Many moons ago when I had identical 04 Prius' (same package, tires, everything) I designed a 12V plugin conversion kit to test the mileage improvement of converting solely the 12v load to a 'plug in'. In other words, the 12V load is no longer powered by the traction battery. (That load is a constant 300 to 900 watts) In my side by side testing I saw drastic differences in MPG especially for driving 50/50 hwy/city...I spent alot of time stopped at lights or waiting to pickup kids and watched the toll that idling took on MPG especially the recovery from 2 pink bars. My question is, if I finally put together a production system for public consumption, would there be interest? The gains (depending on season and driving type) were: Measured as 2.5 to 4mpg for daytime spring highway driving up to 9mpg for nighttime winter/summer driving. This works out to 5% to 20% improvement. Retail pricepoint for the system would roughly be $200 to $400 and annual fuel savings @ 12k miles per year would be $100 to $200 per year. If you compare the "cost to savings" ratio of this mild plugin vs a full fledged plug in conversion, you actually get more bang for your buck. Just looking to see interest
For a simple explanation of why the mpg improvement is so drastic you have to understand that the 400 to 900 watt drain is normally supplied by the traction bat...The trac bat gets its energy from the ICE and since the ICE is only 30 to 40% efficient, and since it costs $3/gal thats not very effective way to power the standby load of the car. So, with a mild conversion, your engine would never kick on to replenish the traction battery (except A/C) thus you are not using the inefficent ICE @ 3 bucks a gallon to power a huge system draw. As far as the installation it takes less than an hour with basic tools.
that explains why a bad 12v cost so many mpg's. how do you plug in a 12v? personally, i don't think you'll get many takers, but idk how many you want/need. a couple hundred maybe?
The post was confusing to me at least but I’m wondering if he means keeping the 12v fully charged while parked? Other posts state that the traction battery maintains but does not fully charge the 12v. Is this true? If so one other option may be to get a high quality solar charger by Battery Tender https://www.amazon.com/Battery-Tender-Solar-Charger-Maintainer/dp/B08BFJ12SF $50 at Amazon Many wiring options
the car will keep the 12v fully charged if it is driven regularly, whatever that means. anything between that and not driven, there is a constant drain on the 12v when off, and the longer it goes the more driving it takes to fully recharge. the pandemic has reduced a lot of driving, some people only use prius for short trips or weekends, any thing that lets it sit too long is a problem for the 12v, but it is an inaccurate science. keeping the 12v charged when parked is simply using one fuel to supplant another. as soon as you start driving, the car has to keep itself charged, which ultimately uses gasoline, unless you have a big enough solar panel on the roof.
First, a 900 watt draw at 12 volts takes about 75 amps. The 12 V battery alone will not supply that kind of power for more than a few minutes. And recharging the 12 V "system" is an ancillary use of the traction battery. It is used mostly in propelling the car under the right circumstances. Your entire post makes NO sense.
