L2 daily charging: restrict to 8A for battery health?

not at all. long term L2 charging will have only a minute effect on the battery life, no worries.

you can leave the car plugged in for battery heating, but you need to read the manual more thoroughly. it staes that leaving the car plugged in for too long can deplete the 12 volt battery

 

I don't see the point in limiting the charge to 8A. Take a look at the attached graph. Under normal EV driving, discharge current goes over 100A - I think I've seen as high as 190A. Charging current due to regenerative braking is 'only' 90A. Granted that these current levels are only present for a very short time, but I don't see how 16A is going to affect the battery's life.

 

This^^
If charging at 16A on L2 was bad for the battery, then, whatever you do, don't DRIVE it! As Ed said, the battery handles a ton more current in normal driving than while charging. And in mountain driving it's even more. Oh! And then there's charge mode which takes the battery from depleted to 80% in about 30 minutes as opposed to 0-100% in two hours.

The sole purpose stated in the owners manual for the 8A option is if there is another load on the circuit you're plugging into that causes the breaker to trip.

Just one data point: I charge practically every day and sometimes multiple times in a day on L2 at 16A. My Prime has 59,000+ miles on it and a full charge takes the same kWh now as it did when I got the car.

 

Say what? Why on earth would that be?
Say it's 0° and me and Ted Cruz can't take it anymore and jet off to the Caribbean and leave the car plugged in at the airport L2's to keep the HV battery happy.
Your saying I could come back in 2 weeks to a dead and destroyed 12V lead acid battery?
Because it got depleted and froze to death. You can't jump start that mess....
No way toyota allows that engineering to exist....

 

Obviously, you do not own PP and have not followed numerous threads dealing with this issue. There have been at least a dozen of threads I have read reports of people leaving the charging cable attached while going for a vacation with an intention that will keep the car happier and the 12v battery maintained, only to find out the dead 12v battery when they come home.

BTW, the traction battery heater does function if the charging cord remained plugged in. However, this function can be turned off by an owner. Thus heating the traction battery during 0°F temp is apparently not required. I am currently testing my PP with the traction battery heater option OFF in -26F arctic blast condition.

 

Obviously, this is a design flaw and should NOT be tolerated.
Are those dozens of people getting brand new 12V batteries replaced under warranty?
How hard would it be to get a SW update to correct this flaw, toyota?

Good luck with your extreme temp testing.
Apparently, NO Li-Ion battery is happy at 0°F temps. Look it up.
And at -26°F you may be doing damage to it if you try to use it, which you must just to get the gasser started.
What do you hope to prove? Good luck.

Proper PHEV's and EV's will give you a 'Reduced Propulsion' msg that the car is limiting power to drive the car to protect pack, when an owner does not or can not leave it plugged in during extremely cold temps.
edit: and it is allowed to go below a SOC where the TMS stops. Maybe 40% SOC to save your bacon.

So someone in the Great White North is suppose to keep this PHEV plugged into an EVSE for heating the HV battery pack, and they should also run a 120V cord to a 12V battery maintainer?
This is unexceptable.

 

reformed smoker?

 

Don't get it....
toyo apologist?

Seriously, the 12V just goes dead? And most likely will need to be replaced? And that's not a big deal?

 

Carry a portable charger and be done with it. Also, my understanding is 8A is an option because some older homes do not have 12A.

Posted via the PriusChat mobile app.

 

Yep, some had successfully replaced the 12v battery under warranty if it was less than 3 years old. But those who with older than 3 years on the car and saw a dead battery after coming home from winter vacation, they weren't that lucky.

It did not get as cold as the initial forecast a few days ago. It was only -16F. LOL Today's high temp -7F is in our forecast. My wife had to drive my PP this morning to get to her appointment because her PathHy would not start. I guess a dead 12v battery? It has an OEM 12v battery so it must be 6 years old now. I hope it is not the Lithium-ion traction battery that went dead. I haven't had a chance to look at it yet. It's too cold! LOL.
BTW, my PP just started fine in -16F temp, but as you predicted it, as soon as the car was turned on, it started the engine. But this behavior is nothing new to me. With or without the traction battery heater option turned on or off (or car plugged in or not), PP will start the engine in very cold temp in my experience anything below 20F is a good bet.

So, my question is why did Toyota even make the traction battery heater "optional" that can be turned on and off by the owner? If it is so vital to have this function to prevent damage to the battery, then I surely hope Toyota has made this function non-optional.

That's exactly what many people do including myself. I was thinking of installing an onboard 12v maintainer with a dedicated 120v plug hidden behind the flippable front license plate holder. Got all the necessary parts for this mod, but have not installed it yet, because I don't know how long I will be keeping the car.

 

This not my experience with our 2022 PP.

At temperatures below -15C, it operates as a hybrid only.
Between -15 and -10C, it uses EV on occasion.
Above -10C, EV is available full time if selected.

I have yet to plug in the block heater or charge or boost the auxiliary battery under the hood. Have started without issue on multiple (~12+) -27C mornings so far this winter. I am trying to find the lower ambient temp limit for starting without the block heater or charger being plugged in and I have not found it yet.

When extremely cold (below -15C, and typically -20C or colder ambient), my routine is to charge the traction battery if below half charge when I return home from work since the cabin and hence traction battery are already warm.

The traction battery provides current at any temperature if charge is available although it has its most optimal range of temperature. Just cannot charge if the battery (not ambient temp) is below 0C. But the BMS takes care of that when the ambient temps are lower than that. No matter how cold, after charging, my range is always in the range of 38.5 to 40 km, just like it was with warmer ambient temperatures.

I have no concerns operating our PP at extreme cold temperatures.


iPhone ?

 

eow, I *strongly* advise you to get a battery monitor for the 12V battery. The charging system in the Prime doesn't do a good job of keeping the 12V battery happy in our Prairie winters. I use the BM2 monitor ( available from Amazon, ebay, even Princess Auto where it's on sale for the next few days) which continuously measures the battery voltage. A phone app can download the data via Bluetooth. My car is only 2 years old and the battery is showing its age because I didn't pay enough attention to it.

Ed

 

Ed, I am not familiar with the BM2, but will check into it. Is it possible that you are creating the issue yourself by attaching a parasitic drain to the 12 V battery?


iPhone ?

 

That's one reason I use the old fashioned method of occasionally popping the hood and putting my multi meter on the battery when I check the oil and other fluids anyway. There's already enough parasitic drain on the battery without paying lots of money to add more.

 

Your number is in agreement with my experience. The cut-off temp you indicated is important, because -10C=14F is what Toyota indicates to be the lowest limit of heat pump operation.

This morning my car's traction battery compartment temperature was -15C=5F. I know this because I have a small BlueTooth Temperature probe under the deck in the traction battery compartment. The car was fully charged the previous day but was not plugged in. Even if it was plugged in, I have the traction battery heater option turned OFF for this month as part of my experiment. Thus the battery was cold-soaked all night. The outside ambient temp was low of -26C=-15F overnight. When my wife drove the car, it started without any hesitation but immediately after starting the car the engine fired.

Since I did not drive the car, I do not know how it behaved for ~37 miles round trip with several stops she made. But since she does not change EV/HV, the car basically stayed in EV mode selected all these 37 miles. I just checked the Eco Diary for today, the car had 36.9 miles distance with 49.4MGP and 3.8miles/kWh Average EV efficiency with a 2% A/C load ratio. The car left with 100% SoC and was back with 52% SoC left.

2% A/C load ratio is almost negligible. The car was set with AUTO 70F HVAC setting. This means almost all of the heating was coming from the engine, not from the heat pump (ie the compressor was not running). 2% A/C load was probably from running a fan or maybe from the heated seat. So, if I ignore the A/C load and assume ~50% SoC was actually used on EV mode to get 3.8miles/kWh. Meaning about 10.64 miles (assuming 5.6total kWh for full EV operation 5.6kWhx50%x3.8miles/kWh) of a total distance of 37 miles (~30%) was driven by pure EV mode without the engine running. All this on a day with the high temp -2F (-19C).

Now, the question is did I damage the traction battery by driving the car on such a cold day? I don't think so. I have been doing this last 5 years, albeit this is the first winter on my new 2021 PP. And if you think about it, if the Li-ion battery get damaged by being in hybrid mode, or must be plugged in all the time to protect from cold-soaking the battery, then I am sure none of the regular Gen4 Prius would be operable in Canada and Alaska winter. I never heard such claims.
I am with @eow on this one.

BTW, I did plug back in the PP as soon as my wife came home to top off the 48% SOC used today. It charged fine and took 3.12kWh from the wall in ~3hours using 120v L1 EVSE, again with the traction heater option OFF.

 

As far as I can tell, BM2 has minimal effect in draining the 12v battery. The spec is 1mA of a draw. If nothing else is on the car, the newer healthy 12v battery can be fully charged by driving ~1hour (or just in READY for 1hr) once a week and will be fine for ~two weeks. What the monitor allows is to quickly scan the behavior of charge-discharge of the 12v battery over time. The graph below is an example of the BM2 display. The red vertical line indicates yesterday morning I realized the 12v battery dropped close to 12.2v very rapidly in less than 2 days after my routine 1-hour drive. What I realized was that I kept the Carista dongle attached to the OBDII since the last drive. It was using more mA than usual even after the car was parked and OFF. With an arctic blast coming our way, I decided to connect the 12v battery to my trusted Victron Charger. The high plateau shown right of the red vertical line is the period charger was connected.

 

I just bought a second BM2 monitor so I made some measurements. Although it's rated to draw 1 ma, it actually draws more like 3 ma. At room temperature, my digital multimeter measures 14.40 V while the BM2 reports 14.36 V. I consider both of these acceptable, even though they're not within spec. Like Salamander, I don't see how a 3 ma current drain will have an effect on the battery.

But, that raises an interesting point. Has anyone actually measured the parasitic drain? I don't remember seeing any numbers.

Ed

 

This is the only actual measurements data I have read.
Parasitic draw & various other draws on 12v system... | PriusChat

What I found peculiar about the way the 12v battery on PP drains is that it is not constant linear discharge. After a full charge, around 12.7v, if the car is just parked, it drops very rapidly for the inial day or two down to ~12.4v and it sits there for a while up to a week or so, then it gradually drops again down to 12.2v.

You can see that behavior in the graph above. From 1/3 after the battery was fully charged to 12.66v by driving ~1hr, it dropped rapidly in the next 24 hours or so to down to ~12.34v. Then the drain slows down. It even went up a bit on 1/5, and gradually lowered to 12.26v on 5th day 1/8 when I drove it again.

 

Thanks Salamander, I didn't see that thread. I'm actually surprised at how low the measurement was. 60-80 ma isn't much of a load. But, at 80 ma, you'll drain the 45 AH battery in about 3 weeks according to a very simple calculation. Of course, real life is never simple! But those numbers are not totally out of line compared to the results we're seeing. Add in a reduced battery capacity because of the cold and the agreement between calculation and reality improves.

The non-linear discharge seems reasonable to me. The magic phrase is "surface charge". It's a characteristic of most (all?) rechargeable batteries that causes them to show an unrealistically high voltage after charge. It quickly disappears after a load is applied and the battery's voltage drops to the proper voltage and stays almost constant until the battery is discharged.

Ed