tonight, disconnect the battery cable. Tomorrow put it back on. If the battery is fine it will start up. If the battery is down you most likely got a bad battery regardless.

[banzai510(hainz)]

fivetenguys procedure is good.

I charge between about 13.4 - 14.1 but varies different days.

 

I think you have a draw o the battery use the test light.

 

If you run the car above 2000K all the time the battery should still charge.

But if your battary wont hold a charge that could be a bad/old battery. if good then you have a draw.

 

to me above 14.3 is getting close to overvolt.

15 is slowly cooking the battery. ck by see if battery bulges or oozez acid out.

 

get a solid state volt reg if you have a external one

[fivetenguy]

Thanks alot. Hmm You brought up a Bad Voltage Regulator?. Mine just started to make a Buzzin noise a few days ago and noticed it like 2 days ago. I will do that test and see what happens. Was your Voltage regulator making a Buzzin Sound?

[/quote

 

On mine when ever I would disconnect the battery or the regulator connector I would hear a click from the regulator. So just as a test I left the regulator disconnected for a week and the battery was still fully charged. I did not notice any buzzing sound or anything.

[deadmonkey]

I agree... 15volts is too much for a battery.

 

the 620 manual says to turn on high beams and fan to high and at idle it should read just over 12.5v between + and - on the battery. RPMS up (think it was 3k) and it should read over 13v up to 14.5 or so. Again all from memory, but 15v on a lead acid battery is too much. If it is doing that then the regulator is working and the bat should be getting a charge. If you have a known good battery you could swap and try again if it stops then you know it was the battery. If it does it again... like everybody keeps saying. May be a voltage drain.

[ggzilla]

1981 Datsun Factory Service Manual - Hitachi LR150 (50A) alternator

 

 

[ggzilla]

1972 Datsun Repair Manual

 

[thisismatt]

I should reiterate that 15v is fine for charging a low/dead battery, but too high for a maintenance charge rate, which is what is typically happening when your car is running. 15v+ will/can cause the battery to boil/gas, and does damage to the battery.

[ggzilla]

:)