Is hypermiling killing the battery?

no, no, no. you're way, way, way off. and wrong on just about every theory.

1) not all taxi's batteries last 'the life of the car' whatever that means.

2) a 'lot' of people here have bad batteries is a tiny fraction of total pro.

3) hypermiling does not use the battery only.

4) staying in ev is bad and not hypermiling.

5) you need to get back to basics, hypermiling 101.

6) no offense taken.

 

Taxi drivers tend to roll up the miles quickly, so their cars tend to wear out from distance, not age. Batteries wear out more from age and heat than from raw distance, so taxi drivers are less likely (*) to see the battery die.

(*) North America only. This forum has seen reports of premature battery failure in European GenIII taxis.

You misunderstand hypermiling. This isn't it.

Don't try to overuse EV, and don't intentionally make a practice of draining the battery down close of empty. This isn't the most efficient use of your Prius, and the frequent unnecessary full cycling of the battery does reduce its lifespan.

 

I have noticed with my Prius C when driving in EV mode (usually doing 25-30mph tops on town streets) that when the battery indicator gets down to 3 bars (2 at the very least) the engine automatically kicks in to start charging it and also takes over propulsion. I'm sure this is a safety method of making sure the battery doesn't get too low.

 

It is. Mine goes down to 2 bars.

I would think that hypermiling would actually not hurt battery life, because with pulse and glide, ideally you draw almost no current from (or to) the traction battery on the glide, and the pulse is usually short. Minimal current means minimal wear.

Instead I would think that any of the following would have a bigger impact on the life of the battery:

1. flooring it while the engine is still "warming up" every time you start the car since you use extremely high current draw from the battery
2. deliberately trying to deplete the battery's charge or overcharge it somehow
3. having your car in extreme heat or extreme cold for long periods of time
4. storing the battery for long periods at extremely high or extremely low charge instead of about halfway

But the hybrid system is designed so that you should be able to get like 100,000 miles out of the battery from "normal" driving...but hypermiling shouldn't really hurt battery life.

 

no, it is not. i don't know where you got that idea. hypermiling is accelerating smartly to a speed somewhere above your intended speed, then coasting (no power/no regen) to somewhere below your intended speed, then repeating the process. this can not be done in heavily trafficked area's in which cue you should just drive and let the car do the work. it will not use enough battery to do any long or short term damage.

 

Slowing down does count as hypermiling, but intentionally cruising any significant distance on EV instead of the ICE, far enough to drain the battery, is counterproductive. All the propulsion energy ultimately comes from the gas tank and ICE. Laundering more of it than necessary through the battery and EV adds additional energy conversion losses, hurting overall efficiency.

In your situation, using the ICE to pulse and glide between 30 and 35 mph should produce better mpg than a constant EV 33 mph.

Here are some primers from hypermiling guru Wayne Gerdes:

Beating the EPA - The Why’s and How to Hypermile

Pulse and Glide plus Warp Stealth in the Prius II for maximum FE

Your Prius is a gasoline car, not an electric car. Leave the EV cruising to the plug-in vehicles.

 

The only times I have done any appreciable amount of driving my Prius C in EV mode was not due to my choice but rather traffic being slow enough that the car itself kept shutting the engine down in favor of using the electric motor. Each time the battery only got down to 2 bars and then the car started the engine for combined charging/propulsion. I don't worry about the battery getting too low because my Prius has always been in charge of restarting when needed and in keeping the battery charged to appropriate levels. I'm not sure I could force it to do otherwise.

 

exactly right.^^^

 

Yes, the EV is more efficient than the ICE. If your car can plug in to recharge the battery (i.e. Volt, Prius Plug-in), avoiding the ICE altogether, then 100% EV is most efficient.

But your non-plugin Prius must run the ICE to charge the battery. That means your EV cruising pays both the ICE penalty and the EV penalty. And your battery wasn't made for this full-time EV service, so its lifespan will be reduced.

Prius EV has its place, mostly in low speed maneuvering and short distances where the overhead needed to run the ICE is large compared to the energy needed to move the car. But not for any long distances.

When you achieve that, show us the pictures proving MPG.

 

this is a theory waiting to be proved. have you thought about adding some more batteries?

 

You can force the car to keep the battery charged up, not draining down to the two bar minimum. A traffic-coordinated Pulse & Glide can do it.

But with the very wide variety of traffic conditions, the difficulty of doing this varies enormously. And with differing levels of driver goals and skill and patience, it often isn't worthwhile.

 

Thanks for explaining hypermiling; and it is done in heavy traffic.
Well done.
The energy used to accelerate above intended average is much less than the savngs from coasting. The trick is picking the above and below target speeds. I have Honda Insight acquaintences that get over 125 mpg by hypermiling in contests. Unreal.

With usual batteries i.e. lead acid typrs drawing the battery stored energy well below 50% does hasten battery end-of-life. I have no reason to believe Lithium batteries are different as a chemical engineer. So I don't recommend taking your batteries to near or at zero.

 

you can't, the computer won't allow it. when you see 2 purple bars, the batteries are still at 40%.

 

Nobody will convince me that driving with the car in EV mode (not pushing the button for it; rather, the car going into EV on its own) is a bad thing. To me it's a silly argument that if you are in EV mode too long, then (gasp) the ICE will have to come on and charge the battery--much better to run the ICE to keep that from happening! While I understand that all energy has to come from the ICE originally, the whole idea of having a hybrid is it captures much of the energy that would be lost in a normal car. And when this happens, you can run in EV mode for a short time for free.

When I take drives at lower speeds with lots of EV time is when I get fantastic mileage.

I'm not looking to start that war or convince the "experts" they are wrong. However, there is an alternate view on the subject.

 

on my understanding:
ECU(controller) will not allow the battery level drop to low level, where ICE will be kicked-in.
2 bar on EV battery level will kick ICE.
EV battery is intended to be used not to be spared.

during my testing, let battery to 2 bars would reduce mpg .

 

If I'm driving along at around 25 mph and the car keeps shutting off the engine and putting me in EV mode despite me trying to keep the engine on I feel it/the designers must know what they are doing better than I do-and when the battery level gets down to 2 and the engine turns.back on I figure that must be by design.

 

It isn't bad, it just isn't optimum.

That isn't what the OP was describing. He was trying to put it in EV when the car otherwise wanted to run the ICE, nearly opposite of your scenario.