12 Volt to Twin 6 Volt Conversion

[Zil]

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.

[uncle_bob]

Originally Posted by franklyfrank

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

[suncoasteng]

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.

[vintage65]

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

[GMFL]

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/

[pteck]

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.

[rmkrum]

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

It accommodates two GC-2 batteries. It’s mounted onto the same set of angle irons the original single 12 volt battery fit into.

[daleyocum]

Originally Posted by uncle_bob

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

[hshovic]

http://www.airforums.com/forums/f449...tml#post514373

[adamkalins]

I too have a Bambi, and I too found I needed more power. I also agree with the tongue weight arguement, and the maintenance of equalization, the KISS of a custom box and custom wiring.
What I did was purchase a basic battery box for a larger AGM, the largest standard AGM that fit in that space. This changed my boondocking from three days to four days. I watched the voltage closely and I discharge to about 50%.
The next thing we did was buy a small 12v inverter, and a small 12v charger-maintainer. Both have practical uses outside of giving us the the tow vehicle as a large generator. This kept us money-efficient.
The last thing I want to mention is that there is a huge void space behind the electrical panel on my bambi, maybe big enough for another AGM. I have not measured it, but next year I’ll probably open that area up and see about another battery.
Clearly, you have options.

[gypsydad]

Lots of data on this topic, and many of us have upgraded....some of us due to necessity, others just want the "best" for the buck. I have gone thru several 12V batteries with my AS's over the past 15 years....even new AS's have battery issues with the newer Interstate 12V's; many say they are not same quality as 6 years ago...can't comment on that. I will say, a good multistage converter is high on my priority list if I was to get an older AS, pre 2018. Multistage converter will help maintain your investment in your new batteries which ever you end up getting. Bestconverter.com, Randy, can answer many questions plus they have great learning documents with their Progressive Dynamics or Boondocker sites, on how the multistage converters tend your battery. I just updated to the Trojan 6V golf cart batteries, and so far on my recent 2500 trip from MT to TX, everything went well...we boondocked 5 days with no issues. I chose the wet cell Trojans after talking with the battery sales guy as he said as long as you maintain water level, they will likely outlast the AGM's, and they are cheaper! His logic was the AGM's also have discharge of gasses so a properly maintained wetcell will outlast...I know, here comes the "experts" on that comment!

[pteck]

Just to offer another perspective. A converter upgrade is at the bottom of my list, or I say not on my list at all.

Why, because it comes down to your predominant use case.

I rarely ever rely on full hookups and plugging in. The times I’m in these situations is when I’m actively “camping” at full hookup sites which is few and far for me. Otherwise, my trailer is either stored outside along my house, or I’m boon docking. In these scenarios it’s the solar charger that’s actively maintaining the batteries. The solar charger is what I largely rely on 95% of the time, and it is a sophisticated multi-stage charger with batt temperature monitoring.

I agree is it comes down to maintaining the batts water level regularly (annually or every 6 mths). Converter upgrade or not. I also agree that a flooded cell is more durable and a better value than AGM.

[AirMiles]

I too bought a pair of 6V wet cell golf cart batteries due to this battery expert's analysis: https://marinehowto.com/what-is-a-deep-cycle-battery/

I chose Duracell EGC2 batteries manufactured by East Penn from Sam's Club as recommended in the article. Trojan T105s are also an excellent choice. Wet Cell 6V golf cart batteries are tough. They keep going and going! You just can't beat the bang for the buck if you are installing the batteries on the Airstream tongue.

[Fair_Enough]

Everyone talks about discharge percentages; reserve capacity; amp-hours, etc. But very little serious talk about charging. Do you know the charging specs from the manufactirer for your battery and do you have a charger that can do what is needed. Unless you have a good programmable inverter charger or a good solar charger that can be customized your 100% is more like 80 - 85% in reality.
WW

[gypsydad]

Originally Posted by Wolfwhistle

Everyone talks about discharge percentages; reserve capacity; amp-hours, etc. But very little serious talk about charging. Do you know the charging specs from the manufactirer for your battery and do you have a charger that can do what is needed. Unless you have a good programmable inverter charger or a good solar charger that can be customized your 100% is more like 80 - 85% in reality.
WW

Likely you know this already, but for me, the information on the Bestconverter.com website from converters by Boondocker or Progressive Dynamics explains their multi-stage technology for maintaining batteries. Lots of good technical data there, that most can understand, about batteries and maintenance...without having to become an expert in this area....least for my needs this has been very helpful.

[AirMiles]

Originally Posted by Wolfwhistle

Everyone talks about discharge percentages; reserve capacity; amp-hours, etc. But very little serious talk about charging. Do you know the charging specs from the manufactirer for your battery and do you have a charger that can do what is needed. Unless you have a good programmable inverter charger or a good solar charger that can be customized your 100% is more like 80 - 85% in reality.
WW

This is a really good point. Here are the Deka/East-Penn charging parameters for my Sam's Club Duracell EGC2 6V batteries: http://www.eastpennmanufacturing.com...eters-1913.pdf Since my Victron 100/30 solar controller is completely programmable with temperature compensation, it is programmed to exactly match these charging parameters. These charging parameters don't match up very well with a PD4655 converter, and my stock Airstream converter was even a worse match. Therefore, I predominately charge my EGC2 batteries with solar using the Victron 100/30 and occasionally (once since installed) boost charge with my PD4655.

[Fair_Enough]

Originally Posted by AirMiles

This is a really good point. Here are the Deka/East-Penn charging parameters for my Sam's Club Duracell EGC2 6V batteries: http://www.eastpennmanufacturing.com...eters-1913.pdf Since my Victron 100/30 solar controller is completely programmable with temperature compensation, it is programmed to exactly match these charging parameters. These charging parameters don't match up very well with a PD4655 converter, and my stock Airstream converter was even a worse match. Therefore, I predominately charge my EGC2 batteries with solar using the Victron 100/30 and occasionally (once since installed) boost charge with my PD4655.

Exactly right AM. I use solar predominantly. Shouldnt have upgraded the converter rather put that money towards an Ms2012 magnum or I have and will keep a samlex 300 w PSW. When I go with the magnum the converter vacated makes a nice place for a small subpanel .
WW

[uncle_bob]

Hi

If you really are going to do charging right .... you need a temperature probe on the charger.

Bob

[68 Overlander]

Originally Posted by uncle_bob

Hi

If you really are going to do charging right .... you need a temperature probe on the charger.

Bob

That is what they said 12 years ago when I bought my Lifelines. They are ready to be replaced now full disclosure with a 4 stage PD converter (no temp comp in Boise ID and stored outside) and in a Lance Camper. The other Airstream was sold to a lady in Oregon and the were at least 6 years old. She might be here but not sure. I'd rather spend 200 to charge for 12 yeas than 1200 to charge the same and buy more batteries with the savings. Maybe Expion if I can afford them.

[uncle_bob]

Hi

First off, in the context of "I'm going to super tune my charge profile", you aren't going to super duper tune it for perfection (max capacity) without temperature data. That's just the way the chemistry of the battery works. It's temperature sensitive.

====

Here's the gotchas with the "worked for XX years for me" stuff:

1) We don't take our batteries down and check them for capacity on a regular basis. We judge "good enough" by our own standards. What's fine with me may not be fine with somebody else. Wear out to 80% capacity is just a number, we never measure it on our batteries.

2) Batteries *do* fail catastrophically and we get all excited when they do. That's not the only way they die. Somehow we expect an abrupt end to all batteries simply because it happens to some of them. That just isn't the case.

3) We don't tend to measure the capacity of our battery each time we charge it. Is it at 125% of rated capacity (it might be ...). Did we only get it to 80% this time? ( maybe so). Voltage readings are not a perfect way to work this sort of thing out. Voltage readings without temperature compensation can be *very* imperfect at the extremes.

4) Batteries sitting here or there is not as big an issue (unless they freeze or dry out) as batteries getting heavily used at this or that temperature extreme. People talking about running on batteries all winter long ....yikes. The same holds for (somewhat unusual) continuous heavy use at very high temperatures.

5) There is variation between different lots of batteries. Like it or not, some do get made on Monday morning. Some do get dropped on the way to the loading dock. Not all dealers are equally careful with their stock. My batteries (same manufacturer and type ) may not be as good as your batteries.

6) One guy pretty much never runs the batteries and does ten cycles a year ( to 60% charge) on them. Somebody else goes a bit crazy and gets in 200 cycles (down to 40% charge) each year. The first guy will only hit 200 cycles in ten years, based just on cycles, he might be good for 20 or 30 years. The other guy likely will be shopping in less than four years.

From the giant number of "battery" threads here, it's very obvious that there is a wide range of user experience in terms of battery life. The stuff above is a lot of what drives this range of experience. Without everything being same / same it's very tough to compare one experience to the other.

Bob