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Draining batery

  #1  
Old 04-01-2017, 03:58 PM
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Default Draining batery

Bought a used 2007 Ion to use for towing behind a Motor Home.Replaced battery in February .If I go several days w/o cranking it , battery is dead and needs charging,then it turns over .How do I check to find where the drain on battery is?For now I disconnect the battery cable while it is parked,when I tried today after reconnecting cable it turned over fine .Also is there a fix w/o replacing radio ?Radio hasn't worked since I bought it,no warranty on car .I don't know what is wrong with it.Dealer wanted to replace it for $500,but I am not just off the boat .Are there any options for either problem??
 
  #2  
Old 04-02-2017, 03:42 AM
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1) Your problems may be related.

Pull the radio fuse and see if that keeps it from draining overnight.

2) In these situations, there are some popular sources of significant drain over the course of a few days.

One of them is when one or more of the diodes inside the alternator goes bad.

A diode is designed to allow current to flow through it in one direction but not the other. If a diode breaks down, it will allow current to flow in both directions.

Because the output of your alternator is tied directly to the + terminal of your battery, any current created by the alternator under normal operation will charge your battery. However, if one or more of the diodes breaks down, the battery may not charge fully.

More importantly when you turn the key off, the flow of current reverses direction as the bad diode acts as drain to ground and slowly drains charge out of your battery in the form of a small steady current that, without attention, will drain the battery low enough that there is not sufficient current to crank the engine over.

The easiest way to test this is to

1) take the vehicle to Autozone or similar and ask them to run a full load test on your car's charging system. This is FREE and they will give you a printout which you can post the results of here and we will help you interpret. Sometimes their results can be wrong but they are usually pretty good at finding the bad diodes if they exist.

or you can

2)disconnect the negative, then the positive terminal of the battery, remove the positive connection from the alternator to the battery AT THE ALTERNATOR. Place the connector end somewhere that it will NOT come into contact with ANY METAL SURFACE while disconnected. This includes the hood when closed.

Why? Because the other end is a live connection to the pos terminal of your battery (will be when we're done)

With the above completed, reinstall the positive, then negative cables to your battery in that order. You now have physically isolated the alternator from the battery.

When your car is at not running (at rest), the DC Voltage betw pos n neg terminals should be 12.2 to 12.6 V

When the engine is idling, expect a reading on the order of 14.4 DC V.

Measure the battery V after you complete the alternator disconnect.

Leave it alone overnight and remeasure the voltage. If it remains essentially 12.2 to 12.6 DC V, then the culprit was pretty likely the alternator.

If the DCV drops significantly, you may have a cell going bad inside your battery. This is something the charging system test should also verify. Or it still may be a current drain from somewhere else.

DO NOT CRANK THE CAR WITH THE ALTERNATOR DISCONNECTED. You run the risk of damaging the car's electrical system.

DO NOT REATTACH THE ALTERNATOR OUTPUT WITH THE BATTERY CONNECTED AND OR THE CAR RUNNING. Unnecessarily dangerous and likely to cause a huge current spike that cannot be fully dampened and may again wreck parts of your electrical system.

When you are done with the test, disconnect the batt cables as above, reconnect the alternator output feed at the alternator.

Now start the car, let it idle for 20 min to top off battery charge, then turn off and measure the V across the battery terminals. Let the car sit overnight again for the same amount of time, then measure the V across the battery terminals.

If it is significantly lower (10-11 volt range), this pretty much confirms that the alternator is providing the path to ground that is draining your battery.
 

Last edited by derf; 04-02-2017 at 03:45 AM.
  #3  
Old 04-02-2017, 06:12 AM
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Ehhhh, derf, contrary to popular belief, an alternator doesn't charge the battery. While I'm happy to admit that if your battery is SLIGHTLY low, it may add a small amount of voltage to it. BUT if a battery is at, let's say 11.5 volts and you jump start it, the alternator will NOT charge it to 12.5. The alternator is basically there to keep the charge that you have in the battery already. If alternators were in fact battery chargers, then none of us would ever have to buy a battery charger, right? I think you're spot on with the testing of the diode as the likely culprit in this situation, however. Rock on, derf!
 
  #4  
Old 04-02-2017, 08:37 PM
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Poor confused friend,

1) The battery has several tasks, but its main one is to store enough charge such that it can provide the required "cranking Amps (CA) " = high current at low voltage to rotate the starter motor at a rotational speed sufficiently fast to rotate the flywheel of the engine quickly enough such that the engine begins to rotate and fire and then the momentum of the engine firing propels the engine rotation sufficiently that the engine runs on its own.

Summary: Battery stores charge to start the car.

2) Alternator

The alternator serves two main functions.

a) to provide operating current for the entire vehicle once it is running
This current supplies everything needed to run the vehicle and all of its electrical/power options (door locks, sunroof, turn signals, PCM, BCM, TCM, ECU, ECM, ABS. ESC, TRAC, SIR, and other subsystems with three letter abbreviations I cannot recall at the moment.

b) to provide a "maintenance charge" to the battery in order to ensure that it is sufficiently charged for the next time the vehicle is started

Your comment

Originally Posted by Rubehayseed
BUT if a battery is at, let's say 11.5 volts and you jump start it, the alternator will NOT charge it to 12.5. The alternator is basically there to keep the charge that you have in the battery already.
is factually inaccurate.

if 11.5V battery voltage indicates by correlation that there will not be enough charge stored in the battery (CA) to spin the starter and start the engine, then you jump start the vehicle with a battery that does.

Once the car with the dead battery is running again, the alternator immediately begins to provide the electricity to run the entire vehicle.

It ALSO sends current to the battery to drive the chemical reaction within the battery to restore the ability of the depleted battery cells within to store charge.

The output of a properly functioning alternator is a high current at about 14.4V. If your battery is at 11.5V, there is an electrical "potential difference) such that current if available will flow from the higher potential to the lower potential. That's just how it is.

Once the depleted sections of the cells are returned to a working state, the begin to store charge; as the stored charge increases, so does the V (Ohm's Law V=IR, R=battery internal resistance which in this case is constant).

If the above did not happen, the next time you went to start that vehicle, the battery would still be unable to start the car.

There is of course the evil case where the 11.5V battery is partially internally damaged/spent and cannot store the charge that is being sent to it by the alternator. But even in this case, the alternator is still providing a slow charge to the battery.

This charging process via the alternator is not quick but does the job for slightly discharged batteries. For deeply discharged batteries, a battery charger indeed makes sense.
------------------
Can you run a car with no battery?
Not initially -- you can't start it.
------------------
Can you start the car and pull the battery?
Sure.
-----------------
Will it continue to run?
Sure.
-----------------
Might you damage the PCM on today's cars?
Pretty likely.
This old timer's alternator test is an absolute no no on today's cars because of the electronics.
-------------------
What happens if your alternator begins to fail and can't generate the current to run the car? Does it stall on the spot?
No -- it starts drawing current from the battery until there is not enough charge in the battery to supply the required current at 12 ish V or 5V etc.
THEN it stalls.
-------------------

>>>>>>If the alternator had been functioning properly, the battery never would have run out of charge.<<<<<<<

------------------

So in summation

A) Battery 's primary purpose is to provide a huge current to the starter motor to start the car.
B) Alternator provides operating current to the vehicle once it is running
C) Alternator provides a maintenance charge to the battery at all times and will SLOWLY replenish a drained battery that is still capable of storing charge.

IF I had just said that at the top of the post, the next question would likely have been "prove it, you damn Yankee son ' beertch", so I just saved us a go-round.

Apologies to the OP for the informational highjack ---HE made me do it
 
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Old 04-03-2017, 07:32 AM
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F I had just said that at the top of the post, the next question would likely have been "prove it, you damn Yankee son ' beertch", so I just saved us a go-round.

No you didn't. This is what you said.
C) Alternator provides a maintenance charge to the battery at all times and will SLOWLY replenish a drained battery that is still capable of storing charge.
Most of the time if a battery is low, there's a reason for it, whether it be a parasitic drain or someone simply ran it down trying to start the car. If it has a dead cell, an alternator will NOT charge it. You verified what I am saying with the last seven words of that statement. And a new car won't run after starting it and removing a battery. If you break the circuit by removing the ground cable, the computers detect that and shut down the engine. Back in the old days, I drove a LOT of cars without batteries once they were started and the battery removed. Of course if someone turned it off, you were screwed! LOL Anyway, I like to get your dander up and get you going on a tangent. That's what friends do!
 
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Old 04-03-2017, 04:30 PM
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Must we go in electrical loops?

1) If the alternator is producing the operating current for the car when running, then unless the PCM is grounded to the frame directly through the negative battery cable, the car SHOULD continue to run. I will likely throw a code for a charging system related issue, but the alternator, along with the voltage regulator, should keep the car running. Unless you spike the current while removing the battery and smoke the PCM.

There are literally maybe 100 connections to ground in the vehicle, including grouped ground splice packs (single point grounding (best practice to avoid ground loop currents)

Originally Posted by RuBeHaYsEeD
Ehhhh, derf, contrary to popular belief, an alternator doesn't charge the battery. While I'm happy to admit that if your battery is SLIGHTLY low, it may add a small amount of voltage to it. BUT if a battery is at, let's say 11.5 volts and you jump start it, the alternator will NOT charge it to 12.5
Ummm, wrong. I've helped my neighbor trace a parasitic drain that left his battery V and stored charge insufficient to start his truck every morning.

Measurement, truck off 5pm: 12.6 V DC
Next morning: truck still off, 7 AM: 10.3V DC; unable to start truck.
Jump start truck, idle for 5 min, go to work.
Vehicle starts fine at work, driven home.
Measurement , truck off 5pm next day :12.5 V DC

Now how in the hell did THAT happen? Battery V from 10.3 to 12.5V ?

Unless you snuck into his workplace with an EXTERNAL battery charger, the alternator provided a charging current to replenish the charge in the battery.
---------
In fact (loads bazooka), Ford has been employing load shedding to actually have the car run off the battery and not entirely the alternator. The theory is that not having the alternator outputting full current all the time and instead lowering its output current produces less drag on the serpentine at the alternator pulley, resulting in better gas mileage.

In such situations, the alt may be commanded (Ford now has "command-able" alternators) to lower its output. The battery is then used to power the vehicle, along with a small alternator contribution to the current. When the battery V drops below 11.3 V, the alt is commanded to run full tilt until the battery V is returned to a minimum of 12.6V and that current from the alternator helps restore the charge in the battery so it is sufficiently charged to start the vehicle when next needed.

So, whether you like it or not, the alternator can in fact DOES charge a jump started battery from 11.5 to 12.2V given enough time. If the battery will not hold a charge, then the battery is defective but that has nothing to do with what the alternator is doing---it is providing current to run the car AND sending current to keep the battery properly charged.
----------
You are now trying to base your entire argument on the one evil case where the battery is defective? That's not what you said above and is silly as it ignores the entire generalnquestion at hand.
--------
Even a battery charger can't restore full charge to a defective battery. Duh. What does that have to do with an alternator???? ?!?!?
--------
1) If the alternator is producing the operating current for the car when running, then unless the PCM is grounded to the frame directly through the negative battery cable, the car SHOULD continue to run. I will likely throw a code for a charging system related issue, but the alternator, along with the voltage regulator, should keep the car running. Unless you spike the current while removing the battery and smoke the PCM.

There are literally maybe 100 connections to ground in the vehicle, including grouped ground splice packs (single point grounding (best practice to avoid ground loop currents)

Originally Posted by RuBeHaYsEeD
Ehhhh, derf, contrary to popular belief, an alternator doesn't charge the battery. While I'm happy to admit that if your battery is SLIGHTLY low, it may add a small amount of voltage to it. BUT if a battery is at, let's say 11.5 volts and you jump start it, the alternator will NOT charge it to 12.5
Ummm, wrong. I've helped my neighbor trace a parasitic drain that left his battery V and stored charge insufficient to start his truck every morning.

Measurement, truck off 5pm: 12.6 V DC
Next morning: truck still off, 7 AM: 10.3V DC; unable to start truck.
Jump start truck, idle for 5 min, go to work.
Vehicle starts fine at work, driven home.
Measurement , truck off 5pm next day :12.5 V DC

Now how in the hell did THAT happen? Battery V from 10.3 to 12.5V ?

Unless you snuck into his workplace with an EXTERNAL battery charger, the alternator provided a charging current to replenish the charge in the battery.
---------
In fact (loads bazooka), Ford has been employing load shedding to actually have the car run off the battery and not entirely the alternator. The theory is that not having the alternator outputting full current all the time and instead lowering its output current produces less drag on the serpentine at the alternator pulley, resulting in better gas mileage.

In such situations, the alt may be commanded (Ford now has "command-able" alternators) to lower its output. The battery is then used to power the vehicle, along with a small alternator contribution to the current. When the battery V drops below 11.3 V, the alt is commanded to run full tilt until the battery V is returned to a minimum of 12.6V and that current from the alternator helps restore the charge in the battery so it is sufficiently charged to start the vehicle when next needed.

So,k whether you like it or not, the alternator can in fact charge a jump started battery from 11.5 to 12.2V given enough time. If the battery will not hold a charge, then the battery is defective but that has nothing to do with what the alternator is doing---it is providing current to run the car AND sending current to keep the battery properly charged.
.
.
 
  #7  
Old 04-03-2017, 04:43 PM
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Now boys......
 
  #8  
Old 04-04-2017, 07:29 AM
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Not my fault that ol' hillbilly don't understand basic automotive 'lectrical consapts.

Just tryin to get his eyes pointin forward again 'stead of...well....you know....
 
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