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Hi All, I am strongly considering going the LiFEPO4 route for power storage in our van that will be our full-time home. Planning to do 300W of solar with 150+AH of usable storage.

Most of my numbers show it is about ~25% more expensive per charge cycle (comparing apples to apples "usable" capacity - assuming 2000 cycles at 80% DoD for Li and 1000 cycles at 50% DoD for AGM).

I'm nearly sold on paying the extra for weight and maintenance (mainly only worrying about replacing every 6 years instead of 3 years), but I am concerned with the lack of proven LiFEPO4 "systems" for RV use. There are a ton of people out there using the Renogy kits or the Blue Sky Solar Boost with AGM. I haven't found a "standard" charge controller that everyone is using for LiFEPO4.

Assuming I am considering a Li battery with built-in BMS, are there other system considerations other than the charge controller?

Please share your systems and experience!

Thanks
 

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Tyler Wick, where are you located, it's not revealed under your name on your post headings... What make/model AGM and Lithium battery data are you referring to?

Anyway - a lot of internet info has gaps, Man'fs advertising FLA/AGM hybrids designed around warranty claim patterns with an attractive impulse buy price point are not much help.

AGM is a nice sealed package compared to FLAs but still have their weaknesses... 1,000 AGM cycles at 50% DOD is pretty much fantasy unless under laboratory conditions, 30% DOD and Joe Normal might make 1k. AGM's like temperatures on the cool side with accurate temperature compensated charging, actual cell/plate temperatures not just the areas ambient. AGMs also thrive on high surge current bulk charging as its the only way the electrolyte gets thoroughly circulated through sudden density/temperature changes in between the plates so mere dinky-doo charging will hurry it along to uselessness, using the C/1 or C/2 charge rate they can* accept for those first few minutes is good.

Beyond all that AGM's might be a good placeholder until LiFePo battery technology gets more mainstream. Buying a store-bought LiFePo set sure is sexy though, starting with raw cells has me reinventing the wheel...
 

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Building your own LiFePO4 pack can save a lot over the pre-packaged batteries like the ones from AM-Solar. But be warned, it is a fair amount of work and trouble to put it together yourself. My 300Ah pack is built as follows:

12 100Ah PWN cells: http://www.electriccarpartscompany....each-Minimum-Quantity-br-US-Stock-_p_366.html
3 protection boards: http://www.batteryspace.com/pcmwith...cells128vlifepo4batterypackat100alimited.aspx
1 contactor relay with coil economizer: http://www.electriccarpartscompany....olt-br-with-9-Volt-36-Volt-DC-Coil_p_744.html
1 BMV-702: https://www.victronenergy.com/panel-systems-remote-monitoring/bmv-700
Some 4AWG and some 2/0AWG welding cable, along with a bunch of lugs

The total cost was somewhere around $2200. A similar off the shelf battery pack is at least $3500.

The cells are wired as 3 parallel strings of 4 series cells each. Each string is wired up with its own protection board. The BMV-702 has a temperature monitor that controls a small built in relay. When the temperature of the batteries drops below freezing, the relay opens. This relay is used to switch power to the contactor relay. All charging devices are switched on this contactor relay to prevent charging the batteries below freezing.

The protection boards provide protection against severe undercharge (<8v) and severe overcharge (>15.6v). They also balance the cells and provide short circuit protection (but you still need a fuse on the whole pack). I opted to not purchase a BMS in addition to the protection boards. As long as I am careful to stay above 80% discharge the batteries should last me a long time.
 

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I am trying to get a handle on battery technology and resorted to FLA golf cart batteries, $180 for 2-6volt 200A-H with a weight of 62 lbs each- 124lbs. Lifetime of 7-10 years (my experience- off grid 110 volt wind plant, and in campers) I follow their draw down, charging, and other requirements. Inexpensive controller, charger etc.
I looked at AGM, shorter life, double the cost, better power retention, no venting, no spill, needs special charging.
I began researching LiFEPO4 but cost was $4K! Special charger? Safety? I would like your take on them and those who help clarify how to produce an electrical storage system with them. I understand I could draw a huge current from them but for a camper I don't see why?
BTW my conversion cost was less than the LiFEPO4 batteries would have been and I travel and camp a lot, plenty of power, easy maintenance, modest cost were my criteria.
 

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Discussion Starter #7 (Edited)
Tyler Wick, where are you located, it's not revealed under your name on your post headings... What make/model AGM and Lithium battery data are you referring to?

Anyway - a lot of internet info has gaps, Man'fs advertising FLA/AGM hybrids designed around warranty claim patterns with an attractive impulse buy price point are not much help.

AGM is a nice sealed package compared to FLAs but still have their weaknesses... 1,000 AGM cycles at 50% DOD is pretty much fantasy unless under laboratory conditions, 30% DOD and Joe Normal might make 1k. AGM's like temperatures on the cool side with accurate temperature compensated charging, actual cell/plate temperatures not just the areas ambient. AGMs also thrive on high surge current bulk charging as its the only way the electrolyte gets thoroughly circulated through sudden density/temperature changes in between the plates so mere dinky-doo charging will hurry it along to uselessness, using the C/1 or C/2 charge rate they can* accept for those first few minutes is good.

Beyond all that AGM's might be a good placeholder until LiFePo battery technology gets more mainstream. Buying a store-bought LiFePo set sure is sexy though, starting with raw cells has me reinventing the wheel...
I am in Bishop, CA. The van will be for traveling full time though including winter weather, so we should see a fair amount of temperature variation.

I have mainly been comparing the manufacturer's specs from Trojan for AGM (they publish a nice DoD vs cycle plot -http://www.trojanbattery.com/reliantagm/) and StarkPower for LiFePO. What do you think a realistic # of cycles is for AGM at 50% DoD?

I am not interested in building my own lithium pack as there is already too much to "geek out" on with this van build and we want to be on the road full time by the end of the year!
 

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East Penn Manufacturing Co makes very high quality AGMs sold under various names. Their best, in my opinion, is the Deka brand widely used in the marine industry. On their website their are some technical documents that you can download that have excellent information on charging, life cycles, etc.

I am on my third DIY camper and still use lead acid AGMs as the system is far simpler than lithium.
 

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I understand I could draw a huge current from them but for a camper I don't see why?
The 3 major benefits to lithium that attracted me were:

1. Very high charging efficiency. Every amp-hr of solar production goes to good use.

2. Very fast charging. I don't have much use for drawing a huge current, but I am very happy that I can sink a huge current into the batteries. My charging setup is 400w solar, and alternator charging. The batteries will pull 175A from the alternator up until 90% charge. That means I can easily charge my bank from empty in about 1.5hr of idling or driving. That is a huge benefit for me as I intend to use the van in the winter when solar is not providing much.

3. Lightweight.
 

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Thanks. The winter short days are somewhat offset by the increased efficency of the PV panels as it gets colder so it may not be as bad as you think. Clouds? another matter.
 

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2016 136WB low roof diesel, converted to an RV by Sportsmobile, TX
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I went with cells and a controller from Elite Power Solutions (http://www.elitepowersolutions.com/). I went with a 24V system rather than a 12V system so that I could run a Magnum Systems MSH-4024 inverter, which can do a sustained 4000W of output. I have a total of 300Ah @ 24V (7200Wh), mounted in a box under my Promaster.

Given your starting specs, I would suggest you consider going to 200Ah - that would be either one set of GBS-LFMP200AH, or 2 sets of GBS-LFMP100AHX cells (I went with 6 sets of GBS-LFMP100AHX, wired series/parallel.) Depending upon where you want to do the mounting, using 2 sets of cells gives you a bit more flexibility in terms of the shape of the cells.

You will need the management system:
The cable: http://elitepowersolutions.com/products/product_info.php?cPath=44&products_id=217
The battery monitor circuits: http://elitepowersolutions.com/products/product_info.php?cPath=44&products_id=207
The controller: http://elitepowersolutions.com/products/product_info.php?cPath=44&products_id=153
A display (any NTSC display can do, but I bought from them: http://elitepowersolutions.com/products/product_info.php?cPath=44&products_id=156)
You also will need a couple of contactors to allow the EMS to control the batteries: I went with this: http://www.digikey.com/product-deta...ense-and-marine/EV200AAANA/A101160-ND/1209930 but that's overkill for your application.
 

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Charge up his golf cart? Top up the Chevy volt? Light up the Brooklyn Bridge? Power an electric Jackhammer? Weld 3/4 plate steel? Just a chuckle.
 

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2016 136WB low roof diesel, converted to an RV by Sportsmobile, TX
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4kW - so that I can run A/C and microwave without worrying about overloading my inverter.
 
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