full_mosey wrote: ... AGM batteries can be damaged by overvolting during charging. I recommend that your charging source NOT exceed 14.4V.
My experience does not agree with that. I never had a problem with charging voltage up to 14.8V. I do agree, typically 14.4 is recommended by many sources. It is my experience with my Lifeline AGM, and my understanding with all AGMs, the basic charging requirements are the same as flooded wet cell batteries.
I have had my Lifeline for seven years. I think I shortened it's life through testing. You can only take it down to 10 volts so many times. It finally began loosing it's capacity.
As I posted, I recently replaced my 100 AH Lifeline AGM with a 100 AH Universal AGM. I hope I get as good of service from the Universal as I did the Lifeline. Only time will tell. My Lifeline, and now my Universal, are/were always connected to shore power and/or 130-watts solar.
I initially used a 65 amp WFCO converter/charger and solar with the Lifeline. The WFCO died (about two years), and I replaced it with a 55 amp Iota with the IQ-4. By far, I think the Iota is a better charger.
If you can spend more for a larger battery, I would do that and not wish you had. I would look at the purchase of a battery as a brick and mortar investment for your TC. It is a long term item and spread that cost out over 5, 7, or more years. I just purchased 2 of the SEARS PM-1 Marine/RV AGM group 31 batteries. Talk with the sales person and see if there is a sale coming up. I was able to finagle a customer satisfaction discount of 15% on the spot so I went from 279.99 to 237.00 each on price. If a group 31 is too large to fit your space, there is also the PM-2 which is a group 27 battery for about 200.00
As for charging, on Redneck's recent converter replacement post, there is information that an AGM battery will take a high current charge at 14.4 to 14.8 volts. That is why Best Converter sells a specially adapted converter called the BoonDocker that has a bulk charge of 14.6 volts in the middle of that range.
full_mosey wrote: ... AGM batteries can be damaged by overvolting during charging. I recommend that your charging source NOT exceed 14.4V.
My experience does not agree with that. I never had a problem with charging voltage up to 14.8V. I do agree, typically 14.4 is recommended by many sources. It is my experience with my Lifeline AGM, and my understanding with all AGMs, the basic charging requirements are the same as flooded wet cell batteries.
Wayne
The OP did not list charging specs.
Yes, 14.8V can be fine if one is aware of the mfgr's actual voltage limits. The concept of an upper limit is introduced when dealing with AGM charging. I believe the 14.4V is sufficient and serves as a warning to those folks who are new to AGM chemistry. 14.4V Is a universal charging Voltage that will charge and equalize(balance cell Voltages).
My Optimas have a 'fast charge' spec of 15.6V, unlimited Amps, so long as the battery temp is kept below 125F and until only 1A acceptance; but I would never recommend that to anyone.
The major difference in charging regimen is that you do NOT use higher Voltage or attempt to stir the acid in AGM batteries like what is necessary with flooded batteries. AGM batteries do not stratify and cannot be stirred. If you fizz, hiss, bubble or sizzle an AGM battery, you will have a loss of capacity because you CANNOT add back any lost liquid.
...
That is why Best Converter sells a specially adapted converter called the BoonDocker that has a bulk charge of 14.6 volts in the middle of that range.
The 14.6V is only used during bulk charge, when the absorption charge begins, the Volts drop to 13.6V. This is not a battery charge voltage, but a power supply voltage.
I have been looking in vain for a charger that can hold 14.4V during absorption.
"Conditioning/Equalizing Charge: 15.5 volts for 8 hours"
Wayne
I am puzzled by the Lifeline specs. At what Amps? Wouldn't the Amps need to be low enough to avoid gassing, or at least not to the point of exceeding the valve pressure?
Also, isn't 14.4V enough to equalize cell voltages for AGM and flooded types?
Most batteries last about 4 years, PERIOD! Use that as a life expectancy figure. Oh, you're going to hear about the one that lasts FOREVER, but that's the exception rather than the rule. Think 4 years.
So, buy an inexpensive lead-acid battery of about 80 to 100 amp hours for about 70 dollar, and you'll have power to spare for about 4 years. Keep water in it, and take care of it.
When it SUDDENLY goes bad after 4 years, spend another 70, and you'll be at full power once again for 4 more years.
If lead-acid wasn't the work-horse that it is, every application out there would come with the the latest-greatest type of battery.
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