Time it takes the alternator to fully charge a nearly dead battery

[ecidiego]

There's battery stuff in Alfa...I wonder if this can be adjusted?

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[MrT]

I am not familiar with Alpha. The battery tester at the parts store would show testing then just return to it's main screen with no results, pretty weird. The did warranty it and replaced it free of charge.

 

[MoxiesDad]

The bottom line is that a replacement battery must be fully charged before installation. The alternator is only good for maintaining a fully charged battery. If you don't drive it long enough daily, you need to put a charger on the battery regularly to keep the battery fully charged. Use your voltmeter to indicate how the battery is doing. If it doesn't drop below 13.0 V by the end of your trip, it hasn't fully charged the battery.

 

[Rubiman]

The bottom line is that a replacement battery must be fully charged before installation. The alternator is only good for maintaining a fully charged battery. If you don't drive it long enough daily, you need to put a charger on the battery regularly to keep the battery fully charged. Use your voltmeter to indicate how the battery is doing. If it doesn't drop below 13.0 V by the end of your trip, it hasn't fully charged the battery.

If you don't drive it long enough daily, you need to put a charger on the battery regularly to keep the battery fully charged - how long is long enough?

 

[ShadowsPapa]

Been constantly at 14.3V when driving so figure it's just a matter of time.

That's not an indicator.
It's going to do that even with good batteries. It's saying that the battery isn't getting hot and there's no need for more engine torque and so on.
Not uncommon to see system voltages in that range in normal vehicles.

Is it safe to assume you were reading the voltage "gauge" in the dash cluster while you were driving?

Which is the same as the off road pages reading.
That's system voltage and not battery voltage although while it's running it would be the same since that's the voltage at the battery as well as most of the rest of the system at the PDC.

I have the ESS (ASS) turned off with a Tazer, so that may be why I haven't had a failure or anything lighting up.

Doesn't really matter.
There's a huge range of how long these last - some have over 3 years on original batteries and allow ESS to function while others "turn it off" via the button on the dash or tazer and lose batteries at 2 years.

If you don't drive it long enough daily, you need to put a charger on the battery regularly to keep the battery fully charged - how long is long enough?

No one can say because it depends on the battery's age, condition, temperature, internal resistance and other factors. Most don't drive long enough, though - commutes of under 30 minutes you can bet it's not long enough especially if it sits a lot otherwise.

Use your voltmeter to indicate how the battery is doing. If it doesn't drop below 13.0 V by the end of your trip, it hasn't fully charged the battery.

I don't really agree with that......... it can sit at 13 volts with a fully charged battery. I've started with full batteries, driven 3 hours, and still sat at over 13 volts at the end of the trip. There's other factors involved. It usually only drops below 13 if there are other circumstances or needs.
But if it DOES drop to 13 or below, it can mean fully charged, or battery is hot, or other needs are taking priority.
Both of my trucks ONLY dropped below 13.0 when a set of conditions was met - only one of those was full batteries. I can charge them with a quality charger and go for a drive and still see in the 13s or higher.

I am not familiar with Alpha. The battery tester at the parts store would show testing then just return to it's main screen with no results, pretty weird. The did warranty it and replaced it free of charge.

He means AlfaOBD - an app for your phone or tablet, requires a bluetooth OBDII connector on your truck. It is like JSCAN - you can monitor, look at settings or change certain settings.

Not a fan of battery testing at parts stores - some of the operators there are clueless and don't know how to correctly check batteries. A simple device can't tell a whole story. If you take in an almost dead battery - if they knew their stuff, they'd charge it before testing.

5 hours @ 70-90mph still seems like a long time to me, anyone know the rate at which an alternator charges a battery?

There's no answer to that question - even in the 1980s there was no answer to that question. Voltage on that screen is only what the system is showing at that time. It's a reading of voltage while many other things are taking current from the running alternator. You have dozens of loads on it, not just the battery. Everything that is electric on that truck is being powered by that alternator - DRLs, brake lights, cooling fan, HVAC fan, dash/instrument cluster, PCM, BCM, and more.
Plus the PCM weighs historical data provided by the IBS, current data and more to decide where to set the voltage at any given time. That can include the battery temperature, history of amp hours taken out of the battery, amp hours put back into the battery and more.
But even in 1980, you could not answer that question because of the differences in batteries - capacity, age, any sulfation, battery temperature, etc. Some batteries will charge faster than others and that varies with the history of the battery itself. If it's been cycled a lot it will have a lower capacity. The last 10-20% charge takes longer and so on.

Watch how an AGM battery charger functions - the phases it uses - periods of constant voltage, periods of declining voltage, it's not simple.

 

[Rubiman]

That's not an indicator.
It's going to do that even with good batteries. It's saying that the battery isn't getting hot and there's no need for more engine torque and so on.
Not uncommon to see system voltages in that range in normal vehicles.



Which is the same as the off road pages reading.
That's system voltage and not battery voltage although while it's running it would be the same since that's the voltage at the battery as well as most of the rest of the system at the PDC.



Doesn't really matter.
There's a huge range of how long these last - some have over 3 years on original batteries and allow ESS to function while others "turn it off" via the button on the dash or tazer and lose batteries at 2 years.



No one can say because it depends on the battery's age, condition, temperature, internal resistance and other factors. Most don't drive long enough, though - commutes of under 30 minutes you can bet it's not long enough especially if it sits a lot otherwise.



I don't really agree with that......... it can sit at 13 volts with a fully charged battery. I've started with full batteries, driven 3 hours, and still sat at over 13 volts at the end of the trip. There's other factors involved. It usually only drops below 13 if there are other circumstances or needs.
But if it DOES drop to 13 or below, it can mean fully charged, or battery is hot, or other needs are taking priority.
Both of my trucks ONLY dropped below 13.0 when a set of conditions was met - only one of those was full batteries. I can charge them with a quality charger and go for a drive and still see in the 13s or higher.



He means AlfaOBD - an app for your phone or tablet, requires a bluetooth OBDII connector on your truck. It is like JSCAN - you can monitor, look at settings or change certain settings.

Not a fan of battery testing at parts stores - some of the operators there are clueless and don't know how to correctly check batteries. A simple device can't tell a whole story. If you take in an almost dead battery - if they knew their stuff, they'd charge it before testing.



There's no answer to that question - even in the 1980s there was no answer to that question. Voltage on that screen is only what the system is showing at that time. It's a reading of voltage while many other things are taking current from the running alternator. You have dozens of loads on it, not just the battery. Everything that is electric on that truck is being powered by that alternator - DRLs, brake lights, cooling fan, HVAC fan, dash/instrument cluster, PCM, BCM, and more.
Plus the PCM weighs historical data provided by the IBS, current data and more to decide where to set the voltage at any given time. That can include the battery temperature, history of amp hours taken out of the battery, amp hours put back into the battery and more.
But even in 1980, you could not answer that question because of the differences in batteries - capacity, age, any sulfation, battery temperature, etc. Some batteries will charge faster than others and that varies with the history of the battery itself. If it's been cycled a lot it will have a lower capacity. The last 10-20% charge takes longer and so on.

Watch how an AGM battery charger functions - the phases it uses - periods of constant voltage, periods of declining voltage, it's not simple.

What would be the correct voltage with no errors that would be displayed?

 

[MrT]

I charged the new battery overnight and drove for about an hour today. The voltage not running to begin was 12.8 during the drive the gauge would show 12.8 most of the time, when it would drop to 12.7 it would the jump to anywhere from 13.9 to 14.2 showing a working alternator. I believe everything is working as it should... hopefully.

 

[ShadowsPapa]

What would be the correct voltage with no errors that would be displayed?

That can't be easily answered, either.
that will vary with ambient air temperatures, battery temperatures, engine load and torque needs, and so on.
It's more of a pattern or historical thing that's hard for me to explain. I have watched voltages over years, two Gladiators, and have become accustomed to how it acts under varying conditions.
In the winter, it hung up in the upper 14s to even 15.0 volts.
In the summer I've only seen it drop into the area below 13 volts when it was hot out on long drives (likely battery nearing full, and/or getting hot). I've seen it vary with whether or not I was needing more pedal to get up a hill, or if I was coasting and/or coming to a stop.

If both batteries are good and fully charged and the IBS hasn't been bypassed or messed with otherwise (like charging below it or pulling a load from the battery below the IBS) then - well, here's an example that seems fitting -

I charged the new battery overnight and drove for about an hour today. The voltage not running to begin was 12.8 during the drive the gauge would show 12.8 most of the time, when it would drop to 12.7 it would the jump to anywhere from 13.9 to 14.2 showing a working alternator. I believe everything is working as it should... hopefully.

- that's close to what I've observed on mine when I knew the batteries were both fully charged, and the temperature was moderate (say, 60-70 degrees) and it would vary on throttle position and hills. When coasting or going down a hill it would be different than when I was going up a hill, moderate to light throttle.

 

[whysoserious]

Which is the same as the off road pages reading.
That's system voltage and not battery voltage although while it's running it would be the same since that's the voltage at the battery as well as most of the rest of the system at the PDC.

Yeah, that was my point of asking the OP the question. But then I got distracted with other things and forgot about it.

 

[ShadowsPapa]

Yeah, that was my point of asking the OP the question. But then I got distracted with other things and forgot about it.

Live in my head a while - a 24/7/365 world of nothing BUT distractions.
Back to the original question, whatever that was....

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