Post from Simon, Karrak Farms, Australia
Creeky says: I thought this was interesting, so I bring this to the attention of those who are interested in LFP batteries for offgrid power storage.
LFP compared to FLA
|LiFePO4||Flooded Lead Acid|
|Total Operating Voltage Range||14.4 – 11.2||15.5 – 10.5|
|Normal Operating Voltage Range, No Load||13.8 – 12.8 (90%-20%SOC)||15.5 – 12.0 (100%-50%SOC)|
|Normal Operating Voltage Range, C/8 Load||13.8 – 12.4||15.5 – 11.0|
|Normal Operating Voltage Range, C/2 Load||13.8 – 12.0||15.5 – 10.5|
|Max sustained charge rate||1C||C/8|
|Recommended sustained charge rate||N/A||C/10|
|Sustained discharge rate||1C||C/8|
|Lifespan||~10 years||~6 years|
|Warranty||5 year prorata (balqon)||5 year prorata (trojan)|
|Cost per kWh||~US$340||~US$130|
|Cost per usable kWh ($/kWh/cycledepth)||~US$523||~US$325|
|Cost per usable kWh per year||~US$52.30||~US$54.20|
What does it mean
What the specs show is a considerably higher charging efficiency for LFP. A longer life span. A smaller range of operating voltages (less sag, no need for high voltage to charge). Wider range of usable depth of discharge (this means LFP packs are usually sized 60-70% the amp hrs of FLA for the same usable power storage).
Also note LFP can handle much higher charge currents and deliver much greater discharge currents. Neat.
Costs over the long term seem pretty equal as well.
Background data derived from:
Trojan T105-RE from NAWS assuming 2000cycles@40% charge/discharge
Winston LYP cells from Balqon assuming 3650 cycles @65% charge/discharge