Battery (?) trouble

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Sorry, long post as there is a fair bit of background.


The vehicle I am having issues with is a 2006 Toyota Sienna with over 156,000 miles. Currently, the vehicle cannot start, classic symptoms of a dead battery: wife went to start it, barely turned over, then everything died, nothing electrical works.

Now, for the important background, which I think ties in to some potential underlying problem areas.

First, the immediate background. Battery is about 4 months old. Branded as an "EverStart" from Walmart, but made by East Penn Deka. Dead battery symptoms on this battery first appeared about a week ago, after we were absent on a month long trip. I didn't have it hooked to a charge maintainer, and forgot to disconnect the battery cable. At that point, the dead battery didn't surprise me.

To revive the battery, we used a very old charger that had a 50 amp start option. Got the vehicle home from where we parked while on vacation, then hooked it up to my own automatic "smart" battery charger. Seemed to work, until a couple of days ago, the battery died again.

So, thinking that it may be an alternator not charging, I tested with a multimeter.

Some additional relevant background: vehicle likely needs injectors cleaned, and is overdue for new spark plugs. This is relevant, as the ECU remapped itself to accommodate for this, however, every time the battery dies, it resets the ECU to factory, leading to poor idle until the ECU relearns. (I will address this issue separately, and this isn't directly part of the problem).

On to the multimeter results: after recharging enough to start with the external charger, I tested with the multimeter reading over 14 volts, while the vehicle did its initial elevated idle. When it dropped down to normal idle, which was rough, and barely at 400 rpm, due to the ECU being reset, the voltage reading was 12.5. With my son reading the multimeter, I manually bumped the RPMs to about 1000 with the accelerator, and the readings slowly crept up to near 14 volts. The results make me suspect the alternator isn't the culprit as initally thought. The ECU seemed to relearn quite quickly, so don't think it was a case of idle remaining too low after the boost, plus all the driving would have bumped the RPMs high enough for charging.

Now more background: connected to the battery are two more leads off positive, for the trailer wiring and brake controller added many years ago to the vehicle. Suspecting that there may be a very slight short in the aged wiring, I disconnected those to eliminate that issue, as I continued to monitor it over the next few days.

I also rigged the charger so that when it is at home, it is easy for my wife to plug it in to fully charge the battery, as the cord hangs from the front like a block heater cord would.

This morning, the vehicle didn't start again, same dead battery symptoms, but this time, it was plugged in to a charger (overnight), and should have been fully charged. All electrical load as off, as I ensured all accessories were turned off, and that the parking brake was on to prevent the daytime running lights coming on.

This leads me to believe that the 4 weeks sitting around has actually fried this battery.

But..., there is even more background, the entire battery history before this one:

I replaced the original battery in 2009. I suspected I had to because I had boneheadedly left the interior lights on too many times (manual switch on), and the latest time was just as temperatures dropped below freezing in the fall. Only open choice that evening with batteries was Walmart, and I had to get my wife up and running for the next morning. So off I went, and got their then branded "Energizer" made by Johnson Controls. Also that year, though I made no connection until recently as a possible cause, was all the trailer and brake controller wiring was installed that summer.

This battery lasted until around January 2012. Acid spewing everywhere, it gave up the ghost, but not before severly corroding the factory wiring leads. I had to replace the damaged section with very heavy gauge wire. Fighting Walmart on their warranty, they agreed to replace under warranty based on the manufacturer date sticker, and got a replacement, branded now as "EverStart" made by JCI.

But the battery woes weren't over. Again, the battery died in early 2014. While out of town this time, of course. The local Walmart there agreed to exchange under warranty. Another EverStart JCI.

And again, issues with that battery, with it being replaced again this March, with another EverStart, this time made by East Penn Deka.

Each time, the alternator tested okay with its output. A couple of times, with the different batteries over the years, there were some instances the battery died, but was successfully revived, while towing with the tent trailer, running the 12 volt fridge. Beefing up the trailer side wiring gauge, and avoiding running the 12 volt fridge seemed to elimate the issue, and so the trailer wiring wasn't suspect at that point.

The van was retired from towing after doing a final trip to take the tent trailer out to storage last fall (towing has been taken over by a different vehicle of mine).

Based on the evidence, I suspect that this is where I am now:

There is some sort of parasitic draw, probably a slight short in the trailer wiring.

Sitting 4 weeks without use completely fried this battery.

It only accepted charges for a short while, and even then, not very well, until now, it isn't accepting any charge at all.

Remedy is probably to replace this battery, but also completely disconnect the trailer wiring, to prevent this from occuring again.

Is this the right track, or am I completely missing something?
 
Originally Posted By: weebl
This morning, the vehicle didn't start again, same dead battery symptoms, but this time, it was plugged in to a charger (overnight), and should have been fully charged.
This leads me to believe that the 4 weeks sitting around has actually fried this battery.


I don't think you are going to be able to resurrect it.

DEFINITELY make sure you have no parasitic loads, or you'll just kill the next one, too.
 
I think you're on the right track. Like mentioned above, finding the parasitic draw should be the top priority.
 
Soooo many words...

About 90% of these stories end up being bad connections at the battery terminals.

Measure voltage with charger connected, to confirm it is indeed charging.

If car will not start immediately after disconnecting charger, battery is bad.
 
Is alternator the original?

If so, at 156k miles BRUSHES are prolly MOSTLY wore out, making for a WEAK field charge ( below 14v at idle, ramps up to 14v with rpm), not charging the battery, and making battery 'do all the work' at high amps load (running AC/blowers - headlights) and leaving nothing to recharge battery to 100% to restart car.

Google your alternator - some are easy to replace brushes WITHOUT removal; best to just REPLACE with a quality lifetime rebuilt one IF yours is weak. . .
 
I recently had a very similar problem with a practically new AAP battery in our 2005 Explorer. If I didn't run it regularly it would die after a short period of time. Then I noticed that the "dumb" battery gauge was very slowly dropping below the 1/2 way mark when I drove it even after charging the battery. I read that bad diodes in the alternator can do this, a slow drain on the battery when not in use. Bought a reman alternator from Rock Auto and it's been trouble free since.

Whimsey
 
Order to fix electrical problems
1) Change battery if it is over few months old
2) Check the connections
3) Take out the multimeter and start monitoring continuously for a day or two
4) Confirm bad alternator via multimeter
5) Get inductive amp probe (very cheap these days) and measure the parasitic current
6) Trace if that current is over 100mA
7) If everything else works out, see if you can rebuild your alternator through a local shop
8) If not, try to purchase a better quality an brand name alternator
 
Quote:
When it dropped down to normal idle, which was rough, and barely at 400 rpm, due to the ECU being reset, the voltage reading was 12.5. With my son reading the multimeter, I manually bumped the RPMs to about 1000 with the accelerator, and the readings slowly crept up to near 14 volts. The results make me suspect the alternator isn't the culprit as initally thought.


Culprit is probably the alternator, and probably the diodes. That can keep a car with a trickle charger on it from charging. The low voltage (well below charging voltage) shows the alternator is shot. The battery is probably 100% OK.

Get the car running and then look for AC ripple voltage with your multimeter (google that).

Replace the voltage regulator with a high-quality one and solder in new brushes and you'll be good to go. Better than a reman. from the auto parts store. My SUV I did that with two years ago charges like a bull. The reman from O'Reilly I put in her car a while back failed 18 months later, and cost more. If you have another daily driver, repair it yourself or take it to a local auto electrical shop (they exist; that's who repair shops will use vs. the failure prone Chinese and Mexican units from auto parts stores).
 
I'd be a little hesitant to blame the alternator, it's a Denso unit and they're about the least problematic out there. The battery is fried, probably sulfated terribly. There is most likely a parasitic draw, check everything for corrosion. Corrosion between opposite poles acts as a resistive load and will slowly drain the battery and the resistance of that corrosion can vary greatly with humidity.

When you mentioned the low idle, revving it up and watching the voltage slowly recover suggests that the battery is eating amps and frying the shrinking, remaining unsulfated plate area. Repeated draw downs and high amp recoveries in this condition will quickly result in battery death.
 
Denso alternator in this car is easy to change and relatively cheap.

You can always have somebody test the alternator.
 
Originally Posted By: oldoak2000
Is alternator the original?

If so, at 156k miles BRUSHES are prolly MOSTLY wore out, making for a WEAK field charge ( below 14v at idle, ramps up to 14v with rpm), not charging the battery, and making battery 'do all the work' at high amps load (running AC/blowers - headlights) and leaving nothing to recharge battery to 100% to restart car.

Google your alternator - some are easy to replace brushes WITHOUT removal; best to just REPLACE with a quality lifetime rebuilt one IF yours is weak. . .


Yes, the alternator is original.

Originally Posted By: Whimsey
I recently had a very similar problem with a practically new AAP battery in our 2005 Explorer. If I didn't run it regularly it would die after a short period of time. Then I noticed that the "dumb" battery gauge was very slowly dropping below the 1/2 way mark when I drove it even after charging the battery. I read that bad diodes in the alternator can do this, a slow drain on the battery when not in use. Bought a reman alternator from Rock Auto and it's been trouble free since.

Whimsey


So bad diodes in the alternator can drain the battery when the vehicle is parked?

Originally Posted By: Vikas
Order to fix electrical problems
1) Change battery if it is over few months old
2) Check the connections
3) Take out the multimeter and start monitoring continuously for a day or two
4) Confirm bad alternator via multimeter
5) Get inductive amp probe (very cheap these days) and measure the parasitic current
6) Trace if that current is over 100mA
7) If everything else works out, see if you can rebuild your alternator through a local shop
8) If not, try to purchase a better quality an brand name alternator


Looks like I have to do number 1 regardless of what happens.

Number 2, if the replacement battery cables in there (now several years old) have hidden corrosion, could this be a cause of battery drain? Considering doing what the car audio enthusiasts do, the "big 3" upgrade, and then all my battery cables are completely new.

Number 4, the alternator seems to put out voltage in the charging range. Anything else to check?

Was going to check for an overall parasitic draw, using the multimeter.


Originally Posted By: Eddie
I think you have efficiently trashed your battery instead of buying a $9.99 maintenance charger. :)) ed


I would say so. lol But I think there is something else going on.
 
Pull the battery, charge it overnight on your smart charger and bring it to Walmart to be tested. Then you can cross that off list.

Look at the two main battery cables, both ends for corrosion.
 
Quote:
So bad diodes in the alternator can drain the battery when the vehicle is parked?


Yes.

Charge the battery and have it tested. Dollars to donuts, it's fine. Check for ripple voltage with the multimeter. Takes a minute or two.

This is the next step in your diagnostic procedure. You have already demonstrated the VR in the alternator is shot, or the brushes. It is NOT making charging voltage (~13.85) at all times.

This is about the time/mileage a Denso alternator in a northern climate will fail in my many experiences with the units. Nothing truly magic about them. Also, that presumes that a) it's Denso (didn't see the OP say that, but maybe), and b) It's the same quality as a Japanese Denso. I believe Hitachi was also making some OE Toyota alternators then. And these cars are made in Indiana, not Toyota City, Japan. I wouldn't presume the same alternators installed in Japan made Lexus end up in Indiana made Toyota models. Quality is not as uniform across the brand(s) as it used to be.
 
Last edited:
An alternator/starter rebuilder can test the alternator in a normal manner and in addition use an oscilloscope.

The output of an alternator is 3-phase AC and is converted to DC with a 6 diode bridge. Using an oscilloscope will pick up if one diode is broken. A diode is a one way valve for electricity. Typically is breaks open and prevents electricity from flowing either way. But it can break shorted, electricity can flow either way.
 
Quote:
An alternator/starter rebuilder can test the alternator in a normal manner and in addition use an oscilloscope.


Or you can put a multimeter in correct AC mode across the terminals while running, and save a lot of time and effort. No need to go totally Disco and do '70s era oscilloscope analysis when we have digital multimeters to hand... The multimeter in AC mode will find the same thing, THIS IS NOT THAT HARD.

I am being a bit harsh on Donald and I apologize. He is totally correct if not advocating the simplest solution. But he pointed out what some of us assumed was understood before - rectifiers fail both ways. And the OP's 1st post is a classic example to anyone familiar with the physics, theory, and construction of these circuits that this charging system is bad, faults elsewhere unproven.

The OP's 1st post shows an alternator fault and if posters did not pick that up, why flood with nonsensical advice? Neck it down from obvious issues and solve it.

Treat the 1st obvious fault and not throw parts or effort at a problem. The battery MIGHT be damaged. Unlikely. The alternator is clearly out of whack, fix it first.
 
Thank you, I will test the diodes using the multimeter in AC mode.

Some interesting observations when I got home last night and looked at the vehicle:

Battery charger was showing that it was maintaining the battery. The vehicle started just fine on the first try.

Ran voltage tests, vehicle running, not running, all voltages seem to be reading normally. After a drive to do a quick errand (the vehicle did not need help restarting), and returning home, I tested the battery after giving it a chance to rest, to determine the charge level (vehicle off, no charger connected): 12.73 volts exactly.

I disconnected the positive cable, and used the multimeter to measure if there was any sort of parasitic load. After keeping the leads connected for a few minutes, the vehicle went to sleep, and the readings fluctuated between 0.00 amps to 0.01 amps. So that seems normal.

I did notice where the insulation on the positive battery cable peeled back a bit, that there was some very mild evidence of oxidation. Nothing heavy, but possibly something inside the cable?

Reconnecting the positive cable, I restarted the vehicle. Except it didn't start, it went through the cranking, then fizzled out mid-crank. Going back to the battery and checking the charge still showed it was good.

Tried restarting again after checking that the cable was indeed tightly on (even snugged it up a bit), not really sure if that did anything or not, and this time, it cranked fine and started.

If the diode test checks out, then my feeling is I need to replace the battery cables, if they are showing signs of oxidation. They are not entirely OEM, the leads near the battery were replaced and spliced far from where that first Walmart battery badly corroded the OEM cable. I had found where the corrosion ended, then went several more inches to ensure the splice was where it was clean copper. This time around, I will do the entire length of cable (unless I find the diodes are the issue, and go down that path).
 
Originally Posted By: Oro_O



This is the next step in your diagnostic procedure. You have already demonstrated the VR in the alternator is shot, or the brushes. It is NOT making charging voltage (~13.85) at all times.




I don't know that was conclusive, under 13.85 volts was happening when the ECU had to relearn idle, and was only at 400 rpm. When it did bump to 650/700 rpm, the voltage came up.

Originally Posted By: Oro_O

This is about the time/mileage a Denso alternator in a northern climate will fail in my many experiences with the units. Nothing truly magic about them. Also, that presumes that a) it's Denso (didn't see the OP say that, but maybe), and b) It's the same quality as a Japanese Denso. I believe Hitachi was also making some OE Toyota alternators then. And these cars are made in Indiana, not Toyota City, Japan. I wouldn't presume the same alternators installed in Japan made Lexus end up in Indiana made Toyota models. Quality is not as uniform across the brand(s) as it used to be.



I don't know with 100% certainty, but I'm sure I saw the sticker on the alternator say Denso and not Hitachi. Also didn't see where the alternator was made, but I suspect it is probably a USA Denso, and not a Japanese Denso.
 
At 140k miles my OE alternator brushes were not all that bad but the slip ring they rode on was seriously eroded.

You should get a cheap plug into the lighter voltmeter to monitor your voltage as you drive. Should go high (~14.5) after starting and then drop into the high 13's as the battery is brought back to full charge.
 
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