PiP Lithium Battery Care Question

That shouldn't make any difference. After all, it's what happens while you drive anyway.

 

That's an efficiency of 1000/1440 = 69% for L1, and 100% for L2. Something is not right here.

 

They don't be able to tell why/how it was abused.. but if they do any type of serious testing they should be able to tell it was abused. As the battery degrades its "charge/discharge" curve changes so by measuring that one can tell a lot about its status. Also many batteries have an embedded counter that tells the number of cycles. That plus the curves and you can determine the difference between age and abuse.

 

What matters is the charge amperage seen by the cells, not the charge amperage coming out of the wall.

Suppose that the charger is constant current, constant voltage (CC-CV) up to 4.2V/cell, or 235.2V. Then peak charging current is 12A*120/235 = 6 amps for L1, and 8A for L2 (240/235 ~ 1). Are you sure that the the draw is only 8 amps at L2? That does not make sense in light of the claim for a 1.5 hour full charge.

If you go by Toyota claims of 3 hours at L1 and 1.5 hours at L2 charge, that implies average current into the cells of 5 amps at L1 and 10 amps at L2. It might be more like 6 amps and 12 amps respectively during the CC phase.

But in the end, there is nothing to worry about, charging at L1 vs. L2. It is less than 1C either way, which is important.

I don't doubt that this data was recorded correctly, but something just doesn't quite add up. The service manual has a value, Battery SoC below 35%, in the operational history data, which tracks "Inappropriate Operation." Other sources of Inappropriate Operation include MG1 and MG2 overheating, shifting into P while the car is moving, etc.

If 25% SoC is at 0 EV miles, then that implies 20% SoC at 1 bar. That seems inexplicable to me, since it is dangerously low SoC for battery health. Someone that never plugs in would always be at 20%-25% SoC which would lead to a short lifetime. It makes more sense to me that 0 EV miles should be at around 40% SoC, and 1 bar/full depletion is at 35% SoC.

 

The PiP pack is 4.3KW, with 3KW usable. That implies 1.3KW of capacity is not being used, 1.3Kw is about %30 of the total packs capacity, if the 0 EV SOC is @ %25, then it implies Toyota lets us charge up to %95 SOC, which seems a little high, but it might be the case. To actually find out will require someone with instrumentation to measure it. We can be "paper napkin engineers" all day, but that's not going to get the actual information, is it?

The amperage numbers are calculations based on the charging power KW display, while the PiP is charging, on L1 it shows as "1KW", and on L2, it shows as "1.9KW". I have not measured the actual current. Of course we don't now the chargers efficiency for L1 or L2, so its hard to say what the actual amperage from the wall is, until its measured.

 

It's actually 4.4 total and 3.1 per recharge. Part of the remaining 1.3 is still available too, just not for EV driving. That chunk is for HV use, similar to regular Prius usage.

 

Anybody have actual recharge measurements via a kill-a-watt? Is it 3.1 kWh, or more than that, to account for Peukert's and charger inefficiency etc.

Anyway, I'm only trying to point out here that (1) the service manual states that SoC will not go below 35% without causing a DTC and (2) if tracksyde's data is correct, then the service manual is wrong, and the average car will see a lot of use at 20% - 25% SoC, which will lead to a short lifetime.

 

while we're on this subject, anyone have any thoughts about this: yesterday i recharged with .4 miles left and it took 3 hours, 20 min. for the lite to go off next to the plug. today, i recharged with zero range left and it took 2 hours, 35 minutes. is it possible i wasn't getting full amperage? i have a dedicated 15a circuit.

 

I did more digging in the service manual. There is a service procedure, for checking weakened packs, that calls for leaving the car in N until hitting 30% SoC, and that 20% SoC would trigger a P3000. The 35% SoC in the Inappropriate Usage list may be a holdover from the 2010 PHV -- I have found a few of those.

Still, it is difficult to fathom having the battery being at 25% SoC under normal usage. I wonder if Toyota considered that the green HOV sticker users may never plug it in, and if that sort of use will have a long term adverse effect.

Bisco, there may be some temperature dependence on the length of time that your charger was running.

 

thanks sei, both were after overnite cooling and ambients around 50-60 degrees. i'm going to watch it more carefully and track chrge times. it's hard because i always forget and you really have to check in 5 min. intervals or so. i wouldn't have even noticed except i was waiting for it to finish the day it took so long.

 

Here's the recharge data from my ChargePoint account report:

2.989
3.129
3.125
2.986
3.032
3.109
3.110
3.201
3.117
2.947
3.067
3.136
3.126
3.088
3.022
3.021
3.081
3.117

That certainly makes 3.1 a reasonable standard value to use.

 

The total resistance of the battery pack could have been different, because of temperature or type of use.

 

While we always say that we are using a 110V receptical, and most of the time we will see 110V, actual voltage can vary from 120V down to about 89V. At the time you charged your voltage supply may have been lower than 110V for some reason for all or part of your charging time.

Noel

 

The Pip built in charger, has PFC (power factor correction) circuit to sustain the required power having in consideration the current supplied by the electrical outlet.

 

Call me dumb, but what I am getting out of this thread is that Toyota has carefully planned their software to not let the battery go below a safe level not get charged in excess. The toyota display may let you think your battery is fully depleted or charged, but in reality there is a margin of safety built in...so why go crazy buuilding in our own "perceived" margins.

 

but they tell you in the manual to try not to charge when the batteries are warm. so they don't have a control to prevent charging until the batteries reach a certain temp. probably because there are times you may want to charge as soon as you finish driving and they are not going to prevent you from doing that, just recommending not to make a habit of it if you want to extend battery life.

 

I wouldnt worry about it.. you could always turn on the remote A/C for 10 minutes just to give it a blast of cool air.. but it has fans in the back anyway that will run while its charging.

I dont know what is considered too hot.. but I've seen battery temps in the high 90s, low 100s. That was just from parking under the sun at work, charging from 3-5:30 and driving home in 75-78F temps with no A/C on in the cabin.

 

If I'm reading all of this correctly, my understanding is that

a) I should charge at night so that it finishes just before I get in the car to go somewhere. Since I leave on weekdays at 6:30am, I'm assuming that a 3am start will work well.

b) In order to recharge after my trip to my son's school each morning, I'm going to have to turn OFF the timer so that it'll charge immediately, OR reset the time so that it starts charging shortly before my trip to his school. Huge pain.

c) Then, after returning from school in the afternoon, I'll need to turn the timer BACK ON in order to have it charge at night.

All of this sounds like a huge amount of trouble to me; I had assumed that I could just drive the car, plug it in each time I return home, and that's what I've been doing these first couple of weeks.

I'd be interested to know how much difference in battery life I can expect if I were to continue my current way of charging, but this all sounds so nebulous that I doubt anyone has definitive info.

Bob

 

The timer defaults to OFF, after each charge, so you don't have to turn it off each time... you need to remember to turn it on when you park for the evening. Do what you can, its not a "life or death" situation, we are just trying to preserve the lithium battery pack for as long as we can, so that its ability to hold the maximum charge is extended for as long as possible. I use the timer so that the PiP is fully charged shortly before I leave for work, I do NOT use the timer the rest of the day. When I get into work, I plug in again, not worrying about the timer... same thing if you are going out later in the evening, after getting home.

The lithium pack is going to hold less charge just due to age anyway, so what we are doing with this delayed charging is trying to avoid having the battery at a high state of charge for a prolonged time, which is also known to reduce it's long term ability to hold charge as well.