Cigarette Lighter and MPG

I don't believe the little bit of power that device is going to pull will affect the MPG. You do realize it will only work when the Prius is in "Ready" mode, accessory mode, or ignition on mode. If the Prius is powered down the blue tooth will not work when plugged into the 12 volt outlet in the console.

 

Of source everything that you plug in will affect your MPG. But depending on actual power consumption of the devise, your average speed and consumption effect will only be something like 0.1 to 0.002MPG.

 

Technically, yes... since it consumes electricity, that electricity has to be generated from the car -- ultimately in the form of fuel being burned.
In practice though, it consumes so little power that there's no way you could reasonably calculate and observe the difference in MPG.
I assume your plan is to plug the 3.5mm jack into the Aux input in the armrest? It's not clear in the description if that jack is an input or output.

 

On a trip to California from Michigan I used a large Igloo cooler. I tested the current flow from a fully charged 12V battery and the cooler consumed 3.75 amps current. That is 45 watts. I also ran a 400 watt inverter to run my laptop computer. That power supply uses .5 amps @12 V = 6 watts. so for for the cooler + HP laptop is 45 + 6 = 51 amps.
The car will supply 100 amps so the inverter + cooler is eating slightly over 1/2 the available watts.

The result was it worked well, but the current draw was large enough to load down the charging of the HV battery. After several hours of driving I found it harder to maintain 50 mpg. It settled in at 45-46 mpg. the battery SOC (state of charge) dropped to 5 bars and lower. I usually lost charge going up those long mountain roads on the expressway. With the cooler on the rebuilding of the battery charge was reduced and would never get back to 6 bars.

6 bars is the optimum charge to get the best mileage.

The solution is to unplug the cooler and drive without the load it imposed. You can plug it in later if needed.

My ride is a 2004 Prius base vehicle.

 

I'm going to go through the calculations for giggles. But before I do, I predict the difference is nothing.

EPA says the energy in 1 gallon of gas = 33700 Wh.
A random BT car adapter on Amazon uses 0.5 W.
For comparison, a standard cell phone charger is rated at 5 W.

Assume you average 50 mph and get 50 mpg.
50 mpg x 0.5 Wh / 33700 Wh = 0.0007 mpg.
If you plug your phone in to charge, it's 0.007 mpg difference. Yep, absolutely nothing.

 

You forgot that only about 33% of energy in gasoline is turned into force at the crankshaft. Then that energy is converted to electricity in MG’s and that energy is fed into converter that turns it into 12V. If we think that inverter/converter and MG’s have combined efficiency of about 90% we get 0.0007MPG/0.9/0.33=0.002MPG difference.

And when Prius is running engine isn’t running all the time. So when the engine is not running the power comes from the hv-battery (which is then charged back to hv-battery at later time). So we also have to take into account the efficiency of hv-battery and its charging circuit.

Of course the effect is still nothing. It’s so small that it can not be measured.

 

Common sense will tell you that little bit of power the bt adapter is going to pull is really not going to amount to a hill of beans. I would venture to say a GPS plugged into one of the 12 volt outlets (Garmin Nuvi for example) would pull more than that bt adapter. Stop and think how many out there are doing that, and no one is complaining about MPG loss. As has been pointed out, the Prius has a lot of power to spare.

 

I just bought this same unit for our 2006 Prius. It works perfectly. I only use it to stream music and use the car's bluetooth for the phone. I can't imagine it affecting the MPG by any appreciable amount.

 

Good to know! Do you have to manually select one or the other on the phone, or can it connect to both simultaneously?

 

I think it depends on what version of bluetooth you have on your phone. My Android phone has bluetooth version 4.0 and connects to both automatically.

 

BTW: I believe you're off on the laptop. The power supply may indeed only draw .5 amps @ 120V, but the laptop most likely consumes more like 40-60 watts DC, or about 3 - 5 amps depending on the voltage it requires. Then there's the consumption/loss of the inverter -- they tend to not be very efficient).