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Old 28-05-2012, 17:02   #1
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Lifeline AGM's Fully Charged Voltage?

For anyone with Lifeline AGM's, when new and you thought they were truly 100% fully charged,
what was your voltage, after they'd settled down for a number of hours with no load or charge?

I've got an OutBack FM80 charge controller with a lot of tweaking options and am trying to see
what might be highest resting voltage to be aiming for beyond Lifelines overly general standard
claim that "12.8V or more" is 100% SOC.

Thanks for any input!
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Old 28-05-2012, 17:14   #2
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Re: Lifeline AGM's fully charged voltage?

google battery maintenance. you will find the numbers in a site from htere. unless gord may has em....
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Old 28-05-2012, 23:38   #3
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Re: Lifeline AGM's fully charged voltage?

12.8 volts.

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Old 29-05-2012, 05:49   #4
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Re: Lifeline AGM's fully charged voltage?

Greetings and welcome aboard the CF, frankson.

The following charging voltages are recommended for maximum battery life for all Lifeline models.
Charging Phase 12 Volt Battery
Bulk/Absorb 14.2v - 14.4v
Float 13.20v - 13.40v

Open Circuit Voltage @ 100% State of Charge = 12.8V or more

See ➥ http://www.lifelinebatteries.com/manual.php
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Old 29-05-2012, 06:08   #5
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Re: Lifeline AGM's Fully Charged Voltage?

The battery return amps is generally a better way to determine if you have the absorption time correct.
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Old 29-05-2012, 07:08   #6
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Re: Lifeline AGM's Fully Charged Voltage?

An addition to Gord's advice: The voltages stated in the battery specs are for a specific temperature, generally 25C (77F). The charging sources should have temperature compensation to raise the voltages when the battery temperature is below the standard temperature and lower the voltage when the battery temperature is above the standard temperature.

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Old 29-05-2012, 07:59   #7
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Re: Lifeline AGM's Fully Charged Voltage?

Quote:
Originally Posted by CharlieJ View Post
An addition to Gord's advice: The voltages stated in the battery specs are for a specific temperature, generally 25C (77F). The charging sources should have temperature compensation to raise the voltages when the battery temperature is below the standard temperature and lower the voltage when the battery temperature is above the standard temperature.
Charlie, Yes, Temp compensation is another parameter that's adjustable with this charge controller.

Some other Lifeline AGM owners have spoken of full resting voltages (after charging and then no load/charge for 6 hrs or more) of 12.8, 12.9, 13.0, 13.1, etc.

I'm just trying to see what some others have experienced, so I know better what to be aiming for in tweaking the variables on my charger to assure a truly full charge on a frequent basis for these new AGM's.
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Old 29-05-2012, 08:09   #8
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Re: Lifeline AGM's Fully Charged Voltage?

14.2vdc
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Old 29-05-2012, 08:29   #9
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Re: Lifeline AGM's Fully Charged Voltage?

Quote:
Originally Posted by rtbates View Post
14.2vdc
Is that the voltage you are charging at?

If so, what do you see at rest, some hours after having charged, with no loads?

Are your AGM's Lifelines?
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Old 29-05-2012, 09:24   #10
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Re: Lifeline AGM's Fully Charged Voltage?

You seem to be confusing resting voltages (overnite with no charge or discharge) with charging/floating voltages provided by your charger.

They are NOT the same, and it really doesn't matter what others are reporting as resting voltages, as there's some variability between batteries, ambient temperatures, measurement devices, resting time, etc.

For Lifeline AGMs at room temperature, use 14.4VDC for charging and 13.6VDC for floating.

Unless your charger settings are this high, the batteries may not get fully charged.

BTW, it takes a long time to get even AGMs really fully charged. For example, a new Lifeline 4D (210AH) charged with a 400A capable source will still accept about 2A after four solid hours of charging @ 14.4VDC.

Bill
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Old 29-05-2012, 09:45   #11
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Re: Lifeline AGM's Fully Charged Voltage?

In my experience most Lifelines will show a resting "full" voltage between 12.77 & 12.89V. This is of course after fully resting. I equalize a bunch of these in my shop so I get to see the resting voltages as they sit on my bench for a few days after equalization/conditioning charge. 12.80V-12.84V seems to be the most common resting voltages I see.

AGM & Gel cells can hold a surface charge for quite a long time. It is not uncommon to see an AGM still over 13V after 24 hours depending upon the temp. I find with some AGM's such as Lifeline and Odyssey it can take a couple of days to reach a resting no-load voltage, again depending upon temps, not the 12-24 hours of a wet cell. Putting a brief load on them can sometimes settle them out but it needs to be a decent load if the bank is large...

When Lifelines are accepting less than 0.5% of Ah capacity in current at 14.4V they can be considered "full". So for a 100Ah Lifeline battery, at 14.4V, when it is accepting 0.5A it is pretty much full.

In Bill's example above the battery was still accepting roughly 1% of capacity, so not totally full yet... Of course age and condition play a huge role in all this and as Lifelines sulfate the acceptance parameters from new change quite a bit..
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Old 29-05-2012, 10:14   #12
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Re: Lifeline AGM's Fully Charged Voltage?

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Originally Posted by Maine Sail View Post
AGM & Gel cells can hold a surface charge for quite a long time. It is not uncommon to see an AGM still over 13V after 24 hours depending upon the temp. I find with some AGM's such as Lifeline and Odyssey it can take a couple of days to reach a resting no-load voltage, again depending upon temps, not the 12-24 hours of a wet cell.
That's new news to me, thanks!

If you did not have but 12 hours overnight, after having charged, to check for a resting voltage the next morning, and saw it then still over 13V, would you be satisfied you'd likely had gotten a full charge? Assuming here temp at 75-80 F.

Quote:
When Lifelines are accepting less than 0.5% of Ah capacity in current at 14.4V they can be considered "full". So for a 100Ah Lifeline battery, at 14.4V, when it is accepting 0.5A it is pretty much full.
Where does the float charge figure into your charging strategy here?

I'd always thought that when floating at 13.2V - 13.4V (after bulk/absorption at 14.4V was done) and the acceptance had dropped to less than 0.5% of Ah capacity at float voltages, that it was then that you were full.
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Old 29-05-2012, 10:41   #13
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Re: Lifeline AGM's Fully Charged Voltage?

Quote:
Originally Posted by frankson View Post
That's new news to me, thanks!

If you did not have but 12 hours overnight, after having charged, to check for a resting voltage the next morning, and saw it then still over 13V, would you be satisfied you'd likely had gotten a full charge? Assuming here temp at 75-80 F.

Where does the float charge figure into your charging strategy here?

I'd always thought that when floating at 13.2V - 13.4V (after bulk/absorption at 14.4V was done) and the acceptance had dropped to less than 0.5% of Ah capacity at float voltages, that it was then that you were full.

For a battery monitor tweak that may be a decent number to consider for a re-set but not necessarily for the bank actually being full.


Most transitions to float are based on voltage, time, and occasionally some other parameters such as % field (for regulators). In my experience these transitions usually occur far to early and can actually cause slower charging of the bank. Seeing as voltage is pressure a lower voltage means less current going into the battery in float mode, when compared to absorption.

Take a battery at 13.4V and 0.5A acceptance and turn the voltage up to 14.4V and you'll likely see 2-3+ amps now going into the battery as opposed to the 0.5A.

If you're at a dock the batteries will eventually charge at float, over time, but I much prefer to adjust a charger or regulator to not go into float until the high 90's as a % of charge. This is not always easy or possible with many regulators or chargers. Proper programming takes time and a charger or regulator that allows it.

Ideally you'd go into float at "full" or somewhere below 2% acceptance at absorption voltage but there is little way to do this, easily, with many of today's chargers and regulators. The best you can often do is tweak the programming. For Lifeline they say 0.5% at 14.4V+ is full..

I am programming a newly installed Balmar MC-614 regulator this afternoon, for a bank of Odyssey batteries, and it will take about 30+ minutes to make the tweaks, check the temp sensors and then load test the alternator. The MC-614 offers excellent adjustments for eliminating premature float and is one of the reasons I like it so much.

I was on a customers boat last week who was hitting float at about 80-85% SOC. He was amazed at how well his alternator charged his bank, and how fast.. Sadly it was just programmed wrong and he never should have been in float. All it was doing was slowing his charging times because he still had 15-20% to go before he was actually "full".. The pre-set charge algorithms are usually set to be very "safe" and are not necessarily geared at recharging quickly and efficiently and err on the side of caution. Premature float is a huge pet peve of mine with charging systems on cruising boats where you want to put the energy back as quickly as possible. Holding absorption as long as possible shortens time to full when compared to premature float..

If using an alternator and you see a properly programmed regulator going into float you may want to consider a trawler cause you're running the engine a LOT..
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Old 29-05-2012, 11:28   #14
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Re: Lifeline AGM's Fully Charged Voltage?

Quote:
Originally Posted by Maine Sail View Post
For a battery monitor tweak that may be a decent number to consider for a re-set but not necessarily for the bank actually being full.

Most transitions to float are based on voltage, time, and occasionally some other parameters such as % field (for regulators). In my experience these transitions usually occur far to early and can actually cause slower charging of the bank. Seeing as voltage is pressure a lower voltage means less current going into the battery in float mode, when compared to absorption.

Take a battery at 13.4V and 0.5A acceptance and turn the voltage up to 14.4V and you'll likely see 2-3+ amps now going into the battery as opposed to the 0.5A.

If you're at a dock the batteries will eventually charge at float, over time, but I much prefer to adjust a charger or regulator to not go into float until the high 90's as a % of charge. This is not always easy or possible with many regulators or chargers. Proper programming takes time and a charger or regulator that allows it.

Ideally you'd go into float at "full" or somewhere below 2% acceptance at absorption voltage but there is little way to do this, easily, with many of today's chargers and regulators. The best you can often do is tweak the programming. For Lifeline they say 0.5% at 14.4V+ is full..

I am programming a newly installed Balmar MC-614 regulator this afternoon, for a bank of Odyssey batteries, and it will take about 30+ minutes to make the tweaks, check the temp sensors and then load test the alternator. The MC-614 offers excellent adjustments for eliminating premature float and is one of the reasons I like it so much.

I was on a customers boat last week who was hitting float at about 80-85% SOC. He was amazed at how well his alternator charged his bank, and how fast.. Sadly it was just programmed wrong and he never should have been in float. All it was doing was slowing his charging times because he still had 15-20% to go before he was actually "full".. The pre-set charge algorithms are usually set to be very "safe" and are not necessarily geared at recharging quickly and efficiently and err on the side of caution. Premature float is a huge pet peve of mine with charging systems on cruising boats where you want to put the energy back as quickly as possible. Holding absorption as long as possible shortens time to full when compared to premature float..

If using an alternator and you see a properly programmed regulator going into float you may want to consider a trawler cause you're running the engine a LOT..
Thank you for your detailed insights, very informative.

Fully understand and agree that float too often is initiated much too early.

Lifeline says bulk/absorb at 14.2V-14.4V and float at 13.2V-13.4V.

Is there any reason not to always shoot for the high end of those ranges, temperature permitting?

Many chargers are time based for absorption mode. Any rules of thumb that you use setting that time duration on chargers that are adjustable?
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Old 29-05-2012, 11:29   #15
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Re: Lifeline AGM's Fully Charged Voltage?

frank-
"Some other Lifeline AGM owners have spoken of full resting voltages "
Unless those folks are using calibrated volt meters, an error of up to .3-.4 volts has to be assumed in whatever numbers they are reading for voltages.

Fancy monitors and controllers are more likely to be more accurate, if they are using those.

So don't worry about vague field reports, use the voltages and temperatures provided by Lifeline.
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