electrodacus
10 mW
- Joined
- Mar 27, 2014
- Messages
- 28
Hi I'm working on a new youtube video where I will be comparing Lead Acid with Lithium (different chemistry) for energy storage.
I will put an accent on the price / energy stored during battery life.
Most only compare price / battery capacity and that is not the right approach.
Price divided by energy that a battery can store during the life time of the battery is a much better number even if is a bit more complicated to get to.
I live offgrid and the house is powered by solar and wind. My main battery is a GBS 8s cell 100Ah and I have a smaller backup battery that is made of 8s cell A123 System 20Ah
One example for the A123 System will be like this
I payed 30$ for one A123 System cell (China Alibaba not sure about the cell provenience but looks genuine or a very good copy then again it my be a reject but is still quite good)
In theory has a 20Ah x 3.2V = 64Wh capacity most just divide the price by this number and compare battery price in this case 30$/64Wh = 0.47$/Wh but this is not good in any sort of comparison unless is just for an UPS that may never be used and then this number + the shelf life of the battery may be sufficient.
Else you will need more info to make this calculation (ex A123 System 20Ah cell)
(20Ah x 3.2V x 3000 cycles x DOD x charge discharge efficiency ) the charge discharge efficiency will depend on the application and discharge rate but is way better on any lithium than it is on a Lead Acid. Then there are other aspects that can be considered like the capacity degradation in this case it seems to be linear and the A123 still have about 90% of the initial capacity after 3000cyclse of 100% DOD
http://www.raceyard.de/tl_files/Newsletter/Dateien/A123-AMP20-M1HD-A-1-Data-Sheet.pdf
So 30$/ (20Ah x 3.2V x 3000 x 100% x 0.95) = 30$ / 182.4kWh = 16.5cent /kWh stored during the life time of the battery.
Let me know what you thing about this and what battery I should include in this comparison.
The battery needs to have a spec where at least this few parameter are provided.
Degradation chart with the number of cycles and degradation in percentage or Ah and the conditions this test was performed like the DOD and charge/discharge rate, similar to the last graph in the A123 20Ah spec.
It has been two years since I made the research for my batteries not sure how much has changed since then what new batteries are available.
I know that for mobile applications things are different compared to stationary where energy density is not important.
I can use Li-ion (LiCoO2) charged at 3.9V and make it last 8x more with 60% of the original capacity thus making that battery 5x less expensive in stationary application where weight of the battery is not an issue.
I'm also working on a fully programmable BMS is open source but only support 8 cells so not sure how much interest is in here for something like that it can be modified to work with double that 16 cells but I will not need something like that so I will not design one.
I will put an accent on the price / energy stored during battery life.
Most only compare price / battery capacity and that is not the right approach.
Price divided by energy that a battery can store during the life time of the battery is a much better number even if is a bit more complicated to get to.
I live offgrid and the house is powered by solar and wind. My main battery is a GBS 8s cell 100Ah and I have a smaller backup battery that is made of 8s cell A123 System 20Ah
One example for the A123 System will be like this
I payed 30$ for one A123 System cell (China Alibaba not sure about the cell provenience but looks genuine or a very good copy then again it my be a reject but is still quite good)
In theory has a 20Ah x 3.2V = 64Wh capacity most just divide the price by this number and compare battery price in this case 30$/64Wh = 0.47$/Wh but this is not good in any sort of comparison unless is just for an UPS that may never be used and then this number + the shelf life of the battery may be sufficient.
Else you will need more info to make this calculation (ex A123 System 20Ah cell)
(20Ah x 3.2V x 3000 cycles x DOD x charge discharge efficiency ) the charge discharge efficiency will depend on the application and discharge rate but is way better on any lithium than it is on a Lead Acid. Then there are other aspects that can be considered like the capacity degradation in this case it seems to be linear and the A123 still have about 90% of the initial capacity after 3000cyclse of 100% DOD
http://www.raceyard.de/tl_files/Newsletter/Dateien/A123-AMP20-M1HD-A-1-Data-Sheet.pdf
So 30$/ (20Ah x 3.2V x 3000 x 100% x 0.95) = 30$ / 182.4kWh = 16.5cent /kWh stored during the life time of the battery.
Let me know what you thing about this and what battery I should include in this comparison.
The battery needs to have a spec where at least this few parameter are provided.
Degradation chart with the number of cycles and degradation in percentage or Ah and the conditions this test was performed like the DOD and charge/discharge rate, similar to the last graph in the A123 20Ah spec.
It has been two years since I made the research for my batteries not sure how much has changed since then what new batteries are available.
I know that for mobile applications things are different compared to stationary where energy density is not important.
I can use Li-ion (LiCoO2) charged at 3.9V and make it last 8x more with 60% of the original capacity thus making that battery 5x less expensive in stationary application where weight of the battery is not an issue.
I'm also working on a fully programmable BMS is open source but only support 8 cells so not sure how much interest is in here for something like that it can be modified to work with double that 16 cells but I will not need something like that so I will not design one.