When Should I Charge?

if there were any degradation, it would be minimal and measurable only by rigid testing. if you are planning to keep your car for a long time, and want to maximize battery life, follow best practices. otherwise, you'll be fine no matter what you do for 50-100k miles.

btw, this is just my opinion, and not based on anything scientific, just what's in the owners manual. i try to abide by it, but i often charge half way in case i need it, then it's only 45 min. with an L2. some will disagree and ymmv!

 

I am planning to keep this car for a long time. I guess I will have to sacrifice some % of EV range over time then.

Nevertheless, it’s my humble wish as the battery technology improves over the time somebody offers an EV range improved snap-in replacement battery pack on the market. At a reasonable price to make it economically justified for almost a decade old PiP then.

 

I have nearly 11,000 EV miles on my PiP over 19 months. That's about ~800 charge/discharge cycles. As Bisco stated, if there was degradation, it's too minuscule for me to notice. I use the timer to charge every night. But there may be holiday weekends that I do not leave the house, meaning the car may sit 2-3 days at full 85% charge.

I think you paraphrased the manual but the message is the same, "as late as possible." That's not very black and white to me and indicates even Toyota is unsure of best practices. I plan what I can plan on the weekdays but my weekend life is dynamic like yours. If there was a concrete statement from a credible source that states 85% SOC is bad for battery, then I would oblige. Current research indicates temperature is a larger factor than SOC on battery longevity.

And finally, if you're really concerned and rather take the safe approach, do what Bisco does and charge partially.

 

It's been since April 23, 2012. Same range as when I got the car. I charge the day before almost every day, sometimes with .9 EV left and sometimes with about 5.0 miles EV left.

 

of course, p/k has only put 3,000 miles on her car so far.

 

8950

My son put 3700 on it last August

SM-G900T ? including this annoying Tapatalk signature

 

that's cheating.

 

I've been googling around and found this essay on LiON batteries, which says:

So I guess coming home, parking PiP in the shade, charging it immediately, and leaving it fully charged over the night - is not that bad. Leaving it fully charged on the scorching sun is.

I understand another story is winter temperature, where late charging provides the battery a healthy warm start.

[1] How to Prolong Lithium-based Batteries - Battery University

 

Trickle-charging is very oldschool. In the days before electronic charge control, it was a reasonable way to charge a battery with minimal damage to the electrodes, but it was still destructive if left on too long.

I destroyed a battery in my T-bird one winter by leaving it on a trickle-charge. Since then, I've used a battery maintainer with excellent results. It uses a charge controller, which constantly tests the battery, and then only applies a charge as needed.

 

While trickle charging was an option for Nickel-based batteries, for Lithium batteries as in the PiP, trickle charging a full battery can lead to a catastrophic (read: fire, explosion) failure. The chargers for lithium batteries know not to do this. I don't know about the ones in cars, but the lithium batteries in cell phones have circuits in the battery itself to prevent this.

 

Come on PK is a man!

Correct. Note also that eneloop is NiMH, not LiIon. And since the Prius never fully charges the battery, always leaving a 15% margin, I think it's very difficult to run into issues unless you live in Arizona and always charge your car to full at noon in the open sun.

I've been charging "whenever wherever" for about 18 months now. No problems. During the winter, when we had temperatures drop to the low 40s overnight, I did have to start using the timer to prevent unwanted ICE startup in the mornings (the car is parked outside).

 

It's smart engineering to charge the battery to 85-90%

Longevity goes way up.