AGM Batteries and Inverter - What Is Best For My Needs?

[Roadlover]

I'm looking at purchasing a couple of group 31, AGM, deep cycle batteries and a new inverter for our AF 1150. We enjoy dry camping but always rely on a generator for making our morning coffee and for my wife to blow dry and curl her hair. So, what direction should I take as far as the correct batteries and inverter? My local CarQuest dealer has 31 group AGM, deep cell batteries for $248.99 each. They said the manufacturer for the batteriy is East Penn. Thanks for your help!

[Grit_dog]

v6toy4x wrote:
sears paltinums, decent price when on sale.Same battery as oddyssey. I run 4 group 31s and 270 watts solar. I re worked the bus bar in my panel so I can't run micro AC or refrig on the inverter.

The maintenance free is huge for me as I am lazy not to mention you can store batteries in areas that are not easily accessible since you don't have to monitor the water levels, like in the bed in front of the wheel wells or under the truck making it easy to have 6-8 if you want.

The fast rate of recharge is also very convenient, short run of generator in late afternoon with solar and you can be powered up indefinitely.

Correct on the Sears platinum batteries. I have had great service life so far out of a pair of Odysseys in my boat for 4 years and transferred to the truck last year to replace the dying OE batteries since the boat was not going to be used for an extended period. Now have 5 years on the Odysseys and going strong.
Just got 2 Diehard Platinums for the boat again on sale were almost $100 less each than Odyssey brand.
east Penn that the OP mentioned makes Deka batteries which are regarded as probably the best around, so should be a solid choice.
Whatever you do stay away from Optimas. I have had terrible service life from all but one of 6-8 Optimas over the years, and I generally take care of my batteries. The one that's lasted is actually the one that always was neglected, weird.
But if you're serious about aH capacity then go 6V.

[HMS_Beagle]

One interesting claim made in passing in the Firefly literature is that they will tolerate prolonged use at partial charge. This would make them unlike most lead acids and certainly unlike other AGMs.

[Bob__B]

HMS Beagle wrote:
Here is a fixed link.

They do claim new technology which may have some substance. However they do not guarantee it for any longer than any other lead acid battery manufacturer. One of the limitations of most battery technologies is the calendar time: once the battery is manufactured, a clock starts and it will be junk in some period of time due to chemical degradation even if it is never discharged at all. For good AGMs this seems to be about 10-12 years.

So one question is, how many discharge cycles (and how deep) do you expect to have in the batteries warrantee period? 6 years of every weekend use and assuming 50% discharge each night used is only 624 cycles - which most batteries will tolerate. And that would be severe use for the batteries. Last weekend watching the battery monitor I was only getting down to 92% each night (two 6V batteries, 220 AH capacity). I wasn't running the heater (which is the largest energy consumer) but I was running the vent fan all night, lights, charging the computer, etc. When I run the heater in very cold temperatures (20 deg) I will go down to 80%. Over two nights with no charging down to 60%. But now with solar it is all recharged by noon the next day so never below 80%. My point is that unless you are living 365 off grid with unusual energy requirements you are unlikely to "wear out" batteries in a camper through too many cycles. Instead they will be killed by improper charging, sulfating them by self discharge during storage, or just calendar time.

So logically you should choose batteries based on criteria other than cycle life (assuming good quality in whatever technology). In the camper, I like AGMs mainly due to no outgassing corrosion, no maintenance, and low self discharge rates. Even self discharge is unimportant in a camper stored outside with solar charging.

That said, by all means you should buy those Fireflys and report back to us on how they work!

I am thinking AGM also, since the batteries are going to be inside the camper and I don't want to have to worry about proper venting.
I can get the Sears 31 AGM (made by Oddysey) for $217 and the Sams Club duracell 31 AGM (made by West Penn) for $176.
I have sent Firefly an email to see if I can buy from them direct and what their price would be since they are only about 15 miles from me.
I'd like to support a local company, but aren't going to pay $150 to $200 more per battery......extra $300-400 per pair.....I could get my solar panels for that extra.

Didn't see the other post til after I posted....was too slow. Thanks for the info about the charge cycles.....Things are starting to clear up in this fuzzy old brain

[Jfet]

This is one reason I kind of laugh at the people who claim LiFePO4 will last 3000 cycles. Using it every weekend of every year would be 28 years before you hit 3000 cycles. The battery will be useless because of age long before then. It may make sense for someone who is boondocking 24/7.

Running the AGM batteries down to 30% and getting 90AH out of a 125AH battery you will still get around 300 to 400 cycles, which for a typical camper used 40 nights a year means 8 years of life.

[HMS_Beagle]

Here is a fixed link.

They do claim new technology which may have some substance. However they do not guarantee it for any longer than any other lead acid battery manufacturer. One of the limitations of most battery technologies is the calendar time: once the battery is manufactured, a clock starts and it will be junk in some period of time due to chemical degradation even if it is never discharged at all. For good AGMs this seems to be about 10-12 years.

So one question is, how many discharge cycles (and how deep) do you expect to have in the batteries warrantee period? 6 years of every weekend use and assuming 50% discharge each night used is only 624 cycles - which most batteries will tolerate. And that would be severe use for the batteries. Last weekend watching the battery monitor I was only getting down to 92% each night (two 6V batteries, 220 AH capacity). I wasn't running the heater (which is the largest energy consumer) but I was running the vent fan all night, lights, charging the computer, etc. When I run the heater in very cold temperatures (20 deg) I will go down to 80%. Over two nights with no charging down to 60%. But now with solar it is all recharged by noon the next day so never below 80%. My point is that unless you are living 365 off grid with unusual energy requirements you are unlikely to "wear out" batteries in a camper through too many cycles. Instead they will be killed by improper charging, sulfating them by self discharge during storage, or just calendar time.

So logically you should choose batteries based on criteria other than cycle life (assuming good quality in whatever technology). In the camper, I like AGMs mainly due to no outgassing corrosion, no maintenance, and low self discharge rates. Even self discharge is unimportant in a camper stored outside with solar charging.

That said, by all means you should buy those Fireflys and report back to us on how they work!

[Bob__B]

HMS Beagle wrote:

Bob B wrote:


The other thing I am confused about is the # of charge cycle for various batteries.
There is a local battery manufacturer (Firefly) who has a group 31 agm battery and say it is good for 3600 charge cycle at 50% discharge.
These batteries are VERY expensive, but the cost / charge cycle could actually be less if you are in it for the long haul.
I don't know what # of charge cycles a good flooded cell golf cart battery would be.

The number of charge cycles is a very nebulous number as it depends a great deal on care, circumstances, and conditions. I would be extremely skeptical of a claim for any lead acid battery of 3600 cycles to 50% depth. 500 or 1000 is a more typical claim. AGMs will not necessarily last more cycles than well cared for high quality flooded batteries. The claims even for LiFePO4 batteries are only about 2000 cycles, and they are considered to be far longer lasting than any lead acid.

My expectation would be about the same number of cycles from well cared for flooded and AGM batteries, where both were set up with a good temperature compensated 3 or 4 stage charger. Under those conditions, the AGMs will take less maintenance, recharge a little quicker, not outgas or corrode their terminals or anything around them, and stay charged much better over storage periods. The flooded cells will require more maintenance, cost less, and stand more abuse in the form of under or overcharging.

I will note that good quality flooded cells cost quite a bit more than cheap ones, and are closer to the price of AGMs. If cost is the most important issue, then you have to look at watt-hours delivered per dollar spent, and cheap flooded cells probably win, if you are willing to put up with them. They don't last as long but the don't cost much. And there is no point in paying for AGMs unless the charging system is properly set up to take care of them.

Here's a link to the spec sheet for that battery http://fireflyinternationalenergy.com/wp-content/uploads/2014/02/Oasis-G31-FF12D1-G31-Spec.pdf

They are a new company with a new technology.....just don't think I want to spend $350 / battery.

Trying Clicky Insert

HMMMM....doesn't work

[HMS_Beagle]

Bob B wrote:


The other thing I am confused about is the # of charge cycle for various batteries.
There is a local battery manufacturer (Firefly) who has a group 31 agm battery and say it is good for 3600 charge cycle at 50% discharge.
These batteries are VERY expensive, but the cost / charge cycle could actually be less if you are in it for the long haul.
I don't know what # of charge cycles a good flooded cell golf cart battery would be.

The number of charge cycles is a very nebulous number as it depends a great deal on care, circumstances, and conditions. I would be extremely skeptical of a claim for any lead acid battery of 3600 cycles to 50% depth. 500 or 1000 is a more typical claim. AGMs will not necessarily last more cycles than well cared for high quality flooded batteries. The claims even for LiFePO4 batteries are only about 2000 cycles, and they are considered to be far longer lasting than any lead acid.

My expectation would be about the same number of cycles from well cared for flooded and AGM batteries, where both were set up with a good temperature compensated 3 or 4 stage charger. Under those conditions, the AGMs will take less maintenance, recharge a little quicker, not outgas or corrode their terminals or anything around them, and stay charged much better over storage periods. The flooded cells will require more maintenance, cost less, and stand more abuse in the form of under or overcharging.

I will note that good quality flooded cells cost quite a bit more than cheap ones, and are closer to the price of AGMs. If cost is the most important issue, then you have to look at watt-hours delivered per dollar spent, and cheap flooded cells probably win, if you are willing to put up with them. They don't last as long but the don't cost much. And there is no point in paying for AGMs unless the charging system is properly set up to take care of them.

[Bob__B]

HMS Beagle wrote:

Bob B wrote:


A couple questions.....do you have an example of a charger that has the ability to equalize a battery?

Are the thin cell Odyssey batteries wet cell or AGM?

Thin cell Odyssey batteries are AGM chemistry.

There are many chargers with an equalize function. Many of the better Magnum and Xantrex chargers have it. Though there is lack of standardization in the industry, what you are looking for is usually called a "4 stage charger" rather than a 3 stage - equalization being the 4th stage. (The stages are: Bulk, Absorption, Float, and Equalization). Some solar charge controllers also do this, although you need a lot of daylight to complete the process. Equalizing is a controlled overcharge, usually at about 15.5-16.5 volts for several hours. It is called "equalizing" because it brings all of the cells in the battery up to the same level. In a flooded battery it also mixes the electrolyte and returns some of the lead sulfate to solution. It also boils some water out which must be replaced afterwards. Most AGM and Gel batteries should NOT be equalized as there is no way to replace the lost water. However Lifeline recommends it on their AGMs under some circumstances.

Great info.....Thanks

The other thing I am confused about is the # of charge cycle for various batteries.
There is a local battery manufacturer (Firefly) who has a group 31 agm battery and say it is good for 3600 charge cycle at 50% discharge.
These batteries are VERY expensive, but the cost / charge cycle could actually be less if you are in it for the long haul.
I don't know what # of charge cycles a good flooded cell golf cart battery would be.

[HMS_Beagle]

Bob B wrote:


A couple questions.....do you have an example of a charger that has the ability to equalize a battery?

Are the thin cell Odyssey batteries wet cell or AGM?

Thin cell Odyssey batteries are AGM chemistry.

There are many chargers with an equalize function. Many of the better Magnum and Xantrex chargers have it. Though there is lack of standardization in the industry, what you are looking for is usually called a "4 stage charger" rather than a 3 stage - equalization being the 4th stage. (The stages are: Bulk, Absorption, Float, and Equalization). Some solar charge controllers also do this, although you need a lot of daylight to complete the process. Equalizing is a controlled overcharge, usually at about 15.5-16.5 volts for several hours. It is called "equalizing" because it brings all of the cells in the battery up to the same level. In a flooded battery it also mixes the electrolyte and returns some of the lead sulfate to solution. It also boils some water out which must be replaced afterwards. Most AGM and Gel batteries should NOT be equalized as there is no way to replace the lost water. However Lifeline recommends it on their AGMs under some circumstances.

[cigar_100]

great topic. last month i replaced my two 5 yr old agm's with four 6 volt 250 amp/hr gam batteries by rolls. i have had great luck in the past with the gam batts, even gave the old ones to a friend. i think he'll get another couple years out of them.

[time2roll]

dadwolf2 wrote:
How can you tell if you have a smart charger or not?

Post the converter make and model.

[dadwolf2]

How can you tell if you have a smart charger or not?

[ISBRAM]

I upgraded to a Progressive Dynamics 9260 inverter with the charge wizard, and a pair of East Penn AGM 6 volt golf cart battery’s this spring. It has worked out great, no more pulling out the battery’s to water them and the charge recovery time is much faster.

[deltabravo]

Bob B wrote:
I had heard that the Sears Platinum 31 were made by Odessey, does anyone know if that is true?

Yes, they are made by Oddessy - all the Diehard Platinums are.