Battery System Model

Ralph Varckette

This battery system models the relationship between battery loads and available time based on Amp-Hours (unit of electrical charge). The battery has 120 Amp-Hours available and amp draw from individual loads can be changed to determine battery life.

The Amp-Hour rating tells you how much amperage is available when discharged evenly over a period. The amp hour rating is cumulative, so in order to know how many constant amps the battery will output for 10 hours, you have to divide the amp-hour rating by 10. Example: If a battery has an amp-hour rating of 120, dividing by 10 = 12.0 amps. Such a battery can carry a 12.0 amp load for 10 hours before dropping to the fully discharged level, at which point the battery needs to be recharged.

This model will simulate battery life with both steady and dynamic loads.

240 volt power system fed from 480 volt service

Electricity is not currently stored in electricity networks, so supply and demand are balanced - inflows must equal outflows. This simulates a simple substation with a variable demand by time-of-day.

The price of electricity depends on the mix of sources. In particular, balancing charges, which are incurred by the grid operator for instantaneous and near-instantaneous services required to balance supply and demand, are more expensive than electricity which is provided against predicted demand. PV increases variability, increasing the need for balancing services.

240 volt power system fed from 480 volt service

Adding consumer photovoltaics to the simple supply model increases the complexity of flows. In particular, flows can now be reversed (into the grid) through the transformer.