I should have made some more explanation in the tread (it is in the video).
2) The size of the battery has noting to do with the price comparison.
You can get larger LiFePO4 or smaller Lead Acid but the price / capacity is about the same and most important the price / energy that can be stored during the lifetime of the battery is the same.
Actually based on the Trojan datasheet there is no advantage if you use 100% of the battery capacity or just first 30% the particular battery L16RE-A had a life cycle of 800 cycles at 100% DOD and 1600 cycles at 50% DOD so there will be no benefit in discharging the battery just 30% vs 80% or even 100% the problem is that it will not last long enough for them to be out of the warranty so they recommend you size the battery to only use 30% thus getting a battery 2x or 3x larger.
There are other reason to get a larger Lead Acid battery like the low capacity and high degradation at high charge and discharge rates.
OK but let me explain the calculations in that table.
You have the LiFePO4 that has a capacity of 64Wh and can be cycled 3000 times at 100% DOD that gets you in a simplified calculation at 64Wh x 3000 = 192kWh of energy that can be sored during the life time of the battery.
On Trojan L16RE-A you have 1794Wh of energy at 10h rate and 800 cycles at 100% DOD so again simple calculation 1794Wh x 800 = 1435kWh during the life of the battery.
Now the cost of the battery is divided by the amount of energy stored in the battery during the life time so
LiFePO4 19$ / 192kWh = 0.099$/kWh
Lead Acid 300$ / 1794kWh = 0.209$/kWh
Now this is not a real number and there are other factors that need to be taken in to account like the battery degradation over time and charge discharge efficient just to name a few but all this will make the Lead Acid look even worse and is to complicated for some people.
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1) limited bandwidth = no Utube video here
2) I don't understand your chart at all. it compares a 3.2v 20ah battery (640 wh)
to a 6v 299ah (1800wh) battery not even close to the same thing.
I understand you can safely get 80% discharge and 90% recharge (70% useable) from Li* cells, and you can daily use 30% of the Pb cells. But as it is, the chart as I read it, does not compute.Leave a comment:
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LiFePO4 vs Lead Acid a cost analysis for energy storage.
Some may already know me even if I'm new on this form.
I had a discussion about my Solar BMS now (Open Source Solar BMS dev board).
I made a youtube video just uploaded today about the cost benefit in using LiFePO4 vs the old and very common Lead Acid.
The video was mostly to show that Lead Acid is a much more expensive option but also talk about the other benefits of LiFePO4.
I was even quite generous with Lead Acid that was why is only 2x more expensive than LiFePO4 if I have included all the other parameters things will have been much worse and in real life I expect Lead Acid to be at least 3 to 5x more expensive over the life time of the battery when compared to LiFePO4.
Of course I'm not the only one to notice this in fact there are people, organizations, and companies that knew this for quite some time over 10 years.
Problem is the DIY community that is a bit slow to change. I hope that this video will alt least make some people read more and get informed about this.
Here is the video
I know some of you have slow and limited access to Internet so I will post here a small jpg of the calculation.
A123 Systems LiFePO4
Trojan L16RE Lead Acid
Then here are some independent laboratory tests done on different LiFePO4 and a VRLA(Valve Regulated Lead Acid) you can see LiFePO4 with just 10% DOD can last for 30000 to 40000 cycles and still retain over 85% of the initial capacity and how the Lead Acid performance is significantly worse around 5 to 10x
LiFePO4 lab test
And here you can read a report presented back in 2007 at International Renewable Energy Storage conference regarding the use of Lithium for energy storage.
Lithium for energy storage
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