New alternator - Bad install vs Parasitic Drain

[K-Tanz]

Hey all! I recently installed a brand new battery to replace the old one which was for sure bad. About a month later the car was dead in the morning, but a jump fixed the issue. The alternator was old so I replaced it. Problem solved with zero issues for about a month.

Now the car dies overnight and needs a jump in the mornings. An ARB compressor and a light bar are my only accessories. They have been installed for years with no issues. My thoughts are initially one of three issues: Parasitic drain, bad alternator right out of the box, or a botched install on my part. The confusing thing for me is that there were no issues for a month or more with the new alternator.

I did some basic testing (I am a moron with electrical systems, please bare with me) and got some numbers as follows after jumping the car and driving around for an hour to get some charge on it.

12.4v at the battery with the car off. 14.1v at the battery with the car running. I subsequently repeated the voltage test with the car running and got a second reading of 13.6v at the battery with the car running. This seems low to me and suspicious for bad alternator, install, or cable from alternator to battery?

I additionally tried to test for parasitic drain by testing amperage from the battery with nothing on. With the negative cable disconnectd, red lead into the negative clamp, black lead on the negative terminal, I got 0.09 to 0.1 amp. This seems to exclude parasitic drain, yes?

I would love if anyone could give me some advice about further testing or suspicious readings above. I know the big 3 upgrade is an option, but I am hesitant to start rewiring major systems as I am no electrical guru and am concerned about making something worse rather than better. My preference is to diagnose the acute issue and treat that rather than to rip out and replace a bunch of wiring.

Thanks so much!

Kevin

 

[MaineRunna]

Have the battery tested to rule that out. You need to test CCA. 90-100 mA is slightly high but an acceptable parasitic drain and certainly not enough to drain the battery overnight. Check the voltage with engine running, high beams on and blower motor on high. Check all of your connections at the alternator and battery especially.

 

[Hepar]

Have the battery tested to rule that out. You need to test CCA. 90-100 mA is slightly high but an acceptable parasitic drain and certainly not enough to drain the battery overnight. Check the voltage with engine running, high beams on and blower motor on high. Check all of your connections at the alternator and battery especially.

2nd testing the battery. They don't like being drained all the way, so there's a chance that if you had a new battery and bad alternator combo and then drained the battery all the way, that you shortened the life of the battery significantly.

 

[Ryance39]

Also might be worth looking into your blower motor/resistor.
The issues could be unrelated, and if your blower motor is staying on when the car is off, that could definitely drain the battery overnight.

 

[K-Tanz]

Voltage at the battery with the car running and load on the battery, blower motor, headlights, light bar, radio on, is 12.5 volts. I don't know what to make of this number.

I'm happy to have the battery tested but it's about two months old and it doesn't seem like being run down to zero once or twice would murder a two month old battery.

Thanks for the responses!

 

[Hepar]

I'm happy to have the battery tested but it's about two months old and it doesn't seem like being run down to zero once or twice would murder a two month old battery.

I suggest it as a possibility because it recently happened to me. Battery was not as new as yours, but around 5 months old. Alternator went which cause my rig to die while it was running. Swapped the alternator out and a few days later the battery was dead again. Got it tested and it showed that it wasn't holding a charge. Costco purchase so took it in and they swapped it out. Haven't had an issue since.

 

[pluton]

Voltage at the battery with the car running and load on the battery, blower motor, headlights, light bar, radio on, is 12.5 volts. I don't know what to make of this number.

I'm happy to have the battery tested but it's about two months old and it doesn't seem like being run down to zero once or twice would murder a two month old battery.

Your recently new battery ain't new any more because it got drained flat multiple times. Be prepared to replace the now-damaged battery.
A thought: Alternator is suspect with that low a voltage with everything turned on.
With just the engine running but no other loads engaged, 13.6v is maybe a touch low, but not if it's really, really hot outside, like Phoenix can be. Voltage regulator varies the charge voltage with ambient temperature--- the hotter the ambient is, the lower the charging voltage.

Most here will suggest a rebuilt alternator from Toyota or Denso, or some trusted rebuilder. Apparently, many of the units sold by the ordinary parts chain stores are prone to failure after a short time.

 

[K-Tanz]

For anyone who has been following this most riveting journey, bated breath in anticipation of what could possibly happen next, I have some resolution for you.

With the multimeter in series with the battery and the car off, I was getting 0.1 Amp draw. I started pulling fuses and BOOM. Pulling the dome light fuse dropped the power draw immediately to zero.

I unplugged all the dome lights in the truck and it was still drawing power for some reason. Turns out there's all kinds of fun stuff on that circuit. The power locks are on that circuit, the radio, and the clock are on there. Any ideas as to how to narrow down where the power draw is coming from? Preferably without ripping the dash apart?

For now I'm just gonna leave the fuse out to stop the battery being drained. Any suggestions regarding narrowing down what's drawing power on that dome circuit are appreciated.

 

[19963.4lsr5]

Look at that amp draw 1 hour after you turn off the ignition to ensure the .1a is legit. some modules go to sleep and draw much less amps than they do right after ignition off.

If it’s still .1 amp start unplugging circuits on that fuse. The Radio I would do first.


Sent from my iPhone using Tapatalk

 

[K-Tanz]

Alright in favor of resolution, I got it all fixed.

I pulled all the dash lights, the radio, the glove box light, no change.

I finally started pulling wires in the back of the switches for the locker and the ARB compressor. Boom. Pin #6 on the compressor switch immediately dropped the amp draw by half. Then I pulled pin 6 on the locker switch and the amp dropped to between 0.01 and flat zero. Problem solved.

I think #6 on those switches is just the back light so problem solved and all is still functional.