The SOC is defined as the available capacity expressed as a percentage of some reference, sometimes its rated capacity but more likely its current (i.e. at the latest charge-discharge cycle) capacity but this ambiguity can lead to confusion and errors. It is not usually an absolute measure in Coulombs, kWh or Ah of the energy left in the battery which would be less confusing.
there are 3 methods for measuring the SOC of battery so far these include the following
there are 3 methods for measuring the SOC of battery so far these include the following
1) voltage method
measures the voltage gained by battery in charging by the charger provided. i have already tested that and the results are plotted in a graph.
It suggests to charge the battery up to 85 percent to save time during random chargings.
2) hydrometer
this method is good but is not applicable for our phantom because it demands a wet acid battery. phantom uses a LI-PO battery so it fails.
3) colomb counting
coulomb counting includes measuring the charges transfered to the battery during charging . this method is the most recommendable for us .
there are again three ways to measure the coulomb count.
- Current Shunt:
- The simplest method of determining the current is by measuring the voltage drop across a low ohmic value, high precision, series, sense resistor between the battery and the load known as a current shunt. This method of measuring current causes a slight power loss in the current path and also heats up the battery and is inaccurate for low currents.
- Hall effect:
- Ttransducers avoid this problem but they are more expensive. Unfortunately they can not tolerate high currents and are susceptible to noise.
- GMR:
- magnetoresistive sensors are even more expensive but they have higher sensitivity and provide a higher signal level. They also have better high temperature stability than Hall effect devices.
