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PriusPlus-Theory

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Revision as of 16:52, 23 February 2007 by Cewert (talk | contribs) (→‎Control Circuit Board: clean-up)
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Click show for a short list of the current PHEV conversion and kit options for the Toyota Prius.

For Prius conversion details see the Prius PHEV article and comparisons table.

  1. Ron's Original PriusPlus History and current Contactor Based PriusPlus documentation for DIY projects.
  2. Ryan's PriusBlue is the testbed for DC-DC PFC Based PiPrius kits and documentation for DIY projects.
  3. Toyota OEM Prius PHEV and Prime Could use some work on this page
  4. Enginer China. But the rest of these appear to all be defunct as of 2020?
  5. |~- Hybrids-Plus USA/Colorado/Li -~|~- EnergyCS USA -~|~- Hymotion USA/Canada -~|~- Amberjac UK. -~|~- EDrive USA -~| Peter mentioned Plug-In Conversions |~-

--={ Project Overview }={ 2007 Maker Faire }={ Theory }={ Instructions }={ Parts List }={ RawData }={ Latest News }=--
--={ Doc Process }={ Mechanical }={ Electrical }={ Electronic }={ Interest }={ Talk:PriusPlus Main Discussion }=--

--={ Historic }={ Battery }={ Schematics }={ PseudoCode }={ Photos }=--

Team Photo from the PriusPlus conversion of Sven's Prius from Nov 2006.

This is the home of the PRIUS+ PHEV DIY (Do-it-Yourself) documentation. These pages are currently anonymously editable, which may change in the future. Please feel free to use the Discussion page for general discussion and commentary on the main article. If you would like to add to an existing section use the "edit" link near that topic's heading. Don't forget to use the Summary field to describe your changes. While editing use the "Show Preview" button to make sure your changes look like you expect them to, before you click "Save Page".



Intro Paragraph here maybe with a link to the main PriusPlus article, links to external sites can appear as formatted CalCars, just plain URLs like http://www.calcars.com, or fancy references such as that in the next paragraph.

Another Paragraph and such, you can get help at our Help:Contents#How do I use the Wiki Website page <ref>http://en.wikipedia.org/wiki/Help:Contents more help using the wiki.</ref> Feel free to simply remove or if you like move all of this example text to the pages discussion article.

Please feel free to hack this up or delete it, as I could have this all wrong. I just wanted to get this started. Jim P.

  • Prius plus:

The Prius Plus is a contactor based conversion for an '04 or newer Prius. A sealed lead-acid battery pack is added along with a standard 120 volt charger and supporting electronics. The converted Prius Plus has an electric only range of about 10-12 miles.

The main components are:

  1. The PHEV battery pack
  2. The Charger
  3. The CAN-View
  4. Control board


The PHEV Battery Pack

The PHEV pack consists of twenty 12 volt 20 amp hour sealed lead acid batteries connected in series. The batteries themselves sit in an aluminum box and are mounted above the spare tire well, but below the false floor in the trunk. The pack has a nominal voltage of 240 volts and has a total energy storage of about 4.8 kWh (not all usable.) In this design, the PHEV battery pack has a higher nominal voltage than the stock NiMH battery and is used to charge the stock NiMH battery. Contactors (large relays) are used to connect and disconnect the PHEV battery pack from the stock battery when charging is needed. The higher voltage pack cannot always be connected to the stock pack, because that would overcharge the batteries. NiMH battery packs also cannot easily be charged in parallel, so simply adding a second NiMH battery pack is not simple. The current from the battery pack is less than 60 amps, and therefore the pack is fused with 60 amp 300VDC (or higher) fuses. The batteries must be connected using 8 AWG wire or larger (smaller AWG number) to handle the amount of current.

Current PbA limitations

  • The conversion adds 300+ lbs to the vehicle’s weight to provide 10 miles of electric range per charge (16.7 usable Wh/kg)
    • Though Ron has safely driven 17,000 miles in his converted Prius, the added weight could possibly cause vehicle instability during driving, and the battery may modify the effectiveness of the vehicle’s rear crush zone.
    • Existing conversions sit 1-2 inches low in the rear. Air shocks or heaver-duty rear springs would be nice, but have not yet been developed.
    • Though there are indications that improved hybrid efficiency due to a lower combined internal resistance of the two-battery combination at least partially compensates for the added weight, city gasoline mileage is otherwise reduced by up to 10%.
  • Operating costs are high due to an expected cycle life of only 300-400 deep cycles, providing only one to two years of daily driving (at 400 cycles, 10 electric miles per 2.1 kWh cycle, and $800/pack, battery cost is $0.95/kWh throughput or $0.20/electric-mile (in addition to the cost of electricity, usually 2-4 cents/mile depending on utility rates).
  • For decent battery life, the battery must always be charged within a day of discharge, making charging a required rather than optional operation (if planning to drive to somewhere without access to electricity, temporarily turn off PHEV operation).
  • PbA batteries perform very poorly in cold weather. Though our design includes a thermally insulated battery pack, heated during charging, this feature has been insufficiently tested due to moderate California temperatures during development.

Possible Future Battery Options

More advanced batteries may be retrofittable to the conversion. This will probably require upgrading to CalCars’ not-yet-designed next version of logic board, and will also probably require additional battery management electronics. Any new battery’s enclosure, mounting, and thermal management system will no doubt also be very different.

Possible future batteries and their likely characteristics (incl. low-volume pricing):

Example pack

Chemistry Usable
Wh/kg
Cycle
life
Yr daily
driving
$/usable
kWh
$/kWh
thruput
Cents/
EV-mi
kWh $ EV mi Wt,
lb
PbA
(current)
16 400 1.1 $380 $0.95 20.0 2.1 $ 798 10 289
NiMH worst 36 2000 5.5 $1,200 $0.60 12.6 4.2 $5,040 20 257
NiMH best 36 4000 11.0 $800 $0.20 4.2 4.2 $3,360 20 257
Li-ion worst 56 1000 2.7 $1,200 $1.20 25.2 4.2 $5,040 20 165
Li-ion best 100 4000 11.0 $800 $0.20 4.2 6.3 $5,040 30 139
NiZn worst 36 500 1.4 $500 $1.00 21.0 4.2 $2,100 20 257
NiZn best 36 2000 5.5 $350 $0.18 3.7 4.2 $1,470 20 257
Firefly PbA worst 36 1000 2.7 $350 $0.35 7.4 4.2 $1,470 20 257
Firefly PbA best 45 4000 11.0 $250 $0.06 1.3 5.25 $1,313 25 257

Note that figures are for usable, not total, capacity in kWh (usually 80%, but much less for the current PbA pack (4.8 kWh total capacity), due to Peukert’s Law).

The Charger

The charger runs on standard 120v (or 240v) AC power and is used to recharge the PHEV pack. Three options are planned:

  • a Delta-q charger (http://www.delta-q.com) designed for the PbA battery pack, at a projected price of $800. We are in discussions with the company and will soon know if/when pre-production units will be available; UL-approved units are likely to be available in 2007.
  • the Brusa NLG503 charger, available through http://www.metricmind.com/index1.htm for $2650 retail including cables (a group rate is possible). Users can reprogram this charger for other voltages and battery chemistries, so it would be a good purchase for developers anticipating an eventual high-tech replacement battery.
  • (eventually) the Manzanita Micro PFC-40 charger, available through http://manzanitamicro.com for around $2000. This charger has programmable but less sophisticated charging algorithms, but can also double as a high-power DC:DC converter between the battery packs. Its output is not line isolated. Its incorporation will require modifications/enhancements of this conversion, and control circuitry and algorithms that have not yet been developed.

Useful information on charging lead-acid batteries can be found at http://batteryuniversity.com/partone-13.htm

The CAN-View

The CAN-View is a computer which monitors the CAN bus (the bus which the different microprocessors in the Prius use to communicate with each other) and both displays information to the driver on a display as well as control the extra plug-in systems. The Can-View computer can be programmed to turn on and off a series of relays which are used to control the PHEV operations. There are currently 2 versions of CAN-View available. Version 3 requires an '04 or '05 Prius and makes use of the built in display (or MFD) while Version 4 works with an 04-07 Prius but requires an external touchscreen (since the built in touchscreens were changed in the '06 model and are no longer compatible.) CAN-View is simple to install and installation typically requires between a half hour to one and a half hours. For more information, see CAN-View.

The CAN-View must be programmed to control the relays which control the contactors. The following are the parameters that Ron is currently using for the CAN-View relays: (RL2 and RL3 are NOR'd together; the result is OR'd with RL5 OR RL6; the EV-only parameter is not used):

  • RL2: > 77 OFF < 75 %SOC -OR- < 55 OFF > 60 CCL for 0 seconds
  • RL3: < 40 OFF > 45 mph -OR- < 5 OFF > 20 %throttle for 3 seconds
  • RL5: < 200 OFF > 235V -OR- < 200 OFF > 235V for 0 seconds
  • RL6: < 60 OFF >63 %SOC -OR- < 60 OFF > 63% SOC for 0 seconds

Note: The result of "RL2 NOR RL3" is the AND of the complement of all four RL2/RL3 conditions. Therefore, the above "(RL2 NOR RL3) OR RL5 OR RL6" control board logic, when simplified (ignoring the "X seconds" timing), becomes the following logic for activating HVRL1, which parallels the PHEV and OEM battery:

( < 77 OFF > 75 % SOC
    -AND- > 55 OFF < 60 CCL
    -AND- > 40 OFF < 45 mph
    -AND- > 5 OFF < 20 %throttle)
        -OR- < 200 OFF > 235V
        -OR- < 60 OFF > 63 %SOC

Control Circuit Board

A circuit board is needed which contains the logic to control the added heaters, fans, contactors, etc. The board is roughly 5" by 6" and is mounted in the electronics tray, between the PHEV battery and the stock battery.

Sub parts of this board are;

  • Power management - takes input from CAN-View and controls the contactors connecting the PHEV battery with the stock battery.
  • Battery Heating & Cooling - senses and controls the fans and heaters to keep battery temperatures within defined ranges.
  • System diagnostics - A simple LED board interface to monitor the technical operation of the system for debugging.
  • Charge interlock - stops the car from being driven away while plugged into a live outlet.

Battery Heating & Cooling

Lead acid batteries do not function as well when they are either hot or cold. The pack is heated and cooled as necessary by three standard 12" x 15" heating pads and three fans. The circuit board is responsible for controlling the heaters and fans. Depending on the layout, vents are provided either throught he bottom of the tire well or through the stock vent behind the storage bin on the rear drivers side of the car.

References

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