| Apr 14 |
What is the best way to condition a Prius battery?  Is there a set of driving habits that leave the Prius battery in best condition? If so, are these habits complimentary with best practice of driving for high mileage? 3 Total TweetBacks: (Tweet this post)
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The Prius is programmed to automatically keep the batteries charged within a specific range (something like between 30% and 80% of maximum charge) to maximize battery life. There’s nothing you can or need to do driving-wise to improve battery longevity.
In terms of fuel efficiency, there are ways to maximize the efficiency of a hybrid. Things like taking off slowly enough that you run on all-electric for as long as possible as well as “shaping” your braking pattern to regenerate the most possible electricity back into the batteries on stops will increase your gas mileage, but in terms of battery life the car is already programmed to do whatever it needs to do to maintain the batteries for as long as possible regardless of how you drive it.
Hi,
Stay with me and I’ll give you a full answer so you have a deeper understanding of how your Prius works. I am an independent eduactor for Toyota in the Chicago Region (Upper Midwest).
The Hybrid Synergy Drive (HSD) system is actually designed to keep the nickel metal hydride (NiMH) battery between approximately 50-70% of peak charge at all times.
The energy flow screen on the dash display which maxes out with full green bars is actually showing that 70% capacity.
The HSD does this to help preserve the NiMH, which deteriorates when it is deeply discharged or peak charged.
This is one of the main reasons why aftermarket plug-in systems are not a good idea. These systems are designed to maximize the charge available for the HSD to use and the NiMH is not protected from peak charging.
To give you an example, the current record I know of for an unmodified, Gen2 (hatchback) Prius is over 360,000 miles in real world driving. The original HSD is just that efficient.
The HSD is designed to generate and store electricity in three ways, from least to most:
1. the friction of the front wheels turning on the ground (without drive power input from the HSD)
2. the internal combustion engine (ICE) running through the Motor Generator 1 (the MG1 is one of the two small machine images you see on that energy flow screen, the ICE is the other) to be stored in the NiMH
3. pressing on the brake pedal, which makes the Motor Generator 2 (MG2) run in reverse and turns it from a motor helping move the vehicle to a generator helping stop the vehicle (the friction of it running in reverse causes the electrical resistance that slows the vehicle down and generates electricity)
All of these combined is what generates the electricity that is stored in the NiMH for potential use at the next acceleration.
As far as how you maximize that available electric potential on an unmodified Prius, there are five things you can do, in order:
1. Double your stopping distance. If (using simple, rough numbers) you normally take your foot off the accelerator and push the brake pedal at 100 feet, take your foot off the accelerator at 200 feet and coast for the first 100 then press the brake to come to a stop.
Remember, the Prius generates electricity even when the wheels are just turning on the ground as well as when you press the brake. Generating more electricity will give you more to use next time.
Taking your foot off the accelerator earlier will also turn off the ICE sooner which means you will be using less gas coming up to a stop.
2. Accelerate like you have an egg under the accelerator and you are trying to roll the egg out each time, not make omelets. In other words, don’t mash the accelerator, which also tells the system to pull more electricity from the NiMH because you are accelerating harder.
3. Get a digital tire gauge and check the pressure in your tires at least once a week. Throw away the cheapy stick gauges, something that cost $1 or 2.00 is just not accurate enough. Use the sticker on the driver’s side door frame for your tire pressure for the original tires and check with the tire manufacturer if you have replaced the tires.
A couple of pounds of air pressure over is ok, but never go more than 5 pounds over. Over-inflated tires have a much smaller contact patch on the ground and will lead to excessive tire wear (called “cupping”) and decreased stability. I can only recommend 35 psi front and 33 psi rear for the original tires since I teach for Toyota.
Properly inflated tires means the system doesn’t have to work harder just to do the same job and you will save on gas.
4. Try to avoid ethanol blends in your gasoline. Ethanol is grain alchohol and is not as energy dense as straight gasoline. You will get less “bang for your buck”. A good rough estimate is a 10% loss of mpg for each 10-15% of ethanol blend. On a vehicle that gets 50 mpg (I get 51.7 as a year long average), that is 5 mpg less.
Once again, the harder the system has to work, the more energy it will use and the less it will store for next time.
5. Keep your Prius properly maintained and look it over on a daily basis. Small damages and not doing regular maintenance on any vehicle can rob mileage.
A person attending one of my classes noticed his mileage went down suddenly when nothing else seemed to change- not the weather, fuel, tire pressure, driving route, nothing.
After checking everything, I looked at his Prius and noticed the small black plastic air diffuser in front of his driver’s front tire was broken (he hit a curb or something). That one small bit of damage caused a 3-4 mpg drop. Repairing it fixed the problem and his mileage went right back up. Take a look at them next time you’re out by your Prius, every Toyota has them.
So, driving and maintaining your vehicle properly will give you the best mpg and the most energy potential for the next acceleration.