Best/proper way to charge GC2's at home

My new 12.7v battery when dipped read low green ~1.25, a smart charger @15A would not initiate a charge, 2A mode did, instead I hooked up a manual charger and left it overnight, 15.3v (.9v higher than the smart charger) minimal amps, high green, temps were mild mid 70's.

I disagree that resting open circuit voltage always relates to state of charge. My previous flooded battery when newer would rest at 12.7+, but voltage would then tank overnight on what should have been a easy depletion for it.

Recharge again, dip the hydrometer and found that 12.7+ resting volts meant nothing. The SG was 1.225, and rather extreme voltages and durations were required after every discharge to get it to 1.275+. No smart charger would have gone high enough or long enough on this battery, and it would have become useless as boobs on a bull charged only until my Schumacher's green light flashed.

That last 4 % makes more than a few months in battery longevity, especially when cycling daily. Time means little anyway, it is all about the accumulated cycles.

One cannot read too much into Mex's tone/ writing style. Just like reading any post by a person you are not familiar with, much is lost in translation from printed text to brain.

And some people just love to be offended, and become indignant, and revel within their indignation, and lash out. Keyboard cojones.

So don't get your panties in a bunch sweetie pie

10 9 8 7 6 5

I believe you may have just succeeded in getting another good thread closed.
Why is it always another persons fault when you act like an "ass" and the thread is closed? No need to answer. Its perfectly clear. You just don't care.

MEXICOWANDERER wrote:


I've yet to use a smart charger that charges a battery to 100%. Give me a shout when you find one.

NEWS FLASH: There is a direct relationship between SOC and no-load voltage in a wet cell battery.


You are so stuck on YOUR perspective of what is the only truth that you aren't listening to what others think. I assume you are so arrogant that you just simply don't care.

Many of your posts carry an underlying tone of: If you don't buy 100% of what I say and do it exactly the way I do it.....then you obviously are just stupid.....and that gets old real quick.

I DON'T CARE if I don't get my batteries up to 100%.
For me, and a lot of others too I think, 97% is more than enough.

I DON'T CARE if I lose 4.5 AH of capacity.

I DON'T CARE if I lose a few months of battery life after several years.

If I can plug it in and forget it.....after determining that it does a reasonably good job.....that's perfect for me.

I have seen the advantages of AGM first hand over many years.
I will NEVER purchase another conventional wet-cell battery ever again.

I hope you don't get a chemical burn on your lips from kissing your beloved hydrometer.

I'm done. I hate getting baited into acting like an ass myself but sometimes I just can't take it anymore.

Please please please (James Brown)

Forget About voltage

The only thing that matters is if or not all cells show 100% recovered density electrolyte. Checking how bad a smart charger lies is the job of a hydrometer dip. Either the charger can fully charge the battery or it can't. Yes or No. No maybe's. Like BFL if it takes six stabs on the equalize button at the end of a full charge to actually fill the battery then push thar ****ed button six times and when that Monkey Business is finished THEN put the battery on the maintainer.

Ever drop a hundred thirty dollar item, break it, be inconvienced by it's absence the go through a hassle replacing it? Well meet your RV battery. Your dropping the item was an accident as is unintentionally mistreating a battery - but the end results are the same.

Until lithium systems arrive that are affordable we're stuck with Hungarian Movie actresses. I would LOVE to FORGET about all my batteries entirely and go fish that hidden lake with 10 lb average weight Largemouth Bass. No need at all to walk to the battery shed. Wait until the Lithiums get to 5% state of charge then recharge.

But I freakin' refuse to pay 4-500 dollars a year because I assssssssumed a machine was automatic. When I tried smart chargers they were more of a hassle than connecting a battery to a charger with a timer then walking away. The battery x voltage reads 12.18 volts. Twist the dial for two and a half hours and walk off
When you return you KNOW the battery is properly charged.

Semi-automatic converter maintenance is one thing and hiring a painter that insists the job is finished when a big swatch is left unpainted is another

Either a charger fills the battery or it doesn't. I've yet to use a smart charger that charges a battery to 100%. Give me a shout when you find one.

Vulcan Rider wrote:

MEXICOWANDERER wrote:

Have you checked the actual state of charge after a portable smart charger gets done with a battery? 93 to 94% state of charge is not 100% charged.

Yes but not recently.

IF you have a battery who's nominal fully charged voltage is.....say 12.8 volts (most flooded cells are less) AND the charger is applying something in the range of 13.2 to 13.4 volts on "float".....then I have better things to do with my time than screw around being sure that I am really getting that last 5%.
There is no GOOD reason to believe that you are not.

And You repeatedly act like that last 5% missing will cause a 50% decrease in the longevity of the battery. That is not true. Not even close. As someone else said: "So what if my batteries only last 8 years instead of 10 ???"

YOu unquestionably know a lot about batteries but you tend to bend and stretch some points a bit and that loses you a few credibility points with me.

Taking good care of your batteries is important; taking PERFECT care of them is just OCD.

Hey, that was me, but you use my 8 vs 10 in the wrong context, and might get some people confused to their cost. :(

The GOOD reason why not, is obvious when you use an hydrometer. Don't ask me what AGM guys are supposed to do. Cross their fingers and pray seems to be it for them! :)

First, most "automatic" chargers get the batts to about 97% full and declare them to be "full". 97 is not 100. Many blurbs say if you get them back to 2% of their rated AH you are full. BS! 2% of 220AH is 4.4AH short of a full deck. Then there is the problem of knowing how many AH went to the battery and how many went to heat loss on the recharge.

Without the 100 plus some for heat loss, you will not be truly full and will get sulfation.

The tricky part is deep vs shallow cycling. If you do successive 50-90s it will take a huge effort to get back to 100 afterwards, but if you do successive 75-95s it is not nearly as difficult to get back to true 100 afterwards.

Depending on your actual scenario it could be 3 yrs vs 6 yrs instead of 8 vs 10, so Mex is quite right about the 50% lifetime loss---depending on your scenario.

However, I do agree that you can't be perfect, and that perfection is the enemy of good enough.

MEXICOWANDERER wrote:

Have you checked the actual state of charge after a portable smart charger gets done with a battery? 93 to 94% state of charge is not 100% charged.

Yes but not recently.

IF you have a battery who's nominal fully charged voltage is.....say 12.8 volts (most flooded cells are less) AND the charger is applying something in the range of 13.2 to 13.4 volts on "float".....then I have better things to do with my time than screw around being sure that I am really getting that last 5%.
There is no GOOD reason to believe that you are not.

And You repeatedly act like that last 5% missing will cause a 50% decrease in the longevity of the battery. That is not true. Not even close. As someone else said: "So what if my batteries only last 8 years instead of 10 ???"

YOu unquestionably know a lot about batteries but you tend to bend and stretch some points a bit and that loses you a few credibility points with me.

Taking good care of your batteries is important; taking PERFECT care of them is just OCD.

westend wrote:
My temp compensated solar system does a better job than I can ...........

Which is to be expected....except maybe with something from Harbor Freight or delivered via boat from China.

I'm sure the OP would appreciate knowing what kind of system you HAVE. ;)

MEXICOWANDERER wrote:
Vulcan Rider
Have you checked the actual state of charge after a portable smart charger gets done with a battery? 93 to 94% state of charge is not 100% charged. A BAD WAY to start off a float charge. 1.272 specific gravity on a 1.285 battery is bad juju. When you find a smart charger that fully charge a battery used all season, please let me know. "Fully Charged" is not a state-of-mind. It's a flooded battery with all cells showing maximum density. A properly cared for GOOD QUALITY flooded battery should last 7-10 years averaging 30 boondocking days a year. This is an average of a few hundred batteries I have cared for.

BINGO.

Vulcan Rider
Have you checked the actual state of charge after a portable smart charger gets done with a battery? 93 to 94% state of charge is not 100% charged. A BAD WAY to start off a float charge. 1.272 specific gravity on a 1.285 battery is bad juju. When you find a smart charger that fully charge a battery used all season, please let me know. "Fully Charged" is not a state-of-mind. It's a flooded battery with all cells showing maximum density. A properly cared for GOOD QUALITY flooded battery should last 7-10 years averaging 30 boondocking days a year. This is an average of a few hundred batteries I have cared for.