AGM 6 volt versus AGM 12 volt

[BobA]

Many folks have chosen the 6 volt flooded lead acid battery (~golf cart) versus 12 volt batteries for a variety of performance reasons, including capacity and longevity.

Does the same reasoning apply to AGM 6 volt versus 12 volt batteries ?

Thanks, Bob in Grand Rapids

[WanderMore]

Bob,

The only replacement you should be considering is LiFePO4. At first blush they look very expensive but due to their long life they actually cost less. Battle Born has a model with a built in heater so you can use it below freezing.

[NJKris]

AGM's deal with heat and vibration better than FLA batts, they are sealed (can be mounted in any orientation), don't require any maintenance (checking and topping off electrolyte), but they are much more expensive. I don't think they are worth the extra cost for RV use. Actual Golf carts are subject to much more vibration, and I don't think golf courses use AGM, just FLA.


https://unboundsolar.com/blog/lead-a...ery-comparison

[boondocking]

Originally Posted by WanderMore

Bob,

The only replacement you should be considering is LiFePO4. At first blush they look very expensive but due to their long life they actually cost less. Battle Born has a model with a built in heater so you can use it below freezing.

I would personally never buy a Lithium battery for my trailer.
Cost vs life expectancy.

My flooding GC2 batteries are 8 years old and still going strong. For the cost of one LiFePO4 (100AH) I can buy 6 pair of GC2 batteries (230 AH/pair). That would give me at least 48 years of service.

[mjbenedict]

Originally Posted by boondocking

I would personally never buy a Lithium battery for my trailer.
Cost vs life expectancy.

My flooding GC2 batteries are 8 years old and still going strong. For the cost of one LiFePO4 (100AH) I can buy 6 pair of GC2 batteries (230 AH/pair). That would give me at least 48 years of service.

One 100AH lithium almost has the usable capacity of two GC2 flooded batteries at 230AH. Charge time is much shorter and more efficient, lifetime is better. Your 8 year old batteries are most-likely much less capacity than new where a lithium would be at pretty much the same capacity as new.
Much less generator run time
Much less weight - nearly ¼ the weight as two GC2 batteries.
Steady working voltage for at least 95% of the capacity - love this the most - holds above ~12.5V through the full range of capacity until close to 5% left. My lead acid batteries constantly set off gas alarm hardware at lower voltages. Everything ran slower.

I understand your logic but I know your math is way off given most just assume Lithium AH = LeadAcid/AGM AH and that's not the case. If you draw more than 50% from any lead acid battery it degrades the capacity a lot.

[SlowrideHD]

Originally Posted by WanderMore

Bob,

The only replacement you should be considering is LiFePO4. At first blush they look very expensive but due to their long life they actually cost less. Battle Born has a model with a built in heater so you can use it below freezing.

The math works for BB or other LiFePo batteries if you really plan on several thousand cycles of your battery bank. I don't think 99% of rv folks are ever going to approach that level of battery bank use.

A main attraction for me is how fast they will recover a full charge from solar and their ability to maintain 13 volts until 10% SOC, or thereabout. Currently I have sixteen Trojan T-105 in a 8s/2p bank for a remote cabin. If I could find a 48 volt LiFePo battery with the technology and performance of the Battle Born 12 volt batteries, I'd take a serious look. The BB don't seem to play well in series to make a 48 volt system and that's what I want to continue using.

[mjbenedict]

Originally Posted by SlowrideHD

The math works for BB or other LiFePo batteries if you really plan on several thousand cycles of your battery bank. I don't think 99% of rv folks are ever going to approach that level of battery bank use.

A main attraction for me is how fast they will recover a full charge from solar and their ability to maintain 13 volts until 10% SOC, or thereabout. Currently I have sixteen Trojan T-105 in a 8s/2p bank for a remote cabin. If I could find a 48 volt LiFePo battery with the technology and performance of the Battle Born 12 volt batteries, I'd take a serious look. The BB don't seem to play well in series to make a 48 volt system and that's what I want to continue using.

These can be wired up to 6 in series based on the specifications: https://relionbattery.com/products/lithium/rb100

Lifeblue states they can wire in series as well. I have a single 300AH lifeblue low temperature version battery in my rig.

[boondocking]

Originally Posted by mjbenedict

One 100AH lithium almost has the usable capacity of two GC2 flooded batteries at 230AH. Charge time is much shorter and more efficient, lifetime is better. Your 8 year old batteries are most-likely much less capacity than new where a lithium would be at pretty much the same capacity as new.
Much less generator run time
Much less weight - nearly ¼ the weight as two GC2 batteries.
Steady working voltage for at least 95% of the capacity - love this the most - holds above ~12.5V through the full range of capacity until close to 5% left. My lead acid batteries constantly set off gas alarm hardware at lower voltages. Everything ran slower.

I understand your logic but I know your math is way off given most just assume Lithium AH = LeadAcid/AGM AH and that's not the case. If you draw more than 50% from any lead acid battery it degrades the capacity a lot.

Not sure how my math is way off.
My batteries are at the same percentage SOC (80% - according to the battery monitor) in the morning as they were when they were new 8 years ago.
Will one lithium battery for the price give me 48 years of service like 6 pair of GC2's would?
Not saying lithium is not good, but for me and the majority of people with solar they are not the best choice.

[mjbenedict]

Originally Posted by boondocking

Not sure how my math is way off.
My batteries are at the same percentage SOC (80% - according to the battery monitor) in the morning as they were when they were new 8 years ago.
Will one lithium battery for the price give me 48 years of service like 6 pair of GC2's would?
Not saying lithium is not good, but for me and the majority of people with solar they are not the best choice.

Yes, a lithium could last that long based on what they claim.
People rarely get 8 years out of a lead-acid battery.
Is that 80% with solar on it, during charge, under load? Battery monitors are finicky and the only real accurate measure of a lead-acid is to check with a hydrometer. I have never had a lead-acid read well after 3-4 years of use and I am OCD about water level/distilled water. To check voltage you need several hours with no charge/no load.

Plenty of research has been done on lead-acids to show that what you are claiming is an anomaly.

[njfishing]

Unless you plan to boondock regularly and for more then 3 days at a clip the Lithium Ion batteries are overkill for your needs. If you have a power hungry residential fridge that does not run on propane that's a different story. Yes they do have the advantages mentioned above. Far more usable power, they charge much faster and have much longer life.

There are however other things you need to consider. They need a special charger so you might have to swap out your converter/battery charger and they don't like the cold. This means if you camp in the cold you won't want them mounted outside on the trailer tongue exposed to the cold and over the winter when not in use, you'll need to store them indoors.

Having said all this, if money were no object and I boondocked a lot more, I'd be using them.

[mjbenedict]

Originally Posted by njfishing

Unless you plan to boondock regularly and for more then 3 days at a clip the Lithium Ion batteries are overkill for your needs. If you have a power hungry residential fridge that does not run on propane that's a different story. Yes they do have the advantages mentioned above. Far more usable power, they charge much faster and have much longer life.

There are however other things you need to consider. They need a special charger so you might have to swap out your converter/battery charger and they don't like the cold. This means if you camp in the cold you won't want them mounted outside on the trailer tongue exposed to the cold and over the winter when not in use, you'll need to store them indoors.

Having said all this, if money were no object and I boondocked a lot more, I'd be using them.

Agreed on all points except:

The new ones with built in heat have the same cold capabilities as a lead acid. Without heat you can install (not just store) indoors. Actually, lead-acid will freeze if you don't keep them topped off and lithiums can be discharged without heating in similar cold temperatures. There are advantages to both but some are being eliminated as tech keeps getting better.

I've gone years with lead-acid and AGM, still have 3-AGM in my boat given I don't want to replace them until they are gone. Would be awesome to have more power for the trolling motor and longer usage between charges. Shorter charge time, lighter weight,...

Forgot to mention, storage is much easier with a Lithium since they have miniscule self-discharge. Discharge to 50% then unhook, check every few months to see if voltage drops below 13V.

[TitanMike]

Originally Posted by boondocking

Not sure how my math is way off.
My batteries are at the same percentage SOC (80% - according to the battery monitor) in the morning as they were when they were new 8 years ago.
Will one lithium battery for the price give me 48 years of service like 6 pair of GC2's would?
Not saying lithium is not good, but for me and the majority of people with solar they are not the best choice.

If you are only using 20% of your total battery capacity all the time then what you have is overkill for your needs. The reason the batteries are lasting so long is that they aren't being deep cycled.

Also, how well do they so when running a 2,000-3,000 watt inverter. Power tends to sag badly with any lead/acid type battery is under that kind of load and unless you have a really large battery bank you'll hear the low voltage alarm alot. Two Battleborns do just fine with my 2,000 watt inverter with no alarm or shutdown.

[boondocking]

Not saying they are not good, but for me they are not a good choice for the price.
Don't have a 2000 watt inverter, the batteries are fine with my 600 watt inverter.

[njfishing]

Originally Posted by mjbenedict

Agreed on all points except:

The new ones with built in heat have the same cold capabilities as a lead acid. Without heat you can install (not just store) indoors. Actually, lead-acid will freeze if you don't keep them topped off and lithiums can be discharged without heating in similar cold temperatures. There are advantages to both but some are being eliminated as tech keeps getting better.

I've gone years with lead-acid and AGM, still have 3-AGM in my boat given I don't want to replace them until they are gone. Would be awesome to have more power for the trolling motor and longer usage between charges. Shorter charge time, lighter weight,...

Forgot to mention, storage is much easier with a Lithium since they have miniscule self-discharge. Discharge to 50% then unhook, check every few months to see if voltage drops below 13V.

Agreed on all counts MJ... Isn't it great when people can agree on something these days

[BobA]

Thanks to everyone that responded to my original question about AGM 6v versus AGM 12v. I'll take what I learned and make the best decision I can.

Bob in Grand Rapids

[Jay2504]

I too am going back and forth on AGM vs FLA for this upcoming season. (I have ruled out Lithium). I originally was going to go with 2 group 65 AGMs one on the tongue and one on the inside under the sink to keep the tongue weight down. Now we have a new TV and tongue weight is of no consideration. Now I am just working out what will meet my goal of being able to run the microwave on an overnight stop at Walmart or a campground for a quick night or 2 on our way to somewhere. Jay

[mjbenedict]

Originally Posted by Jay2504

I too am going back and forth on AGM vs FLA for this upcoming season. (I have ruled out Lithium). I originally was going to go with 2 group 65 AGMs one on the tongue and one on the inside under the sink to keep the tongue weight down. Now we have a new TV and tongue weight is of no consideration. Now I am just working out what will meet my goal of being able to run the microwave on an overnight stop at Walmart or a campground for a quick night or 2 on our way to somewhere. Jay

If tongue weight no concern, 6V golf cart batteries are hard to beat price wise and for capacity. I'll admit I haven't kept up on AGM but do know they are easier maintenance. Surprised there aren't more boxes set up around double 6V configuration. Had a side by side on my hybrid TT and the last TT had them mounted end to end in a white box that was hard to find. Fit well between the rails on the tongue.

[Jay2504]

Although I am a 12 volt guy, 2, 6volts haven’t been ruled out. I had 2 6 volt batteries for a while in our Rockwood. These were older batteries that came off our golf cart when I switched it over to 12 volts. Once on the camper, they seemed to take a lot of water compared to golf cart usage, So much water that it would have emptied out the 12volts that was running on the same camper, but the 12volt batteries are fine.(I didn’t keep them plugged in all the time, and had the WFCO converter). 2 of the 4 I used died at different times. Then I read on here I believe that 2 6 volt batteries have trouble working with standard WFCO 9000 series converter. I don’t know if it’s true or not, a lot of people are running 2 CG2 batteries with no problem. All I have to go on is my own experience. Has anyone ever heard of a WFCO converter having trouble with 2 6volt batteries? Jay

[NJKris]

I can tell you my WFCO OEM converter works fine with my dual GC batts. When it's hibernating, I have it on a CTEK smart charger. Easier to tell at a glance walking by that the charger is working, I have power to it, and batteries are topped off. My trailer is covered all winter.


**Mine is 8700 series, 35 amp

[Jay2504]

I have the camper at the fairgrounds inside storage right now. I think the real number of my WFCO 100% sure. I do know it’s 55 amps for sure. It doesn’t make sense to me that 2 6volts in series would not look like a big 12 volt battery to the converter. I did experience water loss that I thought was excessive, but I didn’t treat them any differently than the “sealed top” 12 volt FLA batteries that I was running before. I never pried the top off the 12 volt batteries to see if they needed water or not. I still have 2 of the 12 volt batteries and one is still in use. I should pry off the cover and check the water level. Jay.