What batteries does a ModX2 use, and how long do they last?

ModX2 uses LiFePO₄ (lithium iron phosphate) battery modules rated at more than 6,000 cycles to 80% depth of discharge, in configurations of 5.12 kWh, 10.24 kWh or 15.36 kWh. At a typical daily cycle depth for a remote monitoring load, that cycle rating corresponds to a service life well beyond ten years.

LiFePO₄ is the right chemistry here for reasons specific to remote sites. It tolerates the daily partial cycling that a solar-charged system imposes, where a VRLA standby battery would degrade in three to five years. It accepts charge fast enough to make use of a short winter solar window. And it is the most thermally stable lithium chemistry in commercial use, materially different from the NMC and NCA chemistries used in electric vehicles, which is the comparison people usually have in mind when they raise lithium safety.

One genuine constraint to design around: LiFePO₄ must not be charged below 0 °C, because lithium plates on the anode instead of intercalating, permanently raising internal resistance. A quality battery management system blocks charging below that threshold. If your site experiences sub-zero mornings, the Southern Tablelands, Monaro, Alpine rail corridors, inland winter minima. This needs to be part of the design conversation rather than a surprise in year two.