240V Charging More Efficient Than 120V?

[Andrew00]

Is it? In either case the voltage has to be boosted to reach a voltage level of about 300V+ in order to charge the battery. Boosting voltage always entails losses but since 240V charging doesn't have to go as far, one might conclude that the losses would be less.

[dwl]

Yup. I haven't specifically tested it myself. But you're on the right track. There is overhead inherent to charging. And losing that overhead for a shorter period of time makes 240v charging a bit more efficient than 120.

[mikeg3]

I think they boost the AC voltage, then convert to DC. AC voltage changes are nearly loss-free. That's why AC won over DC in the first place.

As a power feed, the higher the voltage the lower the losses. That's why long distance transmission is done at high voltage. However, I don't think a few feet make too much difference.

The comments by GM about a more consistent charge at 240V are hard for me to understand. It's the car, not the charger, that decides when to stop charging.

[Slapshot28]

When electrons flow, they generate heat. This is more proportional to amperage (electron flow) than to voltage (electron pressure). In both the 240V and 120V cases, amperage is roughly the same, so the rate of heat generation is roughly the same. BUT heat loss goes on twice as long in the case of 120V charging. As a result, 240V charging has less overall heat loss (same rate, half the time) and thus is more efficient.

[wizkid057]

240V charging is definitely more efficient, as an owner of both the standard and a 240V charger.

The 120V charger seems to pull, on average, about 13.7 kWh from the wall. The 240V charger seems to pull, on average, about 12.4 kWh from the wall... a good 10% more efficient.

-wk

[raj7]

I have voltec 240 v, after the charge how much electricity does the charger and car use if left for overnight plugged in

[MichaelM]

I charge my Volt on 240V. I taped the charger plug to the wires behind my stove. Sometimes I need to wiggle it to charge the Volt. 240 means I have more volts in my battery and it goes faster. My Volt is also faster than yours because it is Red and electrons like Red more. This is why battery terminals are Red because Red helps attract more electrons. This is called the law of magnetic attraction and I learned this on answers.com. Also if you charge at 480V it automatically gives your Volt four wheel drive.

Okay, now really: Who just spit up their coffee?

Thank you, thank you. I'm here all week, folks. Don't forget to tip your waiters and waitresses.

[MichaelM]

But seriously, folks..

I do understand that the voltage conversion losses are somewhat smaller with 240v (Level 2) compared to 110 V (Level 1). As noted earlier, there is also less waste heat (if nothing else, due to the shorter charging time) with 240v charging.

Moving to higher amp Level 2 or Level 3 charging on the Volt would reduce charging time even more, but as Nissan has been forced to admit, charging only at Level 3 on the Chademo charger is less than optimal for cell life.

That said, look for more Level 3 chargers in the wild in coming years.

[Top_Speed1]

With the above statements here and on other sites about slow vs. fast charging, I come up with a simple trade off
-faster charging is well faster and slightly more efficient.
-slower charging is better (longevity speaking) for the battery cells.

...just like life in general, faster is not always better. (and this is coming from a guy named Top Speed! lol)

[sinnombre]

I spoke with a rep at SPX and she told me the standard charger is 12 amps @ 120 V , the 2011 Volts can take a max of 16 amps @ 240 V and 2012 models can take 22 amps @ 240 V . If this is accurate , isn't that close to 5 kWh ?