Battery Vehicle Society

Hi, I have been looking into buying a Prius and converting it for PHEV to extend the EV range. After a bit of research I found a company (Amberjac) in the same town as me (Grantham) which do the convertion. I was a bit taken back with the price (£15000 + vat) and they would not sell the bits to do it as it is too dangerous with high voltages and things! I thought this was a bit too expensive if you add the cost of the car on top. I don't want to save the planet etc as my main aim is to cut the cost of my daily commute and this sort of money would take a long time to claw back. I run an old 205 diesel van with 121K on the clock at the moment which gives me 50-55mpg which I used to run on cooking oil until that went up to the price of Diesel

With me being an electronics engineer and wanted to diy fit it I found a few sites mostly USA with full details with circuit diagrams for controllers etc.

Another site I came across was a company called Enginer who do the whole kit for $1999 or $999 without the Li ion batteries. The kit is for sale on Ebay item no. 200344551230 for anyone else interested. They also do the LI ion batteries at $256 which seemed quite a good price.

Has anybody on the forums fitted one of these kits or used their batteries?

Hi classiccarman,

Welcome to the forum.
There is certainly at least one other person on the forum that has done a DIY conversion so they should be able to help.

I know one other person that has done something similar although she is not currently on the forum.

Good luck.

Rob

There has been some discussion of these "Enginer" kits on the Insight web site as well recently. It looks quite nicely laid out in those photos. The batteries are Thunder Sky so they should be fine IMO.

The kit works by basically keeping the stock Nimh battery fully charged so the car can use more electric power, it does not replace the stock pack.

Looks like a hacked mains inverter is used to provide a 48V input to 270V output dc-dc converter.

Good luck go for it IMHO

As an ex-NHW20 Prius owner, I should point out that if it only keeps the NiMH pack topped up, and doesn't work as a true PHEV system, then it will still have exactly the same EV only limitations that the Prius has (very low EV only speed, forced ICE warm up cycling on start, very low EV only power demand before ICE starts).

I've no doubt that it improves EV performance in terms of range, but this can only be at low speeds and the ICE will still run a fair bit. This may not give the short journey economy that most PHEV owners are looking for, especially in cold weather when the ICE will go through an extended cold start warm-up cycle even with a fully charged battery.

The older NHW11 Prius has an inherently poorer EV only performance than the NHW20 (even after modification), which is worth considering when looking at the choice of vehicle. I'd not want to touch the even older JDM-only, NHW10 model, as there's virtually no UK support for it at all.

For a Prius PHEV conversion to work well I think it needs to integrate properly with the vehicle control systems, so that things like forced ICE start, speed/power limited EV operation settings etc are all altered. The Prius is not a capable EV-only vehicle when running the standard software, just a slight touch too much throttle, or the slightest gradient, will force an ICE start, as will exceeding about 28 mph on the level, or even downhill. Once the ICE starts you've really lost much of your short journey economy, as there's no way to shut it down (short of stopping the car) until it's completed it's warm-up cycle.

As an example of the short journey problem with the standard software, when doing a regular 40 mile each way commute to work, my fuel consumption in the Prius (a 2005 T4) was around 60 to 65 mpg. After a change of job, which cut my commute down to a couple of miles each way, my fuel consumption dropped to between 40 and 45mpg. The Prius is a pretty dreadful performer on short journeys, largely because the systems and software cause it to burn fuel at start up even when it doesn't need to.

Jeremy

Although from what I heard Nik's one went pop and spat it batteries out all over the boot

ChrisB

That sounds scary. The kit I refered to has a built in fire extinguishing system in case of overheating. That would probably wreck the electronics but save the car
With regards to the startup on petrol routine has anybody come across any software hacks to get round this or got any experience changing the built in software? I know there are a number of sites out there mostly US that give details on changing stuff like this. I know you have to be careful as I do this as part of my job on the equipment I work on. You could end up with a useless lump of metal parked on your drive

Good advice from Jeremy a previous owner. Take note.

I believe that the "proper" PHEV conversions for the Prius "fool" the car's systems so that they don't do unnecessary things, like the cold start warm up cycle. How they get the EV only performance limit up I don't know, maybe they use the same technique.

The Prius uses a distributed processor architecture, primarily to simplify functional and safety compliance testing, I believe. Because of this, it is possible to introduce units that can intercept the data from one sub-system to another and change it. I believe that this is the favoured way of altering some of the system behaviours by some of the die-hard Prius modders.

I don't think that anyone has found a way of changing any of the hard coding in the various processors around the car, at least not to the point where it's reliable enough to sell as a product (although I could be wrong).

Much of the code in the Prius standard firmware is aimed at protecting the car's systems and ensuring that it will always fail-safe. Anything that changes this has the potential to cause problems, particularly when you realise that virtually everything on the car has a dedicated processor (steering, brakes, engine control, battery control even the vehicle body peripherals all have their own processors).

The big problem would probably be finding a way to get around the electric motor power restriction. The motor is capable of delivering a lot of power, but is quite heavily limited when in EV only mode. Any high current demand, or speed over about 28mph, will cause the car to trip out of EV mode into normal hybrid mode. I believe that one of the restrictions, the low power delivery when in EV mode, is down to the need to protect the small standard battery pack. It may be that this can be overcome by intercepting the communication between the battery management system and the motor control system.

The EV mode speed restriction might be able to be changed reasonably easily by doctoring the speed signal to the motor control system, but there's little potential for much of an increase due to the way that the HSD works, I believe.

I think that the reason for true PHEV conversions being expensive is down to the massive amount of work that has needed to be done to find ways around the various built in restrictions. I'm far from being an expert on the Prius systems, so the best place to look would be one of the US Prius groups/forums that are seriously in to reverse engineering and tinkering with the car's systems.

Jeremy

There are some simple ways of raising the EV limit - see http://techno-fandom.org/~hobbit/cars/nosquirt/ for example - but note the caveats.

Intercepting and spoofing the communications on the CAN bus is one way of changing the operation of the Prius without hacking the ECU firmware(s). But either way I would be very concerned about insurance and liability. Obviously you have to declare the car as modified. If you then have a serious accident you might have to prove that your mods are not the equivalent of (say) replacing the alloys with lightweight papier mache versions. It is not always easy to show that mechanical mods are safe, it would be almost impossible to prove that your hacks are not responsible if something goes awry (though of course you might not be alive.....).

Thanks Jeremy for this info. Its great to be able to talk to someone who has experience with these cars. Thats what these forums are for

Do you know what the average mileage of the standard Prius gen2 battery pack can achieve before replacement is needed? I am watching a few Prius on Ebay and the asking prices seems to vary a lot depending on the mileage of the car more so than your average ordinary car. How much would a new pack cost and do the motors require replacing ever?

I have read reports of 150,000 miles........10 years........the life of the car.....I don't know what to believe. Usually its charge/recharge cycles but not knowing much on how the car monitors this, I supose it depends a lot on how the car has been used in the past?