1 Battery with Internal Resistance Circuit

You have a battery with an open-circuit voltage of 50V and an internal resistance of 0.1 ohms. You connect this battery to a resistor with 0.5 ohm resistor.

  • Draw a circuit diagram for this situation
  • Calculate the current and voltage for the 0.5 ohm resistor (hint: this is a voltage divider)

2 Battery with Internal Resistance IV Curve

You have a battery with an open-circuit voltage of 50V and an internal resistance of 0.1 ohms. You connect this battery to a resistor with 0.5 ohm resistor.

  • Draw one IV curve for the battery model (ideal voltage and internal resistance)
  • Draw one IV curve for the load resistor resistor
  • Estimate the current and voltage for the resistor from the intersection
  • How is this different from the ideal battery (internal resistance of 0.0 ohm)

3 Battery 4s1p

We have a single string (1p) of four cells in series (4s) to create a 4s1p battery. Each of these cells has a voltage of 3.6V, a capacity of 3000 mAh per cell, an internal resistance of 50 mohms, and a maximum continuous current of 15 amps.

  • What is the total voltage of this battery?
  • What is the maximum current this battery can deliver safely?
  • What is the amp-hour capacity of the battery?
  • What is the energy stored in the battery?
  • What is the peak power the battery can deliver safely (disregard the internal resistance)?
  • EC: What is the internal resistance of the battery?
  • EC: What is the short circuit current of the battery?
  • EC: What is the peak power the battery can deliver (you can disregard the maximum continuous current)?

4 Battery 1s4p

We have four cells in parallel (4p) to create a 4s1p battery. Each of these cells has a voltage of 3.6V, a capacity of 3000 mAh per cell, an internal resistance of 50 mohms, and a maximum continuous current of 15 amps.

  • What is the total voltage of this battery?
  • What is the maximum current this battery can deliver safely?
  • What is the amp-hour capacity of the battery?
  • What is the energy stored in the battery?
  • What is the peak power the battery can deliver safely (disregard the internal resistance)?
  • EC: What is the internal resistance of the battery?
  • EC: What is the short circuit current of the battery?
  • EC: What is the peak power the battery can deliver (you can disregard the maximum continuous current)?

5 Battery 2s2p

We have two series sets (2s) of two cells in parallel (2p) to create a 2s2p battery. Each of these cells has a voltage of 3.6V, a capacity of 3000 mAh per cell, an internal resistance of 50 mohms, and a maximum continuous current of 15 amps.

  • What is the total voltage of this battery?
  • What is the maximum current this battery can deliver safely?
  • What is the amp-hour capacity of the battery?
  • What is the energy stored in the battery?
  • What is the peak power the battery can deliver safely (disregard the internal resistance)?
  • EC: What is the internal resistance of the battery?
  • EC: What is the short circuit current of the battery?
  • EC: What is the peak power the battery can deliver (you can disregard the maximum continuous current)?

6 Connecting Batteries

You have two ideal batteries connected as shown in the schematic below. Battery V1 is charged to 4.0V and battery V2 is charged to 3.8V and the resistor is 1 ohm. When you close the switch,

  • What is the magnitude of the current?
  • In which direction does the current flow?

7 Battery Short Circuit

Assume that you have a battery charged to 50 volts with an internal resistance of 60 milliohms. What current flows if you put a short circuit across the battery terminals?

8 Battery Internal Resistance

You have a 14s5p battery made out of cells with a 4.0 V open circuit voltage, a 15 milliohm internal resistance, and a 45 amp maximum continuous discharge current.

  • Sketch the voltage versus the current of the battery.
  • What is the short circuit current of the battery?

RQ 1

Read chapter 4, “Battery Pack Design Criteria and Selection” from “The Handbook of Lithium-Ion Battery Pack Design” and answer the following questions.

  • How do you see the concept of series being used?
  • How do you see the concept of parallel being used?
  • Why are these concepts important for the battery design?

RQ 2

Read chapter 8, “Battery Management System Controls” from “The Handbook of Lithium-Ion Battery Pack Design” and answer the following questions.

  • What are some important functions of a battery management system?
  • Many folks run batteries without a BMS, what would you be most concerned about?

RQ 3

Read chapter 10, “Thermal Management” from “The Handbook of Lithium-Ion Battery Pack Design” and answer the following questions.

  • Why is it important to remove heat from a battery pack?
  • Why might you need to add heat to a battery pack?

RQ 4

Read the 2018 Wired article, “The Spiralling Environmental Cost of our Lithium Battery Addiction” and answer the following questions.

  • What are the materials in lithium-ion batteries that create social or environmental problems?
  • What sorts of problems are created by these materials?

RQ 5

Chapter 14, “Second Life and Recycling of Lithium-Ion Batteries” from “The Handbook of Lithium-Ion Battery Pack Design” and answer the following questions. “The Handbook of Lithium-Ion Battery Pack Design”

  • Which of the strategies for reducing lithium-ion battery waste do you find most attractive and why?