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

[Dashby]

Thanks Deckofficer, Like you pointed out Charter vessels need to have fool proof systems and I should have known better from experience in other areas.
Now we have a relatively fool proof system we are very happy with the LiFePO4 batteries.
They provide excellent storage capacity and if users are motor sailing like most do there is ample power for the systems on the yacht.
For the first time since we changed to electric refrigeration we can run fridge and freezer all the time.
I have voted in the online poll as you suggested.
Regards

Doug

[deckofficer]

Originally Posted by diugo

Agreed, in theory. But in practicality, would a tiny 750mA wall wart really have any noticeable effect on the cell voltages of a huge 700Ah LFP bank? I guess there's one way to find out...

Maine Sail addressed this in one of his videos. 750mA @ 15 volts = 11.25 watts.

Do I Need A Solar Controller For My Boat? - YouTube

I've heard that our cell's self discharge rate is <2% per month, or 364 watts in a month on the 700 a-hr 26 volt bank mentioned above. A wall cube of 0.5 watt output would match self discharge. A 24 volt wall cube (30 volts) would only be 15mA output.

[DotDun]

Originally Posted by Dashby

Thanks Deckofficer, Like you pointed out Charter vessels need to have fool proof systems and I should have known better from experience in other areas.
Now we have a relatively fool proof system we are very happy with the LiFePO4 batteries.
They provide excellent storage capacity and if users are motor sailing like most do there is ample power for the systems on the yacht.
For the first time since we changed to electric refrigeration we can run fridge and freezer all the time.
I have voted in the online poll as you suggested.
Regards

Doug

Please share your cost per usable AH (defined as 80%DoD), including the BMS.

Trying to figure out the initial cost to change from La.

Thanks!

[diugo]

Originally Posted by Jd1

Just a 'heads up' re Balqon....
- anything ordered prior to the end of the year will ship with zero freight cost to continental US addresses.

That's huge, as shipping heavy Li cells is pretty expensive to begin with, particularly with the hefty hazmat surcharge.

When I ordered mine from Balqon almost a year ago today, I wish I had that deal! I bought them using Paypal on the website. Then three weeks later---after I sent numerous emails---I finally got a call back, during which I was informed I would have to pay another $90 to UPS to ship them less than 300 miles. This had to be paid by credit card (not Paypal) and included a $6 charge from UPS for them to come and pick up the cells at Balqon---which I thought was really lame. It then took Balqon another two business days (incl a weekend) to actually get them out the door.

The only silver linings were, they made no attempt to label the box as hazmat, so I didn't have to pay UPS that surcharge.

And of course the satisfaction of acquiring 260Ah of LFPs for under $850 delivered and thoroughly enjoying them for the past year.

[deckofficer]

Originally Posted by Dashby

Thanks Deckofficer, Like you pointed out Charter vessels need to have fool proof systems and I should have known better from experience in other areas.
Now we have a relatively fool proof system we are very happy with the LiFePO4 batteries.
They provide excellent storage capacity and if users are motor sailing like most do there is ample power for the systems on the yacht.
For the first time since we changed to electric refrigeration we can run fridge and freezer all the time.
I have voted in the online poll as you suggested.
Regards

Doug

I agree, never liked the need to run the engine mounted fridge compressor for a hour per day for the cold plate. Electric compressor lets you leave your boat for inland travel as long as solar meets the fridge's needs per day.

[goboatingnow]

Originally Posted by diugo

Agreed, in theory. But in practicality, would a tiny 750mA wall wart really have any noticeable effect on the cell voltages of a huge 700Ah LFP bank? I guess there's one way to find out...

I don't really know , it's the answer. There's obviously a line , put where it is I don't know. The problem is that you have to do cycle testing and capacity testing to find out and that's a pain

Dave

[diugo]

Originally Posted by deckofficer

Maine Sail addressed this in one of his videos. 750mA @ 15 volts = 11.25 watts.

I've heard that our cell's self discharge rate is <2% per month, or 364 watts in a month on the 700 a-hr 26 volt bank mentioned above. A wall cube of 0.5 watt output would match self discharge. A 24 volt wall cube (30 volts) would only be 15mA output.

Thanks Bob, that was interesting! Of course, the variables are a little different here, 700Ah LFP vs 160Ah lead acid. And power supply vs wall wart, which is constant current vs constant voltage typically. In other words the wall wart may only deliver a fraction of the 750mA when the voltage differential is small, as will likely be the case.

It's the perfect thing for a quick bench test...

Or not. Like I said in my original reply, I would personally prefer a topoff charge at 10A for an hour a day, over any kind of float charge. Better yet, charge at 10A until the bank voltage reaches a good setpoint, then terminate.

[Maine Sail]

Originally Posted by goboatingnow

I don't really know , it's the answer. There's obviously a line , put where it is I don't know. The problem is that you have to do cycle testing and capacity testing to find out and that's a pain

Dave

I know that at 13.8V, left on there until it can no longer push any current at that voltage, my bank will cycle on/off at about 0.1A every so often. My power supply does not do well below 0.1A resolution and my smaller version, which was 5A, and stable out to 0.02A, fell off the work bench and broke.......

Still I don't like to keep my bank at 100% SOC for very long. But in all the studies/white papers I have read no one has put a damage number in terms of a % damage as to what being kept at 100% will do to cycle life. We still have a lot to learn about this technology in off-grid...

[Dashby]

Originally Posted by DotDun

Please share your cost per usable AH (defined as 80%DoD), including the BMS.

Trying to figure out the initial cost to change from La.

Thanks!

Hi
Second lot of batteries were US$1276 for 320Ah (256 at 80% DOD)
Shore power charger, wiring and Votronic BMS: $1147 (replaced some cabling which was undersized)
BMS from ClenaPowerAutoLLC: $300 (including second relay for cut off)

Cost per usable AH USD10.63 per usable AH

Its higher than I initially budgeted for but we have a much more stable electrical system on board now and it has better safety features than we ever had on the LA system. Which was regularly abused with batteries taken down to 10%, meant we only got 5 years from the LA bank which was 240Ah and not sufficient to run systems for 24hrs with no charging.

[goboatingnow]

Originally Posted by Maine Sail

I know that at 13.8V, left on there until it can no longer push any current at that voltage, my bank will cycle on/off at about 0.1A every so often. My power supply does not do well below 0.1A resolution and my smaller version, which was 5A, and stable out to 0.02A, fell off the work bench and broke.......

Still I don't like to keep my bank at 100% SOC for very long. But in all the studies/white papers I have read no one has put a damage number in terms of a % damage as to what being kept at 100% will do to cycle life. We still have a lot to learn about this technology in off-grid...

Yes indeed, the problem is that most of these effects cause loss in capacity. In reality such losses can be completely hidden by the ageing effect loss in Li . Hence it may be difficult to separate out.

Dave

[DotDun]

Originally Posted by Dashby

Hi
Second lot of batteries were US$1276 for 320Ah (256 at 80% DOD)
Shore power charger, wiring and Votronic BMS: $1147 (replaced some cabling which was undersized)
BMS from ClenaPowerAutoLLC: $300 (including second relay for cut off)

Cost per usable AH USD10.63 per usable AH

Its higher than I initially budgeted for but we have a much more stable electrical system on board now and it has better safety features than we ever had on the LA system. Which was regularly abused with batteries taken down to 10%, meant we only got 5 years from the LA bank which was 240Ah and not sufficient to run systems for 24hrs with no charging.

Thanks! Great information.

[Maine Sail]

Originally Posted by DotDun

Please share your cost per usable AH (defined as 80%DoD), including the BMS.

Trying to figure out the initial cost to change from La.

Thanks!

My costs:

4 - 400Ah Winston Cells = $1032.00 (this was a special deal today they are 2k/$500.00 per cell)
Shipping Cells = $250.00 (they come in very well packed wooden crate truck freight)
Tyco EV200 Contactor = $79.00 (this is the load cut relay)
House Power BMS Board = $75.00 (Clean Power Auto LLC.)
Cell Modules = $54.00 (Clean Power Auto LLC.)
Aluminum for end plates/compression = $64.00
3/8" Polycarbonate = $27.00
Anodizing Aluminum = $60.00 (minimum charge)
Nuts, Bolts, Threaded Rod, Washers etc. = $12.80
Bus Bar = $4.80 (Blue Sea)
Switches, Alarm Buzzer etc. $44.00
Terminals = $9.50
High Voltage Cut Relays $24.00
Total Materials (my cost) = $1731.60
Total at current cell pricing $2704.10

Things I already had that you would need:

Balmar Regulator for alternator = $$$
Solar or wind controller with fully adjustable voltage parameters and NO temp sensing = $$
Class T fuse = $
Benchtop DC Power Supply - 30A minimum (for balancing the cells) = $$$
160A alternator with serpentine pulley kit = $$$$$$$$$$$



I have a usable Ah capacity to 80% DOD of about 315Ah's or $5.49 per Ah at my cost. If you factor in current cell pricing that makes it; $8.58 per Ah..

Of course usable Ah's is only a small portion of the cost equation.


If I wanted high acceptance and a battery that holds voltage under load well, in a lead acid battery, I am stuck with Odyssey TPPL's at this point in time.


4 - 100Ah Odyssey PCM2150's for a 400Ah AGM bank = $1613.44
(note I am not even including the hold downs in that price just the batteries)


"Claimed Cycles" (disclaimer: I don't believe either of these "lab" derived claims and do believe they will both be lower in real world use.)

Odyssey Cycles at 80% DOD = 400 Cycles

Winston LiFePO4 at 80% DOD = 2000 Cycles (newer literature claims 3000)

$$ Per Cycle Odyssey = $4.03 per cycle (@ 400)

$$ Per Cycle LiFePO4 = $0.86 per cycle (@ 2000)


If I shoot from the hip and feel these batteries will never do 2000 cycles, I hope they do, I am looking at:


$$ Per Cycle LiFePO4 = $1.44 per cycle (@ 1200 / 80% DOD)

Of course to be fair I then need to do the same to Odyssey because we all know "lab" data never stands up in the real world.
$$ Per Cycle Odyssey = $6.72 per cycle (@ 240 / 80% DOD)


I have already surpassed 200 cycles, most to 80% DOD, with my LiFePO4 bank which would mean even at lab ratings the Odyssey TPPL AGM's would be half dead. The LiFePO4 batteries show zero signs of any degradation and still exceed the 400Ah rating.The costs calculations of LiFePO4 go beyond $$ per Ah and ideally should include many factors not just usable Ah's......

[downunder]

Excellent summation. Thanks again Mainsail

[DotDun]

Originally Posted by downunder

Excellent summation. Thanks again Mainsail

Agree! Thanks!

[Jd1]

I attempted to place an order for 4 200Ah cells and 4 400Ah cells, to be held until the complete order could be shipped, with a provision it should ship before March 16 (the 200 Ah cells are expected in Feb and the 400 Ah cells are expected in Jan) with a 10% deposit. Alas, no go. Samra suggested they could contact me when the cells are in stock. I am loosing out on the free shipping and I do not know if the 400 and 200 cells will ever be in stock at the same time.
In case anybody wonders why I insisted on complete order shipping when freight is free - the free part is only to my freight forwarder in Blaine,WA and I pay to bring the order up into Canada which could end up pretty expensive if the stuff arrives in multi shipments.