Any electric car that uses batteries needs a charging system to recharge the batteries. The charging system has two goals:
- To pump electricity into the batteries as quickly as the batteries will allow
- To monitor the batteries and avoid damaging them during the charging process
The most sophisticated charging systems monitor battery voltage, current flow and battery temperature to minimize charging time. The charger sends as much current as it can without raising battery temperature too much. Less sophisticated chargers might monitor voltage or amperage only and make certain assumptions about average battery characteristics. A charger like this might apply maximum current to the batteries up through 80 percent of their capacity, then cut the current back to some preset level for the final 20 percent to avoid overheating the batteries.
Some systems give you the option of 120-volts from a normal electrical outlet or 240-volt power. The advantage of going with the higher voltage and or higher amperage is the charging time. A normal household 120-volt outlet typically has a 15-amp circuit breaker, meaning that the maximum amount of energy that the car can consume is approximately 1,500 watts, or 1.5 kilowatt-hours per hour. If the battery pack normally needs 12 to 15 kilowatt-hours for a full recharge, it can take 10 to 12 hours to fully charge the vehicle. By using a 240-volt circuit the car might be able to receive 240 volts at 30 amps, or 6.6 kilowatt-hours per hour. This higher voltage allows significantly faster charging and can fully recharge the battery pack in four to five hours.
The cost from the PG&E is the same whether you are using 120 volts or 240 volts to charge your batteries, the only difference is the charging time. However, PG&E does allow homeowners to have a second electric meter installed, dedicated to only the car charger. The advantage of the second meter is that power is calculated at a lower rate than your standard meter. This is a reward or incentive from PG&E for home owners making conscience green decisions and investments. So depending on the cost of the electrical upgrade, this might be a money saver in the long run. Give us a call and we can discuss which option is right for you.
