12V AGM coach battery recommendations?

[dkoldman]

Originally Posted by BobC

In my experience, AGM deep cycle batteries aren't necessarily sold by group size so pay close attention to the length, width and height, including terminals. And be extra careful, a group size designation may be indicative of a dual purpose starting/deep cycle AGM battery, especially if cold cranking amps (CCA) is in the specs.

I've read some posts that say that all AGM batteries are true deep cycle batteries but this contradicts that perspective:

https://www.power-sonic.com/blog/the...er%20batteries.

See the specifications for BCI at the bottom. https://www.vmaxtanks.com/SLR125-12V...tery_p_38.html

In fact all of the AGMs I compared where all Group 31s. FWIW, my coach came with Group 27. But more capacity was priority for me.

https://www.vmaxtanks.com/SLR125-12V...tery_p_38.html

[dkoldman]

Originally Posted by RV-Travelers

Is this worth considering? 100AH for $200, well-known name brand.

https://www.amazon.com/Renogy-Batter...0&sr=1-11&th=1

I just saw this on VMax Website. https://www.vmaxtanks.com/SLR125-12V...tery_p_38.html

You can buy two 125ah for $293 each; so that is only $46 more per battery than I paid.

Don't forget as you were advised earlier by Morich to double check your existing battery size and/or space available.

My logic was super simple. I was never going add 2nd battery bank, so I just want to get max ah/available cubic inches.

Speaking of banks, take this to the bank, sooner or later you may wish you you had those 5 hrs of duty on one charge cycle. Saving $30 - $40 / battery want mean anything then

Good luck with whatever you do

[BobC]

Originally Posted by creativepart

This is true for 6v batteries - either FLA or AGM. But a Group 31 AGM is a standard size and generally has 100 or more amp hours.

I wrote "aren't necessarily sold by group size". In this Renogy link for their "Deep Cycle AGM Battery 12 Volt 100Ah" I can't find a group size in either the description or specifications. If I missed something, it certainly isn't obvious:

https://www.renogy.com/deep-cycle-ag...12-volt-100ah/

[RV-Travelers]

Again, thanks for all of the feedback and recommendations.

I have all the dimensions, ground clearances (in case I decide to enlist some help and DIY from ground level), etc.

That deal on the VMAXTANKS 125AH battery looks like my best bet @ 2 for $294 each with free shipping. Thanks for the recommendations and links.

[spierce617]

Amazon have these for under 200 each.

Renogy AGM 100Ah batteries.
https://www.amazon.com/dp/B075RFXHYK...lig_dp_it&th=1

[Nmdoug]

Centennial CB12-115 12v 115Ah Group 31 sealed lead acid AGM battery.

[RV-Travelers]

Thanks for the additional recommendations. I'll check them out.

[RV-Travelers]

Just wanted to take a moment to thank everyone again for all of their feedback and recommendations.

I ordered the VMAXTANKS SLR125 125AH AGM group 31 batteries, as noted above $293 each (when buying 2 or more) with free shipping.

The batteries were shipped quickly and arrived just 2 days after ordering them.

The batteries were double-boxed, each in a tight-fitting cardboard box inside of an outer cardboard box, with Styrofoam between the inner and outer boxes. The Styrofoam was pretty much crushed into mostly small pieces on arrival, but the inner boxes were unscathed and the batteries were not damaged, so the Styrofoam did a good job of protecting them.

One thing I completely forgot about when ordering the batteries was seeing what kind of warranty they come with. After I got them I checked the site and was surprised the warranty is only 1 year.

The short warranty is a concern, but I can't see ever shipping them back if they fail prematurely, and given the difficulties removing and installing the batteries I just have to hope they hold up well.

[dkoldman]

Originally Posted by RV-Travelers

Just wanted to take a moment to thank everyone again for all of their feedback and recommendations.

I ordered the VMAXTANKS SLR125 125AH AGM group 31 batteries, as noted above $293 each (when buying 2 or more) with free shipping.

The batteries were shipped quickly and arrived just 2 days after ordering them.

The batteries were double-boxed, each in a tight-fitting cardboard box inside of an outer cardboard box, with Styrofoam between the inner and outer boxes. The Styrofoam was pretty much crushed into mostly small pieces on arrival, but the inner boxes were unscathed and the batteries were not damaged, so the Styrofoam did a good job of protecting them.

One thing I completely forgot about when ordering the batteries was seeing what kind of warranty they come with. After I got them I checked the site and was surprised the warranty is only 1 year.

The short warranty is a concern, but I can't see ever shipping them back if they fail prematurely, and given the difficulties removing and installing the batteries I just have to hope they hold up well.

If I had any doubts when I saw the way the batteries were packed. OMG, it was the best packaging I can recall for anything. I kept my boxes, they are in the attic

I not only did not have to pay shipping, but there was no taxes for me in our area; so that further made the cost more attractive

I checked voltage upon receipt and both were over 13vdc. Hard to fake that when shipping.

I have never bought a brand new battery any brand that failed under warranty. My NAPAs were under warranty (18 months old) when I replaced them; they just did not have the capacity I wanted (needed), and were chronically corroding (despite corrosion prevention sprays), not to mention the water maintenance; which to me is an incredible small task for any RV owner. Some buy fancy water systems, but that is even more money.

Not sure if they asked you, but their biggest concern with a battery going defective is the use of a improper or wrong type of charger? That will kill the AGM batteries for sure, and of course the RV owner can get mad and say this battery only lasted 6 months. They had me provide my Converter model BEFORE shipping.

If I can give one suggestion and you may call them back to confirm, or ask others to prove if I am wrong, but I NEVER let my AGM batteries go below 12.4vdc 50% SOC. Some folks say 12.0 or 12.2vdc is SOC; but I don't agree. In fact; my AGS is set to kick on at 12.5vdc. I love to let it go down to 12.5vdc to cycle but some folks habitually will allow the batteries well below 50% SOC for all sorts of reasons; which is not good for the batteries.

FWIW, when I had OEM FLA for House batteries I had it set to 12.2vdc because otherwise; I could barely get 6 hours with everything on

[creativepart]

To each his own. But the 12v battery chart is pretty validated as accurate. But certainly taking less amps from your batteries will extend their lifetime but produce less cumulative power for you to use over that lifetime.

[dkoldman]

Originally Posted by creativepart

To each his own. But the 12v battery chart is pretty validated as accurate. But certainly taking less amps from your batteries will extend their lifetime but produce less cumulative power for you to use over that lifetime.

I have seen those charts, but my Onan EC-30 User Manual has a different chart I noticed a few other with slight variations; thus I sated the way I did. For me, it only came into play when I was programming my EC-30 and of course I followed my manual In a verbal conversation with VMax Tanks; they were saying that 12.6 was preferred. However my AGS maximum set point is 12.5vdc

If I needed more capacity during any given cycle, or was worried about frequent starting of generator, I could always lower i.e. 12.2vdc, but I can go two days with normal usage to get to 12.4vdc. My genny runs a little every day anyway because of things like needing AC or to ensure max charge BEFORE quiet time begins. So it works out nice, I cycle the AGM daily, and genny runs and hour or two. Unless it is very hot and relevant savings in cost; we go with a campsite with no hookups or power because we don't need. I could NOT do that until we got the 250 ah VMax Tanks AGMs.

I was just giving OP an angle since he was somewhat concerned about warranty. Stay above 50% SOC at all times. Check with the Battery Mfg to be sure what they say as SOC. I chose to go with my EC-30 Program/ Manual and Onan because I am also cycling my Generator getting 2 for 1


Update:
Attached is what the manual from Onan says. This why I use 12.4vdc for my AGM

[RV-Travelers]

We bought our ERA used, 2 years old. Knew next to nothing about RVs and very little about batteries at the time.

First trip out we left the refrigerator on overnight on the coach batteries. Middle of the night everything shut down. RV display said the coach batteries were < 10V! Didn't know it then, but I do now just how bad that was.

Surprisingly, the batteries rebounded and lasted another 3+ years before showing signs of end of life. So I guess we were very lucky.

I did speak to a tech at VMAXTANKS as part of the purchase process. I know we talked about the vehicle, battery (group) size and amp-hours rating. Don't recall if he asked or I told him which model of charge converter is in our ERA, or the specs on it.

That said, we were able to complete installing the batteries ourselves yesterday. I started another thread a month or two ago on the Class B forum and will update it in the next few days with some photos and notes on removing and installing the batteries. Short story is it was pretty difficult given the circumstances. Perhaps that info will be helpful to other ERA owners that are pondering replacing their coach batteries and wondering if and how they could do it, assuming the model they have is similar to ours.

[dkoldman]

Originally Posted by RV-Travelers

We bought our ERA used, 2 years old. Knew next to nothing about RVs and very little about batteries at the time.

First trip out we left the refrigerator on overnight on the coach batteries. Middle of the night everything shut down. RV display said the coach batteries were < 10V! Didn't know it then, but I do now just how bad that was.

Surprisingly, the batteries rebounded and lasted another 3+ years before showing signs of end of life. So I guess we were very lucky.

I did speak to a tech at VMAXTANKS as part of the purchase process. I know we talked about the vehicle, battery (group) size and amp-hours rating. Don't recall if he asked or I told him which model of charge converter is in our ERA, or the specs on it.

That said, we were able to complete installing the batteries ourselves yesterday. I started another thread a month or two ago on the Class B forum and will update it in the next few days with some photos and notes on removing and installing the batteries. Short story is it was pretty difficult given the circumstances. Perhaps that info will be helpful to other ERA owners that are pondering replacing their coach batteries and wondering if and how they could do it, assuming the model they have is similar to ours.

You have done good. A one off low drop in charge won't kill you, but if it is habitual; it will ruin the battery.

Not sure if you have AGS?

I use RV year around and when active it is 100% in AGS mode either in AUTO or QUIET TIME, if I do forget and leave something on; when the genny fires up I kind of go oops But I am still sitting pretty at 12.5vdc

I once had my RV parked at a Apartment Complex in Houston 3 days with temps over 96 degrees. No shore power, but genny was in AUTO mode the entire time. I was not near anyone for noise to be a factor. The genny would come on to maintain temperature to 79 inside. I may have burned $60 of gas and that was when gas was at $4+ per gallon. My house batteries were 12.9vdc the entire time

[RV-Travelers]

We have found it's too hot to travel comfortably during the summer months. We are on the move constantly and rarely plugged in to shore power so we don't run the AC often. We typically travel in the March - May, October & December - January, all cooler months.

We usually Walmart- or Cracker Barrel-dock without AC power so we have gotten pretty good at minimizing our 12V usage. We generally only turn the 12V on when we are going to bed at night, to power my CPAP machine and charge phones / tablets / cameras from the 12V and USB sockets. We turn it off as soon as we get up.

The CPAP draws about 5AH per night. I don't know how much power is consumed by the other RV stuff (USB ports, electronics, control panels, etc.). I'd imagine it's at least that much, perhaps substantially more.

On the power usage topic, I looked at installing a battery shunt-type monitor when I was replacing the coach batteries so I'd have an idea how much power we were using. I decided against it as the batteries are located outside of the RV with no protection from the elements and I didn't know if a monitor would hold up to constant water and dirt. The old coach batteries were covered in dirt when I removed them. If they were in an interior bay protected from the elements (other than temperature) I would have gone ahead and installed a monitor.

We went as far as installing a bunch of AA-powered puck lights in various places around the RV and use them when we need a little light for a short time, rather than turning on the 12V and ceiling lights. We power them with rechargeable Eneloop batteries and they usually last an entire trip for us (typically 2 to 3 weeks at a time). We carry an AA/AAA charger or two and can recharge them as necessary on the road when we have AC power (and one of the chargers is USB-powered as well). Here are the lights we installed, they work well for what we use them for.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

The smoke and CO detectors also run on AA batteries.

I also use a rechargeable reading light to avoid using any of the RV lights just for reading.

In cold weather, instead of running the generator and heater we use sleeping bags.

In theory, if we don't do anything stupid and kill our new batteries they should provide way more power than we need and last a long time.

That said, we are looking at a trip of several months duration with very limited and infrequent access to AC power, so perhaps the new coach batteries will get more of a workout than anticipated.

[dkoldman]

Originally Posted by RV-Travelers

We have found it's too hot to travel comfortably during the summer months. We are on the move constantly and rarely plugged in to shore power so we don't run the AC often. We typically travel in the March - May, October & December - January, all cooler months.

We are constantly on the move too, with 30' RV. Travel year around even in areas up North ( Colorado during the winter). Not sure if you have AGS? But we do and it is on all the time, so our coach stays at the temp of the Thermostat 24/7. Even when we leave the coach. You would be amazed at how often we get asked at a guard station are we leaving. They assume since we never hooded up and now leaving that we don't like the place. I drive the RV like a SUV. No Toad for us.

We usually Walmart- or Cracker Barrel-dock without AC power so we have gotten pretty good at minimizing our 12V usage. We generally only turn the 12V on when we are going to bed at night, to power my CPAP machine and charge phones / tablets / cameras from the 12V and USB sockets. We turn it off as soon as we get up.

Based on this statement I assume you do not have a AGS? If we are at a Wal Mart of any Rest Stop, our generator is likely on if it is warm outside.

I can also tell you that you should NOT have to be worried about the things you are mentioning running overnight? Forget the AGS and Genset for a moment, but I can run my outdoor fridge, 2 TVs, lights, T mobile Home Internet and laptops overnight and not put a dent on my batteries. Our indoor fridge is on propane, but I switch to 120vac if my genny is otherwise needed.

The CPAP draws about 5AH per night. I don't know how much power is consumed by the other RV stuff (USB ports, electronics, control panels, etc.). I'd imagine it's at least that much, perhaps substantially more.

See above, I think you have surprise coming with the power you have in your available 125ah from vMax Tanks

On the power usage topic, I looked at installing a battery shunt-type monitor when I was replacing the coach batteries so I'd have an idea how much power we were using. I decided against it as the batteries are located outside of the RV with no protection from the elements and I didn't know if a monitor would hold up to constant water and dirt. The old coach batteries were covered in dirt when I removed them. If they were in an interior bay protected from the elements (other than temperature) I would have gone ahead and installed a monitor.

The only thing on DC power that can take my batteries down overnight if I leave on is the indoor Norcold Fridge if I have it running off the inverter. I put on propane so I never have this concern. My OEM Stock FLA when brand new would barely gets us to 7:00 AM so I know what you are saying. But with the the new batteries it HAS NEVER BEEN an ISSUE And they never go below 12.4vdc, I have House Battery Voltage available to me on my EC-30. I can also read amp usage on my Power control system, but I rarely ever look at.

We went as far as installing a bunch of AA-powered puck lights in various places around the RV and use them when we need a little light for a short time, rather than turning on the 12V and ceiling lights. We power them with rechargeable Eneloop batteries and they usually last an entire trip for us (typically 2 to 3 weeks at a time). We carry an AA/AAA charger or two and can recharge them as necessary on the road when we have AC power (and one of the chargers is USB-powered as well). Here are the lights we installed, they work well for what we use them for.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I am sure they work well and help, but if your lights are impacting you on a overnight, you have some other issue. All my lights run off 12vdc and house batteries. I turn off if not needed, but never recall needing to do even with my NAPA OEM batteries. With the old batteries, leaving two TVs on overnight and falling asleep may do it?

The smoke and CO detectors also run on AA batteries.

I think our Smoke detectors run on 9v batteries and the CO is connected to the House battery.

I also use a rechargeable reading light to avoid using any of the RV lights just for reading.

Wow

In cold weather, instead of running the generator and heater we use sleeping bags.

Ah so you do have a Generator If you also have a AGS, your life could be a lot easier. Do you have propane heater? I don't see the connection with Generator and heater? If it is cold enough for our propane heater, we do not need our generator at all. We can go 6 - 8 months before running out of propane and the heater will consume 75% of it.

In theory, if we don't do anything stupid and kill our new batteries they should provide way more power than we need and last a long time.

Yes

That said, we are looking at a trip of several months duration with very limited and infrequent access to AC power, so perhaps the new coach batteries will get more of a workout than anticipated.

I plan 1st as if I will NOT have shorepower, that is not conventional thinking though. We have spent years in tents so what he have is like staying in the Waldorf Astoria We will boondock by our definition anywhere at any time and we never have shorepower.

[RV-Travelers]

Don't know what AGS is, so I'm assuming we don't have it. :-)

Since we travel mostly in relatively cooler months, we normally crack open the side windows by the beds and run the roof vent fan to pull air through the RV while we are sleeping. Most of the time that's sufficient for our needs. The main problem is on the occasions when we do stay at a campground, apparently there is an unwritten rule that everyone else around us has to have a campfire and we wind up sucking in a lot of smoke.

We also have a couple of battery-powered fans in case it gets too hot. One can be charged via a USB connection and the other either AC or a 12V adapter.

We rarely run our generator. The RV is 5+ years old and according to the generator info on the control panel it's only got 41 hours on it. Speaking of which, I need to dig out the generator manual and figure out what kind of maintenance it needs. I know it's lubricated by oil and I'm sure it's long overdue for an oil change. I don't recall if it has an oil and/or air filter so I need to follow up on those items, preferably before hitting the road again. And I know it needs to be run occasionally when we aren't on the road.

Since we never use the heater (actually, we have used it one or two nights when the temperature dropped below 40F) I actually don't recall if the generator has to be running or not. Probably not. I'm surprised your propane lasts that long. When we tried running anything off propane (generator, cooktop burners, heater or refrigerator) the propane seemed to be consumed pretty quickly. We have a 16-gallon propane tank which I'm guessing must be a lot less than what you have available.

I read somewhere that relatively frequent maintenance is required for an RV refrigerator if it's run on propane. With RV shop labor rates running close to $200 an hour around here I'm leery of doing so. So we bought a decent cooler and just get a bag of ice every 3 days or so.

Perhaps the old batteries were just too worn out and I was overly cautious about running them down. Maybe we could run more stuff off the new ones. I can tell you that when a machine that is helping keep you alive quits in the middle of the night, it puts quite a scare into you and you start thinking about worst case scenarios and how to conserve energy.

And naturally, if the 12V goes out I do have a decent backup battery that will run the CPAP machine for at least a couple of nights. It can be charged via AC, 12V or a solar panel. And since our RV doesn't have solar, I also purchased a 100W portable solar panel just to charge the backup battery in case we break down and are stuck somewhere for several days.

Speaking of breaking down and being stuck somewhere, we frequently tend to travel in rural areas where there is no cell coverage. We are pondering buying a satellite phone for emergency use. I know very little about them. We would likely only need limited minutes per month but even those plans are fairly expensive.

And by the way, thanks for all of the help and advice.

[BobC]

Originally Posted by creativepart

To each his own. But the 12v battery chart is pretty validated as accurate. But certainly taking less amps from your batteries will extend their lifetime but produce less cumulative power for you to use over that lifetime.

This is a great chart but it's important to keep in mind that, for a truly accurate measurement, battery voltages should be measured only after the batteries have been in a no-load state for several hours:

https://www.loveyourrv.com/maintaini...-rv-batteries/

[dkoldman]

Originally Posted by BobC

This is a great chart but it's important to keep in mind that, for a truly accurate measurement, battery voltages should be measured only after the batteries have been in a no-load state for several hours:

https://www.loveyourrv.com/maintaini...-rv-batteries/

For clarity your link covers and specifically states....

This article will only deal with my lead acid type which are generally cheaper but require a little more on the maintenance side of things.

The Batteries OP has purchased are AGM. He can run at 12.4 vdc and accomplish the same results and better with Zero maintenance.

Anyone that says FLA and AGM are the same batteries technology clearly have NOT seen what I experienced when I made the change. No Comparison. i.e. My Honda lawnmower and Lincoln Navigator uses engine same technology.

I will NEVER run FLA in House Application in my RV, but I have no problem with with FLA as my chassis battery.

[BobC]

Apparently some charts are based on "under load" voltage and some on "resting voltage":

https://marinehowto.com/under-load-b...oltage-vs-soc/

And, AGM batteries are lead acid batteries but they're not "flooded lead acid batteries". The chemistry is the same in terms of how the current is generated but the physical construction is different, which leads the clear advantages of AGM over FLA batteries.

[dkoldman]

Originally Posted by BobC

Apparently some charts are based on "under load" voltage and some on "resting voltage":

https://marinehowto.com/under-load-b...oltage-vs-soc/

And, AGM batteries are lead acid batteries but they're not "flooded lead acid batteries". The chemistry is the same in terms of how the current is generated but the physical construction is different, which leads the clear advantages of AGM over FLA batteries.

Good stuff, I really love the link, bookmarked it as a keeper.

I really wish I had known when I bought what I have learned over trial and error. I would have replaced the House Batteries to AGMs on Day 1. Instead I allowed some rust and corrosion to develop inside battery compartment and my brand new concrete on my RV Pad; where excess water runoff carried the rust . Best $500 I ever spent. IMO I made my $500 back in within the 1st year because I use them a lot and cycle quite frequently; and NEVER go below 12.4vdc because I don't need to and because it helps to improve the performance of the batteries.