How about 2 12 volt batterys??

I don't follow. How would it increase MPG?

 

I agree with fuzzy. How would this increase mpg?

You really don't need two batteries unless you plan on building a high wattage stereo system or other high draw accessories.

 

Now who on earth would do that with a Prius?

 

Won't work. It takes the same amount of energy to charge either way, but with two batteries you carry twice the weight. It will actually hurt your mileage just a tad.

Tom

 

Hush, Rob! lol

Tom is correct. The energy spent to recharge the two batteries is the same as one battery assuming there is not a resistance change when wiring in two batteries.

 

But there is a resistance change because now you have 2 in parallel.

But overall, not going to make a shred of difference and any offset gained by the marginally less ohmic load will be destroyed by carrying around a gigantic dead weight 99.9% of the time.

 

And don't forget the doubling of the battery self-discharge, another loss mechanism.

But I'll agree that the extra weight is the largest factor.

 

Who would do it. Or who has lol I might have.....

 

Someone did a "mild plug-in" by adding a 14V deep cycle battery to the 12V system (with some electronics of course). The 14V would be charged to full at home. Then it provides the charging voltage in READY mode while driving so the DC-DC converter won't need to do any work until the 14V battery runs low and gets switched out.

 

2 batteries will decrease your gas mileage, you will be carrying around a few extra pounds all the time. The advantage of a larger capacity 12 volt battery (either by putting in a physically larger unit with higher capacity, or 2 batteries in parallel) is that you will have a longer time that you can leave the car parked with out using it. I think the recommendation is now to start it once every 3 weeks. That could be extended with more capacity. Also, you would get longer operation in accessory mode, when the hybrid system is not ready. For most people, it would be a waste to do.

 

i've had a very larger tractor battery as my 12v for a while.. all this post is really about, is the ability to leave your car sitting for long periods of time... or... thinking you'll somehow pull more power with your reserve battery than the car can handle... (dangerous)

there is one key thing since i see your only have 3 post.. and you mentioned gel battery as if the car runs off 12v....

this car does not use the 12v for powering the car... only for switching on a few computers... then the 250V (roughly) hybrid battery runs the car.

there are kits for this exact purpose already. they cost between 5 and 15 grand (from what i've seen)