Alternator voltage regulator question (1 Viewer)

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Aug 29, 2020
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canada
I recently replaced a battery on an 06 with 140K; it was having trouble starting in the cold. For about two months everything has been ok.
Today I went to start it up and it wouldn’t crank. I got the battery charger out and after a few minutes of charging , got enough juice to start up.
Drove the car for 30-45 minutes with no issues and no dash lights.
I inspected under the hood, not thoroughly because it’s cold and noticed that there is corrosion around the positive battery terminal. This is recent as when I replaced the battery I made sure all the terminals were clean. Doing a bit of research I understand that this is a sign of overcharging and that it could be the alternator itself or maybe just a voltage regulator.
Scanning through websites like RockAuto and Toyota/Lexus pets dealers I can’t see that voltage regulators are sold separately. Does anyone know? I’d prefer to start replacing that before the whole alternator.
I haven’t yet taken the multimeter to actually check the voltage to confirm overcharging.
 
Joined
Aug 29, 2020
Messages
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Location
canada
I recently replaced a battery on an 06 with 140K; it was having trouble starting in the cold. For about two months everything has been ok.
Today I went to start it up and it wouldn’t crank. I got the battery charger out and after a few minutes of charging , got enough juice to start up.
Drove the car for 30-45 minutes with no issues and no dash lights.
I inspected under the hood, not thoroughly because it’s cold and noticed that there is corrosion around the positive battery terminal. This is recent as when I replaced the battery I made sure all the terminals were clean. Doing a bit of research I understand that this is a sign of overcharging and that it could be the alternator itself or maybe just a voltage regulator.
Scanning through websites like RockAuto and Toyota/Lexus pets dealers I can’t see that voltage regulators are sold separately. Does anyone know? I’d prefer to start replacing that before the whole alternator.
I haven’t yet taken the multimeter to actually check the voltage to confirm overcharging.
Did a bit more trouble shooting. This morning the battery was at 11.99V, but when the car was on the alternator was charging at a consistent 14.15V. So I think the alternator is ok.

when the car is off there is a 0.11 amp draw. Is this within normal? I didn’t do a thorough parasitic draw test because it’s -20 here in the garage, but the first fuse I pulled - OBD - had the amp draw go down to .02amps. Is it common for these fuses to go out? About a month ago I used a scanner to get some codes and it worked fine, the fuse ends had this pinkish quality to it not bare metal. Could I be lucky to have found my parasitic draw on the first try?
 
Joined
Sep 3, 2019
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I believe Toyota specs 0.025 (25ma) as acceptable / stock parasitic draw and anything higher should be addressed.

On the battery: Battery terminal corrosion is common - You can buy a tube of Dialectric grease at lowes.


Clean the corroded terminals with a splash of warm water mixed with baking soda.

Then slather the dialectric grease all over the terminal connectors and terminals themselves. use a generous coating.
 
Joined
Aug 29, 2020
Messages
22
Location
canada
I believe Toyota specs 0.025 (25ma) as acceptable / stock parasitic draw and anything higher should be addressed.

On the battery: Battery terminal corrosion is common - You can buy a tube of Dialectric grease at lowes.


Clean the corroded terminals with a splash of warm water mixed with baking soda.

Then slather the dialectric grease all over the terminal connectors and terminals themselves. use a generous coating.
I’ve cleaned all the leads of corrosion and the battery is full of fluid.

I called Interstate Battery. They basically said that a 110milliamp draw would take a couple of weeks to drain a battery, so while above the threshold, and could be a potential parasitic draw, not sure it could drain my battery in a couple of days

what they did say is that if I’m not using the vehicle often I should have it on the charger. I only use it 1 or 2 times a week to pick up my kids from daycare and I’m in Ottawa where it’s very cold. The charger advice makes sense, but what’s confusing is that I have another vehicle that I use under the same conditions with a much older battery and it starts every time.

Interstate also said that anything below 12.6v on the battery means it is discharged. Yesterday I started the car with the battery at 11.9v, drove it for a while and when I parked it, it was up to 12.3V. This morning again down to 11.9V, but it started no problem. My alternator steadily pumps out 13.8-14.2v which is optimal.
 
Joined
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Messages
81
Location
US
I’ve cleaned all the leads of corrosion and the battery is full of fluid.

I called Interstate Battery. They basically said that a 110milliamp draw would take a couple of weeks to drain a battery, so while above the threshold, and could be a potential parasitic draw, not sure it could drain my battery in a couple of days

what they did say is that if I’m not using the vehicle often I should have it on the charger. I only use it 1 or 2 times a week to pick up my kids from daycare and I’m in Ottawa where it’s very cold. The charger advice makes sense, but what’s confusing is that I have another vehicle that I use under the same conditions with a much older battery and it starts every time.

Interstate also said that anything below 12.6v on the battery means it is discharged. Yesterday I started the car with the battery at 11.9v, drove it for a while and when I parked it, it was up to 12.3V. This morning again down to 11.9V, but it started no problem. My alternator steadily pumps out 13.8-14.2v which is optimal.
It's probably a combination of:
- cold weather
- not driving often
- not driving it enough

Even though you are charging at full power (13.8-14.2) It would take an hour or more of driving to get back up to full charge (12.6 resting) if you were all the way down to 11.9.

11.9 is right on the cusp of being dead for an Lead Acid.

Parking at 12.3 is already down to 70%.

Besides the parasitic draw you are probably just never getting it full charged to begin with, the the long sitting and cold weather is making it worse.
 
Joined
Aug 29, 2020
Messages
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Location
canada
It's probably a combination of:
- cold weather
- not driving often
- not driving it enough

Even though you are charging at full power (13.8-14.2) It would take an hour or more of driving to get back up to full charge (12.6 resting) if you were all the way down to 11.9.

11.9 is right on the cusp of being dead for an Lead Acid.

Parking at 12.3 is already down to 70%.

Besides the parasitic draw you are probably just never getting it full charged to begin with, the the long sitting and cold weather is making it worse.
I took my battery in for a test and Interstate said it was fine. They also said a 100milliamp draw would take days to deplete the battery. I usually drive the car every 2-3 days, but only for like 30 min or so. I think I have a combination of a weaker alternator + the draw. It’s just too cold to troubleshoot thoroughly so I got a Battery Tender used for $45 to hold me over until the warm weather.
The confusing thing is I have a Honda Odyssey that I drive the same way and it’s got the power sliding doors plus all these other electronics and the battery is 5 years old; it starts like a clock even in -25C we’ve had recently.
 

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