Stranded - Alternator Problem

Now, since you've cleaned off the terminals, here's a little old school trick.

Get baking soda and put it over the terminals with just a little bit of water. It will most likely foam up a bit. Wait a few minutes, then wash it off with the hose, making sure you wash it all the way down and off the vehicle.

Personally, I spend a lot of money on replacing batteries in all of my vehicles as soon as I get them for a good, quality AGM battery is well-worth the money spent on them, as you have already noticed the amount of time and aggravation spent in dealing with this issue.

Odyssey is my preference, but there are other brands. Sears AGM that's loved here in this forum is a re-badged Odyssey. Yeah, they're upwards of $250 bucks, but you will never get that corrosive acid buildup again. My truck is living proof of that, as its had an Optima since the mid-90's and in the past year, a new Odyssey battery. Terminals were corroded from the previous non-AGM battery in the early 90's, and since that has been removed, I have not had to clean the terminals from corrosion!

Glad it was an easy fix for ya, hopefully that's all it was and your 4r continues to run without issue!
 
flyinhawaiian01 said:
Now, since you've cleaned off the terminals, here's a little old school trick.

Get baking soda and put it over the terminals with just a little bit of water. It will most likely foam up a bit. Wait a few minutes, then wash it off with the hose, making sure you wash it all the way down and off the vehicle.

Personally, I spend a lot of money on replacing batteries in all of my vehicles as soon as I get them for a good, quality AGM battery is well-worth the money spent on them, as you have already noticed the amount of time and aggravation spent in dealing with this issue.

Odyssey is my preference, but there are other brands. Sears AGM that's loved here in this forum is a re-badged Odyssey. Yeah, they're upwards of $250 bucks, but you will never get that corrosive acid buildup again. My truck is living proof of that, as its had an Optima since the mid-90's and in the past year, a new Odyssey battery. Terminals were corroded from the previous non-AGM battery in the early 90's, and since that has been removed, I have not had to clean the terminals from corrosion!

Glad it was an easy fix for ya, hopefully that's all it was and your 4r continues to run without issue!
Click to expand...

Here's an older school trick: Just pour a bit of Coca Cola out of a can on the terminals. Cleans all the corrosion away quickly just like your method.
 
Voltage won't mean too much without amperage to compare with. We've seen a handful of alternators in the last couple years putting out "acceptable" voltage but barely any amperage (never did figure out why).

13.9v sounds acceptable and for the most part I wouldn't question it, but something to keep in mind if issue crops up again.

Also I recommend replacing the positive terminal end if the copper is showing, once it's eaten through the grey coating it just seems to corrode that much faster and a new terminal is like $20-ish at the dealer. I see a LOT of severely corroded terminals on fairly new Toyotas, the thin sheet-metal design coupled with batteries off-gassing from a lot of short-trips and such tend to eat those suckers up fast. Couple that with owner negligence in cleaning them off and the owner's wonder why they need a new harness because the terminal end is completely eaten off.

Post Note-

How did you test the battery to verify that it is in good condition?
 
1engineer said:
Here's an older school trick: Just pour a bit of Coca Cola out of a can on the terminals. Cleans all the corrosion away quickly just like your method.
Click to expand...

Another trick I learned from my grandfather many many moons ago....
Either petroleum jelly with baking soda mixed in or axle grease covering all parts of the terminals will prevent corrosion once it has all been cleaned off!

yes, it works...
:hatsoff:
 
The owner of an electrical rebuild shop I've been using for many years once told me to put the red lead from VOM on B+ alternator post and black lead from VOM on the the alternator case(ground). That measures alternator voltage.

In my experience I find that if I see xx.yy at the battery, I see pretty much the same at the alternator, but I check alternator voltage anyway.
 
BlackWorksInc said:
Voltage won't mean too much without amperage to compare with. We've seen a handful of alternators in the last couple years putting out "acceptable" voltage but barely any amperage (never did figure out why).
Click to expand...

How do I check the amperage? I have the 130amp alternator; what kind of numbers should I be seeing from a 120k mile alternator?


BlackWorksInc said:
How did you test the battery to verify that it is in good condition?
Click to expand...


I had my local mechanic check it with his computer when my electrical issues began. At that time I had to jump start the truck, so I thought the battery was bad. He checked it ten minutes after jump start and said the battery was healthy and full.

Then, this past weekend, I had both Advance Auto and NTB test it with their machines. Both concurred that the battery was healthy, just not totally charged. They both said that it was because my alternator wasn't charging and the truck's electrical system was running from the battery only. I thought this had to be BS because I had been driving for over two hours with every electrical appliance running except for the inverter and no battery could handle that kind of draw and not show it.
 
IMO if I ever need another alternator I have the original rebuilt at a starter alternator repair shop. If it can't be rebuilt I would buy OEM. I have had too many failures over the years with Chinese alternators/starters. I Have used baking soda, coke, chassis greese and vasoline. Only thing I find is dirt gets stuck on greese if not covered.
 
1engineer said:
Here's an older school trick: Just pour a bit of Coca Cola out of a can on the terminals. Cleans all the corrosion away quickly just like your method.
Click to expand...


I knew a guy once who did this (not a 4 runner), but failed to wash it off afterwards. Boy was that a messy, sticky disaster all over his battery, the side of the battery, the tray, the frame and a few other spots down the suspension!

:shrug:

Anyways, yes, that works too! Although, wasting a coke is horrendous! :D
 
People have used vaselene on battey terminals for years. The only problem with it is that it thins out and runs off from the heat generated under the hood. A better way IMO is to use one of the spray products made for terminals. You spray it on and it covers the visible parts of the terminal and is not messy. You should mask off what you don't want covered. It will last quite a while and helps keep the air away from the terminal which slows down corrosion. Covering ground studs is a good idea too.

Also, most all auto shops have what's called a battery - starter tester. It's connected to the vehicle via battery and ground connections. With it you can determine the health of the starting and charging system. You can see alternator output and also load down the system to check that the alternator takes on the load and also see of the battery is being recharged by the alternator after starting load through the regulator (now part of the alternator in newer cars).

I would first check all that above posters have mentioned as to making sure all connections are tight, wires and terminals are not corroded. If the battery is way down, remove it and charge it away from the vehicle first; making sure all cells are filled to the ring. AUto charging systems were not designed to fully charge a dead battery and many have controls so they won't even try if the voltage gets too low.
 
Last edited:
Lester Lugnut said:
The owner of an electrical rebuild shop I've been using for many years once told me to put the red lead from VOM on B+ alternator post and black lead from VOM on the the alternator case(ground). That measures alternator voltage.

In my experience I find that if I see xx.yy at the battery, I see pretty much the same at the alternator, but I check alternator voltage anyway.
Click to expand...

Well ideally, if you wanted to be thourough you'd check the following:

-Alternator Positive to Battery Negative Post (Most Postive Voltage point to Most Ground/Negative point of the vehicle)

-Alternator Positive to Case and/or Block (to check for voltage drop between output and case)

-Alternator Positive to Postive Battery Terminal (Voltage Drop between Alternator and Battery)

-Positive Terminal Clamp to Positive Terminal Post & Negative Terminal Clamp to Negative Terminal Post (Checking Voltage Drop between terminals and clamps)

In reality I usually just throw my DVOM on the clamps or terminals and see what I get; I wouldn't start getting too involved on those measurements unless I really saw evidence that there was excessive voltage drop.

Muddy Duck said:
How do I check the amperage? I have the 130amp alternator; what kind of numbers should I be seeing from a 120k mile alternator?


I had my local mechanic check it with his computer when my electrical issues began. At that time I had to jump start the truck, so I thought the battery was bad. He checked it ten minutes after jump start and said the battery was healthy and full.

Then, this past weekend, I had both Advance Auto and NTB test it with their machines. Both concurred that the battery was healthy, just not totally charged. They both said that it was because my alternator wasn't charging and the truck's electrical system was running from the battery only. I thought this had to be BS because I had been driving for over two hours with every electrical appliance running except for the inverter and no battery could handle that kind of draw and not show it.
Click to expand...

Well if you have an ammeter or a DVOM that can handle more than 10amps inline the specifications call for:

(1) Maintain the engine speed at 2000 rpm and check the reading on the ammeter and voltmeter. (No Load)

Standard current:
10 A or less
Standard voltage:
13.2 to 14.8 V
If the voltmeter reading is higher than the standard voltage, replace the generator.

and

(a) With the engine running at 2000 rpm, turn the high beam headlights on and turn the heater blower switch to the HI position.

(b) Check the reading on the ammeter.

Standard current:
30 A or higher
If the ammeter reading is less than the standard current, repair the generator.

~

But honestly it sounds like the alternator is probably working fine, the voltage drop between the clamps and terminals was excessive enough that it could not effectively charge the battery and maintain good power supply to the vehicle; so theoretically as long as there's no lasting damage to the alternator as a result everything should be fine now.
 
BlackWorksInc said:
Well ideally, if you wanted to be thourough you'd check the following:

-Alternator Positive to Battery Negative Post (Most Postive Voltage point to Most Ground/Negative point of the vehicle)

-Alternator Positive to Case and/or Block (to check for voltage drop between output and case)

-Alternator Positive to Postive Battery Terminal (Voltage Drop between Alternator and Battery)

-Positive Terminal Clamp to Positive Terminal Post & Negative Terminal Clamp to Negative Terminal Post (Checking Voltage Drop between terminals and clamps)

In reality I usually just throw my DVOM on the clamps or terminals and see what I get; I wouldn't start getting too involved on those measurements unless I really saw evidence that there was excessive voltage drop.



Well if you have an ammeter or a DVOM that can handle more than 10amps inline the specifications call for:

(1) Maintain the engine speed at 2000 rpm and check the reading on the ammeter and voltmeter. (No Load)

Standard current:
10 A or less
Standard voltage:
13.2 to 14.8 V
If the voltmeter reading is higher than the standard voltage, replace the generator.

and

(a) With the engine running at 2000 rpm, turn the high beam headlights on and turn the heater blower switch to the HI position.

(b) Check the reading on the ammeter.

Standard current:
30 A or higher
If the ammeter reading is less than the standard current, repair the generator.

~

But honestly it sounds like the alternator is probably working fine, the voltage drop between the clamps and terminals was excessive enough that it could not effectively charge the battery and maintain good power supply to the vehicle; so theoretically as long as there's no lasting damage to the alternator as a result everything should be fine now.
Click to expand...

Hey BW,

When performing these tests, are you putting the DVOM leads on the 2 battery terminals?

Also, off-topic -- I assume alternator positive to battery positive is sending excess charge that the battery uses to re-charge.

Why does alternator positive go to battery negative?
 
amalik said:
Hey BW,

When performing these tests, are you putting the DVOM leads on the 2 battery terminals?

Also, off-topic -- I assume alternator positive to battery positive is sending excess charge that the battery uses to re-charge.

Why does alternator positive go to battery negative?
Click to expand...

If you're using the DVOM you're supposed to be hooking it inline with the circuit, i.e. clipping positive lead to positive from the alternator and negative lead to the battery post. Most DVOMs are rated up to 10amps in the correct setting, so do NOT use the DVOM in this fashion for the "Load" test, but for high idle it should be okay as the desired result is below 10amps. Though a dead/low battery could require more, so just be cautious so you don't blow your DVOM's fuse, an indirect amp clamp would be best.

Yes and no, the alternator is producing current to maintain a constant power supply. Sometimes this means charging the battery up (starting the vehicle will take upwards of a few hundred amps momentarily and then drop to a constant draw of something like 20~50amps while cranking) from a low state; other times it means providing enough current to keep the battery in a 95~100% state of charge as power is being pulled out of the battery.

Think of it like an air compressor and storage tank; your air tool needs 100psi to operate with 1CFM of flow; the storage tank only has 5CFM a minute at 100psi. This means that the air tool can only run for 5min until the compressor has to kick in and top off the tank, if you're running a second air tool that takes 2CFM then the compressor is going to kick on sooner and run longer to maintain that pressure/flow (similar to say the alternator ramping up current when you turn the high-beams on.)

Another thing to remember is that modern OBDII CAN vehicles not only need a constant supply of power, but they need "Clean" power. This is one critical function of the 12v Battery that was not as important in older days, the battery is acting like a giant dampener to smooth out the DC Ripple created by the Alternator and provide a solid stable output around 13.4~14v for the ECM and vehicle to work with. If you did not have that dampening effect, the varying voltages would result in varying reference voltages and varying sensor inputs/outputs that would cause the vehicle to run poorly. Unfortunately since we went to Alternators from old school Generators, they no longer have the ability to charge up a dead battery, they merely top off a low battery (12.0v is pretty low); that's why a dead battery can easily kill an alternator when run too long.

As for your question about the Alternator Positive to Negative, I don't quite understand what you are asking. Are you asking why you would check the Alternator Positive to Ground? Alternator Positive goes to Battery Positive.
 
BlackWorksInc said:
Unfortunately since we went to Alternators from old school Generators, they no longer have the ability to charge up a dead battery, they merely top off a low battery (12.0v is pretty low); that's why a dead battery can easily kill an alternator when run too long.

As for your question about the Alternator Positive to Negative, I don't quite understand what you are asking. Are you asking why you would check the Alternator Positive to Ground? Alternator Positive goes to Battery Positive.
Click to expand...

Interesting... so is that why they say never let the alternator charge a dead battery, instead use a charger?

I was asking why the alternator is required to go to the negative terminal at all. I thought it only needs to feed the positive terminal for the sake of charging the battery when the battery needs it, as you mentioned above. Or is hooking into the negative part of that charging process as well, i.e a circuit?
 
5th gen 2011 Sr5 alternator failed

Hello everyone

Today , while parking at the super market radio went out battery light on dash came on , multiple blinking lights on dash , eventually vehicle turn off by it self within minutes. I jumped started could keep it running at higher rev was able to make it home. Turned off when at a complete stop. Multimeter 12.38 volts truck running should be around 13.9. Issue: Altenator fail , to it to local shop , 4 diodes and plate were bad. Installed a new plate 6 diode —> more capacity oem was aprox. 120 amp now aprox 130 amp with new plate. If you are up to the job removing driver front tire helps to remove altenator rear hidden screw , the rest are visible.

Hope it helps


LM
 
I'm getting my alternator and battery checked today (hopefully) due to similar issues. From what I've read here, it sounds like my battery going bad (I've had to jump it 3 times in the last 2 months) might have ruined my alternator. Now it won't start without a jump, and as soon as I take off the jumper cables it dies. I'll also check for corrosion, since it was mentioned a few times in this post. Good info!
 
Strange27 said:
I'm getting my alternator and battery checked today (hopefully) due to similar issues. From what I've read here, it sounds like my battery going bad (I've had to jump it 3 times in the last 2 months) might have ruined my alternator. Now it won't start without a jump, and as soon as I take off the jumper cables it dies. I'll also check for corrosion, since it was mentioned a few times in this post. Good info!
Click to expand...

A battery with an internal short can do that. Alternator may be fine.
 
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