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Old 04-03-2013, 10:47   #2236
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

For all you Peukert naysayers out there, the results are now in from my third full discharge test. Recall that the Peukert exponent n is a direct function of the duration T and average current I of any two full discharge tests with identical starting and ending conditions, according to the formula

n = (logTa - logTb) / (logIb - logIa)

I have now conducted three such tests, with T1=135h, I1=2.09A, T2=13.55h, I2=18.3A, T3=39.23h, and I3=6.69A. Plugging and chugging, I get three values of n, 1.056, 1.059, and 1.062. This looks like a good correlation to me.

I will be using the average value of 1.06 to improve the accuracy of my coulomb-counting battery fuel gauge. Note that the 1.06 is likely unique to my battery. YPMV.

I can also use the Peukert exponent to determine the SoH (state of health) of my 260Ah battery. Since Winston's standard test condition is at 0.5C (130A), this implies T=2h, in other words, a two-hour rate. Solving for I, the answer is 111A. SoH is simply 111/130 = 85%, which is not unreasonable after 25 months on a shelf and two months in use.

A year from now, I'll repeat the same three tests to determine the SoH then---and more importantly, the capacity fade per year of use. From that, I should be able to estimate the longevity of my battery.
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Old 04-03-2013, 11:12   #2237

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

jg?
"They don't always have to prove anything."
Ah yes, they do, at least here in the US and I'd suspect there in BC as well. And by your own description, they had to GO TO COURT where they couldn't prove their claim and a payout was made after a different source proven.

An insurer can't simply say "it was an act of terrorism or maybe the hand of God, we're not paying". We have laws that say they must PROVE there is a condition that allows them to walk away. We have more laws, that say if the insurer is "acting in bad faith" they can be heavily penalized and barred from doing business as well.

Which doesn't prevent the insurers from being scoundrels, but often if you cite the relevant statues at them, they change their tune very quickly and pay up. If you don't know the laws--they'll often run rampant over you.

diugo-
Speaking of games and batteries...Even the Big Three consumer battery companies in the US play games. You know the "six volt lantern" batteries? They always used to be made of four "F" cells. Nope, for some years now many of them have been made with 4 "D" cells, which are only about 60% as tall, put in the same boxy shell. I got clued in when I called one of those companies asking why i could buy a lantern and battery for way less than the price of just a battery, and they said the "promo bundle" battery would last only 1/2 as long.
Talk about pulling the wool over the eyes...And these aren't fly-by-night companies, either.
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Old 04-03-2013, 11:24   #2238
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

The only 400 amp cells i can buy are direct from China at $2,900:00USD for four plus customs and handling, their stock isn't great either but they are new cells at a premium.

This whole thing may have to be put on the back burner unless supply is there to at least replace defunct cells and honour warranty.
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Old 04-03-2013, 11:39   #2239
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The only 400 amp cells i can buy are direct from China at $2,900:00USD for four plus customs and handling, their stock isn't great either but they are new cells at a premium.

This whole thing may have to be put on the back burner unless supply is there to at least replace defunct cells and honour warranty.
Did you try CALB and Sinopoly and Winston? Right now that's the order I would use for direct purchases. My quotes were 1.25 to 1.30 per Ah per cell, or about $500 each for 400s. Plus shipping, plus customs. GBS does not make that size or you could look at them as well. I was buying about 3 times your quantity though.
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Old 04-03-2013, 11:48   #2240
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Here in Europe i'm not finding holdings in any of the different manufacturers, The 2,900 price was landed prior to customs clearance ex China.

Smaller cells are easier ie 200's but more costly, heavier and more connections to go wrong....

Maybe ev projects have caused a shortage?
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Old 04-03-2013, 11:52   #2241
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Lagoon4us,

A crazy state of affairs, like which came first the chicken or the egg. Do you design a battery that doesn't have a market? Do you then try to create a market for it? Seems Balqon has tried to create a market with their yard tractors. Winston probably hoped the emerging EV market would adopt his cells but they haven't for some reason. From my past experience in off the grid homes, with the cycle life of these cells would be an ideal market. My first off grid job I used L16 6 volt batteries, they did a fair job. Then I started using 2 volt, 700 amp-hr AGM batteries, they lasted longer and had less sag under heavy current than the L16. Other designers of off grid used the very heavy and expensive Rolls Surette cells and had a good life but our LiFePO4 cells have an even longer life, are cheaper, and each cell can be hand moved unlike the 300~400 lb Rolls. Why hasn't Winston and others catered to the off grid market? This is where their cycle life would really shine, not to mention their lack of voltage sag under heavy loads. You size your solar farm to the needs of the home and the batteries are the buffer between 5 hours of solar production one day, 2 hours the next, 7 hours on the third, etc. Typically even during a bad stretch of solar production DOD doesn't get deeper then 50%. At this rate 5000 days of usage before the bank can only store 80% of its new capacity is a real selling point to the off grid home owner. 14 years without swapping out batteries would have made my customers quite happy.
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Old 04-03-2013, 14:10   #2242
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

A good product doesn't always mean good management. The almighty dollar comes in there somewhere often confusing what seems on the outside to be logic.

In short (no pun intended) if we cannot get cells we cannot play, there may be a delay till a player moves and runs with the technology in the way you allude to BUT it might take some time.

Watching with interest......
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Old 04-03-2013, 17:41   #2243
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

HelloSailer, Just doing renewal & standard is I must advise of any modification to the boat. They are limiting electronic & electrical equipment to 5 yrs of age also in this new revised deal. Yes they are smart but no one is as smart as B!!! They must be having a lot of swiss cheese for lunches at B meetings!!. We will be able to learn from this hopefully.

I am having some concerns over the installation & safety aspects we are doing as early? uptakes of Li-Ion batteries as what happened to B had little to do with the type of chem & more to do with how it was put together. I am sure if you shorted out equiv. density LIFEPO4 cells with the same installation, you would achieve the same 600 deg C + temp rise as those events. The plastic used in the cells we are using won't go passed 200 C. Also where have you seen proof & testing. One 400AH cell is close to the total of one battery used in the B787 & we are installing up to eight times as much energy on our boats!!. The cost of a fire proof battery box compared with the cost of batteries is? & is it really necessary? Time will tell.

I will beavering on however and keeping an open mind.

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Old 05-03-2013, 10:03   #2244
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Had communication with European suppliers they maintain demand has outstripped supply.

I've ordered 4 x 400 amp cells ex China, delivery 8 days.... So we shall see.
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Old 05-03-2013, 10:47   #2245
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Why hasn't Winston and others catered to the off grid market?
All the battery makers understand that LiFePO4 batteries will be dominant in the vehicle market but that liquid metal batteries will become dominant in the off-grid market. It's not worth spending a lot of time, money, and effort to penetrate a market that they would soon lose.
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Old 05-03-2013, 10:58   #2246
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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All the battery makers understand that LiFePO4 batteries will be dominant in the vehicle market but that liquid metal batteries will become dominant in the off-grid market. It's not worth spending a lot of time, money, and effort to penetrate a market that they would soon lose.
The liquid metal is going to downsize for single family off grid homes? I'm talking < 50KW-hr.
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Old 05-03-2013, 10:59   #2247
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by Lagoon4us View Post
Had communication with European suppliers they maintain demand has outstripped supply.

I've ordered 4 x 400 amp cells ex China, delivery 8 days.... So we shall see.
Keep us posted.
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Old 05-03-2013, 11:22   #2248
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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The liquid metal is going to downsize for single family off grid homes? I'm talking < 50KW-hr.
Single liquid metal cells are about 5KWh. A typical refrigerator-sized off-grid installation would be about 100KWh and (a few years into the future) should cost between $10K and $50K. There is no reason why they couldn't be made in the range between 5KWh and 100KWh.

One big advantage of liquid metal batteries is that the life cycles are so long, no one has yet figured out a failure mode. They might last as long as a house. The disadvantages that will keep them off boats and out of other vehicles are size and weight.
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Old 05-03-2013, 11:36   #2249
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Single liquid metal cells are about 5KWh. A typical refrigerator-sized blah blah blah... The disadvantages that will keep them off boats and out of other vehicles are size and weight.
Not to mention they only operate at 500C. Everyone wants a smelter in their home or boat.
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Old 05-03-2013, 11:42   #2250
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Not to mention they only operate at 500C. Everyone wants a smelter in their home or boat.
The huge size is due to the insulation.
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