Connect charging cable to 240V outlet?

@Rob43 is your man. He can make you a nice adapter cable for a reasonable price.

 

Welcome to PriusChat !

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Yes, I build a fantastic quality adapter, let me know if you have any questions.


Rob43

PS, JB types faster than I do...

 

... and if you want to read about it before contacting him, check out this thread:
Using the Primes 120v Charger at 240 Volts, Cost $20 !!! | PriusChat

 

It’s nice to see this message much sooner than before.




iPhone ?

 

When you are going back out with it soon, certainly.

But when not, then I'd prefer the greater battery longevity of slower charging, closer to the time of departure.

 

I'm still learning more about the Prius Prime in advance before buying one later, and I have heard about faster charging reducing overall battery life, but how serious of a trade-off is it ?

If someone got a 240v outlet at home to regularly do a fast recharge daily instead of using the slow 120v recharge would the battery life of the one regularly recharged fast using 240v be reduced by years or just a few months compared to the one slow charged using 120v ?

I would think or at least hope that battery technology has improved some over the years to reduce the negative effects of fast charging unless it is a factor that simply can't be much improved upon.

 

I have debated this question back n forth with a friend that's BIG into 1/10th R/C car racing, the R/C modeling world has an excellent understanding of Lipo and Li-ion batteries concerning charging, charging rates, and how to best keep them alive the longest.

I personally build big-ish Li-ion battery packs using 26650 cells, so I have a bit of charging knowledge based on several years of doing this.

After kicking this "How Fast Is Too Fast" question around and around with my R/C racer buddy, he and I both believe that charging a Prime at 240v / 12 amps is still slow and extremely acceptable for prolonged battery life.


Rob43

 

I don't have a good answer for the Prime, but am leaning back towards some previous general battery knowledge and some NDA'd manufacturer product roadmaps, all of which are quite stale now.

Note that this is not just a matter of charge rate, but also of the time spent at full charge prior to actual use. Unlike other common battery chemistries that like to sit fully charged, these types have their best longevity when stored somewhere near mid-charge. The more time spent at the extremes, either full or empty, the faster they age. Toyota does limit this by narrowing the used charge window, but still advises to lean towards not fully charging the battery a long time before use.

How do R/C modelers store their various LI-family batteries?

 

I completely agree with your bold statement.

Let me add to it a little bit more:

1) Toyota allows the Prime to charge at up to 240v / 16 amps, this equals ~3840 watts.

2) A Toyota 120v OE EVSE operating at 240v / 12 amps equals ~2880 watts, this is substantially less than Toyota's allowed maximum.

3) Time spent at full charge is actually a VERY important variable, it is my personal belief (i could be wrong) that 98% of us don't let our Primes sit fully charged for a week or two un-driven. I believe that 98% of us drive that fully charged Prime within 24 hours of said charge and it's my opinion that this 24 hour widow is 100% acceptable. On the other hand, charging up to 100% and then letting your Prime sit for a week or two is a bad idea if done on a regular basis.

R/C modelers typically store at ~40% and some even like to put their Lipo's in the fridge for extended non-use.


Rob43

 

Okay, so if I am understanding correctly, the 240v fast charge will have so little negative effect it should not be a concern at all and the thing to avoid is to avoid having your car fully charged (or almost completely uncharged) for more than 24 hours on a regular basis.

It is normally rare for us to not use our car at all for a whole day, we might occasionally have a day where we would not go anywhere and the car would sit unused for a whole day, but that might happen at most once a week or once every two weeks.

Now having said that, we live in a small town where even the most distant store we would go to is less than 3 miles away so we could run to a few different places in town and get back home and still have only driven about 5 to 6 miles and not drive again till the next day, so would that be almost as bad as having it fully charged ?

My wife works part time about 2 1/2 miles from home usually 4 day a week, so if the car is not used for errands on any of those days then those days would only get about 5 miles of use per day.

The rare occasions we travel to the nearest city about 25 miles one way we would obviously need to use hybrid mode and not the EV mode and those trips might be once a month and sometimes less than that.

Normally I would be the type to want to keep the battery topped off and fully charged each night, but since we often do 6 miles or less a day, would it be better to hold off recharging till it got down to at least 70% or less ?

 

I would use the charge timer, have the car fully charged each morning and drive it each day as you normally do. If you want to skip a day or two of charging if you aren't driving much, that would work also. If I'm not expecting to drive my Prime much the next day, I may not plug it in the night before.

 

If OP uses Rob's pigtail to connect OEM EVSE into 240V outlet, does the car know to shorten the time needed to reach the full charge on its charge timer? Or, does it act as if it is connected to 120V outlet? If so, it will always finish the charge a few hours before the scheduled departure. Of course, if that's the case, you can always schedule the departure time a few hours later than actual.

 

Yes. During the connection, the EVSE finds out the supply voltage and knows the expected charge rate.

 

Sweet!

 

This matches the now-stale 'inside' industry information I used to have.

 

Yep, that thinking on the 40% rule does go way back in time...

But that does not make it wrong, just old.



Rob43

 

So last night I did my first full charge since installing my 240V outlet and starting to use Rob’s pigtail. I started charging at 8:57PM which is when I took the picture. Then, at 11:21PM I received the notification that my car was completed charging. Although the picture says 2hr 50min to charge, it took less than that to finish. If we go by the numbers it took 2hr 24min to charge, but I know the notification can take a few mins to arrive so I figure maybe it took about 2hr 20min to fully charge.

So when I got the notification I went out and put away the EVSE in the trunk. Overnight, the Prime spent about 7 hours charged to 100% because this morning I drove to work. Is 7hrs too much time for the battery to be sitting fully charged? I think not.

In terms of expected performance, I saw no difference today. In fact, if anything, the charge lasted a bit more driving to work today than average. Of course that is within the margin of error and the normal variables. But still I find it was at the upper edge of what I experience every day driving to work.

Another point I wanted to make is that regenerative charging happens every time you brake and when going downhill or letting the car coast. I have closely observed the charging rate when doing this for prolonged periods and it is obvious that regenerative charge appears faster than 240V charging. So I would not be concerned with the idea that 240V charging is too fast, especially when I am charging at 12A instead of the 16A allowed by the vehicle.




iPhone ?

 

Thanks for sharing that, and you made a very interesting point when you said:

"it is obvious that regenerative charge appears faster than 240V charging. So I would not be concerned with the idea that 240V charging is too fast"

I know I would prefer faster charging as long as it did not cause any significant degradation in the overall lifespan of the battery.

As far as a general time limit for how long the car sits having the battery fully charged before using it I wonder if Toyota has a guideline written anywhere covering such concerns, I would hope that even 12 hours sitting fully charged would not be a problem.

 

sitting full for 7 hours isn't going to affect current performance, but if you do that 5 days a week for many years, it will likely affect longevity, which is one reason they include a charge timer.