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Old 02-09-2014, 12:52 PM   #1
2 Rivet Member
2012 25' FB Flying Cloud
Join Date: Sep 2003
Posts: 74
Trimetric and Interstate batteries

I am finishing up installing a Trimetric Battery Monitor on our 2012 FC25FB.
I looked at the factory equipped Interstate Batteries and discovered they are Group 24 but 2 different capacities.
One is a HD24-DP and the other is a SRM-24. To set up the Trimetric I need to enter the amp hour capacity of the batteries. I assume this would be at the 20 hour rate. The Interstate Battery website does not give the 20 hour rate but gives the hours of amp load at 5 amps and 15 amps. This number is different for each battery.
I will contact Interstate Battery and Trimetric tomorrow about this.
Eventually I will replace the Interstate batteries with 6 volt Trojans when I figure out how to make the battery box deeper.
Any ideas out there on the amp hour capacities of these Interstate batteries?
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Old 02-09-2014, 03:01 PM   #2
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1961 24' Tradewind
1969 29' Ambassador
1970 21' Globetrotter
Jamestown , Tennessee
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I set mine up at 150 amp hours even though my 2 golf cart batteries are supposed to be 220 amps. My reasoning is the capacity drops as they age and the manufacturer probably exagerates the capacity anyway.
I prefer to figure these things on the conservative side. I have never discharged below 50% based on that setting and my batteries will be 11 years old in June
Rick Davis 1602 K8DOC
61 tradewind, plus a few others
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Old 02-09-2014, 09:08 PM   #3
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Oswego , Illinois
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I have forgotten the precise numbers right now, but you can dial in your amp hours and corresponding percentage of state of charge by noting the voltage. IIRC, a 50% state of discharge occurs at a bit over 12 volts...like 12.2. So not only can you determine a relatively true amp hour capacity of a new battery, but you can adjust for aging ones as well.

I need to look up the precise numbers, but that's pretty close I think.

"If the women don't find you handsome, they should at least find you handy." - Red Green
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Old 02-09-2014, 11:11 PM   #4
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1974 Argosy 20
2014 20' Flying Cloud
Kooskia , Idaho
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I set mine for 70 amp hours for each of the original type 24 batteries, or 140 AH total. That is approximately right for most type 24's. Close enough anyway. When I put new golf cart batteries in this spring, I will use 220 AH for the set.

Scaller 113, you may find it easier to add height to the original battery box than to deepen it. That is what I plan to do at any rate.
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Old 02-10-2014, 10:50 AM   #5
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2012 25' FB Flying Cloud
Join Date: Sep 2003
Posts: 74
Hi Idroba,
I am planning to eventually install 6volt golf cart batteries. Our 2012 FC25FB has a exterior storage compartment door that hinges at the bottom across the front of the trailer. This door opens down to near the top of the battery box so I do no have much clearance to increase the height of the battery box by coming up. I have to take some precise measurement and may end up extending the box downward.
Thanks for your input.
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Old 02-10-2014, 01:01 PM   #6
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1974 Argosy 20
2014 20' Flying Cloud
Kooskia , Idaho
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Posts: 4,591
Ah, that front storage compartment does make for a problem in raising the top of the battery compartment. My FC 20' does not have that issue.
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