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Anyone know about how much electricity it takes to charge a PEHV over night? What's it comparable to? a TV? a 100w light? ??

I need to know for an argument I am having with someone saying the power grid cant handle plug-ins.

I thought I saw somwhere a study about how at night the power company decreases output due to the lower demand.

Here's a thread about a PHEV conversion kit: http://www.cleanmpg.com/forums/showthread.php?t=14942&highlight=hymotion

Some rough in-head calculations show about 5 KWh total used. (1.5 hours per x-axis mark) That's like 16.7 60-watt bulbs running for those same 5 hours, or 7 bulbs running 12 hours all night. Some people use more power than that to light up their trees and bushes. :rolleyes:

That's only a 7.5% increase over my average power consumption, which is already below the national average, despite having Texas AC and electric heat, cooking, and water heating.


Here is a better graph of the charging process from a depleted pack. The first two hours the pack sucks down a little over 1000 watts and about 10 amps. Then the next three and a half hours it will suck down about 950 watts and 8.5 amps. Then the rest of the time it will suck down about 22.5 watts and .26 amps for what I guess is for cooling down the batteries. Once the cool down period is finished the amp draw is 0 according to my watts up? meter but it still shows about 3.5 watts being drawn.

These two graphs represent about 12 hours of time.

Watts
http://jaygroh.dreamhost.com/priuschat/brem/chargwatts.png

Amps
http://jaygroh.dreamhost.com/priuschat/brem/chargeamps.png

I think your answer is going to be yes and no, depending on the variables....
If everyone plugged their car in at the worse time, then the grid would have problems.
Even at the lowest point in the night, if everyones car started charging at the same time, you could still have issues, but if you can stagger them over the low draw period, the grid should be able to hold up now. That would mean that we would be much closer to capacity 24/7. That would be bad as electric companies would be harder pressed to take down systems for maintance. And image a heat wave across the country where even A/Cs set at 78 run 100% day and night. I'm not sure the grid could even handle that without the cars. So, any chance of telling us the whole bet?

A couple of things to consider. The grid gets stressed in two situations that I know of.

The first is during a hot summer day. So any midday charging of significant numbers of Phevs could be a problem. This seems to be the time of day/year when I most often hear the local power company asking people to cut back on their electric usage.

The second problem time is during very cold winter nights. I don't think this is a big an issue as the first one, but could present problems in areas that use lots of electricity for heat.

Most electric dryers consume ~5 KW when running.

The Hymotion pack consumes ~1 KW when charging.

An EV with 5x the capacity (~100 miles electric range) could charge using the same amount of power as running a dryer (power, not energy... charging the pack would take longer).

Most microwaves are greater than 1 KW.

I think the demand issue would come about after some electric cars have been on the road for a few years. Right now it is all theoretical.

We are only now seeing a switch over to smaller cars, this took high gasoline costs to create.

Initially, the only drivers of plug ins will be the ones willing to sacrifice getting a short range vehicle. They will be used as a daily commuter/short trip type of vehicle.
If they are proven to be a viable alternative, some % the masses will switch.

Some people will not give up the gas burners until there is no more gas.

A couple of things to consider. The grid gets stressed in two situations that I know of. ... The first is during a hot summer day. ...
The second problem time is during very cold winter nights. ...

When I was a young engineer in college, peak demand was in cold weather -- 7 to 9 am in February in Northern climate zones. Since then, heat has taken over -- 3 to 6 pm in August in Southern climate zones.

Any widespread move to PHEVs is likely to happen with (or after) more widespread time-of-day metering, or real time pricing, or load-leveling control from the utility to shut down certain heavy loads when demand gets too high. All of these exist now, but are not common for residential accounts.

I'd hope that soon the battery chargers will have adjustable charge rates, so the user can select the slowest charging that produces the needed charge. At the moment there is little incentive for this.

Most electric dryers consume ~5 KW when running.

Just to clarify that...that's a clothes dryer. A hair dryer (which was my first though despite the fact I don't use one), is about 1.5kWh which is just a little under the max power an appliance can pull through a standard 15amp home breaker.

It seems to me like a good idea to use a lower charge rate for a longer time. In the case above, charging at 500 watts for the whole night, instead of 1000 watts for 1/2 the night. I wonder if there could be a feature to adjust the charge time. If you need it charged sooner, it'll go with the max, but if you're home all night, let it go slowly. That would reduce the momentary demand on the grid.

To actually answer the original question, for your average 40
mile or less daily commute, about 10 KWh. At whatever rate,
i.e. instantaneous current draw, one chooses. You still have
to get the requisite energy onboard the car one way or the other.
.
For some, that's a minor percentage of their home's daily intake.
For others, it would nearly double their electric consumption.
Either way, in sufficient numbers the grid would definitely
start feeling the effects regardless of what time of day it is.
.
The whole "charge at night" thought is flawed because people are
going to charge whenever they feel like it. But "charge at
work" coupled with midday A/C loads is another good argument
for widespread PV deployment, even if the sun doesn't shine at
night.
.
_H*

The whole "charge at night" thought is flawed because people are
going to charge whenever they feel like it.

That's what smart power grids are all about. Even the simplest way to implement...charging more $ at peak hours than off hours, will have an impact. If people can save $25 or more a month, they will pop for a timer. Plug their car in when they get home, but the timer starts your charging at midnight and stops charging at 6am. Just like high gas prices, it can effect consumer choices.

Just to clarify that...that's a clothes dryer. A hair dryer (which was my first though despite the fact I don't use one), is about 1.5kWh which is just a little under the max power an appliance can pull through a standard 15amp home breaker.

1500 W would be the old-standard hair dryer -- gutless and underpowered for the modern world.

Unfortunately, the market has embraced the "more is always better" mantra and gone the FSP route. Nearly all the models on the shelf this year are 1875W, just barely below the NEC limit for 20 amps breakers (80% of 20A*120V). I have refused to allow such a unit into my house because it won't have a dedicated circuit. It needs to share a circuit with other loads (two bathrooms of lights, fans, and a heat lamp), and 1875W puts that branch over the NEC limit.

The few hair dryers on the shelf not marked as 1875W are those that don't disclose power at all on the external packaging.

It seems to me like a good idea to use a lower charge rate for a longer time. In the case above, charging at 500 watts for the whole night, instead of 1000 watts for 1/2 the night. I wonder if there could be a feature to adjust the charge time. If you need it charged sooner, it'll go with the max, but if you're home all night, let it go slowly. That would reduce the momentary demand on the grid.

Batteries also charge more efficiently at lower rates than at higher rates. Higher current always equals more resistive loss.