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11-18-2017, 06:24 PM
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#21
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Site Team
Brand: Thor Motor Coach
Model: ACE 27.1
State: Florida
Posts: 14,329
THOR #7035
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Quote:
Originally Posted by Chance
It's not that simple because Amp-hours IS NOT a measure of energy.
For example, 100 Amp-hours at 6 Volts is only half the "energy" as 100 Amp-hours at 12 Volts. And if we used a 48-Volt system like in many residential solar applications (and auto future) the difference (error) is even greater.
The best way to actually simplify these calculations is to use units of measure for energy, which for batteries is normally kWh (kilowatt-hour). That's how electric cars are rated because Amp-hours would be useless without also knowing voltage. RVs are "usually" 12 volt systems, but even that confuses a lot of people because batteries can be 6- or 12-Volt.
When you look at actual energy storage capacity of batteries, assuming same chemistry and battery weight, there is very little difference between 6- and 12-Volt batteries.
There is usually a "slight" advantage for the 6-Volt over 12-Volt because each cell is larger, requiring a little less packaging per pound of battery. If we only cared about maximizing Amp-hours per battery, we'd go to 2-Volt batteries.
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Actually, all we care about is Amp-Hours capacity at 12 volts.
Most people realize the AMP-Hours in 2 12 volt batteries in parallel are additive and the voltage in 6 volt batteries in series is additive, but the AMP-Hours are not.
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Ted & Melinda
2016 ACE 27.1
2016 Chevy Sonic Toad - Selling
2020 Chevy Colorado Z71 Trail Runner Toad
2024 Chevrolet Trax 2RS - Soon 2B TOAD
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11-18-2017, 06:39 PM
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#22
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Junior Member
Brand: Still Looking
State: Iowa
Posts: 18
THOR #6045
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I installed Two group 31 optima it seems good to go.
6v are much cheaper if cost is all you care about.
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11-18-2017, 06:48 PM
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#23
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Senior Member
Brand: Thor Motor Coach
Model: S.O.B.
State: California
Posts: 1,368
THOR #3483
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Battery Replacement
As I said before, we opted for two of the 6 volt LifeTime AGM batteries mounted on their sides. So far so good but a bit of $$.
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11-18-2017, 07:59 PM
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#24
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Senior Member
Brand: Still Looking
State: Texas
Posts: 6,187
THOR #2121
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Quote:
Originally Posted by Tfryman
Actually, all we care about is Amp-Hours capacity at 12 volts.
Most people realize the AMP-Hours in 2 12 volt batteries in parallel are additive and the voltage in 6 volt batteries in series is additive, but the AMP-Hours are not.
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Do you realize that not all RVs operate on 12 Volt systems?
Another example of why energy content of batteries should be measured and expressed in units of measure that actually represent energy.
When Tesla says a car has 85 kWh of battery capacity, I don't need to know what its voltage or Amp-hour capacity is. It's simpler that way in my opinion.
When Trojan rates a deep-cycle battery at 1.5 kWh, that says a lot about its size to me if comparing to other batteries.
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11-20-2017, 03:15 PM
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#25
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Senior Member
Brand: Thor Motor Coach
State: Georgia
Posts: 155
THOR #9957
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My Battery in 30FE
My battery came as a 75ah 12 volt and was thinking of replacing it with a 200ah 12 volt, deep cycle, agm. The new battery refers to solar. Do I have to have solar or can I replace my existing battery? It’s 23” long.
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11-20-2017, 03:25 PM
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#26
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Senior Member
Brand: Thor Motor Coach
Model: Hurricane 35C
State: South Dakota
Posts: 1,132
THOR #3761
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Quote:
Originally Posted by riskmgr
My battery came as a 75ah 12 volt and was thinking of replacing it with a 200ah 12 volt, deep cycle, agm. The new battery refers to solar. Do I have to have solar or can I replace my existing battery? It’s 23” long.
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You don't NEED solar, but it can help to keep it charged as long as the charge controller knows it is an AGM battery (most solar charge controllers have settings to change between battery types.)
Your original charging system may take 2 to 3 times longer to fully charge your new battery because of the added AH capacity.
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John
2016 Thor Hurricane 35C with pups Piper and Annabelle
2013 Ford Fiesta toad
FMCA - F457085
Blog - https://traversity.us
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11-20-2017, 03:26 PM
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#27
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Senior Member
Brand: Thor Motor Coach
Model: S.O.B.
State: California
Posts: 1,368
THOR #3483
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Quote:
Originally Posted by Chance
Do you realize that not all RVs operate on 12 Volt systems?
Another example of why energy content of batteries should be measured and expressed in units of measure that actually represent energy.
When Tesla says a car has 85 kWh of battery capacity, I don't need to know what its voltage or Amp-hour capacity is. It's simpler that way in my opinion.
When Trojan rates a deep-cycle battery at 1.5 kWh, that says a lot about its size to me if comparing to other batteries.
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Chance,
You commented about the rigs being 12 volt systems when the suggestion was made about six volt batteries. People that DO install the six volt batteries, I am one of them, wouldn't do it if they didn't work. To make them work they are wired "in series" instead of "parallel" connections. But, good six volt, even good 12 volt deep cycle batteries that will actually last, are not cheap. Case in point, the batteries that came on our not even two year old Axis had to be replaced.
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11-20-2017, 04:43 PM
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#28
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Site Team
Brand: Thor Motor Coach
Model: ACE 27.1
State: Florida
Posts: 14,329
THOR #7035
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Quote:
Originally Posted by Chance
Do you realize that not all RVs operate on 12 Volt systems?
Another example of why energy content of batteries should be measured and expressed in units of measure that actually represent energy.
When Tesla says a car has 85 kWh of battery capacity, I don't need to know what its voltage or Amp-hour capacity is. It's simpler that way in my opinion.
When Trojan rates a deep-cycle battery at 1.5 kWh, that says a lot about its size to me if comparing to other batteries.
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We're talking about a vast majority of the MHs on US highways today, not the one-off 24 VDC or even 48 VDC configurations. Does Thor even make a RV with anything other than 12 VDC for the house DC buss?
__________________
Ted & Melinda
2016 ACE 27.1
2016 Chevy Sonic Toad - Selling
2020 Chevy Colorado Z71 Trail Runner Toad
2024 Chevrolet Trax 2RS - Soon 2B TOAD
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11-20-2017, 07:42 PM
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#29
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Senior Member
Brand: Thor Motor Coach
State: Georgia
Posts: 155
THOR #9957
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Quote:
Originally Posted by Tfryman
We're talking about a vast majority of the MHs on US highways today, not the one-off 24 VDC or even 48 VDC configurations. Does Thor even make a RV with anything other than 12 VDC for the house DC buss?
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All my RVs were 12VDC. AH capacity is for units that dry camp and need Power to operate devices in the RV.
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11-20-2017, 08:39 PM
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#30
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Senior Member
Brand: Thor Motor Coach
State: Georgia
Posts: 155
THOR #9957
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Quote:
Originally Posted by 99dart
I have learned from reading here that you want the highest Amp Hours per battery. Two six volt in series create more amp hours than two 12v in parallel. (I hope I said that right)
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Series doubles the voltage and keeps the same AH.
Parallel keeps the same voltsge and doubles the AH.
Deep Cycle batteries are better and AGM is zero maintenance.
I was looking at 2 12v deep cycle 120 AH AGM that would provide my RV with 12v and 240 AH.
My RV came with 1 12v regular 75AH. Not having any issues so far but could.
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11-21-2017, 12:32 PM
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#31
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Senior Member
Brand: Thor Motor Coach
Model: Chateau 35SD
State: Oklahoma
Posts: 139
THOR #8439
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Quote:
Originally Posted by riskmgr
Series doubles the voltage and keeps the same AH.
Parallel keeps the same voltsge and doubles the AH.
Deep Cycle batteries are better and AGM is zero maintenance.
I was looking at 2 12v deep cycle 120 AH AGM that would provide my RV with 12v and 240 AH.
My RV came with 1 12v regular 75AH. Not having any issues so far but could.
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Our 2018 Chateau 35SD came with two 6vdc batteries. I wonder how the factory decides what to install?
wenz
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11-21-2017, 01:41 PM
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#32
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Axis/Vegas Enthusiast
Brand: Thor Motor Coach
Model: Axis 24.4
State: Michigan
Posts: 9,837
THOR #1150
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Quote:
Originally Posted by wenzOmatic
Our 2018 Chateau 35SD came with two 6vdc batteries. I wonder how the factory decides what to install?
wenz
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"Hey Joe what do you have over there?" "uh I have a 6V battery and a 12V battery" "Great 18V MORE POWER lets install both"
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11-21-2017, 02:00 PM
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#33
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Senior Member
Brand: Thor Motor Coach
Model: FourWinds SK 35
State: Virginia
Posts: 251
THOR #4706
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My 2017 35sk Fourwinds came with 2 interstate 27 I do have room for 2 more under steps thinking on solar also just not ready yet
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11-21-2017, 02:38 PM
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#34
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Senior Member
Brand: Thor Motor Coach
Model: Chateau 35SD
State: Oklahoma
Posts: 139
THOR #8439
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Quote:
Originally Posted by jamiegeek
"hey joe what do you have over there?" "uh i have a 6v battery and a 12v battery" "great 18v more power lets install both"
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roflol!
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11-21-2017, 04:11 PM
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#35
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Senior Member
Brand: Still Looking
State: Texas
Posts: 6,187
THOR #2121
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Quote:
Originally Posted by Tfryman
We're talking about a vast majority of the MHs on US highways today, not the one-off 24 VDC or even 48 VDC configurations. Does Thor even make a RV with anything other than 12 VDC for the house DC buss?
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Good question -- I don't know about Thor.
I have seen reference to 24-Volt battery systems, and also converters, inverters, and inverter/chargers for 24-Volt RVs. I expect they would only be used on some larger diesel rigs that have 24-Volt starters and alternators. I've also seen reference to using a DC-DC converter to step voltage down to 12-Volts for some users.
I doubt these are as rare as one-off but I may be wrong. Wouldn't be the first time.
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12-13-2017, 01:01 AM
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#36
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Member
Brand: Thor Motor Coach
Model: Four Winds 23U
State: California
Posts: 51
THOR #9748
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There is a BIG advantage to using 2 6v batteries in Series. That is paralleling batteries is never recommended. Batteries are never the same and do not age the same. The charging characteristics are mismatched, overcharging or undercharging becomes a problem. Overcharging can boil out the electrolyte, cause the battery to get hot and explode.
Considere series L-16 batteries used for solar installations, they are big. You don't get something for nothing.
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12-13-2017, 09:31 PM
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#37
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Senior Member
Brand: Thor Motor Coach
State: Georgia
Posts: 155
THOR #9957
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Quote:
Originally Posted by 99dart
I have learned from reading here that you want the highest Amp Hours per battery. Two six volt in series create more amp hours than two 12v in parallel. (I hope I said that right)
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Just the opposite.
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12-13-2017, 09:35 PM
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#38
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Senior Member
Brand: Thor Motor Coach
State: Georgia
Posts: 155
THOR #9957
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Quote:
Originally Posted by wenzOmatic
On the interstate page for RVs they list the 12v as 220 Amps and the 6v as 447 Amps. My battery box is 27 1/2” x 14 1/2” looks like it would take 4, 12vdc (840 total) batteries if turned sideways or 2, 6vdc (894 total).
Looks like the 6vdc would beat out the 4 12 vdc batteries.
What am I missing?
wenz
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6v doesn’t add AH in Series. 12v adds AH in parallel.
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12-13-2017, 09:53 PM
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#39
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Senior Member
Brand: Thor Motor Coach
State: Georgia
Posts: 155
THOR #9957
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6v 220AH Times 2 in Series = 12v 220AH.
12v 110AH Times 2 in || = 12v 220AH
Since 6v are usually deep cycle, they last longer and if you prefer maintenance free (AGM), they cost more.
Plus both take longer to charge with a converter. Shorter with a solar charger.
I had been looking at replacing my 1 12v 75AH with 2 6v 110AH in Series (deep cycle, agm) but now I’m thinking of a 12v Deep Cycle, agm, 110 AH as I don’t boondock ever.
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12-13-2017, 10:18 PM
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#40
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Senior Member
Brand: Thor Motor Coach
Model: Axis 24.2
State: Idaho
Posts: 533
THOR #1944
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Quote:
Originally Posted by groundpounder
There is a BIG advantage to using 2 6v batteries in Series. That is paralleling batteries is never recommended. Batteries are never the same and do not age the same. The charging characteristics are mismatched, overcharging or undercharging becomes a problem. Overcharging can boil out the electrolyte, cause the battery to get hot and explode.
Considere series L-16 batteries used for solar installations, they are big. You don't get something for nothing.
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Hogwash!
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Axis 24.2 "was" tug'n a JK
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