E T X S E R I E S L I T H I U M B A T T E R I E S
1
Overview
EarthX’s ETX Lithium batteries are designed as a maintenance free replacement for the 12
volt lead-acid or lithium batteries. To ensure a smooth replacement process, ETX batteries
are similar in dimensions to many OEM motorsport or power sport batteries. The ETX
lithium battery consists of 4 Lithium Iron Phosphate (LiFePO4) cells in series and one or
more in parallel with built in electronics to protect the battery from over-discharge, over-
charge, balance the individual cell’s charge level, short circuit protection and temperature
protection to prevent overheating.
Failure to follow all application use, installation, charging, and storage instructions may result
in battery damage and or fire!
Technology Inside
Battery Cells
Our batteries use cells made of Lithium Iron Phosphate (LiFePO
4
). This chemistry is one of
the highest performance and safest on the market today.
Lithium batteries are fundamentally different than lead-acid batteries. A lithium battery
voltage remains relatively constant while discharging, while voltage for a lead-acid battery
decreases. A lithium battery’s storage capability is nearly 100% usable (measured as Amp-
Hour, Ah); while a lead-acid battery designed for motorsports typically only has 30% useful
storage. As such, 2Ah lithium battery has the equivalent “useable” capacity to a 6Ah lead-
acid. Also, a lithium battery’s cranking power is stronger, for the voltage while cranking is
generally higher. But when the lithium battery runs out of power it does so more abruptly.
LiFePO
4
cells by the nature of their chemistry are 3.3 volt. 12V lithium batteries are created
by using 4 cells in series (technically it is a 13.2 volt battery, but nominally full charge voltage
is >13.3V). Lead-acid batteries are also made with cells in series (6 cell). The difference is
that lithium cells are a dry cell technology, where the cells are packaged individually. In a
lead-acid battery the cells are package in the same case with an acid solution that supports
the transfer of charge from higher voltage cells to ones with a lower voltage. Lithium cells
cannot do this, so the cell’s charge level will diverge with repeated charge/discharge cycles
and age. This condition reduces the performance of the battery (reduces capacity), for the
battery charge level is only as good as the charge level of the weakest cell. Moreover,
charging a battery with unbalanced cells results in one or more cells reaching the maximum
charge (voltage) level before the rest of the cells in the series, which leads to over-charging
of the cell(s).
Battery Management System (BMS)
The ETX Lithium battery’s integrated BMS continuously monitors each cell’s voltage. If the
voltage of a cell exceeds the others, the BMS circuits will work to reduce that cell’s charge
