jargon
- LiPo - Lithium-ion Polymer
- NiMH - Nickel-Metal Hydrid
- Discharge Rating
Capacity
Capacity is denonted in milliampers hours (mAh) on the battery. It is the amount of charge stored in the battery. If you have a battery with a capaciy 1 mAh and a motor is drawing 1 mAh then your motor will run for 1 h. In general the \textit{approximate} duration of a battery can be computed by:
\[\mathrm{duration} (h) = \frac{\mathrm{capaciy(mAh)}}{\mathrm{load (mA)} }\]If you have a 4700 mAh battery and it is powering a moter with a 100 mA load, it will keep runing for approximatly 47 hours. reference
Discharge
Battery bank
Combination of multiple batteries reference
- joined in series: voltage increases, capacity remains the same.
- joined in parallel: voltage remains the same, capacity increases.
- series and parallel: both voltage and capacity increase.
A guide to understanding battery specifications
Pixhawk 2.1 battery stuff
- Max continuous current sensing: 30A
- Max burst current: 100A
- Connectors: XT-60
Electricity
-
Ampere: A - base unit. Attractive/repulsive force of \(2 \times 10^{-7}\) Newtons between two wires 1m appart is the definition of \(1\,\mathrm{A}\). \(1\,\mathrm{A} = 1\,\mathrm{C} / 1\,\mathrm{s}\)
-
Coulomb: C - charge transported by a constant current of 1 A in on second. \(1\,\mathrm{C} = 1\,\mathrm{A} \cdot 1\,\mathrm{s}\)
-
Electrical work is the work done on a charged particle by an electric field.
-
Watt : W - power. \(1\,\mathrm{W} = \frac{1\,\mathrm{N} \cdot \mathrm{m}}{\mathrm{s}}\)
-
Volt: V - pressure
-
Ohm: \(\Omega\) - electrical resistance
voltage
\[V = \frac{\mathrm{potential energy}}{\mathrm{charge}} = \frac{N\cdot m}{C}\]Ohm
- Ah - ampere hour
- mAh - milli ampere hour