12v battery charging mod for efficiency

An Extra 2 miles to the tank? You might as well get on the road earlier and drive a bit slower to get to your destination on time and still get similar results.

 

??? Maybe I missed part of this post... Or you didn't post it here?
Anyway...
I don't believe there is much of a "load" of the HV 240 +/- volt to charge the 12 volt battery and
run all the electronics. It's designed to do so, and very efficiently.

Seems like a lot of work, and expense, for extremely minor results...

 

Add 10 psi to all 4 tires. You may not care for the ride quality but it will be a lot cheaper and achieve the same results or better. Since you're a bicyclist, you're probably VERY familiar with this concept.

Also, folks with sharp pencils will ask you to account for the energy to charge the second battery in your calculations whether it was "free" or not.

 

BAD idea.
The amount of energy used to keep the 12 V charged is very small.
The improvement won't be anywhere NEAR what you estimated. More like .05 MPG maybe.
The cost of your parts probably wouldn't be recovered over the course of 30 years.
And then there is the very real chance that your modifications would FRY something.

 

this is brilliant. i have a bunch of these batteries and a charger. can you please post the set up details?

i think you're on to something spectacular here. all the best!

 

No it isn't.

 

it's all about perspective, and frame of reference

 

The charging system for the 12v is efficient, this additional effort doesn't improve gas mileage as far as I can tell... Adding air to your tires will improve MPG and so will pulse & glide driving technique, but not this...

 

I'm also not a believer in using only gasoline MPGs as an efficiency metric when additional energy is piped in from a wall socket. The plug-in electric energy is not free, so must be included in any serious calculation. That is why I pay no attention to 200+ MPG claims from PHEVs, other than as playful curiosities.

OTOH, if that e-bike battery is already sitting around under-used, and more likely to expire from age than from use, I can't object to some projects just for the fun of it ...

 

Ah now you tell us, I was going to say 2 miles extra to the tank for all that work. Will the step down converter be able to handle power going to the other direction; from prius dc-dc converter upstream to the step down converter to the 72v battery? Or will some type of circuitry be implemented to convert and invert power back and forth simultaneously?

 

I know a feller here who has a prime and solar array at home plus free charging at work so he’s free of charge when it comes to plug in electricity.

 

Ran into a guy at the gas station back in January and he was filling up his Prius Prime and I asked him how good his gas mileage is and he said, "I have no idea, I haven't filled up the tank since last Summer and yet I drive it everyday."

 

You have to wonder if the gasoline sits in the tank for that long will do harm to the engine. I heard the volt will detect current fuel in the tank for a time period, if too long ICE will come on to burn the gas in case it goes bad after so and so months.

 

Toyota merely recommends adding 20 liters per year. If there isn't enough empty room in the tank to add 20 liters, then go burn off enough to make room.

See also:
How desiging the Chevy Volt's sealed gas tank brought automakers, CARB together | Autoblog

 

the pip runs every 124 miles, come rain or come shine. t must have learned something to remove it from prime

 

Lol... that's funny... I bet Prius doesn't offer that bad gas burning feature... But it's a good reason to buy no-ethanol gas which is stable for longer than gas with ethanol, which can absorb water.

 

Do tell.