Hi Hannu,
The LFP cycles are taken from the data sheet and are: 80% DoD 2500 cycles,70% DoD 3000 cycles,50% DoD 5000 cycles as are the lead at 50% DoD 2050 cycles.
What I'm doing with my little sheet is trying to show 4 options for a small sailing yacht that compares solutions with similar cycles and range using 1kW of power, hence picking 80% for Lithium and 50% for lead. I understand 50% with lead to be the sensible discharge level. Not saying you can't go more, it's just that voltage sag and life cycle economics come into play more.
I agree NMC is more risky than LiFePO4 and I made sure I mentioned that in the thread. A BMS and cut our relays on hi/lo voltage on a boat seem to me essential.
I agree re temperatures, hence I'm only discussing a small sailing yacht that would likely under constant cruise only have 15% heat lost to ambient atmosphere in the engine space, so we are only talking 150W to around 240W for this situation.
I find your numbers and insights on where we are going with costs and lithium really interesting. Sure capital cost is still high for boats but the purpose of my little sheet is to gain some insight into the fact it's not all about headline prices. It's an exercise I did some years ago, but felt it was time to take another look as things have moved on as you suggest.
For ref here are the datasheets I used:
http://www.northstarbattery.com/product/nsb-210ft-blue PDF datasheet at the bottom of that page.
https://www.victronenergy.com/upload/documents/Datasheet-12,8-Volt-lithium-iron-phosphate-batteries-Smart-EN.pdf
https://www.victronenergy.com/upload/documents/Datasheet-Lithium-ion-HE-Battery-and-Lynx-Ion-BMS-EN.pdf
And these radar charts show the pros and cons of differing lithium chemistries:
http://batteryuniversity.com/learn/article/types_of_lithium_ion
John R
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