House Batteries

[Beanmanaus]

My two house batteries in my 2015 Minnie Winnie 22R have worn out. I had NAPA Premium Marine/RV Dual Purpose batteries. Should I get similar dual purpose batteries or deep cycle batteries as replacements? Thanks in advance.

[Morich]

Depends on how you use the Rv. Many will want a true deep cylce set, even if it costs much more due to wanting much longer deeper cycles on trips as they do not want to hookup to power each day. But if you are somebody who rarely wants to go out in the boonies without power, there is little need for batteries which work for very deep cycle but just need enough to get you by while driving from one electrical hookup to the next. The common car starting battery may be enough for that as the batteries get charged while driving and the drain is very small.

Knowing how and why is the key to getting the best use for the best price. The only time we use the coach batteries is when we stop along the road for meals and even then we may start the generator to use the microwave, so paying extra or adding extra weight to the RV is just not logical for our use.

[DavidM]

No dual purpose battery and most RV/Marine deep cycle batteries do not have the characteristics that allow long life in a deep cycle environment: more room above the plates for electrolyte and below the plates for sulfate buildup and heavy plates.

One of the few true deep cycle batteries that is available almost everywhere are 6V golf cart batteries which you have to wire two in series to get 12V. Not every battery box has the height for these. But they are very cheap, about $100 ea at Costco, and probably provide more amp hour capacity than what you have now.

But as Morich says above, if you never use the deep cycle capability then you don't need them and almost any battery will work. So look for the same size as what you have at Walmart, Costco, Batteries Plus, etc.

David

[dkoldman]

Originally Posted by Beanmanaus

My two house batteries in my 2015 Minnie Winnie 22R have worn out. I had NAPA Premium Marine/RV Dual Purpose batteries. Should I get similar dual purpose batteries or deep cycle batteries as replacements? Thanks in advance.

Your post is not clear on your requirements, but if you have gone 6 years with the Dual Purpose Marine RV batteries and don't have any complaints, or stories to tell about the batteries capabilities or inabilities, I would buy exactly what you have now; and call it a day.

[creativepart]

More than likely, the dual purpose batteries were installed to save money. They work OK and they are cheaper than true deep cycle.

If you always use shore power... always. Then go that way again. If you ever do some dry camping without power it might be worth the money to go with true deep cycle batteries. You'll spend $100 to $150 more per battery to upgrade to true deep cycle.

[TravatoJohn]

Just curious. Are your two 12 volt batteries mounted in the floor right below the steps which is not uncommon. If so you probably are restricted on your height and the golf cart 6 volt may sit to high in the cavity. Just a thought. Travato john

[Elkman]

True deep cycle in a size small enough for most RV battery compartments will be 6 volt and with two batteries wired in parallel to provide 12 volts of power. OK unless one of the batteries has a bad cell and drags down the output of both batteries.

The deep cycle batteries have much thicker plates and can be discharged to a lower state of charge than an automotive battery. A marine battery is functionally a starter battery that can also power boat electronics like a depth finder and not for deep discharge as with many RVs. More than 50% discharge and the battery life is greatly reduced.

The level of discharge without damage to the batteries determines how much usable power they can provide in actual use. If you have two 100Ah batteries that can be discharged to 50% SOC then you get 100Ah for your RV use.

For my own use I prefer having two 12 volt batteries as I would only go to 6-volt ones if I had two pairs of them in the RV. I switched out the factory lead acid ones for lithium-phosphate batteries to nearly double the available current as this type can be discharged to 10% SOC with no worries.

[creativepart]

Originally Posted by Elkman

True deep cycle in a size small enough for most RV battery compartments will be 6 volt and with two batteries wired in parallel to provide 12 volts of power.

Wait a minute... you don't mean wired in "parallel" you mean wired in "series."

Also, there are true deep cycle 12v AGM batteries. This is not in any way limited to 6v batteries.

Lastly, as previously mentioned, 6v batteries are taller and may or may not be an issue for batteries mounted in a stairwell on a Class C motorhome.

[DavidM]

Originally Posted by creativepart

Also, there are true deep cycle 12v AGM batteries. This is not in any way limited to 6v batteries.

Lastly, as previously mentioned, 6v batteries are taller and may or may not be an issue for batteries mounted in a stairwell on a Class C motorhome.

I have concluded that there really is no "deep cycle spec" for AGM 12V batteries. Thickness of plates is irrelevant as sulfate won't slough off AGM plates and will be suspended in the glass mat and so is room for electrolyte over and under the plates. So I suspect any AGM is good for deep cycle use.

GC batteries are usually an inch taller than similar 12V batteries and won't fit in most Class C step wells.

David

[dkoldman]

Originally Posted by DavidM

I have concluded that there really is no "deep cycle spec" for AGM 12V batteries. Thickness of plates is irrelevant as sulfate won't slough off AGM plates and will be suspended in the glass mat and so is room for electrolyte over and under the plates. So I suspect any AGM is good for deep cycle use.

GC batteries are usually an inch taller than similar 12V batteries and won't fit in most Class C step wells.

David

I think the distinction is between Deep Cycle and True Deep Cycle; although both use AGM technology; and yes both can be good for Deep Cycle use; they are built differently. The below states why it is confusing and to tell in some cases may be destructive test.

I keep it simple however. I only distinct between Dual Purpose AGM Deep Cycle vs True Deep Cycle AGMs. The Duracell https://www.batteriesplus.com/produc...RoC1XUQAvD_BwE is designed to maximize CCA & Deep Cycling. They will have two post in the physical design one being for Automotive application. This trade off makes them only last 2X that of standard battery.


The True Deep Cycle AGM sometimes called Pure Deep Cycle is not dual purpose and only designed for Deep Cycling will last 8 - 10 years as it deep cycle capacity is almost doubled. https://www.vmaxtanks.com/SLR125-12V...tery_p_38.html

So simplified further it is question of what do want using same technology? More CCA / Less AH / Less Cycle Counts or Less CCA / More AH / More Cycle Counts.

I have 2 12 vDC Group 31s with 125 ah that were Solar designed with heavy plates about 70 pounds each.

Option Reading (from Google)

Marine batteries are usually a "hybrid", and fall between the starting and deep-cycle batteries, though a few (Rolls-Surrette and Concorde, for example) are true deep cycle. In the hybrid, the plates may be composed of Lead sponge, but it is coarser and heavier than that used in starting batteries. It is often hard to tell what you are getting in a "marine" battery, but most are a hybrid. Starting batteries are usually rated at "CCA", or cold cranking amps, or "MCA", Marine cranking amps - the same as "CA". Any battery with the capacity shown in CA or MCA may or may not be a true deep-cycle battery. It is sometimes hard to tell, as the term deep cycle is often overused - we have even seen the term "deep cycle" used in automotive starting battery advertising. CA and MCA ratings are at 32 degrees F, while CCA is at zero degrees F. Unfortunately, the only positive way to tell with some batteries is to buy one and cut it open - not much of an option.

[creativepart]

I used to say look for an AGM battery that has no CCA rating and you've found a deep cycle battery.

But the truth is, all batteries can publish a CCA number even if it's not built or intended to be a engine starting battery. Many times on sites like Amazon they have a pre-made form with battery output listings and they include a CCA in ALL of their batteries.

I hate to say that price is an indicator of a true deep cycle battery but it is. A dual purpose Marine/RV Deep Cycle is usually $100 or more dollars cheaper than an special purpose true deep cycle. The cost difference is in the thickness and robustness of the plates and internals of the battery.

Lots of folks find out that a deep cycle battery for their RV cost $250 to $300 and they start looking around. Sure enough they find a battery marked "RV" and "Deep Cycle" and it only costs $120. They believe they've found a bargain when what they've found is a dual purpose engine starting battery.

I used two of these in my travel trailer for years. I took very good care of them. Kept them watered, disconnected them always and brought them home to trickle charge whenever there was going to be a month or more between trips.

But I had to replace them every year without fail.

[DavidM]

I think that Creativepart is correct above except- Golf cart batteries are real bargains for true deep cycle use. They don't command the premiums that he talks about because there is such a huge market for GC batteries which keeps the prices down.

I bought a couple of WindyNation AGM 100 amp hour batteries that were advertised as deep cycle and had no CCA rating, on Amazon. They work fine now but talk to me in five years and then I will know if they really are suitable for deep cycle use. Otherwise I have no way of knowing for sure.

Like I have said time and time again- 6V golf cart batteries are always true deep cycle. Other than Lifeline, Rolls-Surette and a few other premium cost 12V batteries I don't know of any reasonable cost 12V batteries that are true deep cycle.

David

[dkoldman]

Originally Posted by creativepart

I used to say look for an AGM battery that has no CCA rating and you've found a deep cycle battery.

But the truth is, all batteries can publish a CCA number even if it's not built or intended to be a engine starting battery. Many times on sites like Amazon they have a pre-made form with battery output listings and they include a CCA in ALL of their batteries.

I hate to say that price is an indicator of a true deep cycle battery but it is. A dual purpose Marine/RV Deep Cycle is usually $100 or more dollars cheaper than an special purpose true deep cycle. The cost difference is in the thickness and robustness of the plates and internals of the battery.

Lots of folks find out that a deep cycle battery for their RV cost $250 to $300 and they start looking around. Sure enough they find a battery marked "RV" and "Deep Cycle" and it only costs $120. They believe they've found a bargain when what they've found is a dual purpose engine starting battery.

Originally Posted by DavidM

I think that Creativepart is correct above except- Golf cart batteries are real bargains for true deep cycle use. They don't command the premiums that he talks about because there is such a huge market for GC batteries which keeps the prices down.

I bought a couple of WindyNation AGM 100 amp hour batteries that were advertised as deep cycle and had no CCA rating, on Amazon. They work fine now but talk to me in five years and then I will know if they really are suitable for deep cycle use. Otherwise I have no way of knowing for sure.

Like I have said time and time again- 6V golf cart batteries are always true deep cycle. Other than Lifeline, Rolls-Surette and a few other premium cost 12V batteries I don't know of any reasonable cost 12V batteries that are true deep cycle.

David

I will add that I found and bought these https://www.amazon.com/VMAXSLR125-2-...QGF8A43SNYV580 a few months ago. I got them both brand new for around $500, the price has dramatically gone up, maybe due to my crowing about them so much

But they have been nothing but awesome. Knowing what I have learned; and based on how they work thus far; I would pay the $790 today asking price but cry

A few times I have opened the hatch over the steps just fishing for something to do, no water needed, no corrosion anywhere But most importantly is the power. I have 125ah available in a Grp 31. I never saw that in any Golf Cart 6vdc that would fit except oddly vMax Tanks made a 6vDC GC; but they recommended I go with the Solar 12vdc; which I bought. Thus far ( 4 months of usage) they have never dropped below 12.5 VDC when I use overnight with all my normal stuff running (Fridge, TVs, light s etc.). I can go two days!!! I upped the AUTO START on my AGS to 12.5 as a result. I know that flies in the face of those that taut lithium's going down to 10%, but in my case, I actually look for opportunities for my genset to kick on and run by itself.

Note: My NAPA Dual Purpose OEMs that I replaced would drop down to about 12.2 VDC in about 8 hours. It was good enough to get through the night, but at 8:00 AM my genset would always have to come on to recharge the batteries.

[creativepart]

I understand why David and others prefer 6v GC batteries. But to me it's putting a 1930s battery in a 2021 RV. The need to add water, the extra weight are serious negatives in my book. The cost is the only plus. Too many times people kill these batteries and change them out every 2-years not every 5-years. They cook the battery, get low on water and cook the battery some more until it's ruined.

The real deal AGMs that came in my Winnebago are now just over 4-years old - NAPA Commercial 9837 batteries made by Eastern Penn. They hold a charge great. I've not touched them in 4-years and I certainly don't see any reason that I'll be required to replace them in the next 10 months.

They cost twice as much as the GC 6v batteries. But they truly have been totally carefree. That's worth plenty to me.

I've been waiting for these to die - because I want Lithium batteries. More available power, no-maintenance, faster charging and 1/4 the weight.

No 90+ year old battery technology for me, but to each his own.

[DavidM]

"But they have been nothing but awesome. Knowing what I have learned; and based on how they work thus far; I would pay the $790 today asking price but cry."

Wow, $395 each!! Some lithium batteries are approaching that price. The WindyNation batteries I bought about 6 months are cheaper now than when I bought them at $186 each now. See https://www.amazon.com/WindyNation-a...aps%2C196&sr=8

I know they are 125 Ahs vs the 106 (at the normal 0.05C discharge rate) for the WindyNation, but still.....Wow!

David

[dkoldman]

Originally Posted by DavidM

"But they have been nothing but awesome. Knowing what I have learned; and based on how they work thus far; I would pay the $790 today asking price but cry."

Wow, $395 each!! Some lithium batteries are approaching that price. The WindyNation batteries I bought about 6 months are cheaper now than when I bought them at $186 each now. See https://www.amazon.com/WindyNation-a...aps%2C196&sr=8

I know they are 125 Ahs vs the 106 (at the normal 0.05C discharge rate) for the WindyNation, but still.....Wow!

David

Agree on price it is double wow, but 4 months ago, they were listed on ebay for $549 for two.

To put in perspective, I was trying to get 3 years out of the OEM FLA. But I hated it, the add water thingy, I tried and prolly made the batteries worst. I try to clean up the corrosion and get acid stains everywhere, including newly built concrete drive for the RV. I didn't care to buy gadgets to to do the maintenance. We still work full time. There is plenty other stuff I must do for the RV.

I have a reserve of $1,500/year to buy things for the RV from money I have thus far saved by not buying the extended warranty. So I wanted to go to AGM. My plan was to spend $179 each for the Duracell at Sams. I actually went to Sams one day to buy 2 as they had in stock, but I did not have the old batteries out So I come home and actually read someone on this site about Pure Deep Cycle I am no mechanic, but I hated the automotive post sticking out just waited to get hit by a novice, so I researched more and put the buy on hold. I called VMax tank to learn about impacts with my Progressive Dynamics Converter and learned a lot more than I anticipated. They had human support and took the time to talk to me. Then they told me I could buy direct, no battery trade in, no added shipping cost, and no tax in my situation and it was a no brainer about $250 each for 125ah I love them Solar AGM 125AHs ( just in case you hadn't noticed ) Having said that I was shocked to see the current today price of $400. May be due to the inflation thing? But for me, right now; I should be good for next 5 years.

[dkoldman]

Correction: They were listed on Amazon for $549 for two

[BobC]

I hate to bring LiFePO4 into this discussion but, given that a 100Ah LiFePO4 battery has approximately twice the useful amp hours as a 100Ah lead acid (flooded or AGM) battery, the costs are getting closer and closer, not to mention the longer life span and considerable weight savings.

I'm not pushing this and, personally, still use 6V golf cart batteries but LiFePO4 batteries deserve serious consideration vs. spending $549 for two AGMs. When it comes time to replace my golf cart batteries I'm giving them serious consideration.

Will Prowse, a well-regarded Youtube solar and battery reviewer has recently posted a favorable review of a $399 100Ah LiFePO4 battery. The only shortcoming was the lack of protection against low temperature charging, which can be added:

https://www.youtube.com/watch?v=74iBMHE3StM&t=2s

[dkoldman]

Originally Posted by BobC

I hate to bring LiFePO4 into this discussion but, given that a 100Ah LiFePO4 battery has approximately twice the useful amp hours as a 100Ah lead acid (flooded or AGM) battery, the costs are getting closer and closer, not to mention the longer life span and considerable weight savings.

I'm not pushing this and, personally, still use 6V golf cart batteries but LiFePO4 batteries deserve serious consideration vs. spending $549 for two AGMs. When it comes time to replace my golf cart batteries I'm giving them serious consideration.

Will Prowse, a well-regarded Youtube solar and battery reviewer has recently posted a favorable review of a $399 100Ah LiFePO4 battery. The only shortcoming was the lack of protection against low temperature charging, which can be added:

I actually gave Lithium as you say "serious consideration". It is very complex process in looking at all of the factors, and how you think you intend to use is of most importance.

I concluded that buying Lithium did not make sense for me right now but in 5 years or so, It may make sense on another coach? Cost was not a deciding factor, but it was a big negative, not to mention all of the other things I may have had to invest to make my coach Lithium ready. The low temperature thing was a MAJOR factor for me because the only reason I wanted new batteries in the 1st place was to not worry about water and ANY maintenance, why spend $2000 TCO and then have another issue to worry about (freezing). We use coach year around.

I tried to find the Zoom Lithium Battery online but could not. However, I saw plenty in the $450 to $500 range. That is a lot better pricing than what I saw 4 months ago. The AGMs that I bought today cost about $400 each; so I agree with your point it something to think about for a guy looking to buy today. When I bought the VMax Tanks; they were about $250 each; so it was a no brainer. It just confirms I got a good deal and bought at the right time. These batteries are just awesome. I stay at 12.8 or 12.9 VDC

But lets go into why I really didn't buy Lithium. I like your words of "Useful Ahs)"

The only problems I had with my OEM FLA, were the water reqmt, corrosion sulfating, and the 90ah stated capacity ( I think I was only getting like 60ah as batteries were not performing optimally in my opinion) I could barely get through the night before hitting 12.2vdc; so my AGS would always start at 8:00 AM to recharge.

So all I needed was maintenance free and about 100 AHs to get pass 8:00 am with no charge required. This would allow me to run all of my normal stuff from 8:00 PM to 8:00 AM with no issues. My genset can then recharge in 2 hours during the next day.

What I got in the VMax Tank AGM was more than I needed because I got 125ahs It has worked so well I raised my AGS up to 12.5vdc to start recharge. I can go 2 days!!!. So while Lithium's can potentially make available more capacity, I really don't need it right now, not in this coach anyway. Not sure my current AGS will even allow me to set a low voltage setting that would be the equivalent of 10% SOC for a Lithium?

[Marine359]

In most discussions about LiFePo4 vrs AGM and FLA, people get too hung up on initial purchase price, when in actuality the price delta is not that great (I paid only $800 for 170ah American made) And considering many have paid more than $100k for their rig, it’s really just pocket change by comparison. What most people are missing are the other great features you get with a quality LiFePo4. Here’s why I’m so happy about having made the switch.

Less than 1/3 the weight of the same ah capacity. Matters mostly to TT owners.
Charge from 30% to 100% in less than 2 hrs; that’s 25% of the time for FLA. if you’re boondocking, that’s huge in reducing the time, noise, and fuel cost of running a generator to recharge. My generator fuel savings will pay for the LiFePo4/AGM initial cost delta in less than 2 years.
Will accept solar charge amperage no matter the SOC.
Easy to remove and carry inside for the winter.
A BMS which will protect the battery by shutting down at low voltage, low temp, or over voltage.
Safe to mount inside, where it’s temperature controlled.

After camping with LiFePo4 for the last 9 months, now I feel it would have been crazy not to switch. Now I don’t even think about my batteries. It’s just a bucket that occasionally I have to throw power at. For me, it’s freedom, and adding more solar will mean even more freedom. If you don’t need this freedom because you have hookups most of the time, you don’t need LiFePo4 or AGM.