Assume that when MEX states voltages, he's referencing the standard 77F. You definitely want temp comp on AGMs although quite a few here on the forums don't bother.
I am a strong proponent of automatic temp-comp charging. Sadly, there are few converter/chargers that do temp-comp.
You know what happens when you ass-u-me. :)
I forgot to mention: those a new AGM. Like in "never used". Stored 8 months, yes, but never cycled. So I wanted to try somebody's idea of measuring AGM capacity when new - by stable 8A discharge, and use this as a reference for future. 1 week of light use shouldn't skew these measurements though.
Sulfatation through self-discharge to 75% - can this really happen?
Conditioning of AGM... Lifeline Concorde - and Mex - are the only people talking about it. There are no instructions, guidelines or setpoints in brands other than Lifeline.
You cannot baseline test them until you recharge them.
What are the battery temps? If they are around 40F and you use the Table 5-1. Charging Voltage at Different Temperatures for a 12 Volt Battery
from the lifeline manual, you should Abs them at 14.9V until the rate drops to 0.05% of C20.
I doubt they need conditioning and you won't know until you get them charged. Per Lifeline, conditioning is a recovery procedure AFTER you detect a loss of capacity and AFTER a full charge.
14.4 volts for an AGM battery is fine. It is just a lot slower for the last 15% of ampere hours of charge.
What about temp-comp chargers?
Would I want to use 14.7V on a 110F battery? I use 13.5V via a temp-comp charger at that temp. A cold battery gets up to 15V.
If you've got the bucks and want the best, get a couple of 6v AGM's.
AGMs ARE not "better" in ALL cases, period.
They are a "specialty" battery which unless you NEED ONE of the "special advantages" you are simply throwing out you money.
One of the supposed advantages is you can recharge at a higher rate which allows you to use a gen for less time. This HAS been proved to be a wash, basically put AGMs might shorten your charging time by a few minutes.
Another possible advantage is can be used in any position and do not outgass which could allow for placing them INSIDE your living space. I for one however do not feel that this is a wise thing to do since AGMs like any other "storage" system which CAN store a considerable amount of energy CAN be subject to abuse which can cause catastrophic failure.
The real advantage of AGMs is allowing you to part with more money, get less capacity for the same physical size as a flooded lead acid.
6V GCs ARE not "better" in ALL cases, period.
AGMs ABSOLUTELY DO recharge at a higher rate which allows you to use a gen for less time. Plus, AGMs DO charge cheaper due to lower resistance so that less fuel is used.
Another REAL advantage is AGMs can be used INSIDE your living space. In contrast, the 6V GCs will outgas and emit Hydrogen gas and acid mist in regular operation and that precludes any consideration of using them inside your living space or near any equipment.
I'm seriously looking to buy some 14" rims and the the smallest of those Kumho's that you pointed out, I've had my eye on them.
I put 2 x 14" rims and the 185/R14 Kumho 857 on my TT this week. If you STFW, you will find that the 857s get good user reviews.
Discount Tire in OKC has them in their computer system now. I will carry a 175/80R13 spare.
What is the difference between ST and LT tires for TT's?
A potential LT owner is someone who has not yet had their first bad ST experience.
After that, the one's that get the second set of ST's don't subscribe to the fool me once theory. :)
The first was the 800W HF and it was too loud for a campground. Used once.
The second was a Briggs&Stratton powered 2000W inverter that at least looked like I was trying to be quiet! It worked fine for four years.
I read the entire CPE2000 topic here and then bought the Yamaha EF2000IS in Apr 2013. This is my third genny and I did not want to take any more chances.
The Yammi is quieter at full throttle than the B&S idling on eco.
I started the Yammi to show someone how quiet it was. Of course, you start with eco off. After marveling at how quiet is was, you should have seen his jaw drop when I switched the Yammi to eco. 51DB is quiet!
I think all MPPT controllers over say, $200, have adjustable setpoints and remote temp and volt sensing. Some also have adjustable rate of temp compensation, i.e. how big voltage increment per every degree above/below 77F....
Good point. I do have a Tristar PWM that is smart as well. I don't mean to omit other brands with smarts.
That's a strange quote. Usually they base everything on 80F or 25C. If max at 20C is 14.6v it is less at 25C.
If you think about it, when a battery's AH is rated at a lower temperature, 68 v.s. 77F, that battery is going to have more AH at 77F.
It is a marketing blunder to spec at 68F as the unwashed will not understand the temp effect on AH. If the other brand 77F rated battery is 80 AH, which one is better? More may actually be less!
Lifeline provides a formula to estimate charge times:
The time to reach full charge at temperatures in the range of 68 to 86°F (20-30°C) can be estimated from the following equation:
Time to Reach Full Charge = ((DOD/100) x Rated Capacity (Ah) ÷ Rated Output of Charger (Amp)) + 2 hours.
For example, charging a 100Ah battery at 50% DOD with a 25A charger would take:
((50/100) x 100 ÷ 25) + 2 = 4 hours to reach full charge.
If a 10A charger is used, it would take:
((50/100) x 100 ÷ 10) + 2 = 7 hours to reach full charge.
A temp comp charger actually simplifies this by adjusting charge stages according to a reference 77F. The charging profile is then based on 77F and you ignore battery temps because that is handled already.
The Tristar models of solar controllers are known for their ability to accept custom parameters that meet whatever your battery manual requires. They can sense both battery volts and temperatures.
Converter/chargers are dumb by comparison.
battery's SoC will gradually "walk down" as it is cycled leading to premature failure. Therefore, it is important to verify that the battery is not being undercharged.
Is not that the same as saying fully charge?
I don't believe that is the definition of a cycle as depicted in life-cycle charts. A cycle must end with some type of completion criteria. In fact life-cycle only means the point in time when the battery has 80% of its original capacity.
Here is the complete quote:
Note that this formula is approximate and the full charge state should be verified using the criteria given above (current drops below 0.5% of rated capacity). If the recharge does not
return 102% to 110% of the discharged capacity, the battery’s state of charge will gradually “walk down” as it is cycled leading to premature failure. Therefore, it is important to verify that
the battery is not being undercharged.
A cycle will meet the criteria of "(charge) current drops below 0.5% of rated capacity" and/or "return 102% to 110% of the discharged capacity". When you complete these criteria, you have a cycle.
I have no idea how to correlate partial use/recharge, or charge while in use to life cycle charts.
A lot depends on how long the sulphate remains on the plate(s) and therefor, needs a special recovery charge to release old, stubborn S atoms as described in 5.5. Lifeline says to observe a loss of capacity AFTER a 5.4 charge(cycle) as the signal to do a 5.5.
There seems to be a belief that AGMs must be fully charge with each cycle. I don't see that in the Lifeline manual.
It's not in the manual. But there was a boaters discussion including consulting with Lifeline engineers that I'm sure many of us have read. They concluded that Lifeline AGM should better be charged fully, otherwise a routine scheduled equalization is needed. They call equalization "conditioning". Last time when I tried, could not access their forum due to some restrictions. From memory:
Fully charge each cycle, estimated life 8 years.
Fully charge once a week and equalize once a month, life 5 Years.
Charge to 85% and equalize once a month, life 3 years.
Lifeline funded that sailor's report at least to the cost of the batteries. I don't mean to say we should suspend belief on the report, just keep that in mind.
What LA battery would not do well if babied with a full charge with each cycle? I disagree with MUST being applied to AGMs alone. Does anyone recall the Amps, Volts and hours of those conditioning runs? Is that what Lifeline now calls 5.5 in their manual? Were the subject batteries taken off line? Compare to what we call RVing.
What exactly does fully charge mean anyway, 100% transfer of every single S atom from the paste and back into the water?; 99, 98, 97......%, where exactly is it time to get back to RVing?
I believe that what I said, do, and did, is very close, minus the high voltage. As we know, even 13.6V will eventually charge an LA battery if left on for days as opposed to hours.
My Deka is 5yo, or to be exact, will be Jan 2014, and may have been treated as unmercifully as those sailors did the Lifelines. I did read that sailor's report more than once but must now rely on mine and other's recollection of the details. I'm sure we all came away with our own interpretations and recollections.
The routine I use was initiated last summer, after acquiring the Turnigy, or about 1.5 years ago. For sure, the Deka is my first lab rat battery and had been subjected to some awful treatment for the first two years. I continue to stress all three AGMs in driveway tests. I have chosen my replacement AGMs and plant to get many years of service from them as well. They will be treated differently with more focus on using them instead of trying to see what torture they can endure.
If my plans go well, I am going to caravan to Q'zite for the Jan events and another dry-camping adventure.
My posts are for entertainment only, facts are AFAICR, IMHO and YMMV. :)
John, I can't tell sulfation with voltage but I don't do the 50-90 thing either and have no routine established like you do. I plan to avoid all of that by spending more money on an even larger battery bank and solar if we ever do any long term off grid camping. :)
With two banks and the largest being 2 x 55AH = 110AH, I don't have enough to power my microwave. I did make 3 pots of coffee once with a 1kw MSW inverter and the 79AH battery. The coffee maker draws 600W.
My big dream upgrade is to replace the 79AH with 2 x 100AH, a Prowatt SW2000, and a parallax paramode 4455TC(temp-comp). That should give me enough to plug in the whole TT. I would use the 79AH at home for computer UPS duty.
There is always too much month left at the end of the money - Phillis Diller.