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Discussion Starter · #1 ·
I accidentally left my Prius in accessory mode to eject a CD and must have forgotten to power the car off completely. I was walking out to the parking lot and noticed a horn going off from a car. When I approached my car I noticed it was my car that was beeping. The horn was letting out a very short a soft "beep". I ended up using my mechanical key for the first time since my smart entry was not working.

I got into the car and tried to power on the car. All it was doing was making clicking noises from trying to turn on the main hybrid battery. I ended up calling Toyota Roadside Assistance. I was very surprised about how little knowledge they had on the Prius. I figured my car needed a jump and was calling them for advice, not necessarily to have someone come out and jump it.

I ended up getting a coworker to jump me. I just cracked open the fuse/relay box under the hood and used the contact in there for jumping the car. I powered on the car and life was good. It was funny; I told my coworker, "Ok, it's started now." Their reply back was, "It is?¿?" :)

On the way home the hybrid battery ran a little lower than normal (probably to charge the 12v battery?) but other than that everything was fine.

Just figured I would share my experiences with the board. 8)
Regards,
BitShifter01
 

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If you read a lot of posts here, you may already know that the 12V battery hates being drained very low. You may see these situations more in the future due to this one...
 

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Discussion Starter · #3 ·
mikepaul said:
If you read a lot of posts here, you may already know that the 12V battery hates being drained very low. You may see these situations more in the future due to this one...
Unfortunately I do a lot of my reading on PriusChat (can't get there from work on my lunch break(of course))although I'm sure there are posts of this situation there.

any idea why the horn was sounding? I'm assuming it sounds when the alarm goes off, so maybe the car though it was getting broken into ;)
 

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BitShifter01 said:
any idea why the horn was sounding? I'm assuming it sounds when the alarm goes off, so maybe the car though it was getting broken into ;)
I know that if you remove the fob from inside of the vehicle without turning the vehicle off, the car does beep at you. This beep is external as well as internal, but I doesn't seem to come from the horn. This may have been what you heard.
 

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There is a jump point under the hood. No need to open any fuse boxes.

Always lock the car electronically. It will complain if it is not OFF or if any doors are open, an easy reminder against draining the 12V battery.
 

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Discussion Starter · #6 ·
richard schumacher said:
There is a jump point under the hood. No need to open any fuse boxes.

Always lock the car electronically. It will complain if it is not OFF or if any doors are open, an easy reminder against draining the 12V battery.
Yes, there is and it's located under the fuse box. At least that's what the toyota manual said. It's funny that you metion about the complaining. I always lock the doors electronically and do not remember hearing the car complain. Maybe I left the overhead compartment light on.
 

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ACC mode will not drain the battery. The ACC mode is supposed to turn off in 1 hour. Are you sure it's not IG-ON?
 

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I beg to differ about the length time to kill a battery in the ACC mode.

In Nov 2005 I decided my cell phone needed to be charged so I left the car in ACC to charge the battery for about one hour.

I magine my surprise with it wouldn't start, Got a jump and wnet to a Toyota dealership, they checked out the battery and said it was ok.

The folk at Toyota said the same thing would happen to most newly cars
on the road.

Tom

ps About two weeks later a co worker did the same thing with the same end result, He said he left his chevy to charge for approx two hours.
 

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Battery Drain

I have found that most Autos have a significant risk of wearing down the 12 Battery.
For example, my 2003 Tundra would not start one warm Austin morning. The battery was completely drained and needed to be recharged. As far as I could tell, nothing was left on and the charging system checked out OK by both me and the dealer.
Furthermore, based on the Full Charge Voltage and Specific Gravity, the battery had permanently lost about 1/2 of its capacity. This vehicle had the larger Alternator and Battery found with the Towing Package, so this incident was a surprise to me! A 'resting no-load battery' at room temperature will display about 12.8V when holding a full charge and about 12.0V when holding almost no charge.
After a lot of battery and current monitoring, I found out that my short (less than 15 minute) commutes were not long enough to fully charge the battery. For example, the Battery Capacity slowly dropped over a period of two weeks with exclusively short commutes to dangerously low levels.
A longer 20-30 minute run was needed to completely charge the battery.

So in summary, all vehicles with 12V battery systems including the Prius have a risk of battery discharge due to:
1- Daily non-use load of Alarm System, etc.
2- High Self-Discharge rates at higher temperatures of Lead-Acid Batteries
3- 'Slow Response' of the Battery Chemistry where a minimum charging time even at high alternator output is the gating factor.
4- Very High Current Drain of the starter (for non-Prius vehicles)
5- Risk of leaving some accessory on overnight
6- Relatively low Amp-Hour Battery Capacities (particularly with the Prius)
7- High potiential Current Load (idling in heavy traffic with lights, defroster, radio on).

The desire to monitor the Prius 12V Battery was the most important reason that I purchased my ScanGage.

Two suggestions:
1) Don't leave your headlight switch in the Auto On position since this will immediately add a high current load on the battery as you Power Up the Prius. This may allow the Prius to Boot Up even if the battery is heavily Drained.
2) If you find the Battery Dead and discover that the cause as something left on; remove the load and allow the battery to 'rest' for 10 or more minutes. The Lead-Acid Battery sometimes recovers from a Dead Voltage State after the load is removed enough to provide enough current and voltage to power up the car.
 

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hendricks101 said:
I beg to differ about the length time to kill a battery in the ACC mode.

In Nov 2005 I decided my cell phone needed to be charged so I left the car in ACC to charge the battery for about one hour.

I magine my surprise with it wouldn't start, Got a jump and wnet to a Toyota dealership, they checked out the battery and said it was ok.

The folk at Toyota said the same thing would happen to most newly cars
on the road.

Tom

ps About two weeks later a co worker did the same thing with the same end result, He said he left his chevy to charge for approx two hours.
Well I don't know but when I sat in the car in ACC mode (I was listening to my CD), after an hour, the car shut itself off automatically. It was rather disconcerting at first having the car suddenly turn off. I turned it back on and it operated normally. I have had several ppl over at PriusChat repeat what I did and they have confirmed that the car is supposed to turn itself off after one hour in ACC mode.
 

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I have run the 12v battery down below minimum-start voltage 3 times in 18 months. Twice when the hatchback wasn't shut tight and the interior lights stayed on and once when I forgot the reading lamps after messing with the Nav system in the garage.... I know Dumb. None of these cases were severe "really dead" (overnight) but still it took a jumper to get it running.
1. It's ready to go almost immediately when hooked to the jumper. I'm reminded that all I'm doing is booting a computer...not spinning a high load starter motor.
2. I've had no sign of a sick or weak battery so far. It stays charged easily for a week or more without being run.
I think the reputation of delicacy is perhaps over stated but I'm being more careful with the hatchback closing now.
I'm very glad Toyota put the jump start connection up front.
I have a Scan Gauge now so I can read exactly what voltage the 12v battery is producing. When running the voltmeter shows between 13 and 14.5 volts. It still holds 13 volts after a week of inactivity.
 

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hendricks101 said:
I beg to differ about the length time to kill a battery in the ACC mode.

In Nov 2005 I decided my cell phone needed to be charged so I left the car in ACC to charge the battery for about one hour.
You can completely avoid this problem in the future by purchasing the power outlet modification from coastaletech. It's been an incredibly useful thing for me so far, not only for charging a cell phone, but also for my NAV system.
 

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If you drain the battery, but immediately catch it (and it isn't freezing weather outside) and recharge it, you may not notice any ill effects of your draining the battery. The long-term shortening lifespan really only occurs if the battery is allowed to freeze in a depleted state, or if it is left for a period of time in that depleted state.

My husband did once get confused with the auto-off headlights on my 2001, and accidentially left the headlights on (with the car off in the driveway). Thankfully a neighbor came by and told him about his headlights within the hour... When he went out to check on the car, on the first time or two to start it, he got the "white screen of death," but the third time to start (with all loads turned off) got the car to start. He let it idle a bit (engine still mostly warm), and it has been at least 2 years (maybe longer) since then and no problems with my Prius. Still on the original 12v battery - will have my 5 year anniversary with it next week.
 

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One night I was unloading groceries when I got interrupted with a phone call. The next morning when I went to go to work, I found the hatchback open and some groceries still there.
Of course it had to be the coldest night so far this year and when I tried to start the car it wouldn’t start. I let it sit for awhile, making sure everything was turned off, tried it again and that beautiful Ready light came on.
 

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The instructions, at least for the 2005 model, are a bit different than what I've been told. If you follow each step, you would start the engine in the vehicle with the booster battery at step #7, and then connect the cables in step #8. I would hook up the cables first, making sure to do them in the correct order, and then start the engine in the vehicle with the booster battery.

I've seen a guy in a parking lot blow a battery up trying to jump start a car, it was like a bomb went off. Acid was everywhere. It was amazing he didn't get blinded. I managed to get somebody to bring me some water from the store to wash his eyes and face off before the paramedics arrived.

Also, when jump starting any car, I have allowed the booster to charge the battery for about 10 minutes instead of 5 as the Prius book says, but then I turn the engine off of the booster vehicle and disconnect the cables. Then I try to start the car with the dead battery. I've been told that keeping the other car hooked up could cause problems. If the car won't start after that it probably wouldn't have started even with the boosting from the other car running.

Also, rghadimi is right about short trips slowly killing the battery. It is apparently a real problem for the people in Japan who mostly do very short trips at slow speeds. I learned that too with my Honda Rebel motorcycle. I never went out on the highway to drive over 45 mph for a half hour or so, and the battery slowly went dead. I was told to charge it on a trickle charger once a month if I never went any distance.
 

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paul16451 said:
hendricks101 said:
I beg to differ about the length time to kill a battery in the ACC mode.

In Nov 2005 I decided my cell phone needed to be charged so I left the car in ACC to charge the battery for about one hour.
You can completely avoid this problem in the future by purchasing the power outlet modification from coastaletech. It's been an incredibly useful thing for me so far, not only for charging a cell phone, but also for my NAV system.
I thought there was a way to recharge a car battery through the cigarette lighter, but I've never used it.

I did a search and found http://www.thingsyouneverknew.com/websi ... &SID=25218, which is supposed to be able to get your car started without even going outside. Just plug it into the power outlet and it is supposed to "start your engine in minutes."

There are also "jumper cables" which used the power outlet from each vehicle to recharge the dead battery. I found this one http://secure.ordersite.co.uk/secure.or ... ductID=179, but that's over in the UK. You can probably find something in the US if you look around.

I'm not sure how well these items would work with the Prius, but that would be another alternative for people.
 

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sub3marathonman said:
I thought there was a way to recharge a car battery through the cigarette lighter, but I've never used it.
....
I'm not sure how well these items would work with the Prius, but that would be another alternative for people.
The Prius' 12v power outlets (aka cigarette lighter outlets) are powered off when the car is off. So, if you would want to be able to jump-start your Prius using one of those kits, you would need to modify your Prius. Either get a 12v outlet directly connected to your 12v battery (parts from Radio Shack or similar store), or make your 12v outlets always on/hot (using something like: http://www.coastaletech.com/powermod.htm or http://www.coastaletech.com/power_outlet_mod.htm ).

You may have a similar problem if you intend to jump someone else's car with the cigarette lighter kit, too.
 

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mrv said:
The Prius' 12v power outlets (aka cigarette lighter outlets) are powered off when the car is off. So, if you would want to be able to jump-start your Prius using one of those kits, you would need to modify your Prius. Either get a 12v outlet directly connected to your 12v battery (parts from Radio Shack or similar store), or make your 12v outlets always on/hot (using something like: http://www.coastaletech.com/powermod.htm or http://www.coastaletech.com/power_outlet_mod.htm ).

You may have a similar problem if you intend to jump someone else's car with the cigarette lighter kit, too.
If you were using the Prius to charge somebody else's dead battery, the Prius would be on, so you should be able to use the cigarette lighter jump starter cables in that situation. However, I'm not sure how much power these kits draw, so that might be an additional problem.

If you were using the Prius power outlet to recharge the Prius battery with either of the previous methods I've mentioned, could you push the Power button so the Prius would be in ACC mode or READY mode? Or if the battery is dead will the Power button not even work?
 

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sub3marathonman said:
If you were using the Prius to charge somebody else's dead battery, the Prius would be on, so you should be able to use the cigarette lighter jump starter cables in that situation. However, I'm not sure how much power these kits draw, so that might be an additional problem.

If you were using the Prius power outlet to recharge the Prius battery with either of the previous methods I've mentioned, could you push the Power button so the Prius would be in ACC mode or READY mode? Or if the battery is dead will the Power button not even work?
Well, there is the possibility that the other car that you want to jumpstart using your Prius and the cigarette lighter jumpers, also turns off its cigarette lighters when off... So, same problem there as with wanting to jumpstart an unmodified Prius.

As for turning on the Prius, it would depend on just how depleted the 12v battery is... Under most flat battery circumstances, nothing would turn on at all.
 

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Well, if the car's aux battery has just enough energy to go into ACC, then the power outlet becomes connected. Then the booster can supplement the 12V main power so that you can then go into READY.

Therefore, those 12V boosters that plug into the outlet might indeed be effective, depending how dead your aux battery is.
 
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