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[CLOSED] UK - New 40Ah LTO Cells
#1
UK Only - Near Luton

I have a shipment of cells on the way into the UK some of which for my own home solar storage unit (18kWh) and will have a number of cells spare as I made the order larger to drop the overall shipping cost per cell.

The cells are new LTO 40Ah (3rd generation cell) and good for over 10k cycles and would be looking at £28 each for them or better in qty. They are from 3rd largest LTO manufacturer in the world and not a no brand random used cell....  The price per kWh is £304 and throughput cost on 12k cycles is 2.54p/kWh. 

They may be the cheapest new branded LTO cell in the UK at this price.

The price  is below a lot of new 18650 pricing on a kWh basis and multiples less on a throughput basis.

I may have around 15kWh available and looking for anyone interested in the cells.
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#2
Thought I would add some numbers to help compare.

New 18650 cells are being quoted around £1 per Ah capacity mark and should last around 1200 cycles. Being optimistic, lets say they are cared for and last 2000 cycles. Taking a nominal cell voltage of 3.7V and £ per Ah this works out to be £270/kWh in capacity and for 2000 cycles this would work out to be a storage throughput cost of 13.51p/kWh. Typical eBay pricing per cell is above £1/Ah and any decent named brand is well over £1 pricing. High capaacity cells can sometimes be a different chemistry and will only last 500 cycles (some 26650 5500mAh from for example).

Comparing 32Ah Kokam pouch cells on eBay at £50 per cell, again 2000 cycles these work out to be £422/kWh and a throughput equivalent of 21.11p/kWh.

Comparing A123 pouch cells quoted on Alli, £241.50 for 12 cells of 20Ah with a cycle life of 3000 (80% DoD) these equate to £271.96/kWh and a throughput cost of 11.33p/kWh. With them beingdirect from China you could then end up with an additional 20% VAT on top and 2.7% duty if they are imported correctly. This would push the cost up by another 20% if they are not impounded. No Taxes might be quoted because they import them under a different duty code to evades the hazardous goods shipping cost and issues...

If you are getting free 18650 cells from recycling then you are on a real winner, just be aware of the cycle life and not to use the low capacity cells as the time to process and use them compared to the benefit gained will be very low.... your time is valuable.

If your paying above 1 (£/$/Eur) per Ah then I would argue they are not really viable at all for a powerwall unless you are off grid and have no option, even then I would argue to look at the options and work out the real cost as to what you are planning.

In the UK with the single rate tariff price at 15p/kWh if you have solar and have the 50% deemed export credit, your exports are effectively 0p/kW energy cost to you, i.e. option price for your exported energy of zero. If your storage throughput cost is (as per the A123 cells) 11.33p/kW and you have an overall in/out efficiency of 80%, excluding inverter cost, the economics stack up to 14.16p/kWh and it is just not viable. Drop the throughput cost to less than 3p/kWh with LTO cells, add in 5p/kWh for inverter plus other costs (10% duty 2kW over 10yrs, £800) and you are at 8p/kWh leavign a margin of 7p/kWh as benefit to you. This in my view is the only viable economic storage option that works for the UK.

In my case my solar (no tariff) costs me around 4p/kWh and my other costs add up to around 3p/kWh, so for me my project cost is looking at providing 100% clean green power for less than 10p/kWh and have near zero imports through the whole of the summer.

If you want any help working out costing for your project I would be happy to help.
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#3
Started my solar panel system project about three months ago.
First 10 weeks spent collecting infos on different technical solutions and materials and jumped to the conclusion that battery cell life cycle is crucial.
To the above very interesting post will add that with a larger (almost infinite for LTO cell ——> 10.000 !!!) cell life cycle you can build a battery pack on your average peak energy demand (using grid as a backup) and have no need to point in covering the absolute demand peak nor to sovradimension pack on Ampere side to avoid low voltage and preserve this way your cell life cycle.
So you can build smaller and more efficent pack (and no need to work on assembling, fusing etc...)
At the moment best options (on life cycle) are 3.7V LiFePo4 (or winston LiFeyPo4) ——> rated between 2.000 and 5.000 and 2V LTO cell ——> rated at 10.000 and above.

Now my questions.
1. Is LTO technology (still around 10-15% more expensive than LIFePo4) already mature for powerwall application ?
2. BMS and voltage control is a crucial point. Will BMS more complicated on LTO cell, having less volt range?

PS. I’m from Italy.... may be interested buying your LTO cells if you still have some to sell.
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#4
LTO is mature and tested as much as you can with over 10,000 cycle life and >10yr calendar life. The cells I have are currently being used in the more recent BYD busses being sold around the world as the older cells were not as energy dense and did not hold the voltage as high under high current draws (1C to 10C).

I believe that when you calculate the cost per kWh of energy through the battery/cell that LTO works out cheaper, even though the purchase price is higher and this is the reason I waited 2 years for these type of cells to become available outside the vertical companies. I think that these only came into the market because BYD was cought out with the cut in subsidies by China in January for Busses and may not be available in new condition later in the year. BYD and an lot of LTO manufacturers are all verttically integrated and will not sell the cells separately, like Tesla will not sell thier cells separately. All the other BYD cells on the market are 30Ah that have been recovered from older busses, capacity tested and then sold on. Watch for the cells with the small red framed label with hand written capacity value.... they are all used...

A good BMS is an energy balancer and not a voltage balancer. BMS systems typically balance against a nominal voltage at the top or bottom of a charge cycle and do not take into account the "energy" in the cells over the cycle range and this should be balanced closer to mid voltage charge equalisation point and not top or bottom balancing. The top or bottom approach is basically because it is electronically easier to implement, top balancing is just a basic voltage level switch to a dump resistor. Anything other than basic top/bottom you need to computerise and monitor the charge over a number of charge/discharge cycles. Basically you want to have for the worst cell in your pack, to utilise the comparable 10% to 90% capacity of that cell. I fthis means you are using 10% to 80% of another cell and 20% to 90% of another cell that does not really matter, what matteris is you are getting 80% of the worst cell in the mid cycle capacity range to make the most of the cell life..

My own approach is to attach an ESP8266 to each parallel set of cells and use wireles. No wires between cells, each parallel battery set is it's own module and all the data and controll is via wireless. Each ESP8266 is powered via a small DC-DC 1V-5V buck to 3.3V for the ESP. The ESP then controlls a bypass/dump resistor that is switched on for several hours or "days" to energy balance. With this approach there is no need to push and pull the top or bottom of the charge cycle and waste cell throughput. Plus, it works out quite cheap for a BMS... and standby power draw is minimal. I will end up with at least 34 ESP untis for the basic pack and likely around 70 for the two systems (1 fully field portable).

Cell voltage is not really an issue as it just means you have more points for the BMS to manage. Your overall pack voltage of say 48V is the key end result and not the individual cell voltages.. Different chemistry, different voltages. 12V lead acid batteries are after all several sub cells inside the case with no BMS and people did not scream out for a BMS for a 12V lead acid car battery.....

Unfortunately I am not looking to post overseas and would prefer for the buyer(s) to collect as this would provide an opportunity to make sure they know the cells, can test them before buying, I can tell them or teach them any additional information and they can also pick which ones they want so it is very open.

I will possibly end up listing some of them on eB at a higher level to cover eB, PP and post charges, although I would prefer not to waste time and buyers cash on paying 3rd party fees. Hence the post here first. I may end up selling all the cells I have if I can get hold of more, although dealing with China can be quite time consuming and risky.

At the moment the cells are doing around 18kn in the South China sea....
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#5
I have decided to keep the majority of the cells at the moment and the few that will be avilaible will be on eBay in around 2 weeks.
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