What to expect after your Hymotion L5 pack is installed

This is for new owners, or people thinking of getting one. PeakOilGarage started a list of things for you to do; this is more a list of things to expect. Please pile on with things I forgot, or haven't run in to yet.

This is what will be different after you get an a123Systems (Hymotion) L5 battery installed in your '04-or-later Prius. It may sound like a negative list, but I'm actually pretty happy with the pack. It's just that it's a big purchase, and people are more likely to take the plunge (and be satisfied with what they got) if they know what to expect--and there are some tradeoffs. Here we go:

1. Your wallet is $10,400 lighter.

2. Your load capacity is 200 pounds less. I mean, your car's load capacity is less. Maybe yours is too while you contemplate the financial damage.

3. You can no longer use the storage compartment under the cargo area.

4. Your spare tire is removed from the storage well. This is actually the thing that bothers me the most. Options:

a. Put the jack & tools next to the new battery, and strap the spare tire in the cargo area (Toyota provided straps for this purpose, because the full-size tires don't fit in the well). Lose some cargo room. Note that there's no protective bag or anything that comes with the kit.

b. Carry flat juice and a patch kit. Lose the ability to keep going if a tire blows. (I have to admit that doesn't happen often).

c. Upgrade to 16" run-flat tires and wheels. Lose a lot of money and some of the mpg you just bought (they're heavier, and in the worst place for more weight).

5. You have to plug in your car now--there will be a hole drilled in the left side of your rear bumper. It's easy enough to do, but you should do it every chance you get. The brake lights will come on to show when it is charging. You need a 25' 14awg cable or a 50' 12awg; you don't get one with the pack. Shorter cables and smaller awg ratings are fine too.

6. The car will occasionally (maybe once every 30 miles?) go "beep-beep-beep". That's the pack and the car arguing about what mode the car should be in. Just ignore it.

7. The pack will repeatedly ask the multi-function display to display the pack charge status. Which is great, except it also tries to display the standard battery status, and then gets overridden, causing flicker. You get used to that fast enough. It will also sometimes switch to the charge status screen while you're trying to use another screen, which is more annoying.

That's pretty much it. You can drive the car exactly as before, and while the pack is charged, you'll probably get somewhere around 100mpg. Of course, at that mpg range, little things can make a big difference. Accelerate slowly, don't use climate control, avoid hills, avoid short cold trips (or install a block heater), etc. Also note that when the pack loses its charge (they say 30-40 miles, we've been seeing just around 40—note that the pack Toyota is testing supposedly only works for 6 miles) it goes back to the normal 50mpg. If you go 40 miles at 100mpg and another 40 miles at 50mpg, your average is only 67mpg, which can be disappointing. Charge the pack every chance you get—carry a cable in the car.

There is an on-off switch for the pack on your dash. You probably just want to leave it on all the time, although it's nice to be able to turn it off if Toyota service is picky, or you are troubleshooting, or you are on a long trip and think the charge will make a bigger difference later (but don't turn it off while you're driving!). There's an LED to show that the pack is charged and ready. If it ever flashes, count the flashes. Stop the car for a few minutes, drive again, and see if it flashes again. If so, call your installer.

I would second everything that SaucyRed wrote.

The most gasoline that I use is the first 5 minutes during a the engine warm-up period. An engine block heater and a programmable timer would likely help a lot in the mornings. Perhaps a 30 minute pre-heat before you typically leave for work? How long does an EBH need?

The Hymotion kit makes it easy to maintain EV mode with the pedal at speeds below 38 mph. The EV button is not necessary. You have plenty of control with the gas pedal. Whereas with the stock Prius, you really have to feather the pedal lightly to get in EV mode. With the Hymotion battery there is A LOT more range in the pedal to use EV mode.

With an engine block heater, staying below 38 mph, and if you live in a flat area, you could easily go a few thousand miles on a tank of gas. I am waiting for the first

When I am on the highway, I set the cruise control at 60 mph. If the highway is flat, it is always 99.9 mpg. Even if there is a slight incline on the highway, I typically observe numbers of 60 mpg or higher during the climbing phase.

The Hymotion battery appears to make the Toyota stock battery think that the SOC is always 7/8 or 8/8 bars. The two different batteries flash back and forth on the screen, with the Hymotion battery being dominant, then the stock Toyota battery having a short flash. However, I don't think the stock battery is really at 7/8 or 8/8. I have turned off the Hymotion battery while driving, and the stock battery seems to recalibrate and return to 6/8 bars within a few seconds.

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www.PeakOilGarage.com

1) 2008 Vectrix electric maxi-scooter
2) 2009 Toyota Prius, Package # 6, Spectra Blue with Hymotion battery upgrade
3) 2009 Tesla Roadster (coming June 2009)

FWIW, the triple beep and the screen change are both related to EV mode. If you try to go EV and are denied, or if you are in EV and cross the 34mph boundary you get the triple beep. The screen changes when an EV mode request is successful. Just keep in mind the difference between EV mode and stealth mode. EV mode is the "ICE warmup delay" mode activated by pushing the "EV" button on asian and euro priuses. This is not the same as stealth mode, which is activated by releasing the gas pedal and depressing lightly. This gets fuzzier on a Hymotion Prius, as their controller is connected to the EV switch and can decide to put you in EV mode without external input. If you are going faster than 34mph, you are definitely in stealth mode, not EV. With the high SOC maintained by the PHEV pack, it is also widely reported that you can transition directly from EV mode to stealth mode upon crossing 34mph without the ICE starting.

Rob