Originally Posted by Attacking Mid (Post 1215924)

I've never run across this concept. Do you have any links to support this? I often use my 0.8 amp CTEK trickle charger to maintain/top-off my batteries. This would indicate I'm actually harming them. Just curious.

AM.

Originally Posted by Crowz (Post 1215927)

...But let me rephrase what I said to say that if you leave a battery long term and I mean years without any use with a low amp charger it isnt strong enough to keep the battery from going bad. This mainly effects 0 draw conditions like shelf storage.

...Battery tender brand chargers dont seem to hold up that well lately either for me or other people I know. I have used them for years on things with a lifespan of 3 years average but of the 4 I bought within the last couple of years only one still works. The reviews I noticed on amazon seem to backup the idea that the quality has declined....

Originally Posted by bdosborn

Here's what I found for conditioning AGM batteries on the Big RV forum.
This is the way I condition AGM batteries

3% A/H constant amperage (3 amps for a 100 amp hour battery)

Allow voltage to rise to no more than 15.2 volts. This will take time and you will see the voltage "spill" occasionally .2 or even .3 and re-climb. This is healthy.

You should monitor cell temperatures. A scanning IR reader is ideal for this. At the rate listed above cell temperatures should not rise more than 5 degrees F over ambient at 68F. But this is a total permitted rise not a sudden rise. And it applies to each individual cell.

I would love to see an amp hour meter used and limit the conditioning charge to 120% of regular amp hour capacity, regardless of the 3% - 15.2 Volt 5 degrees formula. No more than 120% regardless of other factorials. But you must start off with a battery that has been maintained at 14.4 volts for at least 48 hours.

1. Charge at 14.4 for 48 hours

2. Apply 3% amp hours constant current

3. Monitor cell temps and cease charging if cell gain is more than 5F @ 68F

4. Curtail charge at 15.2 Volts or 120% of A/H whichever comes first.

5. 7 Hours at 3 amps sounds about right for a 100 amp hour battery.

6. Make sure NONE of those cells gets too warm. This is critical.

Originally Posted by workingonit (Post 1238604)

I use several brands of battery charger/maintainers (plugged into a cigar lighter socket) in all my cars, trucks, and my homebuilt squareback camping trailer, to keep the batteries up during periods of idleness (ranging from two years, for the trailer, and normally up to 3 months each for the cars & trucks, at most). My wife's current daily driver, a low mileage new-to-her '14 Lexus ES350, never sits long enough to require trickle charging (also, she's been known to forget to unplug the charger, and drives away with it or the cord dragging behind), so it's seldom/never hooked up anymore. I also have four other chargers I can use, but infrequently.

At present, I've got batteries that are from 5 years old (in my X5 and the wife's Lexus), to 12 years old (the Optima Yellowtop AGM in my trailer). I haven't had a battery die in years since using the low amperage charger/maintainers, though I forgot to check the AGM a couple of times, and let it "die", but resurrected it twice.

I depend on the cheap charger/maintainers, and haven't had but one fail over a 12 year period (a Black & Decker BM2B), and I keep adding chargers to my collection. Let me explain:

from a thread on another website (https://www.tnttt.com/viewtopic.php?f=30&t=76241)
it depends on What kind of "plug-in charger" are you using? I use

• 1) a 1.25A Battery Tender for my BMW X5 it's probably 8 years old now,
• 2) two Amazon Basics Battery 2A Chargers both are 3 y.o. for both my Chevy and GMC pickups,
• 3) an Autozone Duralast 1.5A charger 9 y.o, for my HHR Panel,
• 4) a Battery Minder Plus, 1A, 12 y.o., for the AGM battery in my trailer,
• 5) and a Black & Decker Bm3B 2A 11 y.o. charger as a backup (or, for the riding mower, formerly used on my wife's Cobalt, while it was being worked on for 3 years)

All these use high-frequency pulsating power to desulphate and maintain batteries, and can be considered "smart", as they can be left in place for months at a time. Mine are plugged-in immediately at home, after I arrive there, and they keep my batteries charged full-time. They've also prolonged their lifespans, as the average lifetime for the Flooded Lead-Acid batteries has been 11 years, and the AGM trailer battery is now 13+ years (after two occasions where it had to be totally reconditioned, back-from-dead, before I started using the trickle chargers on everything...except my wife's daily driver, because she never remembers to unplug it). These charger-maintainers are good to keep a battery up to snuff, even to keep one from freezing in cold weather (Texas cold, that is), but will not resurrect a battery from the dead.

I have, however, resurrected my Optima Yellowtop AGM twice, Once from 7.3v, and the second time from 9.2v. I experimented on ways to do so, before I used the methodology outlined here (from this thread: https://www.tnttt.com/viewtopic.php?...55957&start=30)



This procedure (with some variations, necessary for my equiments' limitations) worked twice for me, using a combo of two chargers: a Schumacher XCS15 ("smart/automatic" charger/maintainer, 2-6-15A), and a Century wheel charger (fully manual,10-40-150A), but it was a prolonged effort.

I just bought a Solar/Clore Pro-Logix PL-2320 ("intelligent" battery charger/maintainer with "power supply mode", 2-10-20A) which would make battery resurrection much easier, as the "power supply mode" will maintain your settings as well as a fully manual charger (but with the added feature of providing clean power). And, if the battery has fallen below 10v, the Schumacher needed to be fooled with a secondary 12v (provided by a spare battery) so it would turn on, but the Pro-Logix has a special start button that turns it on with no battery power needed. It will be what I use from now on, if ever I need to bring a battery back to life.
https://xoutpost.com/1236822-post1.html

Originally Posted by ajacks8 (Post 1238605)

Thank you for the robust history of charger options. I think I caught wind of you mentioning using the cigar lighter port as a connection point for your all your maintainers, is that accurate?

Originally Posted by workingonit (Post 1238609)

Yes, for the charger/maintainers only, though, since they only input 2 amps and under. But, when I use the other ones

• 1) 2-10 Amp Schumacher SE-1010 "dumb charger",
• 2) 2-10-15 Amp Schumacher XCS15 "smart charger",
• 3) 2-15-40-200 Amp Century Model 87423 "wheeled charger" (listed erroneously as 10-40-150 Amp in other threads), and
• 4) the new 2-10-20 Amp Clore/Solar Pro-Logix PL 2320 "Intelligent Charger/Maintainer/Power Supply"

I'll connect them to the jumping locations underhood on my vehicles (never directly to the batteries), except on the trailer's AGM battery (which would be charged away from the trailer).
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