Cheap 'n easy Prius plug-in mod =)

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uriel8
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My :jawdrop: idea for stretching out the Prius gas mileage to 75 to 100 mpg without spending $8k to $24K for an aftermarket kit or job is to:

1) buy a replacement Prius NiMH battery pack from Ebay where they have them for $800 to $1100. Install it in parallel with the stock battery. Be careful and wear gloves as I've heard the car battery has 288 volts.

2) Install the EV-only switch to the switch blank on the left side of the dash described and pictured here in a PDF.

Since the Prius BMS is designed to override the EV-only instruction whenever the battery falls below 80% charge, the gas engine (ICE) may try to run to recharge it. Try to handle that by installing:

3) manual ignition defeat switch on the ICE starter. I suppose that ignition failure could cause computers to shut off the EV motor, but probably not.

Alternatively, buy the aftermarket BMS replacement box from Hybrids-Plus in Boulder, CO

Then if I know I only want to go 25 miles or less at 34 mph (the governor limit Toyota puts on the EV motor) I won't over-deplete the batteries.

Now I just need a battery charger for a 288 volt battery to plug into when I get home. Where can I get one of those?

Any ideas or experience here, guys?

Bob in San Diego

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vinnie
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Re: Cheap 'n easy Prius plug-in mod =)

Would this actually work???

...and what's up with the governor set at 34mph? That is going to turn so many people away!

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LinkOfHyrule
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Re: Cheap 'n easy Prius plug-in mod =)

Crap, I'd figure out how to remove that governer, first. Why is it on there in the first place? Is it not big enough to make it go any faster? That's what gears are for.

In regards to the mod, sounds neat. IMO, all hybrids need to be plug in. That way you don't have to buy gas to just drive around town. Cheaper.

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uriel8
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Re: Cheap 'n easy Prius plug-in mod =)

How da Prius works - from How Stuff Works website. Can't edit it, but so much prettier than Wikipedia ;-)

How Hybrid Cars Work - The Prius

this has a bunch of cool animations

uriel8
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Re: Cheap 'n easy Prius plug-in mod =)

I want to do something like this, so if you are around Kollyfornia and think you can help me get 75 mpg on a 2004 Prius get back. Thanks!

Efried
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Re: Cheap 'n easy Prius plug-in mod =)

Hello,

just do some pimping and use the burn and coast technique and come back with the MPG results please!
The modifications:
- get rid of the interiors you don't need
- use low resistance tires
- use camera instead of mirrors
- mount some underfloor coverings
- lower the vehicle
- rebuild removable metal sheets by some made of aluminum

cheers

spinningmagnets
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Re: Cheap 'n easy Prius plug-in mod =)

Once you are past the 5 year warrantee, I think this is a great upgrade. I was certain there was a better way to hack this than the Hymotion $17,000 kit.

Toyota isn't calling me for advice, but...

The controller should come from the factory with a large socket to easily add a second battery pack, plus a special socket to add one or two large capacitors.

Its my understanding that chemical batteries can't absorb most of the re-gen watts that are available. I've read talk that a large capacitor can easily absorb braking and downhill regen, but only so much. The cap can then be used for the start-up watts, with the battery being phased in when your speed stabilizes.

By having sockets (like computer RAM chip memory) the consumer can buy an affordably priced base model Prius, and then easily add those devices that suit their use profile and budget.

uriel8
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Re: Cheap 'n easy Prius plug-in mod =)

spinningmagnets wrote:

Once you are past the 5 year warrantee, I think this is a great upgrade. I was certain there was a better way to hack this than the Hymotion $17,000 kit...

Thanks, here is the only answer I received on Yahoo Answers, probably because not too many gear heads there know one end of the resistor from the other, LOL:

Wondering wrote:

"You have one glaring problem with your plan and that is that NiMh batteries cannot be directly paralleled as the charge levels of the 2 packs will not stay equal and one or the other will overcharge and either fail sooner than it normally would or possibly leak/catch fire. This is less likely to happen in the Prius as it keeps the HV battery between 40 and 80% charge at all times to extend its life but it could still happen. Besides the 1 stock pack will only power the car for a few miles tops by itself from all green bars on the MFD's energy monitor screen so the most you could hope for with 2 packs from all green down to 1 pink bar is probably about 6 miles. Cal-cars and others doing conversions use custom electronics and fill the entire spare tire well and bottom of the hatch with batteries. I myself either want a stock Prius or a true BEV such as the RAV4-EV not a combination of the 2."

jdh2550_1
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Re: Cheap 'n easy Prius plug-in mod =)

Hmmm - Wondering is not much of a "can do" kind of guy is he?

1) Install a battery management system to address the pack equalization problem. Talk to the folks who make the BattEQ and see if you can tempt them to make you a suitable system.
2) What is the Ah capacity of the standard NiMH battery pack? What is the kW rating of the motor? Those things should be easy to find out and that should help calculate a theoretical range. Check out my CB-750 blog entries and you can find a link to a spreadsheet that does a fairly complete job of calculating power requirements to push a vehicle at a certain speed. You could edit it to have Prius figures. If you're interested in doing that but can't find the spreadsheet or can't grok how to do it then let me know and I'd be happy to help.

Good luck!

Spinningmagnets - but Toyota should be asking you! ;-)

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imwoody36
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Re: Cheap 'n easy Prius plug-in mod =)

Greetings everyone!
The only way to turn off the ICE is with an ecu hack. Once the engine is off you will also need to write messages to the prius communication network. The cheapest kit to do this is 8500 dollars available from www.autobeyours.com and is also available from plugin supply. The kit includes 7.5 kw/h of lithium batteries. this is current news as of Feb 2009.
Additionally it allows not 32, but 52 mph in all electric mode.
look for my videos on youtube, search for imwoody36 or all electric prius.

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reikiman
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Re: Cheap 'n easy Prius plug-in mod =)

Woody, welcome to V. I had done some research on fuel efficiency in plugin hybrid vehicles and noticed your site having a picture claiming 100 miles/gallon. I recall during the research finding some statements that high miles/gallon in a vehicle that does not go highway speed isn't a real miles/gallon measure. Typically people want to drive highway speed in a vehicle capable of highway speed. I appreciate that you have a conversion kit available, just curious what you think of the tradeoffs of speed and electric only mode that you have made.

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