Why we specify LFP over NMC on weak grids

Battery specifications are usually compared on capacity, because capacity is the number on the datasheet that everyone recognises. On a weak grid it is close to the least useful number to compare on.

How hard the battery works makes the difference

A backup battery in a stable market sits fully charged for months and discharges a handful of times a year. The same battery on a Ugandan commercial site may be called on several times a week. It is doing the work of a cycling battery while being sold as a standby battery, and it will age like a cycling battery.

That is why we write our specifications around cycles, meaning full rounds of charging and discharging, and ask how many useful cycles the battery will still have in year eight.

Thermal behaviour, in a climate that does not help

Heat ages cells, and a plant room in Kampala is not a temperate basement. Lithium iron phosphate (LFP) is more thermally stable than nickel manganese cobalt (NMC). It only reaches thermal runaway, the chain reaction in which a cell overheats uncontrollably, at a higher temperature, and it fails more gently if it does get there. On a site where the battery lives in a warm room next to production, that margin is worth more than the extra energy density NMC offers.

NMC wins on energy density, meaning it stores more energy in less weight and space. In an electric vehicle that is decisive because weight and size are the binding constraints, but in a plant room floor space is rarely what limits us.

What the specification actually protects

Chemistry alone does not deliver service life. Deep discharge, high temperature and hard cycling all age a battery regardless of what is inside it, so we set a minimum charge level the battery is never drained below, monitor temperature continuously and configure charging to protect the cells rather than to hit a headline charge time.

The batteries we build with carry a 10-year product and performance warranty and typically last 12 to 15 years in service. Over a 25-year system life, that means planning for one replacement. A specification that ignores duty cycle and thermal exposure turns that single replacement into two, and the second one lands on the client rather than on the warranty.