I want to charge the battery that comes with the Prius.

[Dan45]

I want to charge the regular battery that comes with the Prius so I can start off in the morning with a full battery. This shouldn't be too hard to do. I was thinking maybe a switch to disconnect the battery from the car and than into the charger. A trickle charger could be very small and automatic so it wouldn't over charge the battery.

Or the charger could be connected to the battery without disconnecting it from the car. This would allow it to keep the water warm and to keep the 12 volt battery charged.

I can see that the main problem would be driving off with the car still plugged in.

Does any company make such a thing?

[patsparks]

I don't think it is worth the effort or the risk. Just drive it.
The battery of your Prius holds about the equivalent energy of 2 tablespoons of petrol.
If you drive properly your battery will be almost fully charged when you put it away at night anyway.

[JimboK]

Just curious: What are you trying to accomplish?

[TransferFunction]

Those batteries hold more than 2 tablespoons of gas worth of energy. It should increase fuel mileage if you could top up the charge every night. This is a great idea.

[aaf709]

But the software in the car would run the engine anyway to warm up the catalytic converter. Plus the car doesn't like a fully charged battery and will spin the engine trying to get it down. Most plans to plug in a Prius is to add batteries to make it worth while.

[efusco]

You should look into the hymotion battery pack if you're serious about a project like this. Many before you have considered the 'complete replacement' option, but it's not as easily accomplished as you might thing. The Battery ECU is sensitive to voltage changes and doesn't like things out of whack. Basically you have to fool the ECU into thinking that there's a lower SOC than there really is with the second pack.

Even with that your range and top speed are limited.

[patsparks]

Originally Posted by TransferFunction

Those batteries hold more than 2 tablespoons of gas worth of energy. It should increase fuel mileage if you could top up the charge every night. This is a great idea.

Pris battery capacity 1310.4 Watt/Hours
1 watt hour = 860.42065 calories
1310.4 x 860.4 =1,137,468.16 calories
a gallon of gasoline contains about 31,000,000 calories
1 US gallon = 256 US tablespoons

31,000,000/256 = 121,093 calories in 1 table spoons of petrol

121093 x 9 =1,089,837
Sorry, your right, it is about 9 tablespoons of gas or 133ml.


now the battery in your Prius only uses 60% of its total capacity so reduce that to about 60% and you have 6 tablespoons or 80ml.

Now I doubt you will pull up your driveway every night with a flat battery or more correctly a battery at 40% charge so lets assume that on average your battery is at 50% of the usable range of charge, you can fit in an additional 3 table spoons worth of energy.

Yep, sorry I was wrong, on average you can put 3 table spoons gas equivalent energy into the battery each night without causing harm to the battery.

Now when a Toyota dealer needs to charge a Prius traction battery they need to get a special charger from head office sent to them, they don't have one in their store because it is so expensive I believe there are only 2 or 3 in the mainland USA. What will your battery charger cost?

[qbee42]

Originally Posted by TransferFunction

Those batteries hold more than 2 tablespoons of gas worth of energy. It should increase fuel mileage if you could top up the charge every night. This is a great idea.

No, it's not a good idea. The mileage gain would be unmeasurable, and the cost and complexity very high. You aren't talking about a 12V lead acid battery. This is a couple of hundred volts of sophisticated battery. You will end up killing yourself, the battery, or setting your car on fire, all to save a quarter cup of fuel. It's just not worth it.

Tom

[richard schumacher]

The OP was talking about the 12V battery. He won't kill himself, but it's still not worth the trouble. Given the conversion losses of a 12V charger and amortizing the cost of the charger it's not obvious that it would save any money or reduce his carbon footprint.

[efusco]

The 12v....you can put it on a float charger if you like, but the impact will be zero in day to day driving.