Data Sheet

BMS10x0
14 www.roboteq.com Version 1.0 March 2, 2018
during charging in a significantly cold environment or makes charge/discharge safer in hot
environments.
Fan or Heater
FIGURE 14. Configuration for Guaranteed Temperature Balance
State of Health
The State of Health in a battery is a vague measurement to infer its wellbeing. In other
words, there is no exact way to specify how many years or days the battery has left until
one of its cells fail.
The BMS10x0 provides the user with the total Charge/Discharge cycles counted from
the first time the pack was connected to the system. Based on the manufacturer’s
specifications as a reference, this may be used as a first indication for the battery’s State
of Health. Not all cell manufactures provide the client with statistics about the typical
endurance of their cells. This is due to the fact that it requires many tests and depends on
the circumstances under which the cells operate.
Another indicator is the nominal capacity vs the actual capacity of the battery. As the
cells age their capacity drops. The BMS10x0 corrects the max capacity variable when
charging and discharging. It also informs the user when the real capacity is significantly
lower that the nominal. When measured capacity reaches 50% the nominal value, the
State of Health is considered to be 0%. SoH 50% corresponds to real capacity and 75%
the nominal. If any of the cells are defined as “dead”, SoH is also considered to be 0%. A
cell is considered “dead” when it is unable to store energy any more or has dangerous
behavior, like constantly overheating during Charge or Discharge. A “dead” cell would
make the system cut off either the Charge or Discharge process long before the other
cells reach their limits. As such, the battery will not be able to delivery nor store energy.
The battery’s charge/discharge cycles are counted as the number of times the battery
delivered energy equal to its nominal capacity. For example, a 10 Ah battery is considered
to have made a charge/discharge when the total of 10 Ah was delivered. In other words,
if a battery that is 100% charged reaches 90%, this gives a total of 10% the nominal