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Prius PHEV

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To this date there have been a number of successful Prius PHEV conversions beginning with Ron of CalCars [1] [2] Original [3] and current PriusPlus projects. Other small startups include the PiPrius [4] [5] and Hybrids-Plus [6] [7] projects. EnergyCS [8] and their European partner Amberjac [9] as well as Canadian Hymotion [10] have converted numerous Prius PHEVs to this point. EDrive [11] will be offering conversion soon. The tenth conversion of PriusBlue was undertaken in public April of 2006 at the Inaugural Maker Faire to help enhance the documentation and help promote PHEVs in the pacific northwest and midwest.

At this time there are two common conversion methods for the Prius. The #Original CalCars Method used in Rons PriusPlus History, EnergyCS, Amberjac, EDrive, and Hybrids-Plus conversions replace the stock battery with a new simple string. The second #Hybrid-Pack Method is used in the new PriusPlus, PiPrius, and by the Hymotion conversions. This second method should be easily adapted from the '04+ Prius to the Classic '00-'03 Prius, Escape, and other Hybrids as they use a hybrid battery pack configuration which uses both a new simple string and the original stock batteries. The new PriusPlus and the PiPrius projects moved to the #Hybrid-Pack Method in order to remedy the CCL Conundrum. Both types, of course, use a Battery Chargers to recharge from the grid. Toyota has warned that such conversions may adversely affect your Warranty.

The Prius PHEV TechInfo page has a lot of technical information on the Prius which may be useful when designing a PHEV conversion. See the Terms page if you aren't familiar with some of the underlying principals or acronyms used through the documentation. Also be aware of the Disclaimer should you be considering a conversion yourself. This PriusDisMan.pdf (Media:Priusdisman.pdf from might be handy for its dismantle and safety warnings

Prius Conversions Chronology

For a more detailed chronology of Prius (and other vehicle) conversions completed since CalCars' first one in November 2004, including pictures, locations and contact information of the owners, see where-phevs-are at The Google site has a map of PHEV vehicles, this was an early attempt at mapping PHEV's and EV's, and the site has charging stations.

Add A Vehicle

Chris Ewert has generously volunteered to collect and organize these lists. Please send him information in the format listed below. Send corrections and updates to chris [at] (Chris Ewert) and copy to info [at]

  • Contact email address *
*(if the contact wants an anti-spam email address like info [at], please indicate that, or if the contact wants to be unlisted but is still willing to provide that info to CalCars (you won't regret it), please send it with that notation.

Please also feel free to edit this page right now with additions or corrections and we'll be sure to forward those changes on the Chris and CalCars.

Current Vehicles


-1. Historic - History of this website, the EAA, Hybrids, CalCars, Plug-in Hybrids, and more...
0. 1993-present - Dr. Andrew Frank from the University of California, Davis and his Team Fate.
  1. Fall 2004 - CalCars PRIUS+/Ron Gremban by Ron Gremban, EnergyCS and CalCars team
  2. Mar. 2005 - EnergyCS by Greg Hanssen, Pete Nortman and team
  3. May 2005 - Energy CS/Clean-Tech by EnergyCS
  4. Sept. 2005 - Amberjac Projects Ltd UK, by (Amberjac/EnergyCS)
  5. Feb. 2006 - Hymotion by Hymotion
  6. Mar. 2006 - Electro Energy by CalCars and Electro Energy
  7. Mar. 2006 - South Coast Air Quality Management District by EnergyCS
  8. Apr. 2006 - CalCars/Felix Kramer by EnergyCS
  9. Apr. 2006 - Sacramento Municipal Utility District by EnergyCS
  10. Apr. 22-24 - Ryan Fulcher of the Seattle EVA by CalCars and the Maker Faire team
  11. May 2006 - City of Santa Monica by EnergyCS, (Los Angeles County, contact rick.sikes [at]
  12. July 2006 - Pacific Gas & Electric/Bay Area Air Quality Management District by EnergyCS, (San Francisco County, contact sxtg [at]
  13. Aug. 2006 - Hourcar by Hymotion, (Twin Cities, MN, contact
  14. Aug. 2006 - Southern California Edison by EnergyCS, (Los Angeles County)
  15. Aug. 2006 - South Coast Air Quality Management District #2, by EnergyCS (Los Angeles County)
  16. Sept. 2006 - '06 Prius for State of Colorado, Energy Office (Denver CO) by Hybrids-Plus (
  17. Sept. 2006 - Manitoba Hydro by EnergyCS, (Winnipeg, Manitoba)
  18. Sept. 2006 - Veridian Corp. by Hymotion, (Ajax, Ontario, contact dhillsmilligan [at]
  19. Oct. 2006 - Chelan County (WA) Advanced Vehicle Initiative's "WhiteBird" was converted with the second PiPrius kit, (Contact Ron Johnston-Rodriguez: info [at] or (509) 663-5159)
  20. Oct. 2006 - Costar Corporation by Hymotion, Annapolis, MD contact
  21. Nov. 2006 - Todd Dore of the Fox Valley EAA chapter, Prius GrayPearl was converted with the third PiPrius kit.
  22. Nov. 2006 - CalCars new PriusPlus conversion of Sven Thesen's 2005 Prius
  23. Nov. 2006 - Fairfax County, VA by Hymotion
  24. Nov. 2006 - Idaho National Laboratory of US Department of Energy by EnergyCS
  25. Nov. 2006 - Idaho National Laboratory of US Department of Energy by Hymotion
  26. Dec. 2006 - DUAL PWR-PHEV by Horacio Calvento, Long Island, NY (contact: mrbigh at
  27. Jan. 2007 - Jim Fell, Peterborough, England PFC40 conversion with 56 x 90ah Thundersky cells named FellUK.
  28. Feb. 2007 - Bay Area company by Hymotion (first car)
  29. Feb. 2007 - Bay Area company by Hymotion (second car)
  30. Feb. 2007 - GreenTomato Cars, (Amberjac/EnergyCS), London UK
  31. Mar. 2007 - Southwestern utility by Hymotion (first car)
  32. Mar. 2007 - Southwestern utility by Hymotion (second car)
  33. Mar. 2007 - EcoFys, (Amberjac/EnergyCS) Maastricht Netherlands
  34. Mar. 2007 - Jim Tech Ltd, (Amberjac/EnergyCS) London UK
  35. Apr. 2007 - Chris Ewert, Wheaton, IL - first individual PriusPlus conversion with modified mounting method (contact: chris at
  36. Apr. 2007 - Private early adopter, (Amberjac/EnergyCS) Bradford
  37. May. 2007 - Philippi Family, Houston, TX - PriusPlus conversion with hinged battery box for access to spare tire. PriusPlus type conversion. 2007 Maker Faire Team
  38. May. 2007 - Northern California water agency by Hymotion, contact info to come#
  39. May. 2007 - '07 Prius for Lithium Technologies (Plymouth Meeting, PA ) by Hybrids-Plus (
  40. May. 2007 - '07 Prius for private individual (Seattle, WA ) by Hybrids-Plus ( Conversion3 gallery PHEV-30
  41. May 2007 - Private early adopter, (Amberjac/EnergyCS) through Toyota dealer, Kent UK
  42. May 2007 - eacon Energy, (Amberjac/EnergyCS) Loughborough UK
  43. May 2007 - Ecordis/Spinnovation, (Amberjac/EnergyCS) Amsterdam Netherlands
  44. May 2007 - Nilars' in house PriusPlus type conversion.
  45. July 2007 - Argonne National Labs - Prius by Hybrids-Plus ( Conversion5 gallery PHEV-30
  46. July 2007 - Private individual in Rifle Colorado - Prius by Hybrids-Plus ( Conversion6 gallery PHEV-30
  47. July 2007 - Raleigh NC, Progress Energy Corporation - 2005 Prius converted by Advanced Vehicle Research Center with Hymotion hardware. (contact: Mike.Ligett (at)
  48. Sept 2007 - Hybrids Plus in Boulder Colorado - Prius by Hybrids-Plus ( Conversion8 gallery PHEV-30
  49. Sept 2007 - The Green Car Company delivered their first PiPrius conversion to King County.
  50. Oct 2007 - Private individual in Charleston SC - Prius by Hybrids-Plus ( Conversion17 gallery PHEV-15

Newest Vehicles

Original CalCars Method

This conversion method was originally demonstrated by CalCars which replaces the OEM battery with a new higher capacity simple string of batteries. Ron's first PriusPlus History conversion used early proprietary EDrive technology. A later version of this method by CalCars attempted to exploit the State Of Charge Drift portion of the vehicles battery management routines in order to accomplish State Of Charge Manipulation with the use of a Battery Tap Emulator. However this attempt was unsuccessful due to the CCL Conundrum. As such further development of the Original CalCars method has been postponed while perusing the #Hybrid-Pack Method which has now been successfully implemented.

A number of companies such as EnergyCS, Amberjac, EDrive, and Hybrids-Plus use this method with custom hardware which replaces the OEM battery management computer in order to dictate the SOC which is communicated to the rest of the vehicles computers. In doing so these conversions report a higher than normal SOC while in Charge-depleting mode in order to raise mileage by increasing the electric contribution to motive power. This higher than normal SOC also encourage more stealth mode and enables longer operation in Prius EV Mode. Once the new higher capacity battery pack is sufficiently depleted the system reports normal SOC values causing the vehicle to return to the normal Charge-systaining mode of operation just like a stock Prius.

Prius PHEV Schematics-CalCars are Dormant.

Navigation Image

Hybrid-Pack Method

The Hybrid-Pack method employs a Hybrid Battery Pack Configuration which has been used in the past as a solution which combines two battery banks in order to mask weaknesses in one or both resulting in a robust overall system. For example a high energy/low capacity and high capacity/low energy battery might be combined resulting in an overall high energy and high capacity resource. Hymotion was the first to employ this type of configuration followed by the new PriusPlus and PiPrius projects. These conversions mask the low capacity characteristics of the OEM battery with a higher capacity battery. While this higher capacity battery also has higher energy, keeping the OEM battery and it's support systems in place eliminates the need for a replacement Battery Management Computer capable of communicating with the rest of the Prius systems. For more core ideas surrounding this method see Prius PHEV Battery Options for more specific battery information.

This method exploits the State Of Charge Drift portion of the OEM battery management routines in order to accomplish State Of Charge Manipulation, but does not utilize a Battery Tap Emulator. The result is the ability to effectively change the target SOC from the normal ~60% to higher values which are more useful for PHEV applications. The Prius EV Mode can also be utilized for longer durations because SOC Drift is capable of maintaining an acceptable SOC value. A CAN device is required to acts as a Prius PHEV User Interface and management device. Such hardware/software will need to follow logic similar to that laid out by Prius PHEV Pseudo Code. The Latest PriusPlus and PiPrius conversions use hybridinterfaces CAN-View Scantool device which is currently available for 2004 and newer Prius, and may eventually be used in other Hybrids such as the Ford Escape Hybrid. You can take a look at Prius PHEV Photos which are available to help visualize parts of the conversion process.

Contactor Based

Ron and CalCars have demonstrated a working contactor and resistor based configuration in a number of vehicles.

See PriusPlus for the documentation of this type of conversion.

PFC Based

Rich Rudman of [[Manzanita Micro] ( and Ryan have implemented a conversion using an upgraded MM-PFC-30, named the PFC40H, as a DC-DC converter and charger. Rich has developed and is offering conversion kits.

Enginer Based

Jack Chen has implemented a conversion using a special designed DC-DC converter and controller made by Enginer (, which monitors stock and PHEV battery SOC to determine conversion kit's discharge rate without CAN interface. This method can support both Gen 1 and Gen 2 Prius as well as other hybrids by adjusting output voltage and current. The interface (5 wires) to the stock vehicle is very minimum resulting in significant cost savings. AutomationTech Inc is offering complete conversion kits under $2000 in US.

See PiPrius for more details.

Electro Energy has successfully demonstrated a PFC based setup with NiMH during CalCars trip to DC.

Kits and Conversions

This div does not appear withing the page but is used to define the references used below. If multiple ref tags were to appear within the table only the text from the first would be displayed. Thus we pre-define them here, the only side effect being that the first "a" backlink does nothing.

<ref name=ev_range> EV range [mi] or All Electric Range (AER) Assuming <35 mph, 210 Wh/mile (260 Wh/mi from grid) per, 1.5 miles is approximately the range with a fully charged stock battery pack</ref>

<ref name=phev_range> PHEV range [mi] or Blended mode Range (BMR) During which the mileage is on the order of 100 mpg. Shows range as stated by organization.</ref>

<ref name=safety> Safety in case of major accident

  1. Many Lithium cells will burst in flames if penetrated. However, phosphate cathode LiIon cells (such as Valence and A123) are flame-proof.
  2. SLA batteries contain lead and sulphuric acid but are spill-proof</ref>

<ref name=charge_time> Charge time [hours] From discharged to the point the pack will no longer be used in PHEV, to fully charged.

(per Orbital, SLA require 8 hr taper -- done at least once every 3 days -- after near full charge, to reach 100% and prevent sulfation)</ref>

<ref name=energy> Available energy [KWh] Because the DOD of the stock pack is limited by the Prius, only about 0.3 KWh of its energy is available (used). It is assumed that additional batteries are limited to a DOD range of:

  1. SLA: 0% down to 50%, due to Wikipedia:Peukert's law much of the nameplate capacity is unavailable.
  2. Lithium: 0% down to 90%, has far less Peukert losses and can be safely deep discharged.</ref>

<ref name=spare_tire> Spare Tire access

  • No the original tire well is covered or occupied by the new battery pack and must be secured and stowed in the rear cargo space.
  • Yes the original tire well is accessible.
  • Opt Optionally the battery box may be implemented in such a way to preserve access.</ref>

<ref name=convert_service> Conversion service: done by the PHEV conversion company, at their location. Conversion kit: done by the owners in their hometown.</ref>

<ref name=status> Project Status:

  • Doc: Open Source Documentation in progress.
  • Dev: Development: Working vehicles on the road but some features still under development.
  • Unknown: Unknown: No public news the last 12 months
  • Prod: Production: Working vehicles on the road, performing conversions or supplying kits.</ref>

<ref name=topology_type> Topology Type:

  • New New Battery Pack and BMS, the OEM NiMH battery and BMS are replaced with a simple string.
  • Hyb OEM NiMH battery and additional battery are both utilized in a hybrid battery pack configuration, OEM BMS continues to manage OEM battery.
    • Con Contactors are used to parallel the OEM and PHEV batteries.
    • DC A DC to DC converter is used to move power forward from the PHEV to the OEM Battery.
    • CV The CAN-View is used to manage the PHEV systems operation.</ref>
Comparison table: PHEV conversion and kit options for the Toyota Prius
Organization :Location Websites (Products)
Conv. service
<ref name=convert_service/>

Conv. kit
<ref name=convert_service/>

<ref name=status/>

# done so far
EV range [mi]
<ref name=ev_range/>

PHEV range [mi]
<ref name=phev_range/>

AC power
Charge time [hours]
<ref name=charge_time/>

<ref name=safety/>

Added weight [kg]
Spare Tire
<ref name=spare_tire/>

Cost [US$]
Warr. [years]
<ref name=topology_type/>
Pack energy [KWh]
DOD energy [KWh]
<ref name=energy/>

Bat type
PriusPlus:CA<ref>CalCars is based in California, however locations where progress is being made and help is available now include CA, CT, CO, IL, and TX.</ref> CalCars (Pb
No Yes Dev Doc 5
<ref>CalCars completed the 1st ever Prius PHEV conversion 11/04, With six by 5/07 (One which became the test bed for the PiPrius project, two of which uses NiMH, and the latest which retains the spare tire.)</ref>
100 to 240 Vac 4+
<ref name=charge_time/>
Flame Spill proof 130
Opt $3-$9K +Labor
<ref>CalCars Batteries: ~$1K ($3-$5K for NiMH) Charger: $0.9-$2K Total: $3-$4K + labor for PbA conversions and an additional $3 to $5K for NiMH</ref>
0 Hyb Con CV 4.8
2.4-3.8 +0.3 stock
PbA (Ni, Li)
<ref>CalCars uses 20 * BB Battery EVP20-12B SLA (Sealed Lead-Acid). Have used Electroenergy NiMH in EEEI Prius and Nilar NiMH in Nilar Prius, evaluating Lithium.</ref>
PiPrius:WA Manzanita Micro, PiPrius, AVI, Green Car Co. No Yes Unknown 4
<ref>PiPrius vehicles include PriusBlue, WhiteBird, and GrayPearl.</ref>
10 20-30 90 to 300 Vac Vdc 0.4-3+
<ref>PiPrius Charges in about 3 hours @ 120v & 15a or can be charged in as little as 0.4 hours (24 minutes) @ 240v & up to 40amps with manual current control from 0 to 40amps.</ref><ref name=charge_time/>
Flame Spill proof 150 no $10K +Labor
<ref>PiPrius Batteries: $0.8K~$1.2K Charger/DC-DC: $3K Target: ~$10K</ref>
0 Hyb DC CV <ref>PiPrius notes:
  1. The PiPrius PFC40H charger doubles at the DC-DC converter between the OEM and added battery packs.
  2. BMS consists of a Mk 3 Reg on every battery, which fully protected each battery on charge and discharge mode.
  3. The BMS is programmable with a laptop, with no security locks (open source).</ref>
4.7 4+0.3 stock PbA (Ni, Li)
<ref>PiPrius uses 15 * Hawker EP26 SLA (Sealed Lead-Acid), 24 * 20Ah SLA., Evaluating Lithium, or users choice of chemistry, voltage and capacity.</ref>
EnergyCS:CA EnergyCS Yes No Unknown 11 30 50 120 Vac 9.0 Flame Spill proof 83 no $40K 0 New 9
<ref>EnergyCS has 9kWh of battery capacity from a 230v 40Ah pack</ref>
8 Li
<ref>EnergyCS uses Valence Saphion phosphate cathode LiIon cells extracted from U-Charge packs</ref>
Amberjac:UK Amberjac EnergyCS partner <ref>Amberjac uses the EnergyCS system electronics but a different battery manufacturer.</ref> Yes No Dev 7 30 60-70 110 to 230 Vac 9.0 Flame Spill proof 83 yes $40K 0 New 9
<ref>Amberjac has 9kWh of battery capacity from a 230v 40Ah pack</ref>
8 Li
<ref>Amberjac works closely with EnergyCS but uses a different battery system and manufacturer though the same (LiFePO4) chemistry</ref>
EDrive:CA EDrive Systems ? ? Unknown 0 32? 60? 100 to 240 Vac 9.0 via cell sep
<ref>EDrive Through cell separation</ref>
? yes $12K 0 New 9.5 8.5? Li
<ref>EDrive uses Laptop Cobalt LiIon 18650 cells</ref>
Hymotion:ON Canada Hymotion /A123 (PHEV-L5) Yes, fleets No Prod 18 15
<ref>In the past, Hymotion has stated 50 km (30 miles) pure EV range. Yet 4.3 KWh calculates out to 15 miles. The specs on their new website say "Up to 100 mpg for 30-40 miles", which means blended mode, and is indeed consistent with the energy stored in the battery</ref>
30 100 to 240 Vac 5.5 / 4.0 Spill proof 72 no $10K
<ref>Hymotion $10K may or may not include installation, depending on source</ref>
3 Hyb 5.0 4+0.3 stock Li
<ref>Hymotion uses Lithium polymer (future: A123 LiIon)</ref>
Plug-In Conversions:CA Plug-In Conversions Yes Yes Prod 15 25 50 120/240 Vac 6/2 Flame Spill proof 100 no $12.5K<ref>Plug-In Conversions High capacity chargers extra</ref> 3 New CV 6.1 5.1 NiMH
<ref>Plug-In Conversions Uses Gold Peak NiMH 10GP30EVH</ref>
Plug-In Supply:CA Plug-In Supply Yes Yes Prod 140 40-50 80-100 110 Vac 8 Flame Spill proof 220 Yes $13K 3 Hyb 10 10.6 LiFePO4
OEMtek:CA OEMtek Yes No Unknown ? 30 50 100/240 Vac 4/6 Flameproof 95 Yes $12K 0 Hyb 9 8 Li
3Prong Power:CA 3Prong Power Yes No Prod 12 10-12 20+ 110 Vac 4 Flame Spill proof 130 Yes $6.7K 1 Hyb 4.8 2.4 PbA
Enginer:MI Enginer No Yes Prod 795 10-20 20-40 110 Vac 3-5 Flame Spill proof 75-90 Yes $2-3K 2 Hyb 2-4 1.6-3.2 LiFePO4
MD-Tech:China MD-Tech No Yes Prod 200 25-30 35-40 110/230 Vac 3-5 Flame Spill proof 75-90 Yes $3K 2 Hyb 4 1.6-3.2 LiFePO4

Notes: <references/>

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