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Old 09-13-2018, 12:09 PM   #15
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1985 31' Excella
st. Paul , mn
Join Date: May 2007
Posts: 68
1st --- study & understand batteries the different chemistries and [ learn what is meant by C rate ] .
Then learn about loads - what they mean .
Then you should [ if you picked up the 1st 2 - you should have learned Ohms law ] .
Then you can apply the above to any situation .
2 main issues dealing with RVs , generally speaking not enough room to put up the needed charging from solar , then not enough space for large enough batteries .
The limited amount of battery space - the most limiting factor in living off batteries , at least with any lead chemistries .
With the limited space your looking at mass / density - or energy density , in a box the size that most Airstreams have - there just is not the space to get what most want / or think they can do .
FLD - Flooded Lead Acid are the best dollar spent for the space & dollars , then 6volt so call cart may be the best option - if you can fit them .
Then you end up with the issue of finding true deep cycle batteries when dealing with 12v batteries , some times you can not fit 2 - 6v deepcycle , so your stuck with 2 - 12v .
Then do not use anything but the FLA , no GEL & no AGM - the cost is too high with generally speaking very little if any better performance - the main difference is that the AGM & GEL can be be inverted - like in acrobatic airplanes - hopefully you are not turning you Airstream upsidedown .
Then depending on details - most often general use - there is more electrical performance with FLD , and for less money .
I use to have a 32' bus that was a mobile tool room and cover the roof with solar panels and then used 4 Trojan L16 at 140lbs each , too big for Airstream - too heavy for the floor [ unless directly over the frame .
I ran everything - including air conditioning , never discharged more than 50% .
And heres the proof of knowing / learning - these batteries had an artificial short life , because after 12 1/2 yrs. , I did not need [ no boondocking , fulltime shore power ] and let then self-discharge & freeze in MN winter .
If you learn to operate quality parts [ batteries ] and a well designed system , you can easily out last the manufactures warrantee .
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Old 09-13-2018, 04:11 PM   #16
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2018 25' Flying Cloud
Portland , Oregon
Join Date: Oct 2017
Posts: 249
Somebody has to say it. The "best" solution, if cost is a secondary concern, would be lithium. The easiest in that family would be a "drop in" replacement battery from the likes of Battle Born These have a built in battery management system. The nice thing about Lithium is you get a lot more energy per cubic inch. They can discharge to 80% with no damage. They cost $950/100Ah however, which have 80Ah usable. They also have a longer lifespan than the other solutions.

You can really geek out on Lithium and you'll find many posts on the forum about doing just that. Talking to the folks at Battle Born (who actually answer the phone) about your charger would be a place to start. Some are lithium ready and some less so.
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Old 09-13-2018, 05:26 PM   #17
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2017 30' Classic
Anna Maria , Florida
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Quote:
Originally Posted by uncle_bob View Post
Hi

A pair of T105's will give you about 10% more capacity than a pair of Group 27 AGM 12V batteries. One tradeoff is that they are flooded batteries and are a bit more picky about maintenance. The group 27's are slightly smaller than the T-105's. Both will require you to fiddle things a bit to fit them in. There's not a lot of room in a 16' trailer.

An alternative would be to replace the single lead acid you have with a Lithium battery. That will give you essentially the same usable capacity as your two T-105's or the two group 27's. A pair of lithium's will give you twice what a single battery does.

Bob
What happens with the Lithium batteries when it's below zero ? Can they handle it ?
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Old 09-13-2018, 08:44 PM   #18
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2006 34' Classic S/O
Fort Worth , Texas
Join Date: Feb 2007
Posts: 718
If you place you lithiums inside the TT your house heater will always keep them warm. Besides, if you use aquarium heat pads under the cells, they can be warmed up if it is colder and you have no heat on. They are fine discharging at any temperature. The do not like to be charged when it is below32 degrees. I find winter operation no problem. Just keep a temp readout near them. Even with out heat they will stay above freezing under your bed when the temp outside goes down for a few days.
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Old 09-13-2018, 11:11 PM   #19
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2007 27' International CCD FB
San Diego , California
Join Date: Sep 2014
Posts: 659
I'm in the midst of upgrading my batts from 2x Group 27s to 2x 6V GC2. This is my preferred route as it's cheap, durable, and easily sourced. I don't intend to use more reserve, but a larger batt means usage each day is that much more shallow. Combine that with the deeper cycle architecture of a GC2, and it's no wonder so many RV's switch to these.

On most AS models, this involves an easy modification to the battery box, adding a spacer between the box and lid, to accommodate the added height of the GC2.

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I have an 27FB, which has a front opening storage hatch that opens over the battery box. A spacer above won't work for me.

I chopped off the bottom of the batt box, 1" up from the bottom. Added large angle extrusions as legs to extend the structure down 2.5". I have a welder, but using bolts and nuts would certainly work too.

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To be continued...
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Old 09-13-2018, 11:52 PM   #20
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2018 25' Flying Cloud
Portland , Oregon
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Quote:
Originally Posted by franklyfrank View Post
What happens with the Lithium batteries when it's below zero ? Can they handle it ?
The Battleborn batteries also have built in electronics that prevent them from accepting a charge below freezing. They can discharge below freezing fine.
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Old 09-14-2018, 05:23 AM   #21
Zil
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egg harbor city , South Jersey
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Posts: 259
I too urge you to become our early tester and get the lithium battery. Then come back next year with an update. Since 2017, I am happy with a 4 x EGC2 bank, but expect to upgrade in 2022. Yes, the draw back was I had to build a custom box.
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Old 09-14-2018, 08:08 AM   #22
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2017 30' Classic
Carlisle , Pennsylvania
Join Date: May 2017
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Quote:
Originally Posted by franklyfrank View Post
What happens with the Lithium batteries when it's below zero ? Can they handle it ?
Hi

If you are going to store any batteries where it goes well below 0F, you should be careful. That very much includes flooded lead acid batteries. The state of charge *does* matter a lot on lead acid's when it gets cold. Not everybody seems to be at 100% success with over winter charging ....

Yanking out the much lighter weight lithiums in the winter is *way* easier than doing the same with a bunch of T-105's.

All that said, yes, your point is correct, storing lithium batteries well below 0F is not at all a good idea. Your magic BMS will not protect you in this situation.

====

Heading off topic .... have I mentioned just how much I *hate* that popup that wants me to sign up yet again for the news letter? How many times should one have to sign up? It comes up and kills your post if you head off to grab some data . Then you have to re-type the whole post. By then you have forgotten if the magic number is -6F or -16F .... grumble grumble grumble .....

====

Another thing worth considering is just how cold it actually gets in your specific storage location. Indoor storage has benefits beyond just keeping you out of the rain and snow. I *very* much will not be out camping in my trailer when it's below 0F outside ....

Bob
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Old 09-14-2018, 11:51 AM   #23
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1999 28' Excella
Lake Mary , Florida
Join Date: Mar 2008
Posts: 32
I just carry two 12V Deep Cycle Marine batteries. After day two, I swap them out and put the first one on a solar charger to bring it back up.
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Old 09-14-2018, 09:53 PM   #24
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2017 16' Sport
San Diego , California
Join Date: Sep 2016
Posts: 8
Holy Smokes, Thanks to everyone for all the great information. This is just what I was hoping for! I plan to put the two 6 volt batteries in the same location as my single 12v battery, which is exterior in front of the trailer and behind the propane bottle housing. Same set up that it looks like GMFL showed in the first response. Can GMFL, or anyone else tell me what brand that twin battery box is and where I can find one? That looks like exactly what I will need. I'm guessing there are other nice twin battery boxes some of you are using, and I'd love to know where you got your boxes as well.

FYI- I hope this is the correct place to post my response (Yikes!) Darren
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Old 09-14-2018, 10:35 PM   #25
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Dadeville , Alabama
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Battery box brand.... hmmmm Mine is stock from I can give you the dimensions in the morning and you can have one made up pretty easy it’s just made from 1/16” steel plate. I fabricated the extension ring for the stock box to accommodate the taller 6 volt batteries.
Here’s a link to my blog that describes the process
http://www.airforums.com/forums/blog...-upgrade-2923/
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Old 09-14-2018, 10:46 PM   #26
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2007 27' International CCD FB
San Diego , California
Join Date: Sep 2014
Posts: 659
Finished my box today.

Welded up the support structure, then added a stainless steel beauty panel. While I was at it, gave the whole tongue a nice new coat of paint.

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Old 09-14-2018, 11:18 PM   #27
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2007 22' International CCD
Corona , California
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12 Volt to Twin 6 Volt Conversion

Mine is polypropylene plastic. Provided by the dealer my son bought the AS from.

It accommodates two GC-2 batteries. Itís mounted onto the same set of angle irons the original single 12 volt battery fit into.
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Old 09-15-2018, 12:29 AM   #28
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2018 25' Flying Cloud
Portland , Oregon
Join Date: Oct 2017
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Quote:
Originally Posted by uncle_bob View Post
Hi

If you are going to store any batteries where it goes well below 0F, you should be careful. That very much includes flooded lead acid batteries. The state of charge *does* matter a lot on lead acid's when it gets cold. Not everybody seems to be at 100% success with over winter charging ....

Yanking out the much lighter weight lithiums in the winter is *way* easier than doing the same with a bunch of T-105's.

All that said, yes, your point is correct, storing lithium batteries well below 0F is not at all a good idea. Your magic BMS will not protect you in this situation.

====

Heading off topic .... have I mentioned just how much I *hate* that popup that wants me to sign up yet again for the news letter? How many times should one have to sign up? It comes up and kills your post if you head off to grab some data . Then you have to re-type the whole post. By then you have forgotten if the magic number is -6F or -16F .... grumble grumble grumble .....

====

Another thing worth considering is just how cold it actually gets in your specific storage location. Indoor storage has benefits beyond just keeping you out of the rain and snow. I *very* much will not be out camping in my trailer when it's below 0F outside ....

Bob
Lithium is supposed to go down to -40c in discharge, just not charge. Freezing is a thing to be concerned with with Lead Acid. https://batteryuniversity.com/learn/...w_temperatures
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