Prius Prime: detail about Charge-Mode

It's a "choice" only if people are aware of it and know how to "exploit" it.

 

Yes to your last statement. When the EV miles remaining goes to zero, the Prime starts the ICE and runs like your 2006 prius using (and automatically recharging) the remaining portion of the traction battery. The (forced) CHG is more aggressive and will add up to %80 of the usable traction battery charge whereas driving the Prime with zero EV miles is just managing the traction battery capacity needed for Hybrid Prius driving. So unless you are going down a big hill, it is hard to add EV miles back unless you use the (forced) CHG mode.

Sometimes I wish i could override the Hybrid Mode when I hit zero EV miles and use the last power in the traction battery to get home. But I think it would run the remaining battery charge down very fast and it would be bad to start the ICE and not have a nice buffer of traction battery power to use while the ICE warms up to 67F-ish (observed in 2012 Prius v) and can start to contribute locomotion power with minimal emissions. Then I repeat my Prius mantra “just drive it,” and I’m happy again.

 

I’m in the research phase. 2 questions:
Is there a resource for finding charging stations?
How difficult is it to set up charging at home?

Thanks

 

If slower charging (overnight) is OK the car comes with a charger than can be plugged into a normal receptacle in your garage,

 

So I would be ok with a 10 amp circuit for that, correct?

 

You need a 15A circuit, which is standard for 99% of residential garage circuits in the US. If for some reason you actually have a 10A circuit (I haven't heard of anyone who does), you could set it to charge at 8A max and that would work since the continuous load has to be no more than 80% of the circuit rating.

In other words, yes you can plug it into a normal plug in your garage and that will work as long there's no other significant load on the circuit. The garage door opener and lights are OK to share the same circuit. A space heater or large power tools would not be OK to use at the same time on the same circuit, but you could unplug the car if you need to use those.

 

Thanks! my garage is from the 1920’s, I wish I had an opener!

 

If it's that old, it might just have 10 amp circuits. Our house in Ohio was built in the 1850's. I don't know when they wired it, but there was a bunch of stuff that wouldn't pass the code these days.

 

Driving a Prius or Prime at highway speeds isn't efficient, but it certainly is nice while out on the road.

 

It’s actually charging fine and we looked. It is 15 Amps with a GFCI!

 

That sounds perfect. The portable charging cord which comes with the PRIME will bring the vehicle to full charge in about 5-1/2 hours (or less if the PRIME is not fully discharged when you plug it in.)

If you do a lot of short trips -- like to the supermarket and back home again -- you can plug in your PRIME to "top off" the battery to keep it at full charge.

When and if you decide to get a 240-volt "Level 2" charging device, the time from zero to full charge is about 2-1/4 hours.

How you manage your charging really depends upon your travel pattern. If you're a commuter, you charge overnight. If you're just doing lots of short errands and returning to home several times during your day, just plug in when you can. And, of course, you can also take advantage of public charging -- often provided free -- at some parking lots, parking garages, or various businesses.

You need to develop a different way of thinking about the process. Unlike gasoline refueling, you don't benefit by "running the tank down to empty" to minimize the number of visits to the gas station. Electric vehicles want to be plugged in whenever and wherever they're parked.

 

Yes, but you will need to set the charging rate limit to 8 amps (an option on your dashboard displays). Then, instead of a full charge in 5-1/2 hours or so, it will take closer to 8. Still OK for an overnight charge.

 

If you're really dedicated to keeping the car a long time without replacing the battery, there are a number of things you can do to greatly minimize the natural degradation of capacity. The manual covers some of them. Another option, not necessary but possible, is to keep the state of charge as low as possible, but not zero. For example, if you only drive 5 miles per day, driving around at 100% charge each day will wear out your battery much faster than charging to 30% (to give some margin), driving your 5 miles, and then charging back up to 30%. The worst thing for a lithium battery longevity is sitting around at 100% charge, especially when warm (even 70°F/21°C).

 

Right, but with lithium batteries, the lower the SOC, the slower the degradation. The only reason not to store them at 0% is self-discharge may take them to the point that they will be damaged. Charging to 30% will last far longer than charging to 84%. For example, charging the batteries to 100% usable/84% "real" SOC and discharging them before charging again will give about 1200 charge cycles before losing 30% of its capacity, but charging to 30% usable will get you about 3,000 charge cycles before losing 30%.

Since the Prime's instrumentation doesn't give the user a way to see the "true" SOC, the best the average driver can do is keep it a little above 0% to provide a margin for self-discharge while maintaining the ability to see the self-discharge. The actual SOC may well be ~20% when the display shows 0%, but that leaves the driver with no way to determine when self-discharge is taking place.