So my 2 month old car went completely dead…

When topping off the battery with a maintainer, before putting a wire harness on the actual 12V battery, I always found some metal close to the battery that looked to potentially grounded, and tried them. Not always a solid connection, but always worked, at least for a low current battery maintainer.

That EGR connections sounds more solid than what I usually used, more important for a true jump start.

 

I have a question if you don’t mind. : ) I pulled over to take a call and shut my 2009 Prius off but forgot to open my door to shut head lights off. Was on the phone for 20 minutes and battery died! Battery was replaced within the last year. Would this be normal drainage? What was weird is a guy tried to help me with a fairly new small portable charger and we couldn’t get my car started. Once someone came with a big truck and regular jumper cables it started no problem. Getting oil changed next week and having battery tested. Wish my new Prius would arrive or another comfortable, reliable 50 mpg car would be created. : }

I was surprised to see the OP’s car being towed and not on a flatbed. I thought a Prius required a flat bed. Just looking for clarification because I always request one when needed.

 

If your 12V battery went too low, those fancy portable booster have a fail safe that it will not boost a too low voltage battery. Many have a bypass but you have to know how to activate it. Of course, plain booster cables have no such restrictions.

 

I do believe it's one of those typical over-cautious manual warnings covering an edge case.

I believe there's only an issue if it's plugged in but never draws any power from the socket. Once it starts drawing power, there's 12V generated by the charging system that should charge the 12V battery.

On a fine note, that function doesn't keep on the "battery heater" function described elsewhere, it's a separate "warming control" function. Same hardware, obviously, but a different algorithm with different rules. Notably, "battery heater" respects the charging schedule, "warming control" does not.

So I think that if you're leaving it plugged in for a long period when the battery heater or warming control will be active, then there's no issue. Battery gets charged every time it decides to draw power for heat or EV charge.

The issue is when it's plugged in and there would be no reason to draw power except to top up the 12V battery. It seems reluctant to just randomly draw power and potentially create a billing event - the schedules are primarily about that. And there's a particularly bad case where it negotiates with a charger but the charger isn't prepared to offer power.

So there are cases where having it plugged in may just be wasting 12V power and it would never get topped up by a charge/heat event, but it won't be an issue if you actually are keeping it attached for the heat and getting it.

 

Yes, prime has different programming in Canada, I don’t know the specifics

 

If you have a FWD not an AWD Prius a flatbed isn't required. Just make sure the tow truck lifts the front wheels. An AWD Prius requires all four tires off the ground, for a tow.
Re: jump boxes, I believe Sylvaing, answered that question or the kind stranger didn't have a very good connection to the jump point. You pretty much only need a few amps to close the traction battery relays and everything should fire back up.
Hopefully lesson learned, Keep the car in "Ready mode" whenever your still sitting in it. While headlights on for 20 minutes shouldn't have killed the battery; I'm pretty sure the battery was already low. I charge my gen4 everyday and check the aux battery every quarter. I've found it as low as 11.75 VDC and placed a 10A charger on it for 15 minutes. This gets it back to 12.5VDC, which indicates that the battery is good and operating properly. You may want to install an automatic battery maintainer. Winter months are hard on a battery. My weather is fairly mild when compared to yours.

Hope this helps....

 

I learned about the EGR stud/nut point literally as we were signing the the purchase agreement for our ‘10. We needed to verify kms on the odometer:

car had (apparently and unbeknownst to us) been sitting on their lot, or somewhere, for about 15 months. The 12 volt battery was doornail dead. They’d had it running when we showed up for test drive, “warming it up for us”.

anyway, it would not restart when we went out to turn on, to display the odo. I was watching them jump start it, and the salesman I think remarked that this was the neg point they always used.

no clue about EGR at the time of course; it’s funny how we progress.

 

Proper jumping requires the negative cable on the jumpee car to be attached to a ground point. Negative to negative with ungrounded batteries can lead to bad things. The ground point just needs to a metallic point with an electric connection to the frame. Seen a jump work by scratching the clamp teeth through the paint down to bare metal on the frame. An option if you can't find another spot.

My most recent cars had a short ground line going from from the negative connector to the frame. So the negative to ground for jumping may no longer be a concern when you can reach the 12V. At least I haven't run into problems going negative to negative.

 

I just had a problem with the 12V battery too. I live in San Diego (not very cold). I plugged in Sunday evening and left plugged in until Tuesday evening and went to take the car in an errand and found it dead. Took some effort to jump it; I called roadside assistance because I didn't know about this issue and didn't know what was wrong. He eventually was only able to jump it by connecting directly to the battery in the trunk (had fun trying to pop open the power trunk with no power but eventually got it). He said if it died again that I should take it in for warranty repair because the batteries don't do well after being jumped a couple of times. While waiting for him, I found this thread of somebody fighting the good fight on the same problem. This seems pretty common, and it's not clear if it is a battery thing or a charging circuit problem.

 

You don't have to reach into the trunk to boost. There are boost point under the hood.

 

For some reason, he couldn't get it to work. Maybe it was his bad... Don't know. I do see in the manual where it says to go under the hood, but he just couldn't get it to work for some reason.

 

The jump point under the hood has a metal plate with a plastic surface behind it.

Some jumper cable clamps, even though they have copper teeth on both jaws, only have one side connected to the cable. If you put the clamp on with that jaw on the plastic side and the unconnected jaw on the metal side, nothing happens. In that situation, try turning the clamp around.