2020 Prius Prime Sitting Since 2/29/2020 Due to Covid

OP,

There are threads popping up all over PriusChat on this unfortunate subject. Here's a thread with excellent 12v battery info for you:

12v Battery Is Discharging, Re-Charge Now ! | PriusChat

If you don't currently already own a trickle/maintenance charger, I'd recommend spending ~$25 to ~$50 immediately. Here are two good choices:

www.amazon.com/Battery-Tender-021-0123-Junior-Charger/dp/B000CITK8S/ref=sr_1_6?crid=W3KPP640EB2K&dchild=1&keywords=deltran+battery+tender&qid=1589178071&sprefix=deltran%2Caps%2C373&sr=8-6

www.amazon.com/Battery-Tender-Selectable-Lithium-Charge/dp/B07XMJDJX7/ref=sr_1_7?crid=W3KPP640EB2K&dchild=1&keywords=deltran+battery+tender&qid=1589178162&sprefix=deltran%2Caps%2C373&sr=8-7



Rob43

 

Unfortunately, the turning off SKS on the fob has no effect on the 12v drain. It stops the fob sending the signal, only to save the fob battery, but the car SKS still remains on and, presumably using 12v. I am checking this right now, but the first 2 days after fob switch to turn off SKS did not change the 12v drain. In order to turn off SKS, you need to visit a dealer (or Techstream or Carista?). I am going to try the Carista next to turn off SKS in the car to see if that changes the 12v drain.

 

Welcome to the forum! As mentioned above, your 12V battery has run down due to lack of charging it either by driving, or by spending time in READY mode (sitting or driving), or by being charged by a external charger.

Even though your battery is new, I am VERY concerned about its health since it has run down twice. All vehicle batteries these days don't like to be deeply discharged (run down). I can't say this strongly enough, you need to get your battery fully charged ASAP. If you keep letting it run way down, it will get to a point where it will no longer hold a charge sufficient to be usable.

If you have access to an external charger, use it ASAP. If not . . . read on.

If you can get in your car and get it into READY mode, the car IS charging the 12V battery whether the engine runs or not. Since we don't know what your battery voltage is, assume it's very low. If you can "safely" leave it in READY mode for an hour it will greatly help. Longer is better. If you can do that 2-3 days in a row you will be much better off in the future. After that, I'd recommend putting it in READY mode for 20 minutes a day until you can start driving it again. Then, please, go get your battery tested at an autoparts store or a neighbor that might have a smart charger.

We don't know if you have a safe place to do this like a garage. If not, stay with the car or someone will steal it. It's in READY and ready to drive away by anyone.

Normally, driving once a week is enough to avoid this issue. Many vehicles are having this problem due to lack of driving. Let us know how it goes. Be safe.

 

No, turning off the SKS from the fob is listed under "Electric Key Battery-Saving Function". My understanding is that it only saves battery in the fob. It dose not save 12v until it turns itself off after 5 days of inactivity. I have checked it using battery monitor and with SKS on and SKS turned off from the fob, there is no difference in 12v drain. Next experiment I will do next week is to turn the SKS permanently using Carista, and see the effect on the 12v drain.

 

That's the way I read it, too.

 

Soooooooo, what have you decided to do? Let us know.

 

Getting run completely down more than once could well have killed the 12V. Definitely worth testing to see. Whether or not you need a new 12V, you for sure need a trickle charger. This would be true for any modern car that sits very long. Just like with your entertainment system, there's lots of stuff going on when it's "off."

Engine running has nothing whatever to do with charging the 12V. The inverter charges the 12V whenever the car is in READY regardless of whether you're burning dead dinosaurs.

Nice to get it good and warmed up. I did an 80-mile drove Friday just for the fun of it.

It very lightly charges the 12V at the same time it charges the traction battery. If it's not charging the traction battery, it's not charging anything. And it's not doing much even when active.

No it won't, but it will probably shorten the life of your incredibly expensive traction battery. Might want to study up on that part of the manual to better understand, but here's the gist of it from page 133 of my manual.

There's been quite a bit of discussion around here about the best level to leave it at for long term storage lately. One of the two schools of thought are to do as the manual says and run out the EV range, and the other is to leave it somewhere around the middle (plus or minus a little bit depending on who you ask). Full is definitely not the best option even though "full" isn't physically full.

 

I think I have confirmed that turning off SKS functionality of the fob by pressing unlock twice while pressing and holding lock button does not turn off the SKS sensors in the car.

I turned off the SKS from 1st fob using the procedure described in the manual. Then, I used 2nd fob to see if the door unlocks with SKS. The door responded to 2nd fob SKS, but not to the 1st key fob. So, the key fob procedure is only acting on the fob not to send or receive the signal from the car, but the car continues to have SKS functionality. I also confirmed that while both fobs SKS are disabled, the 12V battery continued to drain just as much SoC as before with both fobs with SKS ON.

In my last PRIME, my key fob battery died in ~2 years of use while my wife's key fob which was used much less did not. Changing the coin battery in the fob is not expensive or difficult, so this fob battery saving function has very small benefit, IMHO.

 

Personally I would just remove the battery

 

Yes, and about 4 dealers gave me bad info on this very simple and basic question.

My question was "If I don't wanna drag the big cord around, but still want to enjoy EV mode when in bumper to bumber traffic, is there a way to charge the big traction batt by just driving around? Answer was "no, completely separate systems, big batt ONLY charges with big cord, etc".

That was all wrong, because they are really, really stupid. One of the idiots came from Service Dept as their "prime expert".

Here is facts.
Lower part of dash there are 3 square buttons in a row. Right most switches from "eco-normal-power" driving "modes" which seems to be throttle sensitivity. MIDDLE button switches from "Electric Vehicle"(no engine, but only works if enough charge) to "Normal"(car switches engine off and on automatically) or "Charge"(car kinda sorta runs engine more than "Normal" but still shuts off downhill). To use this button you hold it until it cycles around to "Charge" then let go. Once fully charged it will default to "Normal". Turning car off and on again with charged battery will default to EV. Using "Normal" with charged or semi-charged batt will tend to keep the charge at whatever level it is. There is a little indicator light about in middle of upper readouts. IIRC it will show EV or CHG but NOTHING (blank) for "normal".

About 30mins of driving in Charge mode will give full charge from zero.

You should drive for about that long once a week for other reasons, such as giving engine and A/T oils chance to burn off any varnish, water, etc, give brakes chance to burn off any rust, give an nesting rodents under the hood the bum's rush (no joke), and give the tires a stretch. Alcohol can also settle out of gas after about a week, so even if you can't drive I'd suggest rocking the car vigorously to keep gas mixed.

 

Just to clarify, the CHARGE mode replenish the traction battery only up to 80%. It will not let you have a full charge. Although it can be convenient way to replenish the traction battery SoC when plug-in is not an option, it still is quite wasteful using gasoline engine to generate electricity. You get better gas mileage by just driving on HV mode.

Also, the OP's question is not about how to charge the traction battery using POWER mode, but @lwpreeyeprime was asking if keeping the traction battery charged will help the 12v battery from draining. The answer is NO. Simply having the traction battery charged will not keep the charge in the 12v battery. In order to charge 12v battery one has to put the car in READY mode. You do not have to drive a car, but keeping the car in READY will charge the 12v battery. OTOH, the just plugging-in the traction battery charge cord does not charge the 12v battery.

 

Or connect a 12 volt charger.

 

Yeah, if you have one, then sure that would be the best way to keep the 12v battery charged.

I am looking into installing a dedicated small floating charger like @MSantos had it in his PRIME. Only thing I am concerned about that set up is having 120v plug dangling from the grill... I don't know if I like that.

 

I'm looking at that one too, the 4amp NOCO I believe. @MSantos recommendations you can take to the bank lol.

I have a wall mounted charger in use now, and another similar one in the hatch, for out-and-about use if ever needed.

Which begs the question: why another? The on-board style is intriguing though. You only need run the 120 volt AC plug out through the grill*, like a block heater cord. It has generous leads too.

* Need to be careful with active grill shutters. Maybe run cord through upper grill opening? Is there one?

 

I don't know about the upper grill opening. I really haven't explored an option yet. Even with a convenient opening, if it can be connected to an extension cord easily without opening the hood, then the 12v plug end must be exposed to elements like rain, snow, ice, and salt. Would that cause problem? Say if the 120v plug ends short circuited by salty slush from the road?

 

Where does this come from? My understanding is that alcohol and gasoline are completely miscible. I haven't heard of anyone needing to stir it later.