12v Battery Requires Service

12v Battery Requires Service

Also Vehicle will consume more power at Idle error.

OK so yes seems like I need a new 12v battery car is 1.5 years old and 28k miles.

Question is why does my HVAC now not work at all is this normal with the 12v issue.

007bond | 2020年3月31日

Yes I did search the forums did not see an answer to the HVAC matter and yes I have a ranger appt for next Monday (a week with no car and back to ICE bummer).

I was at work came out and when I opened the door seen the 12v messages and no HVAC. Drove home windows fogging so opened up the window but could not get any response from the HVAC at all.

Car has been 100% trouble free up to this point.

Driving the ICE today as car is not much good with no HVAC and error continues.

Anyone know if you can just charge the 12v to get past this matter until the ranger comes?

I did not want to put my 12v charger on the battery and mess something up. Battery meters 12.6v BTW a bit low but far from dead and why does the car not just charge it. I was at 50% when I came home charged the car but 12v still the same issue.

007bond | 2020年3月31日

OK seems they took a look at the car remote and just let me know this cannot be handled by a ranger. I now have an appt at the service center for next Monday.

Magic 8 Ball | 2020年3月31日

My guess is a DC to DC converter issue.

Frank99 | 2020年3月31日

Haven’t heard of a link between 12v battery failure and hvac before. I’ll agree with M8B - likely something more serious masquerading as a 12v battery issue.

007bond | 2020年3月31日

Yes I think maybe it is not the battery and something more as there is no change in the 12v battery voltage overnight after charging the car.

My concern now is car will sit for almost a week will it even start next Monday to take it to the service center. Does anyone know if I can put a battery tender on the 12v to top it off so I don't have an issue next Monday?

Also maybe a good idea to pop the fronk now and leave it open.

sheldon.mike1010 | 2020年3月31日

If you do put a trickle charger on it, disconnect neg terminal of the 12V first.

007bond | 2020年4月7日

So did not have to charge the battery it held 12.5v till Monday and I drove it to the service center. Interesting no interaction all cars must be key dropped (with I had known I could have done that over the weekend and not Monday at 8am). Got a txt yesterday that my car would not be ready and I would be updated today. Today they took the car in and then called me to let me know it was done and all it needed was the 12v battery.

Now remember the HVAC was not working and it said system fault. I had a ranger appt on Friday that was canceled as I was told remote diag showed a ranger could not fix it the car had to come to the service center. Then today I get the call that all it was was the 12v battery and that is also way the HVAC was not working. Seems odd as a ranger could have replaced the 12v battery last week no issue so not sure why the trip to the service center was for if nothing else was wrong.

Anyway at work so cannot go pickup the car till later tonight so have to wit to see if everything is really working.

FISHEV | 2020年4月7日

Thanks for follow up.

007bond | 2020年4月7日

Picked up the car and all seems fine. So looks like when the 12v battery goes bad it can cause your HVAC to fail as well.

Tronguy | 2020年4月7日

@007bond: As it happens, the SO has the M3, I drive a Prius. In some respects, the Prius resembles the Tesla in fault groups and control. Yup, the Prius has a 12V battery, just like the Tesla. The Prius also has a traction battery that (a) provides power for the full-time hybrid motors, (b) power for the ICE oil and water pumps, (c) the air conditioning motors, and the radiator fan. The 12V powers the lights, radio, and computers, and, as these things go, is a relatively low energy storage box, powered by a traction battery to 12V inverter. Just like the Tesla.
Ya can't make the AC go if the computers upon which it depends are out to lunch. And that's what I meant by "Fault Groups".
In general, it's often more efficient to run a motor like, say, a water pump with the traction battery. Say the pump needs 120W to run. One can run the pump at 12V, in which case one needs 120/12 = 10A, or one can run it at 300V, and the current is 120/300 = 0.4A. The tricky bit here are the losses in the copper. Copper has resistance, the losses in it are I*I*R, where R is the resistance of a hunk of copper. So, 10A would vaguely tend to have more copper losses than 0.4A. One can kind of make up for this by using thicker hunks of copper, but those are more expensive. And 10*10 = 100, 0.4*0.4 = 0.16, so it's clear that since the power is proportional to the square of the current, and the resistance of a wire goes linearly with the diameter of the wire, this is a race that's much easier to win with higher voltage.
Now, at some sufficiently high voltage there's problems with breakdown and such. But this is the reason that long-haul power transmission lines run at very, very high voltages: It's all about reducing the I*I*R losses.
(The limitations on high-tension wires and how high a voltage that can run on them sounds almost like science fiction. Corona discharge, where the high potential actually causes the air to break down is one; the other one is that as the voltage goes up and one sticks to 60Hz, the power lines actually couple into the air, and a significant portion of the power is radiated away into outer space and such. Somebody with a long antenna that can pick up 50/60 Hz can probably detect the Earth from _very_ far away. Which is one reason that the very highest voltage high tension wires run DC, not AC, seeing as DC doesn't significantly radiate.)

FISHEV | 2020年4月7日

007bond | April 7, 2020 Picked up the car and all seems fine. So looks like when the 12v battery goes bad it can cause your HVAC to fail as well."

It loses the controls. Really no different than any car losing it's 12V battery.

007bond | 2020年4月9日

I'm just saying that on other post about the 12v battery no one notes that the HVAC is also not working. In fact as above some noted that I may have bigger problems. So just posting so that others if they have just the 12v fail they are not surprised that the HVAC also does not work. Seems sometimes when the 12v fails the HVAC still works.

FISHEV | 2020年4月9日

007bond | April 9, 2020 Seems sometimes when the 12v fails the HVAC still works."

I thought you lost the screen when 12v fails? If that's the case, no way to turn on HVAC. I would think HVAC controls and fan are part of 12V system.

007bond | 2020年4月9日

Screen, streaming radio, wipers, all other controls and accessories were working just no HVAC and the error msg about the battery on the screen. When I would park the HVAC would have a msg Not available system error.