My 2000 Toyota Prius

My Prius

Pros and Cons: Why I bought one
EV Range Extending: Adding a 2nd HV battery
Shorten Cold Running Time: Adding a Block Heater

Pros and Cons: Why I bought one
1. More than twice as economical as my previous car and larger inside too.
2. More environmentally friendly. The Prius emits CO2 Emissions of around 104 g/km.
3. Cheaper to service - Toyota Dealer full service is £195.
4. Cheaper insurance - £260 for fully comprehensive cover for both my wife and I.
5. Looks - Some people don't like the look of the Prius, but the car's styling is growing on me.
6. Gadgets - Boys and their toys - the Prius is quite a gadget:
    1. In-dash touchscreen LCD display.
    2. Anti-lock brakes.
    3. Good factory immobiliser and alarm.
    4. Good factory radio and CD player.
    5. Power steering.
    6. Central locking.
    7. Electric windows front and back.
    8. Electric adjust rear-view (side) mirrors.
    9. Sat Nav and reverse camera are"upgradeable" options
    10. When the car is cold, setting the heat to Max - powers a 100w electric heater.
7. Very quiet car - stops the engine when halted or reversing.
8. Very economical - 50 to 55 MPG.
9. Runs on the electric motor only at around 30 MPH (for a mile or so).
10. Lots of leg-room in the rear.
11. Clever storage spaces in the car.
12. High seat position and great visibility.
13. Safety - Driver and passenger airbags and a 5 Star NCAP rating.
14. A Toyota - so reliable.
15. May be 'upgradable' to a PHEV. See below for my EV range extend idea.
16. Very smooth ride.
17. Extra high roof is great. The shape results in a cd of .29
18. Cheap Tax.
19. £10 PA congestion charge - a possible saving of £2000 PA.
20. Parts are common, also some Celica, Verso, Yaris, Corrola parts will fit the Prius too.
21. Has fold-flat (60/40 split) rear seats.
22. Uses regenerative braking to charge the batteries during braking.
23. Neat planetary gearbox - very smooth "automatic gear changes".
Also mine has a full service history - 20k miles till the next service.
Still has 10,000 miles of battery warranty left.
1. Looks rather twee.
2. Rear-view (external, side) mirrors are not heated and are not (power) folding.
3. Tax is £115 not £15 - for me as my Prius was registered before 2001 - grr.
4. Mine is the saloon, not the hatchback shape I would have preferred.
5. My Prius has cloth seats, not leather - well at least no dead cows were involved!
6. I do not have the :
    1. Sat Nav system with voice recognition
    2. Bluetooth phone interface
    3. Reverse camera
    4. Self-parking option
    5. Cruise control
    6. EV mode switch
    7. 6 CD changer
    8. Keyless entry (SE or Smart Entry) nor SS (Smart Start) - now known as SKS.
    9. Self-leveling HID headlamps
    10. side-airbags
    11. VSC (Vehicle Stability Control)
    12. HID (High Intensity Discharge) self-leveling lights
    13. Secondary lights
    14. LED brake lights
    15. Rear wiper
    16. Electrochromic (auto-dimming) rear view mirror

EV Range Extending: Adding a 2nd HV battery

As what you read here may induce you to start tinkering with your own Prius, could the more litigious among you please read the disclaimer? Carrying out modifications such as I describe here will certainly void your warrenty and requires working and making electrical connections in the vicinity of a 200 plus volt battery (or two!) and is inherently dangerous.

Remember - I don't want your widow contacting me!!!

It occurred to me that although the (High Voltage (HV) battery was a significant 200 plus volts, the capacity was rather small at 6.5 Ampere hours and that I could effectively double my all-electric range by adding a 2nd Prius battery in parallel.
I read that there were various parameters (State of Charge, Charge Current Limit etc.) which were monitored by the ECUs on the car - this meant that basically any extra capacity would be ignored (as the Battery ECU would have reported that as x amount of amps had been drawn from the battery, start the engine as the battery must be becoming depleted) as the battery is monitored and SOC computed.
(I think) I've worked out a simple method to fool the battery ECU that it is dealing with half the current that it actually is, thereby providing/receiving twice the Ah it would normally (and use my extra capacity) using a voltage divider (see pic below).

Circuit Diagram

Remember, this will not result in a pluggable hybrid electric vehicle (PHEV) - that would be an expensive and quite complex achievement - my idea is something MUCH simpler: Halve the voltage 'seen' via the current sensing wire and add my battery to the existing one - in parallel. This should give me twice my electric range. Not a PHEV by a long way, but a good first step.
For details see half way down this page: Current sensing wire details (page curtesy of Graham Davies).
annotated graphic

Relay and ECU

Shorten Cold Running Time: Adding a Block Heater

As I have a really short commute (just over 4 miles) a proportionally large amount of my commute distance is spent driving with a cold engine. I decided to do something about that. I decided to spent $59 on a (Canadian) Toyota block heater.
I'll also need a110 volt site transformer to power it as it's designed to be powered from 120v.
The Toyota part number is C0140-00885.

Block Heater

As it pumps out 400 watts at 120volts, I should realise 366 watts of heat @ 110volts.
I'll add more details when I get the thing....