REVIEW: Hymotion Battery Plug-In Prius

If you've got a GPS that keeps track of "moving average", like
my not-new-anymore Garmin does, that might help. The newer Garmins
[Nuvi, notably] appear to have taken useful functionality like
that and breadcrumb trails and altitude away, which is really sad.
.
_H*

 

Thats awesome, nice work! Appreciate the updates!

Rob

 

My Hymotion installation date is now scheduled for Oct. 7th at Fitgerald Toyota in Gaithersburg, MD. The anticipation is almost over.

Thanks Jay for the great write up.

---Kent

 

well looking at around a 100 mpg IMPROVEMENT with mostly city/suburban driving...that cuts gas cost to about a third. factor in a bit for electricity and you are looking at a real savings of 3-4 cents per mile driven...

big question since you should qualify... what do you know about the stimulus package as far as the plug in credit talk... would you qualify? or is it for purchases going forward?...

i have heard it both ways. i have a few people at work that says i qualify even though my purchase was in 2007... i kinda doubt that, but since i did not get a credit, i was wondering if any retro credits would be in the works

 

Really Dave ? I thought the credit was only for new car purchases.

 

that is what i believe as well. the first i saw on it says the credit would not start until 2010, so it would not apply to any purchases made THIS year either...so who knows?

i would rather get a smaller tax deduction YEARLY as long as i use the vehicle for my daily commuting purposes... couple that with the freebie electrons my employer provides and i would have it made!~!...then again, that might be asking for a lot

 

Felix Kramer posted this on a Wired blog:

Last Friday, Congress passed and the President signed a bill providing up to $7,500 in tax credits for new plug-i hybrid passenger vehicles and more for larger vehicles. Next year we hope they'll extend to conversions.
-- Felix Kramer, Founder, CalCars.org

Posted by: Felix Kramer | Oct 5, 2008 11:24:10 AM

 

The Force, I read over the new version of the L5 owners manual that you posted and discovered something that I didn't know before. The regen braking of the Prius never charges the L5 battery pack. I am guessing that while using the L5 the stock Prius battery gets "regened" until it is fully charged and then the extra regen is wasted, am I correct? I also noted in the manual that you are strongly warned not to turn off the L5 battery back while driving. My thoughts were this:
1. What would happen if you did turn off the L5 battery while driving, would it really cause any problems?
2. Could you drive with the L5 on and use the regen to fully charge the stock Prius battery. Then switch off the L5 battery and drive in regular EV mode until the stock battery is down to only 2 charge bars. Then switch the L5 back on and regen the stock battery again? Assuming you could do this 5 times before the L5 is discharged it could gain you 5-10 extra miles of EV only driving.

O.K. Force so now tell me why I'm an idiot and how this won't work. The only reason I can see is if the regen does not go to the stock battery when the L5 is engaged, but rather is just wasted as heat. If that is the case then I would love to see the first hack to make it so the L5 accepts the regen charge from the Prius.

 

That is sort of correct. The regen energy only goes into the NiMH stock battery. In the background, you can see that the stock battery spends most of the time at 7/8 or 8/8 of capacity. It is almost always green. But that energy is being used also at the same time as the Hymotion battery.

I do see it going down to 6/8 sometimes, but it easily goes back up to 7/8 or 8/8 while just driving around town in pure EV mode.

It is as if the Hymotion system just floods the Toyota system will all of the electricity that it could ever want.

Based on where the Hymotion battery is connect, it is directly at the same point between the stock NiMH battery and where those cable lead to the Toyota drive system.

So the Hymotion is not "behind" the NiMH battery. It is accurate to describe them as side by side together feeding the Toyota drive system.
And the NiMH is not being asked nearly as much to contribute, so it is typically at 7/8 or 8/8 most of the time.

Some of the other Hymotion owners might be able to add more to my observation.

I have done it many times to save the Hymotion battery for in city driving, especially if I know I am driving more than 30 miles. I would rather conserve the Hymotion battery for speeds under 40 mph. The only time I use the Hymotion battery on the highway is if I know that I have enough remaining charge to get home or to work (where I can also recharge).

There are no negative effects to turning off the Hymotion system while driving. It might cause your cruise control to lose it's settings. No big deal. The Hymotion system turns off automatically while your are driving if you run out of energy, so clearly there is no harm to the vehicle from turning it off with the switch.

I have done that a little. If I notice that the stock battery is at 8/8, I have switched off the Hymotion battery and driven a little bit until it is 6/8, then I switch the Hymotion battery back on.

I think the gasoline engine would come on automatically a long time before getting to 2/8. But also, it would be difficult to maintain EV mode that long with only the stock battery.

When the Hymotion battery is on, it give you A LOT more play in the gas pedal to stay in EV mode. Very easy to maintain EV mode. Also, the Hymotion battery will go all the way down to 0/8 and keep providing 100% until the bitter end.

With the stock battery, it turns on the gas engine to recharge a long time before it gets too low.

 

I did a Hymotion pure EV range test tonight.
Here is what I did. Full Hymotion battery to start.

I drove around with the Hymotion battery off in order to warm up the Prius. Then I made sure I had a relatively flat course and traffic was at a minimum. The traffic was light, but for the first 10 miles, I hit a lot of red lights. I tried to maintain a speed of about 33 to 35 mph. Also, it was raining and there were a lot of puddles on the ground. I am not sure if that causes a measurable difference in terms of resistance on the road.

Under these conditions, I got 20 miles out of the Hymotion system in pure EV mode.

I think that if I had not been dealing with so many red lights I would have gotten 22 to 25 miles in pure EV mode.

Also, I have heard that the battery range gets better after a few discharge cycles. We will see. I will try again tomorrow night on a route without the red lights.

After that, I will be testing my highway electric assist range at 60 mph with cruise control on.

 

"After that, I will be testing my highway electric assist range at 60 mph with cruise control on."

want to see that!

 

.double

 

Very interesting. Thanks for such a detailed analysis.

 

Great job Jay,

Thank you for keeping everyone informed. I'm anxious to see your final write up, but the mileage alone is very impressive.

---Kent

 

Jay,
On your review will you show inverter temp? I've been reading up on Grill Blocking and I didn't know if you saw a difference between pre and post Hymotion install.
Thanks
Chris

 

What is the inverter temp symbol on the scangauge? This would be very interesting to watch when doing a lot of EV.

---Kent