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11-23-2015, 11:47 PM
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#1
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Member
Winnebago Owners Club
Join Date: Dec 2012
Posts: 59
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GC2 or 2 Group 31's Interstates
What will give me better performance? My coach has 2 Group 31 Interstate RV/Marine house batteries and often after watching a dvd and some usage of the furnace during a 40-50* night keeping the coach at 60-65* at bedtime, the 31's are down to 12.0-12.1 volts by morning. I charge with the PD9260 and wizard for upto two hours and then let 200 watts of portable solar repositioned numerous times during day giving the most out of the sun. Two questions I guess, will the GC2'S give me any more available amp hours and do the 6 volt batteries recover better from the discharge. The 31's are much less than a year old and I have not been please with their performance. For the time being adding additional batteries is not an option because of available space. The existing bank is under the entry stairs and there is no nearby compartment vented well enough or lacking an ignition source . Thanks to those that have input.
Len
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11-24-2015, 12:01 AM
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#2
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Senior Member
Country Coach Owners Club Solo Rvers Club iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 37,725
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Yes, deep cycle GC-2's would be better! We had four of them in our Dutch Star, lasted 10 years and were still good enough to last all night. We didn't have solar on that rig.
__________________
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft, HWH Active Air
Charter Good Sam Lifetime Member, FMCA,
RV'ing since 1957, NRA Benefactor Life, towing '21 Jeep JLU Rubicon Ecodiesel
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11-24-2015, 01:16 AM
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#3
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Senior Member
Join Date: Nov 2013
Location: Burien ,WA
Posts: 1,062
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I would talk to a battery guy. The battery's come in different designs and some perform a lot better. If you space problems there are taller battery's and agms that might perform better. Lifeline has specs and sizes on there web site and there easy to talk to. I have seen some who use Trojan that looked taller then a standard gc. I don't know much about battery's but I don't believe you get twice the amps when running 2 6volt in series vs running 2 12volts parallel. hopefully someone that knows something about that will chime in.
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11-24-2015, 08:45 AM
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#4
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Senior Member
Join Date: Dec 2003
Location: Motor City, Mich
Posts: 3,419
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A few thoughts:
You should be able to put more batteries under your step, lot's of Winnebago owners have done it.
http://www.irv2.com/forums/f23/batte...de-217250.html
Real deep cycle group 31's (which you don't have) are a little bigger than GC2's and would have a little more capacity. Batteries vary a bit, so you need to compare actual specs.
LOTS of threads about adding/changing batteries. The link above it just one of MANY threads here at irv2.com
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Tim.
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11-24-2015, 09:20 AM
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#5
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Moderator Emeritus
Join Date: Jan 2000
Location: West Palm Beach, FL. USA
Posts: 28,505
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It's not the 6v/12v difference that matters. If you can get the Group 31 12v's in a true deep cycle (not marine type), they will perform every bit as well as the two GC2's. Amp-hour ratings will be essentially the same. Chances are, however, that the GC2 will cost less than the 12v deep cycles. GC2 (golf cart) batteries are produced in much greater volume than the specialty 12v deep cycles, so pricing is usually better.
__________________
Gary Brinck
Former owner of 2004 American Tradition and several other RVs
Home is now West Palm Beach, FL
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11-24-2015, 09:35 AM
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#6
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Senior Member
Join Date: Jul 2014
Posts: 37,082
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What Gary RV Roemer said.
Your looking for what ever gives the most AH and fits.
2, 100 AH 12 volts in parallel is the same as 2, 200 AH 6 volts in series.
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11-24-2015, 09:37 AM
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#7
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Senior Member
Newmar Owners Club
Join Date: Jun 2012
Location: Spicewood Texas (West of Austin)
Posts: 4,574
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Quote:
Originally Posted by Gary RVRoamer
It's not the 6v/12v difference that matters. If you can get the Group 31 12v's in a true deep cycle (not marine type), they will perform every bit as well as the two GC2's. Amp-hour ratings will be essentially the same. Chances are, however, that the GC2 will cost less than the 12v deep cycles. GC2 (golf cart) batteries are produced in much greater volume than the specialty 12v deep cycles, so pricing is usually better.
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I agree completely..I just bought bought 8 Trojan T-105's last week for $129 each. The 12V true deep cycles are more expensive. If you look on Trojan website you will see very little difference I'm Ah/LB across the board, but the $$/Ah is lower on the 6V batteries.
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Scotty and Kristen, Airedales Wyatt and Belle Starr
2007 Newmar Mountain Aire 4528, 450 HP ISM, Allison
2024 Brinkley G4000
2022 F350 DRW King Ranch 4 x 4
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11-25-2015, 09:51 AM
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#8
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Senior Member
Damon Owners Club Workhorse Chassis Owner
Join Date: Mar 2009
Posts: 24,024
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Two Group 31's are 260 amp hours (Source Interstate battery)
Two GC-2 regualr are about 220 amp hours. (Same source)
HOWEVER
MARINE/deep cycle really do not like 50% SOC at this level serious damage is setting in.
DEEP CYCLE do not mind 50% SOC (State of charge) and in fact are designed to go to 50% before serious damage starts setting in.
So it's a toss up. I would (did) go with GC-2's (Deka G-20's 230 amp hours)
Also.. And this may "Flip" the decision.
In some RV's accessing the batteries for maintenance is a real pain in the anatomy. IN this case the Group 31s Maintenance free. styles have the clear advantage due to their lower maintenance needs.
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Home is where I park it!
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11-25-2015, 10:27 AM
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#9
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Senior Member
Join Date: Jul 2014
Posts: 37,082
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There all all sorts of trade offs between the Marine/ Deep cycle 12 volt type and the Golf Car 6 volt.
One that many overlook, is the specs on amount of cycles it should give you.
You need to dig deep in the specs to find the info.
If I remember correctly, Marine/ Deep cycle batteries offer aprox. 300 50 % cycles. Plenty for the weekend camper.
The Golf Car 6 volt batteries are rated for 700 to 1000, 50 % cycles.
As a full timer, off grid charging with solar, that makes for a better battery in my situation.
I'm sure if you dig into the 12 volt "true" Deep Cycle ( more expensive ) batteries specs you will find the cycle life.
On a side note, if your the type to park the rig, let the batteries die and boost them for the next time your using it, get the cheapest batteries out there. Your killing them anyway.
Happy shopping.
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11-25-2015, 12:06 PM
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#10
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Member
Join Date: Nov 2015
Posts: 33
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GC2 or 2 Group 31's Interstates
The Interstate 31's are about 120 a/hr each x 2 = 240a/hr's.....
The Interstate GC2's are 232a/hrs.....
But....You can safely discharge the GC2's to a deeper level than the 31's, so technically they have more "usable" power.
I find it odd that your using 50% capacity (12v) with minimal TV & one nights worth of furnace use on 2 31's. The Interstate's are great batteries for an RV/Marine non true deep cycle battery. The new Pro ECL line are even better !!
https://m.interstatebatteries.com/su...ding/v1_proecl
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11-26-2015, 03:51 AM
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#11
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Member
Winnebago Owners Club
Join Date: Dec 2012
Posts: 59
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Thanks again to all those that have replied. I have been very aware of the availability of true deep cell to be able to take a bigger hit of discharge and recover from it. As suggested by one of the posts to talk with a battery guy, well I have and that is how I ended up with the Marine/RV batteries. He assured my they were great batteries. They are the second set of Interstates in this coach and the second set I have not been impressed by. The coach has all LED lighting and even with those we conserve, conserve, conserve. While in storage they are put to sleep absolutely fully charged and are maintained by small solar in sunny and dry California. I always check the voltage on them before any kind of load is applied and they are at 12.6-12.7 every time so I know I am not slowly damaging them while stored for 3-4 months at a time. I do not have a Trimetric but would like to know what kind of amperage is consumed daily just barely keeping the coach awake during a 24 hour period from someone who might have an experienced estimate. I am happy (very) to learn that others have actually fit 4 6's in the stairwell. I have wanted to add more available amp hours for a while now. How large of a modification was needed to be done to the battery tray to make that accept the additional two batteries? I am always reading on these forums of those with two even smaller than 31's going days before needing to recharge. How do they do that, I ask myself every morning as my generator is doing its thing.
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11-26-2015, 05:05 AM
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#12
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Senior Member
Join Date: Jul 2014
Posts: 37,082
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My first question would be, how do you watch DVDs.
If you are using an inverter, do you leave it on all of the time ?
Many inverters suck power out while in idle mode. Find the brand and check the specs or be sure to shut it off, when not needing it.
I had an inverter that, over a 24 hour period, used more power ideling then the residential refrigerator used running. Delegated as a spare now.
My TV, auto tracking Sat Dish and sound bar draw about 10 amps DC. If I watch for 4 hours a night, that's 40 AH out of my batteries.
With 2, 100? AH batteries, leaving 100 AH usable, that's almost half of your capacity.
The heat probably draws 10 amps also. If you sit with a watch and time the time it runs per hour, you can figure it's use.
30 minutes an hour would equal 5 AH.
From 9 PM to 9 AM will use 60 AH.
Between 4 hours of TV and 12 hours of heat, you have just run your batteries down to 50 %
Do that a bunch of times and the RV/ Marine hybrid batteries start to loose capacity.
Golf Car batteries are designed for 50% discharges, up to 700 times, before loosing capacity.
This is why electric golf cars, all over the contry, use them.
Before I setup our system, I studied, studied, studied. Still made mistakes but learned from them.
Good Luck
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11-26-2015, 10:52 AM
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#13
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Member
Winnebago Owners Club
Join Date: Dec 2012
Posts: 59
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Twinboat, The inverter is only being used during the time the DVD is being watched
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11-26-2015, 11:25 AM
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#14
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Moderator Emeritus
Join Date: Jan 2000
Location: West Palm Beach, FL. USA
Posts: 28,505
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The wording here is vague enough to make the answer difficult. While GC2 golf cart batteries are nearly always designed for repeated "deep discharge" cycles typical of golf cart use, the typical "marine deep cycle" is not and has roughly the same 300 deep cycle life as an engine starting battery. But if you buy a quality 12v deep cycle like a Trojan SCS225, it delivers 130AH and should easily last 600+ cycles. You probably pay 2x as much, but getat least 2x the battery life as well.
http://www.trojanbattery.com/pdf/dat...ata_Sheets.pdf
Battery price can be an indicator of "true" deep cycle vs a lighter duty type of 12v. The light duty ones are derived from 12v car starting batteries and priced around the same, whereas the true deep cycle designs (different internal construction and lead plates) will nearly always be substantially more expensive. They are a low volume specialty item, and priced accordingly.
__________________
Gary Brinck
Former owner of 2004 American Tradition and several other RVs
Home is now West Palm Beach, FL
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