REFERENCE
POWERmini USB User Guide 2.1.0A
12
350-00103-5
Battery Health
A healthy battery has a low internal resistance. Internal resistance causes the battery terminal voltage to
fall as the load current increases. You can see this effect in real time by viewing voltage bar on the
POWERmini USB status screen (Figure 8). When you key up the transmitter, the increase in load current
(relative to receive current) will cause the battery voltage to fall. A small reduction in voltage is normal,
but if the voltage drop is excessive it is an indication that the battery is either under-sized, or, has high
internal resistance.
Another more dramatic problem that causes the battery voltage to fall dramatically on load results when
one (or more) of the battery cells is damaged. An unfortunate aspect of having a defective cell is that
during the charge cycle the remaining cells will become overcharged. For this reason, battery chargers
(including POWERmini) will not charge a 12V battery if the total battery voltage is below 10V.
If you have a battery that has an abnormally low terminal voltage, then you may be able to recover it by
using a very low charge current for a short period of time. This is known as trickle charging. If the terminal
voltage can be brought over the 10V limit then you can continue charging it normally.
Battery Settings
CAUTION: Always follow the battery manufacturers recommendations for maximum charge voltage. Note
that the default factory settings for maximum voltage are generic. You should consult the specific voltage
settings from the specific battery that you are using.
Setting the maximum charge setting too high may result in damage to the battery, while setting the
voltage too low will mean that the battery will not reach the 100% charge point.
Battery Management Systems (BMS)
IMPORTANT NOTE: Some batteries are equipped with internal intelligent battery management systems
(BMS) which have a strict maximum voltage limit which should not be exceeded.
Batteries with BMS may disconnect power internally if the maximum voltage is exceeded shutting down
the complete power system.
