CHARGING BASICS

• Standard Charging:

• Charging at rates of 16-18 A/100 Ahrs
• 7-10 hour charge intervals
• 100% daily recharge
• Most suitable for single shift operation

• Opportunity Charging:

• Charging at rates of 25 A/100 Ahrs
• 4-6 hour charge intervals
• 100% daily recharge
• Suitable for extended shift (1.5 shift) operation

 

• Fast Charging:

• Charging at rates of 40+ A/100 Ahrs
• 1-2 hour charge intervals during week days
• 80%-85% daily recharge; 100% once a week
• Suitable for 2+ shift operations ? Eliminates battery changing

Fast Charging Technology

• Fast Charging Technology

• Charging at rates of 40% to 50% of battery Ahr capacity: 3 to 4 times conventional charging
• Recharging from 30% - 80% SOC in 1-2 hrs
• Frequently charging during breaks, lunches and at the end of shifts
• Operating with One battery per truck
• Distributed charging throughout the plant vs. centralized charging rooms

Fast Charging – Benefits

• Reduces number of batteries per truck

• 1 battery per truck vs. 2-3
• Less lead and acid under roof

• Eliminates battery changes

• Improves battery utility & truck performance
• Improves workers' safety

• Eliminates the need for battery rooms

• No battery room attendants
• No discharge to the environment

Fast Charging - Savings

• Labor cost impacts

• Eliminates battery changes: 15-30 min/shift
• Increases worker's productivity
• Eliminates battery room attendants:
• ½ workers / shift

•Safety cost impacts

• Reduces pedestrian/truck incidents near battery rooms (during shift changes)
• Eliminates dropped batteries due to changing
• Eliminates acid exposure with single point watering

Fast Charging Value Proposition

• Increase Battery (Asset) Utilization

• Batteries are used for 1 shift / per day (8 hours)
• Charging takes 8-10 hours
• Battery Utilization: 33%
• 2-3 batteries / truck are needed: $3000 – Z$4000 ea.

• Fast charging technology entails

• Only one battery per truck is needed
• Charging at much higher rates during breaks
• Reduced charging times: 1-2 hrs vs. 8-10 hrs
• 100% battery utilization

• Sequential /Parallel Charging

• Inflexible System

• Can't easily upgrade or expand

• Can't expand beyond main power server capacity
• Can't easily add, move or remove stations

• Susceptible to Single Point Failure

• All stations will be down if power server fails

•Average Power per Station is Low

• Can't ensure continuous high rate charging

Dedicated Charging

• Fast Charger Components:

• Single vehicle charge
• Distributed charging stations

• Premises: Battery and truck use is quite similar

• All batteries need max power at the same time

Dedicated Charging – Facts

• Very Flexible System

• Can be easily upgraded or expanded
• Easy to add, remove, and move to new locations

•No Single Point Failure

• Only one failed unit at a time
• Remaining chargers are still available

 

• Average Power per Station is Very High

• Charge each battery at maximum rate

High frequency (HFC) Charging

• The battery charging industry is dominated by:

• Ferro-resonant chargers (Ferro Chargers)
• SCR Chargers

• These technologies are characterized as being:

• v Basic Technology --> Heavy and bulky
• x Have limited electrical performance
• x Lowe Efficiencies & Power Factor
• x High kW Demand Usage --> High energy bills
• x High AC ripple --> Higher battery temperatures

Charger Efficiency:

• Efficiency: the ratio of Output to Input power
• The difference between input and output power is “wasted power” --> Heat

Energy Costs – Basics

• An end user's energy bill consists of:

• KWhr energy cost
• Demand kW distribution & supply costs
• Contributes more than 50% of the energy bill
• Billed at much high rates during peak hours

Typical Electric Billing Rates

HF Charging – Benefits

• Higher charging efficiencies:

• Lower energy bills (10%-20%)

•Higher power factor:

• Lower AC current draw
• Smaller circuit size (20%-40%)

•Lower kW Demand:

• Lower demand kW billing rates
• Reduced energy costs

• Reduce KWhr energy use by 10% or more

• 10%+ utility bill savings

• Actively manage demand kW

• Stagger Chargers – Reduce peak power use
• Charge during off peak hours
• Limit maximum charger output power

• Integrated opportunity charging capability

• Easily adaptable to changing work load needs

Fast charging has attracted new suppliers to the market and nearly anyone with an electrical engineering degree can design a charger, BUT:

Will it charge the battery?

Will they be around 5 years from now?

How will they support it?”

Do they understand the application?

Is their charger approved by the battery vendor?

Can they also supply conventional chargers?

• Flexibility – one charger does it all

• Conventional Charging
• Flooded and sealed lead acid batteries
• Opportunity charging
• Rapid charging
• Multi-voltage & Multi-ampere hour
• 6, 12, 18 and 24 cell
• 12, 18, 24, 36 and 40 cell

•Temperature Compensation

• Interactive temperature compensation
• Battery temperature monitored by BID
• Maximize battery life
• Most battery manufacturers require some sort of temperature management

•Charging Options

• Three basic charging regimes
• Conventional charging
• Charge rates of 16-20A/100AH
• 8 hour recharge time from 0-100%
• Opportunity charging
  • Charge rates of 21-35A/100AH
  • 3 hour recharge time from 20-80%
• Rapid or Fast Charging
  • Charge rates of 36-50A/100AH
  • 2 hour recharge time from 20-80%

•Power Quality Management

• Efficiency – the ratio at which the charger converts AC Power to DC Power, the higher the efficiency, the less energy cost per charge cycle
• Power Factor – the ratio of real power to apparent power
• Total Harmonic Distortion – the ratio of the sum of powers of all harmonic components to the power of the fundamental.

Power Quality Efficiency

One of the inherent characteristics of a well designed high frequency charger is higher efficiency

Power Quality

• An electrical device can draw current from the grid in almost any shape. It can be a “pure” sine wave that matches the line voltage shape perfectly, or it can be drawn in an irregular wave form that has gaps, sharp corners or high peaks.

When the current wave shape is a pure sine wave that matches the pure sine wave voltage provided by the utility, it is like putting a round peg in a round hole; you can use all of the capacity available. When the current wave shape is irregular, it is like putting a square peg in a round hole; you have to shrink the size of the peg to make it fit, leaving gaps that are not filled by the square peg. You are unable to use all of the capacity available.

Cost Analysis

Many factors will affect the cost effectiveness of opportunity rapid charging in any given application including: