prius main battery drained?

<div class='quotetop'>QUOTE(christet @ Sep 2 2007, 09:21 AM) [snapback]505776[/snapback]</div>

Hi Christet,

This is normal. The lowest bar is like 40 % state of charge on the battery, so it was far from drained at 2 bars, probably around 50 % state of charge. To prolong the life of the battery, the car is programmed to get the battery recharged from that level in priority over other functions. But, it will avoid using the engine in a stationary situation, and let the battery run down.

By running the AC in the car-wash, the engine did not have a chance to run, but you required the AC to use electricity from the battery for a prolonged time. As soon as you triggered the engine, it went into double duty to move the car and charge the battery.

Getting caught out in the sun, during a 95 degree day, in stop and go traffic will cause this same thing. The source of the heat in your situation, was the hot water from the car-wash. Same thing really, long time, without a chance for the engine to run, with allot of heat input.

Possibly, having just got the car, and not living in an area with common high temp/humidity index days, you have not seen this during your daily driving. If you are concerned about this even after this explainantion, next time set the AC interior temp up to 82 F during the time in the car-wash, and set the outdoor air control to recirculate (so you do not pull in hot air from the car-wash).

 

I had a similar experience at a car wash this weekin my 2006. As I was almost through the car wash, car on and in neutral, the check main battery light appeared. I am not sure if it stalled or not. My battery was just about drained. I re-started the car and it has been fine since. I am puzzled by this and not really sure what happened. Very strange indeed..

 

Hi Even4...

Setting the car in neutral locks in the engine operation at the time of the shift. If the engine is off, and you set neutral, the engine will stay off, until you shift out. If you use allot of electricty at this time, you can run the battery down too far. 2 bars is not a problem. I personally, have only seen one bar, once. My opinion is to operate the car so it does not get down to one bar.

If the engine is running, and you shift to neutral, the engine will remain running. But I do not know if the battery will be charged in this condition either. I think not, but maybe others with better knowledge can confirm or deny this.

So, yes, be careful about using allot of battery when the car is in neutral, and the engine off.

 

The ice can not charge the battery in neutral. You need the transmission in drive or reverse or park to allow the engine to charge the battery. The Prius can charge the battery when stationary but due to the nature of the power splitting device it will load up the transmission to do it. There is no real neutral in the Prius, it alows the electric motors (M1 & M2) to freewheel to achieve a neutral like state. If they are both free wheeling they can't be generating electricity. As soon as the HSD is required to generate electricity it will put power to the front wheels unless the transmission is locked by the park pawl.
Thinking about it I'm not sure the Prius can charge the battery in reverse.

Is there a reason the transmission needs to be in neutral?

 

Sometimes when I'm parked outside Panera Bread stealing free WiFi access my main battery will drain down to two bars. That's when I figure I had better log off and go recharge.

 

The traction battery does not hold very much charge. It was never intended to propel the car very far, or support its operation without the engine for very long. It really just acts as a buffer, absorbing excess energy and delivering needed energy, but only in small amounts. This is a cost:benefit compromise. A bigger battery would improve performance, but would cost a lot more.

It is not even necessary to have the A/C running for the battery to drop way down. I had a long wait at the border once, coming back from Canada, and the battery dropped several bars in a relatively short time. Since a battery at "full" (8 bars) will only drive the car about 1 1/2 miles before the engine kicks in (at 2 bars) and the car normally gets around 45 to 50 mpg, if we assume $3/gallon gas, each bar is only worth about 1.5 cents worth of gas. An insignificant amount.

But the battery will NOT charge if the car is in neutral, so it's a good idea to shut the car off if you must put it in neutral to go through a car wash.

 

All the car washes *I've* been to (admittedly few) require the car to be in neutral so the tires will turn freely along the track. Since the Prius main battery will not charge in neutral, you MUST turn off all accessories so the battery doesn't drain too much.

 

The answer has been posted. This condition is not "dangerous", you can not fully discharge the traction battery. The system will shut down before that happens.

So if you are going through a car wash, put the car in neutral and turn off the A/C (the only accessory that draws enough power to seriously deplete the traction battery). Use the button on the steering wheel so the fan will also go off. You don't need to be blowing the very wet outside air in a carwash into the vehicle.

Bottom line. Don't worry about the car, it will take care of itself. It's smarter than we are.

 

<div class='quotetop'>QUOTE(daniel @ Sep 2 2007, 07:36 AM) [snapback]505814[/snapback]</div>

You can't power down, because that engages PARK. You have to lighten the electrical load and use Neutral.

 

<div class='quotetop'>QUOTE(IndyDoug @ Sep 2 2007, 09:13 AM) [snapback]505803[/snapback]</div>

Leave the car ON and in Park, and it will recharge itself as needed until it runs out of fuel.

 

<div class='quotetop'>QUOTE(richard schumacher @ Sep 2 2007, 11:41 AM) [snapback]505877[/snapback]</div>

True, for charging a laptop or just killing time with the AC and radio on, both the HV and the aux bat will maintain a good SOC. However the problem was in the car wash. In that situation, try not to run any power (in neutral).

 

<div class='quotetop'>QUOTE(daniel @ Sep 2 2007, 07:36 AM) [snapback]505814[/snapback]</div>

...except that when you shut off the PRIUS it will auto-set the park mechanism and the front wheels will lock.

oops: Rick Auricchio already mentioned this -

 

<div class='quotetop'>QUOTE(christet @ Sep 2 2007, 07:55 AM) [snapback]505821[/snapback]</div>

That's why nobody drives my Prius but me, except at the dealership, where I believe they know the car. (Not all dealerships do! But I believe mine does.) Valet parking? Forget it. I don't patronize such establishments. Car wash? If I can't drive it through myself I won't take my car there. I go to the do-it-yourself car wash.

<div class='quotetop'>QUOTE(Rick Auricchio @ Sep 2 2007, 09:36 AM) [snapback]505874[/snapback]</div>

I thought there was a way to do it. I seem to remember this discussed way back in the early days. But I don't remember.

 

<div class='quotetop'>QUOTE(David Beale @ Sep 2 2007, 08:40 AM) [snapback]505848[/snapback]</div>

Does the AC even use power from the traction battery? My limited understanding is that it only powers the traction motors and all other electrical demands (radio, headlights, wipers, AC, etc.) are taken care of by the 12 volt system.

Also, in order to allow the Prius to be "pulled" through a car wash, it must be set in neutral and left on. So if the AC is running, it may deplete the 12 volt battery but won't show this on the traction battery screen icon.

I agree the car is pretty smart, if fact smarter about power management than most of us.

 

<div class='quotetop'>QUOTE(christet @ Sep 2 2007, 07:55 AM) [snapback]505821[/snapback]</div>

The best Prius info I know of can be found John's site ( http://john1701a.com/ ) and on Hobbit's site ( http://www.techno-fandom.org/~hobbit/cars/...s-linkfarm.html )

Also, Galaxee is a great resource on this board. Her hubbie is Prius tech.

 

<div class='quotetop'>QUOTE(banjoman @ Sep 2 2007, 05:32 PM) [snapback]505989[/snapback]</div>

Hi Banjoman,

Where would the 12 V battery get its charge then ? Indeed, the 12 V battery in the Prius does gets its energy from a DC to DC converter that is powered by the traction battery. So, even if the A/C was run by the 12 V battery, it would deplete the traction battery.

Why do it this way? No alternator, or loss due to the high friction belt drive to an alternator. The car has this 10 HP generator right there in the transmission which has a much more efficient gear drive and its charging the traction battery.

But, no, the second generation Prius cars has an airconditioning motor/compressor run off the traction battery through the inverter. The power required for A/C is the largest auxiliary draw in a vehicle. This means 12 V wires would need to be huge for sufficient power, besides you would need a 12 V battery heavier than the traction battery for it.

Think about you home airconditioner. It runs on 220 Volts single phase in the the typical US home. If that house has gas for heat, cooking and hot water, the A/C is the only appliance that runs on 220 volts. In the Prius they just put in another 3 phase bridge circuit in the Inverter package to run the A/C motor.

There is a great advantage in doing this. No parasitic 2 to 4 hp belt waste power for the A/C compressor either. Which would waste at least 2 HP anytime the engine runs. And, a motor can be made variable speed, so the compressor can be run only as fast as it needs too for the cooling needs at the moment. Which saves even more energy. The variable temp setting was not a design goal, it was a happy circumstance of electric powering of the A/C. That is why the Prius is a relatively cheap car, yet with the usually luxury car automatic temperature control feature. It just works out that if you want to save gas, you get this for pennies extra.

This is one of the synergies of the Prius. Saving Gas, implies Hybrid, implies Big Battery. Which then allows the removal of the alternator, A/C, and Power steering pumps. Because now there is enough electrical power to run the A/C and PS on electricity. Indeed, Toyota has said the HSD is actually cheaper to put in a car than the cost of the traction battery. Because all the other auxiliary stuff in a standard car that can be taken out. As battery costs drop, one can forsee a future maybe 50 years from now when a HSD like system is cheaper than a traditional car at time of purchase, let alone after 5 years of operation.

An electric engine cooling pump is probably next. This would be a unit without large side loads on bearings, and should last for very long time. And there goes another HP worth of belt drag loss, as well.

 

<div class='quotetop'>QUOTE(daniel @ Sep 2 2007, 12:20 PM) [snapback]505956[/snapback]</div>

Don't get your wheels aligned either! (Actually, you can, but ask first because some shops need to have the car in N on the alignment rack.)

I have had my traction battery ran down to one bar two times so far - both times it was on the alignment rack. I had to shift the car into neutral myself for one of the alignments because the tech didn't know how to do it.