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Prius that plugs into the mains

Posted: Sat May 26, 2007 8:48 pm
by PeteB
I posted this on the Yahoo Prius-UK group, and a member of this group suggested it might interest members of this group:

I should explain, I bought an old model Prius in April 2002, and last year ended an IT career and became a Private Hire (ok, minicab) driver for a (then) new firm in London using the hybrid Toyota Prius ( A year, nearly 50,000 miles and 1½ thousand journeys later, I started having circulation problems in my legs due to spending so many hours in a car each day, and now work in their head office.

Well, I FINALLY got to drive our plug-in Prius today, and it was a revelation. Amberjac ( took it back and put their latest battery and software into it and returned it yesterday. It was plugged in all last night and I brought it home today. I'll have it maybe for a week or two, and will monitor how much electricity it uses via a plug-in power monitor socket I bought from Maplin (currently £26, but they occasionally sell it for about £14).

I filled the tank just after leaving the office, and then drove another 39 miles (missing the M1 car park from J6-J10). It just reverted to normal hybrid operation as I pulled into our drive. The standard energy monitor still showed 99.9 mpg, so I predict it will be a while before I fill it up again and calculate consumption (yes, I KNOW 1 fill will have a margin for error, but it's the best I can do! - I will go to the same pump and station if possible, and I've probably filled up a Prius more times than most here, having driven some 50,000 miles in various current models, and filled each new car before handing it over to the driver).

As I predicted, it felt like a normal Prius does when the HV battery has completely filled to the max after going down a VERY long hill, when the system tries to use some electricity as quickly as possible to make regeneration possible again. When using engine power, it gets helped by the electric motor much more than a standard Prius, and even at 70 mph on a light throttle pressure it will go into EV mode for brief periods. Crawling through St Albans and Harpenden was almost entirely EV - lovely.

The car looks almost the same as any other Prius (of course, ours has green tomatoes all over it), but there is a flap on a corner of the rear bumper that conceals the power socket, and a small box behind the steering wheel with an LCD display.

There is an SD memory card in the side of the box, and Amberjac ask that a file on it is emailed to them weekly, so they can monitor performance. The car performs just like any Prius, but some of the under boot space is lost, there's no room for the spare tyre so run flats or a tin of gunge and a pump are needed. The monitoring system slugs the 12v battery so they tell you to plug in at least every 2 days - this also charges the 12v battery. I'll be asking Amberjac what the other numbers mean, watch this space...

- update after 1 recharge

Looking at my meter this morning, it took 7.38 kVA (kilo volt-amperes) to recharge the Prius. Assuming my meter is reasonably accurate (which I have no way of checking), at my current nPower tariff that's 30p worth of overnight electricity. If I'd charged it during the day it works out to £1.53. I can't say how much of the 41 miles I did since leaving the office (filled the petrol tank 2 miles after leaving) were in EV mode, but it sure seemed like a lot.

And an update at the end of today

Just used the plug-in Prius for local journeys today, totalling 35 miles. About 5 miles each way to Hitchin is 70 mph, with a steep hill. Apart from the dual carriageway it was mostly around 30 mph or less, and in EV mode.

Another thing I've noticed about the conversion; the EV button doesn't seem to do anything, the Amberjac control unit seems to have taken over that role.

Will be interesting to see how much electric it uses tonight.

BTW according to my meter, the charging process was drawing about 1800 watts, to begin with, at least. I didn't look again, as it was on a timer so that it used off-peak electricity.


PeteB - Luton UK
- 02 Silver 'Classic' Prius - 87k miles

Life mpg 51.03 ~ 42.49 ~ 5.54 ~ 18.06 [184 fills]
(UK ~ US gal ~ I/100Km ~ Km/I




Posted: Sat May 26, 2007 8:54 pm
by aminorjourney
Hi Pete,

Very interesting. Thanks for posting this on the forum. One of the BVS members (Jim Fell) has actually done a conversion of his own to a second generation Prius using lithium ion (Thundersky) batteries and a high-power inverter.

It would be great to see these two cars together to compare them.
I know the version of the Amberjack Prius I drove went into EV mode at start until about 31 mph when, like the regular Prius, the engine came on. Is the restriction of EV mode still 31mph? I've noticed that on a regular prius the engine will switch off and the car will move on motor along above this speed, but not if the EV mode is selected.

It would be great to see some photos too. I've seen one in the flesh but I don't know how many others have.

And of course, the other question I'm sure other people are interested in is if it's made you think about an EV as a good complementary car to a Prius (or should that be the other way around? ;) )

Thanks so much for this great input.

EV mode

Posted: Sat May 26, 2007 9:16 pm
by PeteB
aminorjourney wrote:Hi Pete,

the version of the Amberjack Prius I drove went into EV mode at start until about 31 mph when ... Is the restriction of EV mode still 31mph?

It would be great to see some photos too.

made you think about an EV as a good complementary car to a Prius?

No, they've overcome that to some extent. It does EV at 70 on a light throttle on the level with no headwind. On the additional LCD display that Amberjac fit behind the steering wheel an a horizontal bar indicates the throttle pedal position and a small arrow indicates the point at which the engine may start. Keep the indicator below the arrow (although going very slightly past it seems to be ok) and it stays in EV mode at any speed. The arrow moves around a bit and it on occasion it would be annoying to following traffic to stay in the 'EV zone'. but engine fire periods are kept very brief if one is sensible.

The regular Prius will also go electric only at any speed (as will the Mk 1 Prius [which owners refer to as the 'Classic']) if the power demand is low enough and the HV battery state of charge high enough.

I have a few photos, but not sure how to upload them to this forum yet (only joined in last hour or so, and mainly used Yahoo groups previously [and CompuServe before that - gosh I must be old!]).

I've long thought that an EV would make an ideal second vehicle at some point, but it would not be practical at present. I DO have an electric assist bike which has a basket at front and a large motor-cycle locking box at the back, so it has lots of capacity for carrying shopping, recycling etc, even if it does look a bit odd!


PeteB - Luton UK

Posted: Sun May 27, 2007 9:40 am
by aminorjourney
Nice photos Pete!

70mph in EV mode! Excellent! I suppose it's all about how quickly you accelerate. I know if you accelerate smoothly in traffic in non-ev mode you can get into the high 40s and I have noticed on the motorway with the "ticket saving" cruise control that the engine does switch off on the M4 hills near Swindon (if you're going downhill that is).

Do you have a video camera? It'd be great to see some video of the car doing it's stuff :)

Cheers for all your great input!


P.S. How does the Classic and new style Prius compare?

Posted: Sun May 27, 2007 12:11 pm
by PeteB
aminorjourney wrote:P.S. How does the Classic and new style Prius compare?

That's a hard question - they are so alike and so different at the same time. If I was teleported blindfold into one doing 50 mph in a big open space, I would have to concentrate quite hard to say for sure which I was in, unless I felt for the switches, which would give the game away.

Appearance, dash and interior layout are so different, yet they feel identical to drive. When I was driving a current model 200 or so miles a day all week, then getting into my Classic on my days off (even though it's now 5 years old with 87,000 miles on the clock) I never felt I was getting into a lesser car in any way. The engine sound is slightly different under hard acceleration, the NHW20 seems to use slightly fewer revs of the petrol engine in a given situation, but the Classic still feels very refined, if anything, slightly more so with its ever so slightly softer suspension and seating - in fact the one thing that lets the new car down in my opinion is the firm ride (at least on London's poor roads) - it's not actually bad, but the car is so refined in other ways it leaves one concentrating on the ride quality more than might be the case some other cars.

My ideal would be a Classic with some of the improvements of the '20', such as rear wiper, single wipe facility, steering buttons, EV switch, brake assist (not that the Classic can't do a good emergency stop!), VSC and side air bags (plus heated mirrors that are a criminal omission on a modern car in my humble opinion).

If I needed to replace my Classic, I'd be tempted to find another second hand one - the current model is just too big for my humble needs, plus I like a proper spare wheel. However, for taxi work, there's no question, the '20' is much more suited (but a Classic would be ok).

It's almost a shame Toyota didn't carry on making the Classic alongside the NHW20!


PeteB - Luton UK
- 02 Silver 'Classic' - 87k miles

Life mpg 51.03 ~ 42.49 ~ 5.54 ~ 18.06 [184 fills]
(UK ~ US gal ~ I/100Km ~ Km/I)

Posted: Sun May 27, 2007 9:11 pm
by aminorjourney

My In-Laws (Kate's mom and dad) have a '20' but Kate's elder sister has a classic. Kate's mom and dad brought the '20' because they liked the Classic's comfy seats before then discovering the newer model wasn't quite as good.

They're also a bit miffed about the fuel economy (the published figures being a lot more than they actually get).

Still, it would be good to see a classic prius. I don't think it'd be any good for us though as we quite like having the hatchback style (and use it quite a bit!)

Posted: Tue Jun 12, 2007 12:51 pm
by marktime
Hi Pete, I've been meaning to say hi! but not got round to it. I recognise you from the Prius forum but I dont think we have corresponded directly.
Now that I know you are here I had better doubble up on my factual accuracy as I can see you have far more Prius experience than me.


Posted: Tue Jun 12, 2007 12:53 pm
by aminorjourney

I'm sure Pete will forgive us if we make the occasional faux pas!

Posted: Tue Jun 12, 2007 8:19 pm
by PeteB
marktime wrote:Hi Pete, I've been meaning to say hi! but not got round to it. I recognise you from the Prius forum but I dont think we have corresponded directly.
Now that I know you are here I had better doubble up on my factual accuracy as I can see you have far more Prius experience than me.


Hi MarkTime - sorry missed your post before. And don't worry, I still make the occcasional goof myself.