Many systems in the realm of RV have a severely limited ability to recoup their daily loads. One of the biggest limiting factors in these systems is roof space for a suitably sized PV array. By utilising one of the least emphasised beneficial characteristics of LiFePO4 you can yield more power daily from the same sized array.
As you know SLA batteries require a multi stage charging algorithm to obtain 100% SOC. Which means that the charger really only can supply its rated current for around 80% of the batteries capacity. Sure it is only missing 20% of its capacity but if but if this battery is being charged at .1C you are looking at close to seven hours of reduced charge rate and say you are only discharging the bank to 50% SOC this means that 20% is now 40% of charging cycle.
Unlike its SLA cousins the LiFePO4 will accept close to 100% of the available charge current almost to 100% SOC. This in itself allows a large gain in possible solar yield with the same sized array.
Most people will agree when I say the cost of a LiFePO4 battery is an expensive option for an energy management system but you will find the majority of the cost lies within charging/management equipment and labour. If you look at cycle life vs price the LiFePO4 Comes out on top.
100Ah AGM = $300 with an approximate cycle life at 50%DOD of 500 cycles, $0.60 per cycle
100Ah LiFePO4 = $1785 with an approx. cycle life at 50%DOD of 5000 cycles, $0.36 per cycle
As you all know a LiFePO4 charger is essentially just a two stage charger. Most of the big name chargers are compatible with LifePO4 these days so generally you would be using the same chargers that you would normally be quoting. Even some of the older regulators are compatible by utilising programming options such as some of the Plasmatronic gear. Many of the DC-DC chargers on the market now support a LiFePO4 charging profile such as BCDC1225D, BCDC1240D and the EN3DC40+.
LiFePO4 also comes with significant weight advantages for example a 100Ah AGM is around 30KG when a 100Ah LiFePO4 is only 15KG so you are looking at a 50% weight reduction. We all know how important weight savings are in a RV environment.
Thank you for reading another “Know Your Products” update by Adam Griffith.
If you have any questions or comments please discuss with other staff members or email me.