Questions about effects on battery

toyota has taken care to protect the battery, with top and bottom buffers that are hidden from view on the screen.
you can find them with the right scanner.
charge it any way you want to, you can't hurt it long term.
try not to leave it fully charged for long periods of time, that can be detrimental to battery life if done consistently.
the only question i have about charge mode is how fast it charges the battery. hopefully toyota has taken care of that, but i would think there would be a small hit to mpg.

 

1) How far do you let the capacity drop before plugging in? I have access to a Level 2 charger at work; what's the consensus on charging it back to full when I get to work (charging to full from about 50%ish left)? What about when I get back from lunch after getting a full charge (charging back from about 80% left)?

Just drive it.

My 2012 plug-in Prius was recharged twice a day for countless years before I sold it... started full at home, drained it entirely on the way to work... recharged to full for the commute home. All these years later, it's still working just fine for the friend who bought it.

My 2017 Prius Prime is now in the hands of my niece. Same commute & routine for many years, except in the summer I would arrive at work with a few miles still remaining. All those recharges, no big deal. My wife is still using her 2017 Prius Prime that work. That's fine too.

In other words, just plug it in when you can. Don't ever worry about the % left. Use electricity whenever you can.

 

That's the more interesting question. That new feature to you isn't an efficient choice. There are only certain circumstances when that actually pays off. One is simply when you haven't used the gas-engine in a very long time. Engaging charge-mode will help to exercise the moving parts & fluids.

With regard to battery-life, the charge-rate is double from the wall... 7.2 kW instead of 3.6 kW. That's not enough to really make any aging difference. It's just ordinary AC speed. So, no need for concern.

 

I think the standard things that dramatically shorten battery life should be avoided.here

Excess heat

Make sure to never cover the cooling ducts in the back. Check the duct filters at regular intervals and clean them when needed.
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Excess charge/discharge rates

The vehicle's AC/DC converter (charger) limits the current so overly fast charging isn't really possible. I would think that avoiding use of long-term uninterrupted use of full-throttle is also a problem. Not so much the getting from 0-30, or 60 and keeping up with the rest of the traffic are going to be a problem. It's the heavy duty towing and mountain climbs that could cause long-term damage.
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Charging/discharging outside of the normal ranges

The vehicle's charging system keeps you from overcharging. Letting the car sit idle for long periods while the battery self-discharges could also be problematic. This is going to eat the auxiliary battery long before the HV battery, I suspect.​

As to the charging mode

There's not much to be gained by using an ICE that's got only around 30% thermal efficiency to charge the battery. There are only a couple of legitimate uses of the charging mode, I've fouind only two that work for me, and there only on rare occasions. Here's a thread that explores this topic.

Is there a legitimate use for charge mode in the Prime? | PriusChat​

 

I'm one of the Prime owners that's a big fan of charge mode. I"m always looking for new ways to use it to my benefit while getting the most from the car and least effect on the hybrid battery pack. I use DrPrius app and when there is no traffic or other distractions around I watch the AMP readout from the app.
I've found that charge mode typically charges at 20 amps no matter what speed the car is steadily holding between 75 mph all the way down to around 20 mph. < steady speed on a flat and expect 20 amps of charge from charge mode. Comparing that 20 amps to charging from the plug, I typically see 9 - 10 amps while plugged into a Level 2 charger and 4+ 5- amps while plugged into a Level 1 charger. Charge mode will only charge up to 80%, and this is in case someone wants to use charge mode several times on a 100 mile trip to help keep the pack from overheating.

If out of EV range and 0% showing on the battery charge screen expect it to take about 1/2 hour to get back to 80% charge. Big tip, No One Says you have to use charge mode to charge from 0% to 80% every time the EV/HV button is held in for 5 seconds. It's a button that can be very helpful if the driver learns how to use it.

A couple of hints. Try not to use charge mode when the car is getting lower than typical mpg. like going uphill or into a strong headwind. With a tail wind or on the downhill side, that's when you'll get more benefit and less wear on the engine and motor/generators.

Battery degradation is something we all have to deal with. Some of us pay more attention to it than others, so take advice about it with a grain of salt. The more you want to keep your pack healthy the more you have to learn about what stresses it. And it's pretty much the opposite of what you'll hear everyone into rechargeable batteries is interested in. Fast charge, High Speed. There are two recent posts about driving a Prime in EV at 80 mph until reaching 0% EV and letting the engine start cold at that speed. I"ll just say "Do the math"

Another hint. There's a reason there is an engine in the Prime. Learn how to use it to your advantage and your battery will thank you for it.