Battery Knowledge - Skyrc MC3000 Instruction Manual

BATTERY KNOWLEDGE

What Does 0.5C, 1C, -C/4, etc. Mean?
It is a short way of specifying charge transfer rates as function of battery capacity. Substitute
the nominal capacity for "C", divide by 1h, then multiply with the factor.
For example:
0.3C for a 2100mAh battery equals a charge rate of 630mA or 0.63A (=2100mAh/1h * 0.3 ).
-C14 or -0.25C for a 3400mAh battery equals discharging it at 0.85A.
Choosing The Right Charging Rate
Rechargeable Li-batteries: Battery manufacturers define the so-called "standard charge" most
often as a 0.5C charge at room temperature. The user is advised to look up the confirmed details
in the battery specification sheet.
Rechargeable Ni-batteries: Charging too fast may damage the battery and not charge as fully,
whereas charging too slow requires longer time and may prevent the charger from terminating
correctly. Hence charging at a rate below 0.3C or above 1.0C is not recommended unless
otherwise indicated. In case of doubt, adhere to indications on the battery wrapper, look for the
spec sheet, visit candlepowerforums, or call the battery manufacturer and ask for the optimal
charging rate.
Choosing The Right Discharging Rate
The battery industry defines the so-called "standard discharge" as a controlled constant current
-0.2C discharge at room temperature. Per definition, discharging a fully charged new battery
under these conditions will yield its nominal capacity. Furthermore, battery manufacturers often
list minimum or rated capacities at higher, more typical discharge rates such as -0.5C or -1C in
the specification sheets. Yet a more common practice for analyzing and comparing batteries
from different sources is to always assume the same fixed discharge current, -0.5A or -1.0A, i.e.
decoupled from the nominal capacity.
Battery Matching
As a general rule, do not mix batteries of different types, different capacities, different voltages,
or from different manufacturers in a multi-cell application. Use the Refresh mode to determine
capacities of the same battery product, then pair up or group matching cells within ±5% of the
measured capacity. Unmatched batteries in a multi-cell application can lead to reduced
performance or runtime, or ultimately to battery damage, over-discharge or reverse polarity.
Battery Forming Charge
NiMH/NiCd batteries, new or stored for extended period, can become chemically deactivated.
Battery Forming Charge is a Charge-Discharge-Charge cycle which forces a full charge into the
battery at a very slow rate. This process reactivates the battery. In certain cases, it needs to be
repeated two or three times. Battery forming charge can be emulated by using the Break-In
mode with the C>D>C sequence. For very best health and condition though, cycling two or
three times at standard charge/discharge rates may be more effective.
MC3000 Manual Rev. 1.13
Page 17