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Old 03-09-2013, 10:38 AM   #21
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If you are hooking a second battery to a first, they need to be the same type, size and age. If you want to switch them (run one for awhile and then another). Then you can get whatever. Lots of other important details on these types of q's. A single large battery bank handles large discharges better (per Peukert) than two singles. A good battery monitor will also help to gauge the amount of AH's you are using and help protect the battery, or batteries from deep discharge that will reduce their life.
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Old 03-09-2013, 10:46 AM   #22
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Thanks, I've not looked to see what batt our th came with,it should b new,so if I add I can just get the same one or mult of same? Going to put them in a tongue box,do you think one or two small vents in box will be ok?
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Old 03-09-2013, 11:00 AM   #23
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As I read about the Trojan batt,I am curious as to how a yellow top optima compares? As adding at least one more batt.is second on my list(just after buying a spare tire,I can't write my thoughts of why a 28-44,000 $ tt would not have come with a spare.) this seems deceitful by both my dealer and forrest river,but too late now,it would seem a spare tire is considered an option by FR Really!!! Anyway,is the extra $ of the optima worth it as compared to the Trojan,and is it even as good?
I've not had a lot of experience with Optimas but they have their benefits (spill proof, mount in any direction, little self-depletion) and drawbacks (not many Ah for the $). Here's a bit of reading for you. Several members on the board have them.

The thing about the spare is that FR (at least Rockwood/Flagstaff) includes in into popular option packages or as a standalone option. Weird, but that's the way it is.
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Old 03-09-2013, 11:14 AM   #24
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Thanks, I've not looked to see what batt our th came with,it should b new,so if I add I can just get the same one or mult of same? Going to put them in a tongue box,do you think one or two small vents in box will be ok?
Yep if it's new, and you get one just like it then they may equalize together pretty well. New means you ordered it and just built it. I bought a new 5er once that was 18 months old, sitting on the lot and the battery was already toast. So make sure that new is NEW.

In a tongue box a vent hole in the top and bottom should be fine IMO.
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Old 03-09-2013, 11:18 AM   #25
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A long time ago I bought the optima's red top for my trucks because they had a lifetime warr. But not anymore,so now the $ factor is an issue.i parked the TH in the area I normally use for snow,now there is a large pile o snow around the front o trailer,may be next wk I can check what batt came with it.i want to get a locking box mounted soon,because this yr we have had batt's stolen from backhoe,tractors,and skid loader,on different job sights,little plastic box is not much deterrent,and kind of an advertisement to would be thieves.so box-then add batt's.
Thanks!
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Old 03-09-2013, 11:20 AM   #26
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Dealer kept batt in shop for the same reason,THwas there a while,but I hope the batt is new
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Old 03-09-2013, 12:16 PM   #27
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Dealer kept batt in shop for the same reason,THwas there a while,but I hope the batt is new
The "old" battery will tend to suck down the new one to it's level, but if you are careful, you may get acceptable service out of the pair.
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Old 03-21-2013, 07:27 PM   #28
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Ok' I have two batteries in our present 5er, on Monday March 25th we are taking delivery of a new unit. Since the batteries I have are matched ( 2 12volt group 24 ) and that the dealer did not want my two battery set up I removed them from our trade-in. The question, I will be getting a new battery with the new unit, can I add this to my 2 battery set-up. The present 2 batteries are about 1 1/2 years old, how much would the new battery pull down the other 2. Would I be gaining anything by adding the third battery or should I just stay with the 2.
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Old 03-21-2013, 07:53 PM   #29
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Ok' I have two batteries in our present 5er, on Monday March 25th we are taking delivery of a new unit. Since the batteries I have are matched ( 2 12volt group 24 ) and that the dealer did not want my two battery set up I removed them from our trade-in. The question, I will be getting a new battery with the new unit, can I add this to my 2 battery set-up. The present 2 batteries are about 1 1/2 years old, how much would the new battery pull down the other 2. Would I be gaining anything by adding the third battery or should I just stay with the 2.
There is not enough information to make an informed decision.

1) First the "matched" Grp 24s - Mfr and AH capacity when new.
2) Mfr, Grp, and AH of the new OEM


If all 3 batteries are very similar, a 3 cell bank is possible; but maybe not practical. Might be better to have 2 bank system 1 single new and the matched pair controlled by a 2 battery shutoff switch.

If faced with your situation, I personally would sell the new OEM battery back to the dealer and install my matched pair.

Then when my matched pair finally died (could be a few years if you take good care of them) I would buy a matched set of Trojans.
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Old 03-21-2013, 08:12 PM   #30
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Herk, this is what I found online, all three batteries are Interstate Marine/RV Deep Cycle. I thought as long as I would be getting another battery maybe I could make a 3 bank and hold off on doing a solar option for now?

SPECIFICATIONS
Product ID: HD24-DP
Amps: 505
Cranking Amps: 505
Cold Cranking Amps: 405
Voltage: 12
Termination: M
Weight: 41.2
Width: 6.88
Length: 11
Height: 9.5
Plates: 18
WET/DRY: W
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Old 03-21-2013, 08:23 PM   #31
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Originally Posted by f150k View Post
Herk, this is what I found online, all three batteries are Interstate Marine/RV Deep Cycle. I thought as long as I would be getting another battery maybe I could make a 3 bank and hold off on doing a solar option for now?

SPECIFICATIONS
Product ID: HD24-DP
Amps: 505
Cranking Amps: 505
Cold Cranking Amps: 405
Voltage: 12
Termination: M
Weight: 41.2
Width: 6.88
Length: 11
Height: 9.5
Plates: 18
WET/DRY: W
RV.Net Open Roads Forum: Tech Issues: Battery Question?

If this post is correct, the Interstate HD24-DP has about 63 AH each when new. You could easily dump the weight of 3 batteries and replace them with a single Trojan and have the nearly the same available AH.
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Old 03-21-2013, 09:27 PM   #32
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I am not sure of the furnace in our unit, but do I understand this correctly?
Amp draw on these items:
Furnace 7., LPG .2, Refrig on LP 1.2, plus some water pump, round off to 9. So if I did but all 3 batteries in and say they are 63ah rated time 3 = 189 So I would divide the 9 into the 189 =21 hours. But really you should not go below 50% of battery, so than I would have only 10 1/2 hours. ( right ? ) This would just be ball-parking it on paper and would depend on real time use.
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Old 03-22-2013, 06:51 AM   #33
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As a "Rule of Thumb"; yes.

For the complete story, the AH rating must be adjusted for the actual amp draw. The more you demand; the less able the battery is to deliver. The less you demand; the more life the battery will give you for a given charge state.

Manufacturers rate a battery at a given draw (5, 10, 20, or 25 amps) for a time (hours for AH and minutes for RC) under ideal conditions.

If you draw less; the battery can give more time; conversely at higher amps less time.

The attached graph is based on a 100 AH single battery at various amp draws and the effect on deliverable AH. Note in the example, that the manufacturer rated their battery at 5 amps for 100 hours. The graph can be adjusted for other manufacturer's AH rating systems with a bit of skull work.

I use the chart to determine actual capacity as a percentage of charge. For example say I have a 75 AH (at 5 amps) battery; it will deliver 50% of 75 AH at 35 amps demand (ie running the inverter to deliver 420 watts).

So the effective capacity of my 75 AH battery is 35.7 AH or about an hour of use until it is dead.

However, if I spread the load over TWO 75 AH batteries, an amazing thing happens.

The effective AH is NOT 75AH for the bank. Provided the load is even across the two 12 volt cells (importance of matching), EACH will only be required to serve up 17.5 amps. Using the chart you will see that the effective AH of each 75 AH battery is now 65% of 75 (times two) or 97.5 AH as a bank. Now my 35 amp draw will last for 2 hours and 48 minutes; not 2 hours.

Across 3 batteries the effect is even more pronounced as only 11.6 amps is required from each battery or 75% of 75AH (or 168.7 AH)

The downside to severely mismatched batteries is the effect of the higher resistance battery's drag on available current. In effect, it will quit faster and take available power from the "good" batteries to maintain its charge status in relation to the others.
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Old 03-22-2013, 07:04 AM   #34
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Thank you Lou I am not sure what I am going to do, maybe I should get 1 or 2 Trojan batteries. We go to Yellowstone in the fall, sometimes overnight temp in the 30's, I would like to use the furnace. Getting up in the camper with the temp in the 30's is not fun.
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Old 03-22-2013, 07:12 AM   #35
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Thank you Lou I am not sure what I am going to do, maybe I should get 1 or 2 Trojan batteries. We go to Yellowstone in the fall, sometimes overnight temp in the 30's, I would like to use the furnace. Getting up in the camper with the temp in the 30's is not fun.
I have 2 75AH (at 20 amps) OEM DC24 batteries and as long as I run the generator every day for a few hours I have never woken up cold.

I do use the generator to power a "Ship-n-Shore" battery charger and NOT use the onboard converter though. Just always make sure to check your water level and fill to the molded line in the cell neck before hooking up the charger.
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Old 03-22-2013, 07:32 AM   #36
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Lou, if you run your furnace, lets say all night about, about how many hours do you have to run the Gen and "Ship-n-Shore" battery charger. I do have a honda 2000 gen.
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Old 03-22-2013, 07:44 AM   #37
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Hard to say since the battery level is never the same and I am using the generator for other things at the same time. I also have a Trimetric 2025RV and monitor the "in and out" using it. I always try to get at least 95% capacity before I kill the generator.

You won't get 100% back without a few days on shore power has been my experience.
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Old 03-22-2013, 08:23 AM   #38
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Lou, thank you again, sorry for all the questions, this forum is great.
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Old 03-22-2013, 11:24 AM   #39
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Lou,

I am installing two Trojan SCS225 Batteries. I have also installed the PD9260 Converter, and the Trimetric 2025RV.

My question is, what values have you programmed into P1, P2, and P3?

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Old 03-22-2013, 12:34 PM   #40
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Lou,

I am installing two Trojan SCS225 Batteries. I have also installed the PD9260 Converter, and the Trimetric 2025RV.

My question is, what values have you programmed into P1, P2, and P3?

RodeoGeorge
http://www.forestriverforums.com/for...tor-32428.html

This thread has everything you need. The P values for MY 75AH batteries are in a thread there along with the logic used to determine those values.
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