LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[durundal]

For those interested, here's what I did with the 100Ah sinopolys I got from EVolution in Colorado. The battery holder is sized for a group 31 (IIRC) max size, and this just fits - the edges have maybe 1/2" clearance, and top and bottom is within an 8th. When I glassed in the shelf it ended up being not quite true (it's under the cockpit and limited access) so I had to cut down the rear plastic feet it rests on but seems to fit nicely now. The black thing below it is the mount for the main power switch, planning to install the fuses directly to the lugs with a Blue Sea 5191 fuse block and drop the cables out the gap on the bottom. The circuit breaker panel is located up top, not quite sure how to deal with the service loop I'll need unless I install the cover in situ instead of with the battery removed.

The cost and time to buy and fabricate the raw materials for the housing was not insignificant, it sure would have been nice to have been able to get one pre-boxed up but it seems to be a pretty decent little package.





Now to find a power supply to top balance all the cells in parallel, then charge it up for the first time. The cells all have around 3.30V on them so hopefully won't take too long to hit the knee.

Andy

[durundal]

For real use, I'm leaning towards having both the outboard (6hp Tohatsu with a 50W magneto) and a 30-60W solar panel with a Genasun controller, the genasun has an integral low voltage cutoff load that it seems like I could run a contactor for the power panel on. The top balance would prevent any individual cell from being overcharged and the low voltage cutoff should keep anything from being drained completely, and if it does have some sort of cell fault I would rather have the cells be energy depleted than energy full. The outboard is slightly concerning in its voltage regulation method (or lack thereof) but if it was designed primarily to charge lead acid it doesn't seem like it could be too high of a voltage anyway.


Any glaring issues with this plan?

[downunder]

Originally Posted by Lagoon4us

Fresh from CHINA to Croatia, arrived today serial numbers Y11692 Y11691 Y11690 and Y116989. Build date is 8th March 2013....

We sail for Corfu on Saturday and there i'll start charging the cells. They are 400amp.

Looking good. What did they cost delivered to Croatia?

[FlyingCloud1937]

enjoy

1D spinodal type phase transformation in a LiFePO4 nanoparticle - YouTube

watch a squence

http://www.youtube.com/watch?v=3pd7e...871B057A6ECDBB

[Lagoon4us]

Originally Posted by downunder

Looking good. What did they cost delivered to Croatia?

Delivery was $560:00, cells cost $600:00 each BUT they are less than a month old, consecutive build numbers and are delivered fully charged.

Kinda makes the American supply a bit less desirable?

Cheers.

[Lagoon4us]

Nice work Andy some good thinking there...

[hellosailor]

Lithium-ion battery - Wikipedia, the free encyclopedia

Very interesting note in the Wiki tonight. After all the discussion about different lithium types and charging strategies and the best way to get power out and back into them...They mention that there's a new project basically putting tin needles in the batteries and if that one works, they expect to TRIPLE to power capacity at basically no extra cost or size.

So if you're happy with Li-whatever now...cross your fingers, and start investing in tin futures.

[Maine Sail]

A puzzle..

Ok so I also have a "reserve bank" that is LA that I will need to charge. Problem is that I am charging my LiFePO4 bank to 13.7V (3.43VPC) then dropping back to 13.4V or 3.35VPC in order to discontinue charging when the bank is full (solar and alt reg are programmed this way).

I had planned to use a new Sterling Power product to boost the ouptut voltage to the reserve battery but the product is not yet shipping and I just found out the "on" voltage is fixed and can't be changed (I had been lead to believe by Charlie that the input trigger voltage would be adjustable.

Obviously I don't want to have this device "on" at 13V as it will always be sitting there on as my bank rests higher than that and I would prefer something that can "boost" to my reserve bank.. I suppose I could just leave it "on" but I would still want to hit my reserve battery with absorption every now and then. As it sits now I have a Balmar Duo Charge that I have adjusted the "on" voltage but this device only follows the voltage of the house bank and will only pump out the 13.7V the house bank will be charged to..

I have some creative ideas of how to accomplish this but I am curious as to the groups thoughts on how best to deal with this puzzle.

I have now done over 30 cycles on my bank using the voltage parameters I have chosen and find them to be working perfectly. I gave up a small amount of top end capacity, perhaps 10 Ah's at best, but the cells are still in perfect balance and I am well away from the knee's..

[deckofficer]

Maine Sail,

We always come to you with questions and want to reciprocate if I can. How large is the LA bank and what is it needed for?

On a thread drift, 15 minutes ago Reuben Trane of Island Pilot DSe fame, just joined the Trawler's Forum touting his switch from AGM to LiFePO4 1000 a-hr cells for his 48 volt bank. I asked him why he chose (16) of the Winston 1000 a-hr cells at 94 lbs per cell vs (32) of the 700 a-hr cells at 47 lbs per cell. Waiting for the answer here.. Lithium Ion Batteries - Page 4 - Trawler Forum

[hellosailor]

Maine, I suspect the answer will be "buy another dedicated charger" and short of that, anything else will be a voltage mismatched kludge. Depending on whether this is a boat or shore battery your options will vary. Or not.

Oh, wait, you can get rid of the LA bank and buy more lithium.<VBG>

[diugo]

Originally Posted by deckofficer

Winston 1000 a-hr cells at 94 lbs per cell vs (32) of the 700 a-hr cells at 47 lbs per cell.

I think the 92lb figure is a typo. A slick, brand new brochure on the Balqon site shows it weighing 33 or 35kg (73-77lb) depending on the model:

http://www.balqon.com/upload_images/...ttery_2013.pdf

[deckofficer]

Thanks Doug, I corrected it on the Trawler's Forum. There is a lot more acceptance here on the Cruiser's Forum of LiFePO4 than on the Trawler's Forum.

[hellosailor]

Bob, have you ever heard of a lead acid battery cell with a nominal voltage of 3.25 volts?

I ask because I was looking at Balqon's broken ynglitch in their current battery brochure, which is http://balqon.com/upload_images/sect...ttery_2013.pdf

and on page 5 they compare discharge curves--with lead acid starting at the same 3.25v as some lithium cells. That would make a conventional 6-cell lead acid battery 19.5 volts, which would be an interesting state of affairs.

It just makes me wonder about their math sometimes.

Meantime, has anyone put 500 or 1000 deep discharges on their Winstons? How are they holding up with 80% discharge cycles, as recommended?

[deckofficer]

I do like their math when it comes to a-hr rating. While the lead camp gives the rating based on a 20 hour (0.05 C) discharge rate, from my and Maine Sail's experience, the LiFePO4 get their rating at 1.0 C and only down to 80% DOD. So what ever rating could do the job for you using LA, you would only need 1/2 that for LiFePO4.

[Kettlewell]

I hesitate to participate here, but as to MaineSails question, if you have both a LA and LiFePO4 bank, how about dumping all the charging into the LA bank and then have some sort of charge device that spills over into the LiFePO4 bank if the voltage over there is below whatever charging threshold you want to set? That would allow you to have standard charge controllers on everything going into the LA bank.