I am in the process of re-visiting this technology. At present I have two 100 AMP AGM batteries and wish to increase my capacity. My existing batteries are only 15 months old and one appears to perform a little better than the other which in turn creates issues with my charging systems - They tend to be fooled into reducing the charge before the batteries are full. AA Solar have two options available to me. 4x 6v 260amp AGM's around $1200 plus cabling and install. (5 year pro-rata warranty) The second option that I am seriously considering is a 200amp LiFePO4Y battery which will provide a similar capacity with a considerable weight advantage and a hefty price disadvantage
The long term performance benefits would appear to make the extra investment worthwhile, not to mention the reduced weight and the 10 year warranty.
Below is some info cut and pasted from the AA Solar website http://www.aasolar.co.nz/AA%20Champion% ... s.html#GEN
At 3.3V per cell, a package of 4 cells can replace a traditional 12V lead acid battery. We can supply the best charger or solar controller to suit the requirements of the system voltage that you need to run.
Unlike standard lead acid type batteries which have a charge efficiency of 88%, LiFeYPO4 batteries are over 98% efficient. Their voltage remains almost unchanged down to 80% discharged state. They can be discharged 70% 3000 times with no loss of capacity. Discharging by 70% 5000 times results in < 5% capacity loss, and 7000 times results in < 10% loss.
LiFeYPO4 batteries are very safe. They won't leak, and don't emit explosive gasses. They are ideal for electric vehicles, mobile homes and boats. Their long life also make them superior for house use as well.
See below for the conditions on our 10 YEAR WARRANTY.
Yttrium is found in most rare earth minerals, as well as some uranium ores, but is never found in nature as a free element. About 31 ppm (parts per million) of the Earth’s crust is yttrium making it the 28th most abundant element there, and 400 times more common than silver.