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It does not seem like that long ago my Prius was modified in the best kind of way. One year ago I had my Prius modified to be a plug-in by installing a Hymotion battery. I have learned a lot over the past year and have not had any major trouble with the extra battery. I will run through some of the stuff I have learned over the past year.

Learning how to drive all over again.
In order to get the most out of the Hymotion battery a manual EV button is a must for city drivers. Letting the Hymotion battery do all the work is OK for the average user but if you have a short commute or terrain that is hilly or unpredictable manual control of EV will get you higher MPGs.

Because I'm driving in EV mode more than using gas the coolant temperature will be colder longer and may not be optimized for EV driving. To get around this you have to fake the coolant temp. This is more for advance users that can monitor the coolant temp. If you can fake the coolant temp to above 159F you can enter EV mode and warp stealth a lot sooner.

With the combination of the manual EV button, the coolant temp hack and a good mostly low speed route I am able to achieve 300-500MPG according to my ScanGauge on my trip to work and back. If I can maintain a normal commute for the length of a tank of gas I believe I can achieve 3000-5000 miles without stopping at a gas station to fill up.

I have estimated with my CAN-View that the pack holds about 16.5Ah and on my commute I use about 12.5-13Ah. Thats about .59Ah per mile. From the wall I measure that the car uses about 250Wh per mile all electric.

You do have to be careful not to draw too many amps for long periods of time or you will start to drain the stock battery. I have found a continuous draw of 30A seems to be about the point at witch you will not draw the stock battery down but the Hymotion wont charge it either.

All electric driving on flat roads.
To sustain speeds these are the least about of amps you can draw.
MPH -- AMPS
25 -- 15
30 -- 20
35 -- 20-25
40 -- 30-35
41-50 -- 40-50
55 -- 55
55+ not really possible because 60A is the most before the engine starts to burn gas.

When the engine is on at highway speeds the car will draw about 30A and you will get about 150MPG at 55MPH.


Small issues / problems.
I have not had any major problems with the battery so far.

My battery was upgraded with the latest firmware a while back.

I have had the flashing lights a few times for a low 12v battery.

I have had flashing lights for a current sensor malfunction but that cleared its self and only happened once.

I have only had a few partial charges. I think it was due to very hot weather.

The day before Hybridfest 2009 I had my battery checked for a small manufacturing oversight. The problem was the first few batteries that were made had the fan positive and negative wiring reversed. This was a quick fix and hopefully helped the partial charging issue in hot weather.

When I had the firmware upgraded one of the wires must have come loose from the pin on the wiring harness. Instead of having to drive 100's of miles to get it fixed I soldered the wire back on to the pin and reinserted the pin back into the wire harness. That was an easy fix for me.


Mileage stats.

Total miles: 9594.6
Gas used: 75.6 gallons
Total gas cost: $181.92
Total kWh: 1380.4
Total kWh cost: $110.43
Total fuel cost: $292.35
Avg. Wh per mile: 143.87
Avg. MPG: 126.9
Avg. CPM: 3.0

Best tank
2502 Miles
299 MPG


Since its been about a year since I have done my first mileage tests I will try to perform an all electric drive and all highway drive to see if the battery capacity has changed. I will try to do these tests on my next days off that are nice and sunny.

So far I love my Prius PHEV and I don't know what I would do with out it. I will never buy a regular gas car again and I will never buy a regular hybrid again. My next car will have to be a plug-in or an all electric vehicle.

Hi Jay:

___Not only a huge thank you but god bless you for taking up the PHEV and making it sing like nobody else in the world right now!

___Good Luck

___Wayne

With the combination of the manual EV button, the coolant temp hack and a good mostly low speed route I am able to achieve 300-500MPG according to my ScanGauge on my trip to work and back. If I can maintain a normal commute for the length of a tank of gas I believe I can achieve 3000-5000 miles without stopping at a gas station to fill up.


Wow - kinda makes the ICE seem like dead weight, doesn't it? Bring on the EVs, I say!

-Simon

I guess the real question is....is it cost effictive?

I'm ball parking about a $500 or less savings over a normal prius. So we are probably talking about a 10 year or greater payback time. I'm not sure thats a great deal for a car that already gets great mileage.

My HiHy has averaged about $2000 a year in gas. Assuming I could knock 75% of that off and that I would pay around 1/3 for electricity verse gas, I could save $1000 a year. That might be a little better except that the cost of the system is higher for a HiHy...for those companies that even make one.

I still think we are going to have to see a fair number of production PHEVs before retro kits become cost effective.

But dollars aside, thats for the info. Its hard to believe its already been a year since you announced that you got one. I wish we could all do it to help drive the technology along.

Hi

Thanks for the great write up.
Belated congratulations on the 2502mile tank.

Good Luck
Andrew

Very informative Jay. This adds a very nice touch to the hybrid world.

Jay,
Thanks for leading the way. I've got a few questions.

What did the Hymotion setup cost and has it dropped in price in the last year or improved in someway?

What improvements would you suggest should be made to your system for future versions?

Do you have any idea how many of these upgrades are on the road now?

Knowing what you know about your car which EV would you want to trade up to? - Dale

Jay,
Thanks for leading the way. I've got a few questions.

What did the Hymotion setup cost and has it dropped in price in the last year or improved in someway?


About $10971.00, I dont think the price has come down.

What improvements would you suggest should be made to your system for future versions?

Must have an EV button and the coolant temp hack would help. Also need some way of displaying actual energy use as in total kWh used and average kWh per mile.

Do you have any idea how many of these upgrades are on the road now?

I have no idea but I could guess either less than 1000 or somewhere near it.


Knowing what you know about your car which EV would you want to trade up to? - Dale

The only one I could afford. The Aptera. If I had the money I would go for the Tesla Roadster. I would keep my Prius even if I were to buy one of those cars.

I ran an EV only test yesterday and here are my results.

The years results

Course same as last year.
Temp was colder.
This time it was at night with my lights on and PC running.
I did not have any problems with the SOC getting too low. I'm guessing it was because I was limiting my amp draw to 40A for acceleration and 20A to keep speed.
Speed was around 30MPH

Distance - 26.6 miles
Can-View reported 14.9Ah used
Amount of Electricity to fully charge – 4734.2Wh
Wh per mile - 178Wh


Previous year results
Actual Distance – 33 miles
Estimated Distance – 25 good easy miles. 33 miles if you work at it.
Fuel used - Technically 0
Estimated Pack Size – 18.5Ah
Amount of Electricity to fully charge – 5295.7Wh
Wh per mile - ~160Wh


You cant really draw conclusions from these tests but given that it was colder and I was driving at night with my lights on and my PC was on I can only guess that the batteries have not lost much capacity if any at all.

I will try to do a highway test on the next sunny day I have off.

I will also perform another test next year around the same time.

Distance - 26.6 miles
Can-View reported 14.9Ah used
Amount of Electricity to fully charge – 4734.2Wh
Wh per mile - 178Wh


I think I can draw one conclusion. EV would be CHEEEEP for me!

178 Wh/mile = 5.6179 miles/kWh

Cost of 1 kWh in Berwick, PA (zip 18603) = $0.08

Cost to drive 100 miles in EV: $1.42

After deregulation, my cost per kWh will be up to about $0.20. SO:

Cost to drive 100 miles at $0.20/kWh: $3.56

:woot:

The hymotion pack is a lithium pack right?

Yes its a lithium battery

everyday that 13,500 (Canadian dollars) looks more tasty everyday to upgrade a 04 prius rather than buying a whole new vehicle all together.

I'm glad your still happy with your hymotion pack theforce, despite its limitations im glad there are workarounds to the problem (such as coolant hack).