A Plug In Hybrid Conversion: Step By Step
By Bill Moore
Posted: 11 Oct 2009
Having now observed two Plug In Conversions Corporation Prius conversions, including our own car this week, I have a pretty good idea of what the process involves in a very general sense. Exactly which wires go where, I'll leave to PICC's chief technician, Mike Dibble.
There are, of course, some pre-requisites: an engine hoist, preferably a car lift, various hand tools, electric meter and several assistants to help position the battery pack. In the case of our car, Nebraska license plate LIVN GRN, Omaha's Metropolitan Community College (MCC) Auto Tech Training shop provided most of the above. PICC brought the rest. Allow for two days: one for the actual install, the second for testing.
So, with the caveat that I don't advise you trying this without knowledgeable supervision, here is a basic step-by-step guide to the process as I observed it.
- Remove the rear cargo panels, including fenders and cargo deck, exposing the spare tire well and stock battery pack.
- Remove rear seat and remove spare tire carrier, exposing spare tire well. This is where the new battery pack will be installed.
- Remove plastic cover over battery cooling intact duct.
- Remove battery master circuit breaker, disabling the battery.
- Wait or use ohmmeter to discharge static charge in stock battery terminals.
- Remove battery case covering and disconnect battery terminals.
- Remove the battery air flow duct.
- Unscrew and remove stock NiMH battery pack which weighs about 70 lbs. (31.7 kg).
- Remove stock Toyota battery control board.
- Unscrew and remove NiMH battery modules from stock battery tray. Tray will be reused.
- Raise car with hydraulic lift and replace stock Toyota Prius coil springs on rear wheel suspension. No compression tools are needed to install stronger coils to cope with added weight of battery.
- Hoist replacement battery and position in vacated spare tire well. Mark holes to be drilled. Remove battery and drill holes into body.
- Re-hoist and position battery into well. Bolt pack into place.
- Screw stock battery tray back into its original position.
- Install small fan in now empty stock battery tray
- Install Battery Tender charger to keep stock Toyota accessory battery charged.
- Install Brusa programmable 1 kW charger
- Run battery charger cable to rear fender. Cut hole in fender and install 110V plug.
- Route and wire tie spaghetti of power and data cables.
- Install custom battery air duct connecting stock Toyota system to PICC battery pack.
- Position and tape in place cooling duct thermistor at battery tray air intake.
- Begin connecting cables and plugs.
- Place PICC custom-made battery tray cover and screw in place.
- Re-bolt stock battery tray braces.
- Replace and lock in place stock Toyota battery pack circuit breaker. Pack is now live.
- Start car to check that system is working. If error code(s) result, begin debugging. If no error codes develop, it's almost Miller time.
- Replace rear seats, air intake cover, cargo area fender covers, and cargo deck lid.
It should be noted that because the battery pack is located within the car's crumple zone, any rear-end collision, depending on its severity, will likely damage the pack. Make sure you maintain adequate spacing between the cars in front and behind you to reduce the risk of collision. PICC is planning to conduct crash safety tests as its business develops to insure the pack does not enter the passenger area. Also, because the modules don't use any liquid electrolyte, there is little risk of chemical burns. PICC deliberately engineered its kit to make maximum use of Toyota's safety system, so in the event of a crash, the battery will automatically disconnect, as it does in the stock Prius.
For a personal account of how the conversion of our own Prius went this past week, be sure to read The Conversion of LIVN GRN.
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