21/09/2020
Battery Life
The life of a battery is influenced by how many times you discharge and recharge it. It is rated at x recharge cycles.
What is key to making decisions around battery choice is understanding the relationship between DOD and recharge cycles.
DOD, short for the Depth of Discharge, is used to describe how deeply the battery is discharged. If we say a battery is 100% fully charged, it means the DOD of this battery is 0%, If we say the battery has delivered 30% of its energy and still has 70% energy reserved, we say the DOD of this battery is 30%.
The deeper you discharge a battery, the fewer times you can recharge before it may die on you.
If a distributor or reseller tells you that a battery has 2400 recharge cycles at 20% DOD then at 50% DOD it may only be able to recharge 800 times!
At axPi we believe that traditional deep cycle batteries should be evaluated and purchased at a 50% DOD rating. This means that when we do a design and an installation we would double the capacity that you calculate the building would need at night to allow for a 50% DOD.
However, Lithium batteries have changed the landscape for the better. Typically the Lithium DOD is 20% AND you have much more recharge cycles, thus giving you a longer lifespan. It has reached a point where it is cheaper per recharge cycle to purchase Lithium batteries. So far during 2020 axPi and Silverton Solar has only sold Lithium-based batteries.
The temperature will also affect battery life as it affects the chemical process inside the battery.
The ideal temperature for most batteries is between 19˚C and 32˚C.
