PiP Lithium Battery Care Question

I was kinda wondering the same thing... Would it be better to leave the batter charged, or discharged?

 

Door #3.

Also, if you will be leaving town, leave the battery at or near 0 EV miles. Lithium is happier at 50% SoC for storage.

 

I think that people are stressing just a wee bit too much over the batteries and when to charge or not charge. If you live in a hilly area, you will be putting way more stress on the battery just going up and down the hills than you will from charging. When you are plugged in, you are putting about 5 amps into the battery. When you go down a hill and doing moderate braking, you can be putting somewhere between 50 and 100 amps into the battery.

My charging pattern is thus:

Get home from work in the evening, plug car in, set timer to start charging at 1am.
Leave for work at 9am, get to work around 10am, plug-in, immediately start charging.
If I leave for lunch, I'll plug in again and immediately starting charging again.

Rinse, and repeat as necessary.

If it is friday, and we're going out of town for the weekend, I will delay plugging in until I get home from the trip. I park outside, and the EVSE is plugged into the garage, with the cord snaking out from underneath the garage door, so there's little point in plugging in if I'm going to be away for a few days.

The reason I charge at 1am is just to put less stress on the electrical grid. When I get the solar installed on the roof, it will be to take advantage of lower rates at night. Might as well get into the habit now.

 

Read pages 47 and 93 of the PIP Owner's Manual to find what Toyota recommends.

 

I will chime in, since the text quoted was from me

Lithiums longest usable service life is when the pack isn't at %100 SOC, in other words most Nissan Leaf owners usually time the charging so that it finishes shortly before they will be driving the car. With that said, don't go nuts about this , just charge and use the car, but if you go to work everyday at 7:00AM, and your are using a L2 EVSE (as I Am), I set my charging timer to start at 5:00AM, and the email usually arrives around 6:30AM, that charging has completed... When I get to work, I plug in the Toyota supplied 120V EVSE in the parking garage, and I immediately charge, so when I leave work, I have a full charge. I don't use the timer at work as sometimes I go out on service calls (as I did on Wednesday), and it's nice to have the EV capability in the city (the drive to and from the call was in all EV). When I was back from the service call, I plugged in again, I had 3 charges that day.

The point being, do what you can that's convenient for you, but don't stress out about it...

 

Just a guess.. but I believe mitch was referring to the original post.. the quote was his

 

interestingly, when you sell/trade your pip, no one will know how you charged it, coddled it or abused it.

 

Absolutely true my fellow Bostonian

But what if you plan on keeping the car 8-10 years, you might find if you spend a litlle time now doing a few simple things, your EV range might not diminish as quickly as the PiP ages, and all lithium packs degrade over time anyway, the point is to try and minimize it as much as we can.

 

So here's a question: would there be a difference in the life of the battery if it were always charged at L2, or always at L1? I mean the difference in watts is negligible, but it never hurts to ask, right?

 

Good question! Usually, the rule of thumb is that rapid charging is bad. However, the difference between 5 amps and 10 amps charge rate is arguably negligible in light 100 amps of regen.

 

agreed. i'm thinking more on the line of a future buyer. this is probably the most critical user affect that has ever been on a car. other than just beating it to death maybe. anyway i try to do the charge and go thing as much as possible. i wonder what it's like for someone like john1701 who is constantly coming home and throwing it on the L2 for the next trip?

 

L1 120V charging uses 12 AMPs, about 1KW to the pack
L2 240V charging uses 8 AMPs, about 1.9KW to the pack

They are both tiny compared to the discharge rate from the car, there is essentially no difference between them.

If you look at the Nissan Leaf's DC fast charger, for example, that can put out 50KW, and a Leaf can be charged several times a day at that power level, without much affect on battery pack life. It does cause the pack to heat up, which is why the Leaf has a battery temperature gauge, but the built in BMS (Battery Management System) in the Leaf just lowers the charge current, if the pack gets too hot.

We have nothing to worry about with the PiP pack

 

At home, it's still just a L1. That's almost always started via timer set for 4:50 AM. At work, it's a L2 which I plug in following lunch. So, there's always a long rest in between. Most recharges are for full capacity too, though there have been a handful with a small amount left over from before.

 

L1 120V charging at 12 AMPs would be 1.4KW.

I'm wondering how sure we are about these numbers. Has anyone carefully observed the charging rates at 120V and 240V near the start, midpoint and especially at multiple times near the end in order to see whether the charge rate changes over time?

I have not done this for my Volt but over time have randomly checked it's charge rate at different points in the complete cycle. It begins drawing the full 120V at 12A or 240V at 16A and does so, as far as I have noticed, for the large majority of the cycle. Near the end, it begins scaling back on the charge rate although I have not observed this carefully enough to say how early it begins ramping down and how that behavior differs between 120V and 240V.

Note, for "240V" charging in the U.S. you need to distinguish whether the charging station is really connected to 240V (at a residence or small building) or at 208V (at a larger commercial building with a 3 phase utility hookup). 240V at 16A is 3.8 kW but 208V at 16A is only 3.3 kW. So, the maximum charging rate will be slower for 208V setups.

 

thanks john. does charging from partial capacity have a negative effect?

 

At near 0 EV miles, SoC is around 25%. 50% SoC is probably around 5-6 EV miles remaining.

Below is the data recorded by Tracksyde.