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

[downunder]

Originally Posted by Maine Sail

Blue anodized wins....





Expenses so far:

4 - 400Ah Winston Cells = $1032.00
Shipping Cells = $250.00
Tyco EV200 Contactor = $79.00
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
Solar and Alt HVC relays = $8.60 (Cole Herse 70A)
Bus Bar = $4.80 (Blue Sea)
Switches, Alarm Buzzer etc. $44.00
Terminals = $9.50
Total Materials = $1720.70


Compare that to a bank like this:


4 - 100Ah Odyssey PCM2150's for a 400Ah AGM bank = $1509.60
(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

$$ Per Cycle Odyssey = $3.77 per cycle

$$ Per Cycle LiFePO4 = $0.86 per cycle

Excellent work you have done so far tends to make me a fanboy for Li.

Thanks for your ongoing informative posts.

[Opie91]

Originally Posted by Maine Sail

Expenses so far:

4 - 400Ah Winston Cells = $1032.00
Shipping Cells = $250.00

Where are you getting 4 cells for $1032?

[Cotemar]

Balqon > Store > Clearance. The 400ah cells are all sold out now

Balqon - Advanced Transportation Solution

[deckofficer]

Originally Posted by Opie91

Where are you getting 4 cells for $1032?

They sold out of the 400 a-hr cells on the clearance price, still have them at $380 per cell. Still have 700 a-hr at the clearance price of $462 per cell.
Balqon - Advanced Transportation Solution

[deckofficer]

Way to go Cotemar, brilliant minds think alike, your just faster than me.

[T1 Terry]

Hi Mainsail,
Can you tell me if the part number on each cell starts with LFP or LYP, I can't quite make out the label over the vent cover to see if they are the newer or older cells.

T1 Terry

[Maine Sail]

Originally Posted by T1 Terry

Hi Mainsail,
Can you tell me if the part number on each cell starts with LFP or LYP, I can't quite make out the label over the vent cover to see if they are the newer or older cells.

T1 Terry

I believe it is LYP...

[T1 Terry]

LYP cells will certainly give you 2,000 cycles to 80% DoD, I think the numbers on the Winston site are up around the 3,000 cycles or 5,000 cycles on the bigger cells if the discharge is limited to 80% DoD.
The very early figures were computer modeling using data from the level of degradation between new and a set number of cycles, now they have had the time to do the actual cycling they have discovered that the degradation is not linear and in some cases the capacity improves after the first few hundred cycles.
Don't drag them below 2.8v or above 3.6v while in service and they should give a long cycle life. Most of the cell failures are the result of neglect or abuse, but I guess time will tell. Mine are still working like new after 700 plus cycles, at least 5 of them have been 100% discharges down till the inverters screamed for mercy, 10.5v, they have bounced back each time.

T1 Terry

[Ram]

It all seems very complicated to me somehow, I think I will buy some cheap LA batteries and wait a few years to see how things progress, I appreciate all the posts and will continue to follow here-

[goboatingnow]

Originally Posted by Ram

It all seems very complicated to me somehow, I think I will buy some cheap LA batteries and wait a few years to see how things progress, I appreciate all the posts and will continue to follow here-

The ancillary equipment isn't much more then you should have on a good LA setup and the gains from Li are significantly better.

Dave

[NahanniV]

Originally Posted by T1 Terry

LYP cells will certainly give you 2,000 cycles to 80% DoD, I think the numbers on the Winston site are up around the 3,000 cycles or 5,000 cycles on the bigger cells if the discharge is limited to 80% DoD.
The very early figures were computer modeling using data from the level of degradation between new and a set number of cycles, now they have had the time to do the actual cycling they have discovered that the degradation is not linear and in some cases the capacity improves after the first few hundred cycles.
Don't drag them below 2.8v or above 3.6v while in service and they should give a long cycle life. Most of the cell failures are the result of neglect or abuse, but I guess time will tell. Mine are still working like new after 700 plus cycles, at least 5 of them have been 100% discharges down till the inverters screamed for mercy, 10.5v, they have bounced back each time.

T1 Terry

Terry: How old are your cells with "700 plus cycles".
You seem to know a lot about these cells, do you have any data on maximum calendar life ?
My cells are the older Thundersky LFP circa 2009.

[witzgall]

I tried to "tap" into the wires leading from the batteries to the BMS yesterday for the Celllog 8s, and found that while it would show voltages for each of the cells, the voltages were obviously in great error. For example showing 3.14v for once cell, 3.41 for another, when in fact they were all around 3.3X within 10mv of each other. Any ideas why the values were so off? I am guessing that because I was taping so close to the board, it is measuring the voltage of the board, and not the cell?

PS - remember, I have my cell boards centeralized, not like the current Housepower bms.

Chris

Originally Posted by witzgall

Hi,

I got the housepower bms installed over the week-end, but only the balancing part, no disconnects wired in yet. My cells, when installed are oriented such that taking voltage readings is only possible on two of the four cell groups. I have a celllog 8s that I would like to use for spot checking voltages. The manual shows the first wire going to the negative terminal of the furthest cell, but then it shows each of the remaining wires going to positive terminal of one cell, and the negative of the next in series?

I would have thought it would be wired up just like the BMS, with negative on C1, then a positive on C1, C2,C4,C4. If so, could I not just tap into the wires coming from the cells to my cell boards (mine are not on the cells, but remote to them in a box with the "Main" board, different then the currently sold housepower bms)?

Chris

[senormechanico]

Were any of the cells shunting at the time?

[witzgall]

No, I do not believe so, but I will check. These shunt only at the top end of charge, or do they shunt anytime when the voltage is X different from the other cells?

The tap is to the wire coming directly from the cells, lead to the main board. it is not directly connected to the cell boards - they are also connected to the main board, but at a different terminal.

Chris

Originally Posted by senormechanico

Were any of the cells shunting at the time?

[senormechanico]

Even if three cells were nearly dead and the fourth one was nearing the top end of its charge, it would shunt the fourth cell.
That's the purpose of individual shunts, so it's entirely possible that's what you were experiencing.