Low Traction Battery Problem w/ Prius at my Car Wash

You should try Optimum No Rinse. Absolutely the best hand wash and you only use two gallons of water for the whole car. I do it in the garage every other week all year.

 

If the battery SOC gets below 25% it will give you that warning. (And it's not good for the battery pack either.)

Also, below 40% SOC the battery will not be used for propulsion (As someone stated.) That is what causes the hesitation. If you don't like the hesitation, just wait after the carwash with the engine running and in park. It will shut off the engine when everything is recharged which would only take a few of minutes.

The radio is fine in the carwash, but using the A/C on a hot day will drain the battery very fast. Just turn it off and endure the heat while in the wash.

Assuming you start with only one bar of battery showing, you can still easily go 15 minutes with the A/C off in neutral before the warning comes on.

"D" will also charge the battery, so you could put the car into drive and slightly hold the brake to keep the car from driving ahead. They will probably get very pissed at you for this... I wouldn't do it.

Also, if the traction battery drops too low, you may not be able to drive your car at all. The traction battery is used to start the ICE and if not enough power is available, that's it -- you will need a tow to the dealer for them to charge your battery.

 

The problem is to get to IG-ON and neutral, you have to turn the car off first, which puts it into park. Tricky... Plus you have to push the brake to get the car back into READY mode again.

The only way to get the car to stay in neutral forever is to go to IG-ON, put it into neutral and disconnect the 12v aux battery in the rear hatch.

This keeps the parking prawl from engaging. Then you have to connect 12v under the hood so you can open the rear hatch again. (Or crawl through the car.)

 

This has happened to me a couple of times. The first time I panicked and put it in park which locked the wheels-very bad idea! I had posted a thread to this forum and was told to turn off AC etc. the last time was just the other day. I had checked my battery a few minutes prior to entering the carwash and it was full. When I went in, I turned off the climate control and the headlights. The only thing I had running was the bluetooth audio. I did have to wait in line for a while as a lot of people were getting their cars washed after some snow a few days before, but it was 10 minutes at the most. Half way through the message came on and it started beeping at me! We when I checked the battery again it was on one bar.
Is it normal for the battery to run down that quickly? Btw, I was NOT in neutral while waiting to get into the wash.
I never had this problem with the 2006 Prius.

 

Why engine cannot charge battery in neutral in the first place? Sounds like a silly design.

 

I think it's required to have a neutral, and that neutral has to not apply power to the wheels. this is the only way to do it, without having a clutch to disconnect the PSD from the wheels. that would be bad for efficiency, and be something else to break (the Volt has three clutches).

The carwash design just sounds weird, i wouldn't like the idea of my car being dragged along by a large mechanical mincer.

 

Prius is the first car I've encountered that doesn't allow you to shut down in neutral. There are several useful times for that state: the car wash for one, rolling a car in a garage (though EV mode can usually manage that) and Forced Auto Stop, which seems to be impossible with a Prius, due to lack of key-off neutral.

 

No you can do a FAS by cutting power to the fuel pump, not sure why you'd want to though, since it'll stop the engine for you.

 

it almost happened to me today i got down to the last bar the warning came on !!!! hahaha i panicked the guy in front of me as taking his sweet time moving that made my panic worst hahaha i finally thought of throwing it in drive the engine kicked in right away and when i took of acceleration was sluggish.........that's the last time i go for a wash without having a full battery ....

 

+1

 

Was it low to begin with? I have done some testing before and with accessories off (A/C, fan, lights, etc.) the car does not drain that quickly. The bottom bar is about a 45% state of charge of the battery.... the car will start the ICE to charge at around 40%. The "Low Traction Battery" warning comes on when you hit 25% and it takes my car at least 15 minutes to go from 45 to 25 by just sitting there with the dome light on. (But other accessories off.) It might have been longer ...

A/C will drain power like no tomorrow, especially in hot climates.

 

Neutral normally means the engine is disconnected from the wheels. This is not possible on the Prius as there are no clutches to disengage like on all other cars.... So to get Neutral the two electric motors are electrically disconnected which allows them to "free-wheel" ..... which is essentially neutral. You can have the ICE running and go into neutral and it will keep running ...... BUT since the electrical motors are disconnected it is not possible to charge the batteries even at that point.

The Prius does not use an alternator ... so the only way to charge is with the motor/generators.

This might only be a problem in drive-through car-washes. I would like a way to over-ride the auto-park mechanism ..... like if you hold Neutral while turning off the car.... but this doesn't seem to be possible.

Worst case here if the warning comes up is just put the car into drive and very lightly hold the brake to keep it against the car-wash rollers... not too hard as it might roll under your wheel.

When I wash my car the entire time I'm in neutral is only like 4 minutes ... so even if I went in at 45% battery it would not run out of charge in that time.

 

If your prius is being pushed by the car wash mechanism while in neutral, MG2 is being turned by the front wheels. Perhaps having MG2 producing electricity when it is not driven by the engine is confusing the ECU into thinking something is wrong with the traction battery?

 

Not silly at all with HSD, this derives from one of the emergency failsafes. After the SUA scares and controversy last year, most drivers should understand the need for a Neutral setting that disconnects the engine from everything.

Similarly, at first it seems silly that the traction battery cannot start the car when the 12V battery is dead. But after reading more about emergency procedures after crashes, it becomes clear why this is an intentional and necessary design.

 

Ya also quite simply you need the computers running to maintain safe operation of the inverter... and those computers need 12 volts to boot up. Once the computers boot and startup the inverter the car switches over to inverter power to run everything. (And it starts charging the 12v battery)

During startup if the computers detect any anomalies with the high voltage system it will not energize -- protecting components and potentially passengers.

You could use a switching power supply to take voltage off the high voltage battery pack and feed the 12 volt circuit hut this would defeat the safety measures.

 

Nah -- you can use neutral driving at any speed without issue. Over 62mph the ICE should be spinning to not overspeed the electric motors. (The only way for that to happen is to start under 43mph with ICE off, go to neutral and go down a hill and go over 62mph while still in neutral.)

 

After the warning beeps and flashing message came on the first time while in the car wash and scaring the $# 1+ out of me I'm very careful to make sure I have no ac or accessories on. However it happened again even though I had checked my battery level just before getting in line to go through the wash. It seems to go low very quickly just by waiting in line...(NOT in neutral). This never happened with the 2006 Prius.

 

If the ICE isn't running and the car is "READY" it will drain the same amount of power from the battery in any mode. (D, R, N, P, etc.) Only in D, P, B and R can the computer startup the ICE to charge. It kicks the ICE on at about 40% charge and then shuts off around 45%. If you just sit in your car in PARK in READY mode and let the battery run down you will be able to see how long you have between 45% and 40% on the discharge.... Wait until ICE shuts off and see how long it takes before it comes on again. You can go all the way down to 25 before the warning comes on ... so if you enter N with the ICE shut off, that means you are at least at 45% battery.... and have a full 20% to drop before the warning or at least 4 times longer than the 40%-45% interval.

With a ScanGauge II you would be able to see battery charge, AMP draw and whether the ICE was running or not.

Perhaps there is some parasitic draw in your car causing the power to drain faster than normal?

 

It almost happened again today. Before I entered the facility, my battery was showing at least 6 bars. It wasn't busy and I wasn't in line for long - maybe a minute or two, when I found it had gone down to 4. I immediately turned off the AC completely as well as the radio. By the time I got to the cashier, it was down to 2 bars and I almost turned back. Then I had a problem shifting it into Neutral at the wash! I thought I had, but had in fact put it in Reverse, and found myself backing up towards the car behind. I got it back into Drive and much to my chagrin the attendant decided I needed his help to pull it into Neutral. Anyway, I was hoping it wasn't going to start screaming "Low Battery" at me during the wash, but it remained at two bars.

When I saw the battery level dropping before I got to the wash, I didn't know what to do to charge it back up (without leaving the facility and speeding it up). I tried hitting the gas while my foot was on the brake but that didn't turn the ICE back on. Is there any way to force it on?