Steve_S
Emperor Of Solar
As we have seen numerous times past....
B/Bulk 280AH cells test out as anywhere from 275-280AH for the GROSS AH meaning from 3.650 down to 2.500 and their usual NET AH were often coming in around 270AH. This improved a little over time but not terribly much.
A-Grade cells usually tested out above the "nameplate rating" but most often only by a few percent, so it was not unusual to see 290AH+/- from the GROSS side and usually hovered around 280AH from the working range.
Now things have yet improved a bit more and now an A-Typical A-Grade (proper) 280AH will test out around 300AH GROSS which will consistently deliver the 280AH from the Working Voltage Range. This applies to the Major Makers across the board.
IF one builds their own Battery Packs or buys commercial assembled units from a company like say SOK and operate the battery packs within the WORKING VOLTAGE RANGE of 3.000-3.400 (2.900-3.475 in practical universe with Low Volt Cutoff no lower than 2.800Vpc) any noticeable deterioration will take YEARS to Notice. A QUALIFIER !!! This also assumes that the battery packs are kept within Nominal Temps (10C-40C / 50F-104F) and NOT ABUSED by being frozen or overheated and such.
Things that can stress cells but in ESS rarely do....
- Pushing the Charge & Discharge C-Rates to the limits.
- Charging & Discharging cells outside of nominal temps.
- Pushing / Using the cells beyond the Practical Working Voltage Range ! (there is no practical gain doing so).
- ESS systems are intended to be Right Sized so as to never stress them while having the real capacities that you really need.
Case in Point using my own system as the example.
Take 6x 280AH Packs in Parallel: Can discharge @ 1,200A collectively and take 600A charge collectively. Obviously I will never pull 1200A / 30,700W from that and while I can "PUSH" 305A Charge (SCC's, Inverter & external charger) I don't do that either (but have tested it in my Thrash Tests which was pushing all gear to performance edge). My SCC's provide 165A which is awfully "gentle" and easy on the packs as it is divided between them.
The BIG Q - Why so big with small solar (2080W & 2370W)... I use between 3.5-4.0 kWh per day (year-round) but in Winter I can easily see 10 days without any significant solar, so my reserve reflects that. Even if I have to use a Genset for 8 hours to charge my bank, 8 hours genset = just under 5 days battery runtime.
These Days (summer 2024) the Availability & Quality of cells has improved for several reasons which is a WIN for everyone ! There is no reason to not buy proper A-Grade Cells now that they are available at reasonable prices (cheaper than last years B Grades) and people CAN SHOP AROUND for the deals too while sticking to KNOWN GOOD VENDORS that have at least 3 years track record.
THE GOTCHA THAT GETS MANY !
Why Match & Batch ! Cells with a Lower IR will take charge & discharge faster that those with a higher IR. They will be runners within a pack and in fact the worst place for them is to be on Position 1, 8/16 (Batt Leads) as that WILL limit & handicap the packs. Matching & Batching ensures that cells collectively have the same IR whether at 3.000 or 3.200 or 3.400 regardless if Charging or Discharging.
SADLY most vendors only IR Match cells at the storage voltage as they received them.
Some Vendors use a 3rd party to Test & Validate cells (They usually charge extra for that)
Some other Vendors use the Manufacturer to complete the cycles (beyond just cell validation tests) & provide the manufacturers test reports.
TOP 10 LFP Makers as of MARCH:2024
BYD: https://www.byd.com/pc/
Ufine Battery (Guangdong Ufine New Energy Co., Ltd.): https://www.ufinebattery.com/
Contemporary Amperex Technology Co. Limited (CATL): https://www.catl.com/
LG Chem Ltd.: https://www.lgchem.com/main/index
Panasonic Corporation: https://na.panasonic.com/us/
Samsung SDI Co. Ltd.: https://www.samsungsdi.com/
CALB (China Aviation Lithium Battery Co. Ltd.): http://www.calb.cn/
Lishen Battery: https://www.lishen.com.cn/
Farasis Energy (Ganzhou) Co. Ltd.: https://www.farasis.com/
EVE Energy Co. Ltd.: https://www.evebattery.com/
-! Bold/Italics = Most common cells available from Vendors/Resellers selling to DIY & Others.
NON-Bolded = Generally unavailable to "Public" and therefore not easy to get.
B/Bulk 280AH cells test out as anywhere from 275-280AH for the GROSS AH meaning from 3.650 down to 2.500 and their usual NET AH were often coming in around 270AH. This improved a little over time but not terribly much.
A-Grade cells usually tested out above the "nameplate rating" but most often only by a few percent, so it was not unusual to see 290AH+/- from the GROSS side and usually hovered around 280AH from the working range.
Now things have yet improved a bit more and now an A-Typical A-Grade (proper) 280AH will test out around 300AH GROSS which will consistently deliver the 280AH from the Working Voltage Range. This applies to the Major Makers across the board.
IF one builds their own Battery Packs or buys commercial assembled units from a company like say SOK and operate the battery packs within the WORKING VOLTAGE RANGE of 3.000-3.400 (2.900-3.475 in practical universe with Low Volt Cutoff no lower than 2.800Vpc) any noticeable deterioration will take YEARS to Notice. A QUALIFIER !!! This also assumes that the battery packs are kept within Nominal Temps (10C-40C / 50F-104F) and NOT ABUSED by being frozen or overheated and such.
Things that can stress cells but in ESS rarely do....
- Pushing the Charge & Discharge C-Rates to the limits.
- Charging & Discharging cells outside of nominal temps.
- Pushing / Using the cells beyond the Practical Working Voltage Range ! (there is no practical gain doing so).
- ESS systems are intended to be Right Sized so as to never stress them while having the real capacities that you really need.
Case in Point using my own system as the example.
Take 6x 280AH Packs in Parallel: Can discharge @ 1,200A collectively and take 600A charge collectively. Obviously I will never pull 1200A / 30,700W from that and while I can "PUSH" 305A Charge (SCC's, Inverter & external charger) I don't do that either (but have tested it in my Thrash Tests which was pushing all gear to performance edge). My SCC's provide 165A which is awfully "gentle" and easy on the packs as it is divided between them.
The BIG Q - Why so big with small solar (2080W & 2370W)... I use between 3.5-4.0 kWh per day (year-round) but in Winter I can easily see 10 days without any significant solar, so my reserve reflects that. Even if I have to use a Genset for 8 hours to charge my bank, 8 hours genset = just under 5 days battery runtime.
These Days (summer 2024) the Availability & Quality of cells has improved for several reasons which is a WIN for everyone ! There is no reason to not buy proper A-Grade Cells now that they are available at reasonable prices (cheaper than last years B Grades) and people CAN SHOP AROUND for the deals too while sticking to KNOWN GOOD VENDORS that have at least 3 years track record.
THE GOTCHA THAT GETS MANY !
Why Match & Batch ! Cells with a Lower IR will take charge & discharge faster that those with a higher IR. They will be runners within a pack and in fact the worst place for them is to be on Position 1, 8/16 (Batt Leads) as that WILL limit & handicap the packs. Matching & Batching ensures that cells collectively have the same IR whether at 3.000 or 3.200 or 3.400 regardless if Charging or Discharging.
SADLY most vendors only IR Match cells at the storage voltage as they received them.
Some Vendors use a 3rd party to Test & Validate cells (They usually charge extra for that)
Some other Vendors use the Manufacturer to complete the cycles (beyond just cell validation tests) & provide the manufacturers test reports.
TOP 10 LFP Makers as of MARCH:2024
BYD: https://www.byd.com/pc/
Ufine Battery (Guangdong Ufine New Energy Co., Ltd.): https://www.ufinebattery.com/
Contemporary Amperex Technology Co. Limited (CATL): https://www.catl.com/
LG Chem Ltd.: https://www.lgchem.com/main/index
Panasonic Corporation: https://na.panasonic.com/us/
Samsung SDI Co. Ltd.: https://www.samsungsdi.com/
CALB (China Aviation Lithium Battery Co. Ltd.): http://www.calb.cn/
Lishen Battery: https://www.lishen.com.cn/
Farasis Energy (Ganzhou) Co. Ltd.: https://www.farasis.com/
EVE Energy Co. Ltd.: https://www.evebattery.com/
-! Bold/Italics = Most common cells available from Vendors/Resellers selling to DIY & Others.
NON-Bolded = Generally unavailable to "Public" and therefore not easy to get.
