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Flooded Cell Vs AGM


Daveh

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Embaugh's monograph suggested by Daveh in posting #26 is quite good. I think Embaugh also goes by Maine Sailor on the Cruiser Forum. The LFP thread is now about 277 pages and 4152 postings.

 

http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069.html

 

There are a lot of circular discussion and got to about page 30 or so (600 or so postings). Much of the discussion is whether to manually balance the individual 3.5 V nominal cells or to use a battery management system (BMS). Embaugh is in the "don' need to use BMS" camp as are the folks he references at the end of the monograph, notably T1Terry (an Aussie).

 

The RV LFP using world is a fairly small one at this time and so have been in contact with Dr. Jones (first to use LFP in his motorcoach), T1 Terry, the Wynnes, and Chery and Christ of Technomadia. Everyone seems to be quite happy with LFP and they are about half BMS and half hand-balancing. Have had a lot of PMs at the Northern Arizona Wind and Solar and the Solar Panel Fora since the moderators are not LFP friendly at Arizona.

 

The question as whether to charge LFP below freezing temperatures has often been posited. What I have read and gotten from the Manzanita Micro technical representative (which I have probably written about before) is that they can be charged but only at 0.1C and lower. Our battery bank is 9.6 kW-hr and we are not going to get 960 W delivered to the battery bank in winter time. We have gotten 1330 W in mid-summer.

 

I googled capacity loss for LFP iafter a year of use and found nothing that indicates 15% loss (losses are quite possible with mishandling of the batteries, notably over voltage) but the article noted that LA (lead acid, a new acronym for me - along with LFA or flooded lead acid) can easily lose 10 to 15% in the first year.

Reed and Elaine

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Reed with regard to the loss of capacity issue, look at the comments, including those by a chinese manufactuer,at the end of this blog. http://www.panbo.com/archives/2014/08/the_diy_lithium_battery_bank_bob_ebaugh_has_330_cycles_so_far.html Also look at pages 276 and 277 of the discussion board you posted. Technomadia reported the same thing. It sounds like some of these batteries were operating well above stated capacity to begin with so no one considered this a deal breaker. Just another thing to watch,

Dave and Lana Hasper

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Read through Bob's article and the replies. There are differences in the chemistry of the different LFP cell manufacturers. Bob is using GB's and we have CALB (Chinese Aviation Lithium Battery). A few caveats were noted in the replies:

 

1. Bob's batteries are situated in the engine room and it gets up to 135 F.

2. He leaves them unattended for apparently 6 months at a time. Other fora suggest that they be discharged regularly to below 30% DOD.

 

So I remain undecided about the 10 to 15% drop in capacity. Should like to find a refereed paper on this subject.

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Yea, and I saw plenty of others saying they have had no drop at all. I have been kinda eyeballing these since South Bend is only about 90 minutes from my house.http://www.ebay.com/itm/100Ah-3-2V-Lithium-LiFePO4-CALB-Batteries-100-available-/271704729933?pt=US_Rechargeable_Batteries&hash=item3f42dd294d%C2'> $1600 for 400 amp hr. The whole new but have been stored thing has me hesitating after reading that capacity stuff.

Dave and Lana Hasper

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I am not seeing any drop with my LiFePO4 batteries, which were installed by AM Solar. There is one downside of LiFePO4, you need to keep them above 32 degrees F to charge them. When I get back to AM Solar in spring they are adding a thermostatically controlled 12 volt heater under our batteries, since they are exposed to the outside air. With little internal resistance, LiFePO4 do not warm up when charged like other batteries.

2004 40' Newmar Dutch Star DP towing an AWD 2020 Ford Escape Hybrid, Fulltimer July 2003 to October 2018, Parttimer now.
Travels through much of 2013 - http://www.sacnoth.com - Bill, Diane and Evita (the cat)
 

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I posted the below as #27 above

 

The question as whether to charge LFP below freezing temperatures has often been posited. What I have read and gotten from the Manzanita Micro technical representative (which I have probably written about before and as above) is that they can be charged at low temperatures but only at 0.1C and lower. Doubt if you can get 0.1C or higher under winter conditions with the usual panel to battery (seems that a 1 to 10 ratio is normal). If you were to charge at high C rates, then problems can occur. However, I can find no refereed article on normal LFP. There have been reports that I googled that showed satellite (space-based and it might have been for some setup on Mars, but not sure) LFP charges at extremely low temperatures.

 

 

We have only utilized line or generator power for 5 days total in the last 18 months so we have only used solar. We left our rig at older son's (the solar designer/fabricator/contractor) at 7800' in northern NM from December to March while we were galvinating about Guatemala and Honduras. The temperatures dipped to -15F and the batteries cycled each day. We checked capacity when we got back and there was no discernible loss.

Reed and Elaine

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Based on what I read on Starlight's website, lithium batteries cannot be used/kept in high temp environments. So living at least part of the summer and storing the RV in southern Arizona would seem to preclude their use, since highs can be 110-115. Or, am I misreading?

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This is by far the best and most practical Lithium article I have read. Anyone that is considering LFP needs to read and UNDERSTAND ALL of this article. One comment - the Magnum inverter lines have changed since he wrote this and can now be programmed to properly handle LFP charging profiles.

 

I'm certainly no expert on Lithium batteries, but from my perspective this article is outstanding and totally applies to an RV environment. Read this carefully, then examine the batteries available from Starlight....

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the Magnum inverter lines have changed since he wrote this and can now be programmed to properly handle LFP charging profiles.

 

X2 This is definitely one of my peeves when it comes to LFP's. There seems to be a general misconception in the market that propriety charging equipment is required when making the jump. It certainly doesn't help that some charger manufacturers are taking advantage of the "mystic" with "lithium" chargers. Most serious folk that have already invested heavily in their power systems are more than capable of changing their charging profiles to seamlessly meet the demands of LFP batteries. Regardless of what you call it.. it's simply juice in.. juice out.. Do you research.

 

I'll step off my soapbox now. LOL

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Started with wet cell batteries. I know batteries, 8 plus years as a submarine electrician, and their maintenance factors. Wet cell batteries are maintenance intensive. Record keeping is critical. Then you have to do a test discharge to determine actual battery capacity and base the replacement on that test.

Now no more wet cell batteries for me again. No more monthly maintenance of cleaning, watering and checking specific gravity.

 

I am lucky in that the battery wholesaler is also my go to auto service facility. When I need to buy batteries I call them and get used,maybe one year old FAA backup at $125 to $150 each for 8D AGM's.

 

Bill

Bill & Lynn Baxter

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Started with wet cell batteries. I know batteries, 8 plus years as a submarine electrician, and their maintenance factors.

Nothing like crawling around in that battery well on your belly to help you to understand batteries!

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
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We stuck with wet-cells for now. They are a PITA but we don't full time (or even snowbird) yet (3 years away) so for weekends and vacations the investment in wet cell was worth the trade-off.

 

Hopefully in 3 years the LFP technology will be even more competitive and we'll move in whatever direction makes sense then.

 

 

WDR

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We stuck with wet-cells for now. They are a PITA but we don't full time (or even snowbird) yet (3 years away) so for weekends and vacations the investment in wet cell was worth the trade-off.

 

Hopefully in 3 years the LFP technology will be even more competitive and we'll move in whatever direction makes sense then.

 

 

WDR

These are my exact thoughts. My first system (when I retire in 3 1/2 years) will probably use cheap GC-2 FLAs (8) as a learner bank. When they die (probably in another 3 years or so) I will either going with 8 Rolls/Surrette S-550's LFAs or an equivalent capacity 48v LiFePO4 (possibly graphene lithiums) bank - depending on how technology advances and how much the price drops by then. At today's prices, the mature technology of the lead acids make more sense financially, but I'm sure this will soon change.

 

Chip

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Guest ticat900

If your living off the grid so to speak AGM is the absolute way to go.If your on RV park power all the time using flow through system

Then to me AGM are a waste of money because of costs./I only add water once a year so no big deal when I get to the point I can not do a simple task as to add battery water I will quit RVing as there are many many tougher challenges than a simple add water situation when it comes to RVing.Most people whom cant add water just use the auto fill system.

To each their own

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If your living off the grid so to speak AGM is the absolute way to go.If your on RV park power all the time using flow through system

Then to me AGM are a waste of money

 

Even someone in a park may find themselves off-grid so to speak for a few hours to a couple of days if transformers blow. And what might be a waste of money to you, may be a good investment in making their life easier because of limitations that age put on the body.

 

Barb

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Interesting! One shoe does not fit all. That is what makes our life Merry. Very good read. Thanks.

 

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  • 3 weeks later...

Well, you start a thread about flooded acid vs agm and end up with 600 AH of Calb Lifepo4. It just made more sense to me for a fulltimer starting from scratch. Thanks to everyone that provided advice. The battereis arrived today and the service from http://store.evtv.me/ (Jack Rickard) really exceeded my expectations. Responsive, very fast and everything packed great. Highly Recommend.

Dave and Lana Hasper

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Well, you start a thread about flooded acid vs agm and end up with 600 AH of Calb Lifepo4. It just made more sense to me for a fulltimer starting from scratch.

Yes, probably so. Certainly, if you're going to be off the grid much. For guys like me, at least 2 years away from even snowbirding, wet cells make more sense. The technology is likely to change over the next 24 months or so and I can bide my time. And distilled water is cheap. :P

 

Keep us posted on your project, please. :)

 

WDR

1993 Foretravel U225 with Pacbrake and 5.9 Cummins with Banks

1999 Jeep Wrangler, 4" lift and 33" tires

Raspberry Pi Coach Computer

Ham Radio

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Well, you start a thread about flooded acid vs agm and end up with 600 AH of Calb Lifepo4. It just made more sense to me for a fulltimer starting from scratch. Thanks to everyone that provided advice. The battereis arrived today and the service from http://store.evtv.me/ (Jack Rickard) really exceeded my expectations. Responsive, very fast and everything packed great. Highly Recommend.

600 AH of CALB has me thinking (24) 100AH cells - some pretty big dent in the wallet! What components did you get and how are you putting it together?

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Jim & Wilma

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Yea, it carries risk and expense. These cells are in liquidation as the new Calbs are out. That means no warranty. They were 90 a cell. I had them shipped to a business address so shipping was very reasonable. Everytihing ended uo at about 2100 including all battery connections. After i get them charged and balanced which will take a while because part of the process after having charged them in para[lell is to just let them sit that way to balance out. I was encouraged today that every battery matched very closely in voltage. So in the next week i will get them all hooked up in paralell and charge them to about 3.6 v and then let them sit a while longer in paralell without chatgr. I also have purchased and will be installing different ways of monitoring therm, The plan is to put groups of 6 in pareallell and then put those 4 in series. Our fifth wheel will not be here for a couple months so I plan to set up my system first in the house using the magnum inverter and see how everythin perfroms under load. Hopefully, that will give me time to get familiar witth these things

Dave and Lana Hasper

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Daveh, that's really a great price for 600AH and sounds like you have a good plan forward. Keep us posted how your testing goes and how you decide to monitor them.

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Jim & Wilma

2006 Travel Supreme 36RLQSO

2009 Volvo VNL730, D13, I-shift, ET, Herrin Hauler bed, "Ruby"

2017 Smart

Class of 2017

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