Should I Use AGM Batteries

[Dr Jay]

Hi, My 2013 Sightseer 33C house batteries need to be replaced. I am thinking about buying 2 AGM deep cycles batteries as the repacement. But, I have been hearing that you need a smart charger to use with these batteries. Does the Sightseer have this type of charger? I have checked manuals and there is no clear indication on the charger type that came with my RV. I am the original owner. Thak you.

[Tucsontoy]

The plus on AGM's is that they are maintenance free but that is about it. If you are wanting maintenance free then look at the new lithium batteries. The problem is they are expensive. Most RV'ers are switching to golf cart type deep cycle batteries because they have a larger electrical storage capacity and a longer life than CCA type of batteries. There is a lot of posts about house batteries on this site. I use an AGM for my chassis (engine) and Trojan Deep cycle in the house.

[l1v3fr33ord1]

DrJay-

According to this Winnebago wiring diagram, the converter is inside a space to the left of the entry stairs- kind of behind the outside stereo. It appears to be a single-stage, 55-amp converter, probably the Schumacher 7455 or 7455T.

If you plan to replace your batteries, you should replace the converter, too- no matter what kind of batteries you purchase. I recommend the Progressive Dynamics PD9260. A link to buy one is here.

A link to buy Lifeline 6V 220Ah model GPL-4CT batteries is here. I notice the price just went up about 10 percent ($25). Lifeline is one of the expensive brands. I happen to think they are worth the money, but not everyone feels that way. Flooded lead-acid batteries are much less expensive to buy than AGMs.

A link to all the wiring diagrams for your coach is here.

[LarryW]

I’d buy AGMs, Dr Jay, if my batteries were hard to check for water level and corrosion or I needed to carry them on their sides. Otherwise I see no advantage. I agree about upgrading the converter.

[al1florida]

Originally Posted by Dr Jay

Hi, My 2013 Sightseer 33C house batteries need to be replaced. I am thinking about buying 2 AGM deep cycles batteries as the repacement. But, I have been hearing that you need a smart charger to use with these batteries. Does the Sightseer have this type of charger? I have checked manuals and there is no clear indication on the charger type that came with my RV. I am the original owner. Thak you.

Do you almost always stay in places with electric hookups? If so I would just replace your batteries with the size and type the RV came with, or go with a pair of 6V golf cart batteries wired in series. Golf Cart batteries can be bought at Costco or Sam's Club for around $85-$95. To go with golf cart batteries you will need an additional cable to wire the batteries in series. Details in battery wiring here: The 12volt Side of Life (Part 1) No need to upgrade your converter.


If you dry camp or boondock a night or two or maybe three, a few times a year, then upgrading to golf cart batteries and a three stage charger (converter) would be much better.

[navnaz]

I have a 2017 Sunova 33C and had a solar upgrade while in Arizona. We do alot of dry camping in Colorado. As far as batteries and converter, he put in 2 Lifeline 12 volt batteries (model GPL-31XT) and the Progressive Dynamics PD 9260 converter that Mark mentioned above. It was pricey but my house batteries are much harder to drain and charge back up much more quickly than the original house batteries. The solar panel and solar charger are always on so my batteries are charged everyday whether out camping or in storage.

[Winterbagoal]

Originally Posted by Dr Jay

Hi, My 2013 Sightseer 33C house batteries need to be replaced. I am thinking about buying 2 AGM deep cycles batteries as the repacement. But, I have been hearing that you need a smart charger to use with these batteries. Does the Sightseer have this type of charger? I have checked manuals and there is no clear indication on the charger type that came with my RV. I am the original owner. Thak you.

I have no idea what sort of converter/charger your unit has.
Regarding AGM batteries, one of the lesser known advantages of them is their ability to handle extreme cold, like we get up here in Canada on occasion. I think we all know that a frozen battery is not a good thing. Not always fatal for a battery, but definitely can cause an early demise.
I have used AGMs for both chassis/starting and for coach/house batteries for years and have never had one freeze, no matter how cold it gets. The design of the gelled electrolyte glass mats between the plates is the main reason that they resist freezing.
Just a thought, if you happen to live and camp or store your coach in a colder climate, where temps often get below freezing.
Another after thought, if they tip over they won't leak and will generally still function.

[LarryW]

IMO the only two reasons for using an AGM battery is because you need to mount it on it’s side or it’s difficukt to check the water level on a wet cell battery. This freezing issue is not important at all. For instance Trojan says at https://www.trojanbattery.com/tech-support/faq/

“9. Can a flooded battery freeze?
The only way that a battery can freeze is if it is left in a state of partial or complete discharge. As the state of charge in a battery decreases, the electrolyte becomes more like water and the freezing temperature increases. The freezing temperature of the electrolyte in a fully charged battery is -92º F (-69º C). At a 40% state of charge, electrolyte will freeze if the temperature reaches approximately 16º F (-9º C).

At 16 degrees F your water tank and waste tanks will be solid ice.

[sajohnson]

Lots of good advice here.

That converter looks like a good deal.

We use 2 oversize (taller) GC batteries, but I am considering buying AGM batts when the GC batteries begin to get weak, for one primary reason:

We have a relatively large 2,000W Magnum Energy inverter that really should have 4 GC batteries for optimum performance.

The problem we are having is not storage capacity (although more is always welcome). It is that unlike chassis/starting batteries, deep cycle batteries like GC batts are not designed to put out high levels of current.

The reason that's important is that when the inverter is running a heavy load like the microwave or hair dryer, the input voltage dips dramatically. If it drops too far, the inverter will shut down due to low voltage.

The low battery cutout (LBCO) is adjustable, IIRC it goes down as low as 9 volts. The problem with just turning it all the way down is that with a light load, there will be very little voltage drop. So if, for example, you leave some small 120Vac load on -- a fan or light -- by the time the voltage drops to 9V(!) and the inverter shuts down, the batteries will be deader than a doornail.

With GC batteries, we have no choice but to set the LBCO lower than I would like, around 10.5V, so that we can run the microwave without the inverter shutting down.

Sometimes we run the engine so the alternator can give the GC batteries a boost.

With AGM batteries -- even though they have the same 220 Ah capacity, that should not be an issue. My understanding is that they will put out and accept an almost unlimited amount of current.

Which brings up a second advantage: The inverter has a 100A smart battery charger built in. With the GC batteries I have to dial it back to about 50A. With the AGMs I could run it flat-out at 100A for fast charging.

Otherwise, as others have mentioned, the other advantages are usually lost on RVers. They can be mounted in any position; they do not off-gas; they are very resistant to freezing.

The latter might be an issue for those who store their rig in a cold climate -- if, say, a converter or charger failed or became disconnected, there was a power outage, etc. Of course removing the batteries is always an option.

The one advantage everyone can appreciate is zero maintenance.

[Winterbagoal]

Originally Posted by LarryW

IMO the only two reasons for using an AGM battery is because you need to mount it on it’s side or it’s difficukt to check the water level on a wet cell battery. This freezing issue is not important at all.

You live in California. Freezing batteries isn't an issue for you. Think outside the box.

Originally Posted by LarryW

For instance Trojan says at https://www.trojanbattery.com/tech-support/faq/

“9. Can a flooded battery freeze?
The only way that a battery can freeze is if it is left in a state of partial or complete discharge. As the state of charge in a battery decreases, the electrolyte becomes more like water and the freezing temperature increases. The freezing temperature of the electrolyte in a fully charged battery is -92º F (-69º C). At a 40% state of charge, electrolyte will freeze if the temperature reaches approximately 16º F (-9º C).

Batteries freeze because their state of charge isn't always 100%. Murphy's Law states that if something can go wrong, it will, given the chance. Human nature and mechanical failures both play a role here. Why take the chance? Get the AGM, it's less likely to freeze versus flooded.

Originally Posted by LarryW

At 16 degrees F your water tank and waste tanks will be solid ice.

Pardon??? My water and waste tanks are heated.
Next......

[LarryW]

SAJ, very clear and detailed explanation of what you have, what you want and why! Excellent.

[NYBobbo]

For me AGM made more sense - No maintenance, no corrosion in the battery bay, uses my OEM Zamp charger and my 200w of solar keeps them topped up when sitting in my driveway running my exhaust vent (thermostat controlled). When camping I can now watch TV etc and use my CPAP throughout the night and still have plenty in the batteries. (I had to start my gen between 3-4 am to boost the OEM batteries)


I chose the Lifeline 6v when I changed out my OEM. What a difference! Golf cart batteries, AGM or LI or even a bunch of AAA batteries are better then the OEM.



BTW... If I recall correctly the LI also are not great in high temperature environment like the south or the desert.

[LarryW]

“BTW... If I recall correctly the LI also are not great in high temperature environment like the south or the desert.”

That’s my concern, NY.

[Tucsontoy]

Here is a table for a lithium battery. It actual performs better at 140 degrees.
https://www.lithiumion-batteries.com...on-battery.php


TEMPERATURE PERFORMANCE
ADVANTAGE



Temperature Performance Celsius Fahrenheit Usable Capacity 60 140 103% 50 122 102% 40 104 100% 30 86 100% 20 68 98% 10 50 92% 0 32 83% -10 14 80% -20 -4 70% -30 -22 60% -40 -40 10% -50 -58 0

[LarryW]

Three percent better! Supposed to be 118 tomorrow at Furnace Creek in Death Valley. Close enough. Let’s go! lol

[sajohnson]

Originally Posted by Tucsontoy

Here is a table for a lithium battery. It actual performs better at 140 degrees.
https://www.lithiumion-batteries.com...on-battery.php


TEMPERATURE PERFORMANCE
ADVANTAGE



Temperature Performance Celsius Fahrenheit Usable Capacity 60 140 103% 50 122 102% 40 104 100% 30 86 100% 20 68 98% 10 50 92% 0 32 83% -10 14 80% -20 -4 70% -30 -22 60% -40 -40 10% -50 -58 0

Well sure, but what about when it gets down to -40*F? Then there's only 10% of capacity available.

I really like the idea of using lithium batteries. They have several advantages, not the least of which is reduced weight.

I see these are 25 lbs each, so 3 of them would weigh just slightly more than one GC battery. That's a huge reduction.

Their nominal capacity -- 75 Ah / 900 Wh -- is less than a typical GC battery (~220 Ah x 6V = 1,320 Wh), but Li batteries can be discharged almost 100%, whereas GC and AGM batteries are better off if they are not discharged below 50% SOC. So in routine use we can figure half of that 1,320 Wh, or about 650 Wh per std size GC battery.

With that in mind, even just two (2) of these Li batteries would have more capacity than the two GC batteries most class C owners use.

One potential problem for those with a large inverter is the amount of current Li batts can deliver. The specs say 75 amps max (presumably no time limit) and 750 amps for 5 seconds.

I guess with 3 of them in parallel, and each capable of supplying up to 75A (225A total) we'd be in good shape.

The inverter should never use more than that. We've seen a max of about 185A when running the microwave.

*If you appreciated this rambling, please contribute to my lithium battery fund...

Seriously, lithium batteries are still expen$ive. I keep hoping they will come down in price before our GC batteries need to be replaced.

[LarryW]

“I keep hoping they will come down in price before our GC batteries need to be replaced.”

Your hope should be...slim.

[Cloudrnnr]

I'd love to move to lithiums, but we usually make a couple of winter trips where the temps drop well below freezing, and the cold charging issue becomes a factor. Well, that, and the fact that there are other toys I can buy at triple the cost of AGMs!

[al1florida]

Originally Posted by Tucsontoy

Here is a table for a lithium battery. It actual performs better at 140 degrees.
https://www.lithiumion-batteries.com...on-battery.php


TEMPERATURE PERFORMANCE
ADVANTAGE



Temperature Performance Celsius Fahrenheit Usable Capacity 60 140 103% 50 122 102% 40 104 100% 30 86 100% 20 68 98% 10 50 92% 0 32 83% -10 14 80% -20 -4 70% -30 -22 60% -40 -40 10% -50 -58 0

However using or storing Lithium batteries at over 100 F decreases the life of the battery, even though you may get 3% capacity out of the battery.

[Bob Loblaw]

Originally Posted by Dr Jay

Hi, My 2013 Sightseer 33C house batteries need to be replaced. I am thinking about buying 2 AGM deep cycles batteries as the repacement. But, I have been hearing that you need a smart charger to use with these batteries. Does the Sightseer have this type of charger? I have checked manuals and there is no clear indication on the charger type that came with my RV. I am the original owner. Thak you.

Hey Dr Jay, I use 2 Trojan T105. They are relatively inexpensive compared to AGM and the only maintenance required is to remove during the winter (if you live somewhere cold) and make sure you top them up occasionally with distilled water - maybe once a season. Super simple. Best part - they last for close to a week for us. We love them.