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Old 12-02-2018, 08:11 PM   #1
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Brand: Thor Motor Coach
Model: Four Winds 31E (2019)
State: California
Posts: 243
THOR #12270
Is it new battery time?

So I am doing some yard work and have had the RV parked in the street now for little over a week. All 3 batteries (1 chassis 2 coach) were fully charged when I parked it. Left it with everything off and switch in Store. Yesterday I went out to start the Generator and everything was dead. Dead as in rotting carcass.

Disconnected batteries and measured voltage.
chassis = 10.22v
coach 1 = 7.95v
coach 2 = 7.84v

Nothing worked in the coach; not even the tank level meters. I could turn on the ignition and the idiot lights came on but everything went off when I tried to crank the V10. So I tried jump starting the house to get the generator going. (The shore plug is on the street side and I didn't want a car or truck to shear the plug off) With my jump pack connected, and both house batteries reconnected, the voltage was 10.92. Tried the Generator anyway. Just clicking. So I borrowed my neighbors jump pack and got the generator slowly cranking. It started resiliently but everything came to life. Let it run for 2 hours. Then tried to crank the V10 with emergency start. Let it run another hour then shut everything down.

Since I want to keep the RV in a Evacuation ready state (here in wild fire / earthquake CA), I have some concerns. I also plan to use my 2000 watt inverter alot while boon-docking. (using the generator as a backup if I have to) so I would like alot of AH; goal would be 4-500AH.

Should I replace the questionable stock batteries with new?

Im finding conflicting data on rather a 31E can fit 4 or 2 batteries. I think the tray is big enough for 4 but can it support the weight? My RV dealer says 2 is max.

Is it true that AGM is better than "standard" lead acid? Or will standard last longer?

Also is 6v or 12v better? With 6v I could get 100 to 225AH that im looking for.

I was thinking of this battery kit:
https://www.amazon.com/WindyNation-a...etwork-20&th=1

Would 100 - 200W solar be enough to maintain charge on such a large battery bank?
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Old 12-02-2018, 11:54 PM   #2
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THOR #6411
AGMs have these advantages, no out gassing, no maintenance, no equalization, varied mounting positions, faster charging capacity, and little self-discharging. The major disadvantage is cost. Flooded batteries self-discharge at 0.07% per day while AGM batteries self-discharge at the rate of 1% per month. The amp hour rating for all batteries using lead/acid chemistry is due to the amount of lead in each battery. A 63 lb 12 volt battery will have an amp hour rating of about 110 AH. Two 12 volt batteries in parallel will weigh 126 lbs and give about 220 AH rating. A 63 lb 6 volt battery will have an AH rating of about 225. Two 6 volt batteries in series will weigh 126 lbs and will have a 230 amp hour rating @ 12 volts. The relatively short reported battery life of flooded batteries is usually due to owner neglect.
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Old 12-03-2018, 12:03 AM   #3
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THOR #6411
200 watts at 13.8 volts (needed to charge a battery) is 14+ amps not considering electrical losses. On a sunny day in the summer if you move the array, figure 130 amps. If the array is fixed and pointed south figure 80 amps.
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Old 12-03-2018, 05:00 PM   #4
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THOR #908
I'd plan on changing them.

in my very limited experience, once a starting battery is drawn down too low like that, it will never quite be the same. A couple times my wife left some lights on in her car, reasonably new battery each time, but in at least one of the cases I couldn't get it to hold a charge at all, and another case it did recharge but to a noticeably reduced capacity. Basically once or twice down past zero like that and they are completely gone....starting batteries or the marine/RV hybrid types....

I'd say that if your house batteries are golf cart types they can handle draw downs to maybe 30% or so (I can't recall the exact number Trojan published in the manual I read) ...they might take a usable charge, maybe, but will be compromised going down that low (past "0%")and won't have nearly as much capacity.
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Old 12-03-2018, 06:38 PM   #5
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THOR #12231
I would replace all 3 with AGM's.

AGM should last you longer plus all of the benfits shown in the above posts.

I like my Full River 6v AGM so far. They come in at 73# each so make sure your battey compartment will hold them - esp if you can put 4 in the same hole (thats almost 300#!).

If you can fit 4 of them that would be great. They are rated at 220 amp hour (at 6v) so you lookin at 440 with FOUR 6v batteries.

But using the 50% rule thats around 220 usable amps. (But I also read the 6v will take a beating much better plus some pull down to like 40% no neg effects). I try to follow the 50% rule anyway.
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Old 12-03-2018, 06:54 PM   #6
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THOR #8860
Please throw another vote on the pile for new AGM batteries all around.
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Old 12-03-2018, 07:14 PM   #7
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re. that 50% rule of thumb....

I have no idea what the number is for AGM's, but if you're only using half it doesn't strike me as a good investment, especially for such an expensive battery...unless you need it for a non-vented installation, or inverted, etc...
so I say get a trojan deep cycle (or similar true deep cycle I suppose)
...you can use 80% of their capacity
from Trojan's user guide...
"Do not discharge your battery to more than 80% depth of discharge. This safety factor will eliminate the chance of over-discharging and damaging your battery"
(means that you should be able to take it down to 20% of the capacity (100-80=20)

Now I realize these numbers are considered to be generalizations, and that folks like to add safety factors on top of safety factors, often for good reason....

Anyway I wish I could have found one that fit when I was on the road and needed a new house battery....so I'm stuck with a very limited usable fraction.

This whole thing got me curious so I went and looked it up.
excide (just used as a typical cheap battery example) says in their user guide for lead acid to recharge at 12.3V...which seems to be regarded as about 70% state of charge (30% useable)...but I'm guessing that's probably a generic number to cover their starting batteries as well as their marine batteries.
Incidentally, Excide says 12.4 volts for a minimum for their AGM's.... does that imply that they are no better at handling deep discharges than a lead acid?
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Old 12-03-2018, 07:57 PM   #8
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4-6s vs. 2-12s

I keep following these battery posts hoping someone will throw us a bone and tell us they've tried 6s vs. 12s.

I have room for 4 batteries. I currently have 2-12s side-by-side that measure 9h x 12L x 6.75w.

Looking around, I can get 4-6s into that space or two more 12s the same size.

Now, you have your 12v deep cycle and your 6v deep cycle. See my dilemma?
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Old 12-03-2018, 08:12 PM   #9
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[QUOTE=blw2;156489]re. that 50% rule of thumb....


from Trojan's user guide...
"Do not discharge your battery to more than 80% depth of discharge. This safety factor will eliminate the chance of over-discharging and damaging your battery"
(means that you should be able to take it down to 20% of the capacity (100-80=20) QUOTE]


The quote is correct but your inference is not. Discharging any lead acid battery beyond 50% of it rated capacity, VLRA, AGM, GEL or flooded, will shorten it life span. Drawing the battery down to below 20% of its rated capacity tends to kill it outright, just like letting the water level get below top of the plates kills a battery. How much will that extra 30% of discharge shorten battery life is debatable among battery manufactures, but it is significant (up to 1/3 in some batteries). After all; all lead/acid batteries use the same chemistry. Alloying the plates with antimony, selenium or calcium doesn't change the chemistry. The paste used is inert and only acts for a seed for the lead sulfate crystals and leads to a higher potential discharge rate without stratification.
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Old 12-03-2018, 10:05 PM   #10
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Quote:
Originally Posted by RvEd View Post
I keep following these battery posts hoping someone will throw us a bone and tell us they've tried 6s vs. 12s.

I have room for 4 batteries. I currently have 2-12s side-by-side that measure 9h x 12L x 6.75w.

Looking around, I can get 4-6s into that space or two more 12s the same size.

Now, you have your 12v deep cycle and your 6v deep cycle. See my dilemma?
All I know is the 2 - 6V AGM I have are far superior to the OEM 12V's mine came with. But perhaps with a good aftermarket 12V battery it it would not be so dramatic.

I researched this whole 6v VS 12v subject for about 3 mo before I purchased mine and im glad I did.

Plus the part about maintenance free, quicker charging, slow discharging and longer life make it worth it to me. They are super heavy duty (73 # each vs like 46# for my OEM) with thick lead plates and more acid?

The main reason I went with Full River was the reviews were good but they fit under my step with ZERO mods. So I have about the most amp hours that I can fit under my steps.

I purchased mine at Battery Outfitters. When I showed up I asked for a disccount and he knocked off 10% without any problem. I think its because they are like $250 each and they had good margins. So $225 each is was not that bad IMO for AGM's.

Im very happy with mine.
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Old 12-03-2018, 10:56 PM   #11
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THOR #8860
If you have the room for some 6 volt deep-cycle batteries: go for it!
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Old 12-03-2018, 11:15 PM   #12
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THOR #6411
The internal resistance for AGM batteries is about 10% of that of flooded batteries. This allows for much faster charge rate, because with a lower resistance there is less internal heat in the battery case. Still the recommended charge rate is 10% to 13% of the 20 hour AH rating for AGMs as well as flooded batteries. Thus with a 550AH @ 12 volts battery bank, the max charge rate would be 55 to 71.5 amps for the bulk charge. Charging a LA battery too fast can cause some undesirable chemical reactions; as well as, warping the plates because of excessive localized heat. This is why a flooded battery must be fully charged before equalizing. As slow discharge followed by an immediate slow recharge rate will result in extended battery life when compared to fast discharge and recharge rates.
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Old 12-04-2018, 07:02 PM   #13
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Quote:
Originally Posted by Long & Winding road View Post
All I know is the 2 - 6V AGM I have are far superior to the OEM 12V's mine came with. But perhaps with a good aftermarket 12V battery it it would not be so dramatic.

I researched this whole 6v VS 12v subject for about 3 mo before I purchased mine and im glad I did.

Plus the part about maintenance free, quicker charging, slow discharging and longer life make it worth it to me. They are super heavy duty (73 # each vs like 46# for my OEM) with thick lead plates and more acid?
cut
If I understood correctly, the size difference only left room for one row (too deep)?
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Old 12-04-2018, 08:05 PM   #14
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THOR #908
6V vs 12V
I'd suggest comparing AHr rating vs $

As far as I know beyond those two variables (and what will fit of course), there isn't really any substantial difference.

As I understand it, the driving reason folks tend to go with deep 6V is that since they are more commonly used in golf carts, they are more readily available and therefore cost a bit less.

All else the same, I'd prob go 12V... my logic could very well be flawed, but if I have a bank of two "batteries" and I have a cell go out in one of them and have to disconnect that one battery....then I'm left with 6V if using the 6V version....so I'd be dead in the water
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Old 12-04-2018, 08:27 PM   #15
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[QUOTE=Beau388;156515]
Quote:
Originally Posted by blw2 View Post
re. that 50% rule of thumb....


from Trojan's user guide...
"Do not discharge your battery to more than 80% depth of discharge. This safety factor will eliminate the chance of over-discharging and damaging your battery"
(means that you should be able to take it down to 20% of the capacity (100-80=20) QUOTE]


The quote is correct but your inference is not. Discharging any lead acid battery beyond 50% of it rated capacity, VLRA, AGM, GEL or flooded, will shorten it life span. Drawing the battery down to below 20% of its rated capacity tends to kill it outright, just like letting the water level get below top of the plates kills a battery. How much will that extra 30% of discharge shorten battery life is debatable among battery manufactures, but it is significant (up to 1/3 in some batteries). After all; all lead/acid batteries use the same chemistry. Alloying the plates with antimony, selenium or calcium doesn't change the chemistry. The paste used is inert and only acts for a seed for the lead sulfate crystals and leads to a higher potential discharge rate without stratification.
maybe so...but everything has a finite number of cycles....and what good is a tool or a toy if it's not used to it's potential.

Regardless, I'm no battery engineering expert, but my gut logic tells me the switch from ok to shortened life is not a specific finite level...and it's not likely even linear.....also I'd guess it to be a very safe bet that a starting battery compared to a true deepcycle compared to a marine hybrid do not all three trip over to the same amount of relative "damage" at some magical 49.599%...or whatever the number....
but regardless, if 50% is good, why not set 51% as your floor....or 53%....or 75%? Wouldn't that be even better from the perspective of maximizing life?

It seems more or less generally accepted that the deeper they are discharged the shorter the life....and at any give discharge rate they have some finite number of cycles. Not arguing that of course, and I see your point...but I've gotta believe that if Trojan says it's ok to draw down to a 20% floor "without damage".....and keep in mind they would apply a factor of safety to a spec....then it seems it would be ok for me to add another factor of safety to the number and set let's say ballpark 35% as an acceptable floor...well below the 50% rule of thumb...so certainly 45% would be good, right?

Anyway, I guess my overall thought is to ask what is my goal in it? Is the end game to get my money's worth out of the battery, or is it to never have to buy a replacement the rest of my life but never use the thing?
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Old 12-04-2018, 10:03 PM   #16
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From the Trojan web site for their batteries. Please note the cycles side of the chart is logarithmic so an arithmetic chart would show a much steeper decline'

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Old 12-05-2018, 06:00 AM   #17
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Quote:
Originally Posted by Diemaster View Post
So I am doing some yard work and have had the RV parked in the street now for little over a week. All 3 batteries (1 chassis 2 coach) were fully charged when I parked it. Left it with everything off and switch in Store. Yesterday I went out to start the Generator and everything was dead. Dead as in rotting carcass.

Disconnected batteries and measured voltage.
chassis = 10.22v
coach 1 = 7.95v
coach 2 = 7.84v

Nothing worked in the coach; not even the tank level meters. I could turn on the ignition and the idiot lights came on but everything went off when I tried to crank the V10. So I tried jump starting the house to get the generator going. (The shore plug is on the street side and I didn't want a car or truck to shear the plug off) With my jump pack connected, and both house batteries reconnected, the voltage was 10.92. Tried the Generator anyway. Just clicking. So I borrowed my neighbors jump pack and got the generator slowly cranking. It started resiliently but everything came to life. Let it run for 2 hours. Then tried to crank the V10 with emergency start. Let it run another hour then shut everything down.

Since I want to keep the RV in a Evacuation ready state (here in wild fire / earthquake CA), I have some concerns. I also plan to use my 2000 watt inverter alot while boon-docking. (using the generator as a backup if I have to) so I would like alot of AH; goal would be 4-500AH.

Should I replace the questionable stock batteries with new?

Im finding conflicting data on rather a 31E can fit 4 or 2 batteries. I think the tray is big enough for 4 but can it support the weight? My RV dealer says 2 is max.

Is it true that AGM is better than "standard" lead acid? Or will standard last longer?

Also is 6v or 12v better? With 6v I could get 100 to 225AH that im looking for.

I was thinking of this battery kit:
https://www.amazon.com/WindyNation-a...etwork-20&th=1

Would 100 - 200W solar be enough to maintain charge on such a large battery bank?
So why did all three batteries completely discharge in a week?
Don't waste a lot of money on new batteries until you figure out what is going on. I can understand there being something pulling down the two coach batteries, but what was drawing down the chasis battery at the same time?
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Old 12-05-2018, 06:11 AM   #18
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Quote:
Originally Posted by dlbeck27 View Post
So why did all three batteries completely discharge in a week?
Don't waste a lot of money on new batteries until you figure out what is going on. I can understand there being something pulling down the two coach batteries, but what was drawing down the chassis battery at the same time?
I am investigating this. I think its just damaged batteries. who knows how many times and how far down they were drained on the dealer lot. I had to find replacement fuses for my DVM and i got them from amazon today. so ill do a parasitic draw test tomorrow. measured voltage today 2 days later. coach batts are 12.03 (about 50%) and chassis is 12.56 (id say ~95%)

thanks to all the replies and advice. i have decided to definitely go AGM and im currently shopping around.
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Old 12-05-2018, 12:55 PM   #19
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THOR #10991
I went to Sam's and got my 31's and 24 at advance Auto parts with a 40 USD coupon
Your experience may vary
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Old 12-05-2018, 06:37 PM   #20
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Poor Batteries from Get Go

Quote:
Originally Posted by Diemaster View Post

thanks to all the replies and advice. i have decided to definitely go AGM and im currently shopping around.
I am looking at same in CA as well and would like to hear your final determination.
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