12 volt battery

[SageBrush]

Thank you Pat.
Was my test the equivalent of checking with a voltmeter on the battery itself ?

[Patrick Wong]

Mostly, except the voltage reported by the MFD secret screen may be off a few tenths of a volt compared to using a digital multimeter, and you can't measure IG-OFF battery voltage.

[SageBrush]

Am I right in thinking that a direct voltage check while the car is Ig-off would likely be a bit higher than what I did, since no electrical drains are occurring?

Jayman posted in another thread that he uses a trickle charger -- presumably related to living in the frozen tundra. My car lives in a snow climate, but nothing so extreme. Do you think the charger would extend this battery's life a couple of years ?

[Patrick Wong]

Yes, the IG-OFF voltage should be a bit higher than the ACC-ON voltage.

The trickle charger won't hurt and may help, if you don't drive your car frequently and long enough to keep the battery charged up.

[SageBrush]

Thanks again, Patrick.

Batteries are *such* interesting creatures. If I was 18 years old, I would be tempted to make them a life-long interest and endeavor.

[DFWPrius]

I owned a 2005, driven daily, for two years, I did leave it sitting at home many times for up to a week with the Smart Key System on and never had the 12 V battery drain out and die on me.

Now I have a 2007, with 23000 miles, driven daily, and the 12 V battery is showing signs of a weak cell.

Background info. 5 days a week, round trip to work, 13 miles each way, 30 to 45 minutes, in the last month, I did not use headlights or heater or AC. 30% of the time I will use the freeway, 70% I will use streets for the round trip.

I started finding the clock not keeping the correct time 4 times when I started up on after sitting for one day.
Checked this forum and found out how to read voltage on the MDF.

Checked when it was in the READY mode. Reading was 13.8 Volts.
Checked when it was in ACC. mode just after driving and in the morning.
Just after driving 12.2 volts, load test with headlights volts drop to 10.8.
Morning test readings 12.0 volts, load test readings 9.9 volts.

After reading every post under this title, I think Toyota may have, had some bad batteries in supply line when they bulit my car or replaced other batterys. One group of batterys were border line when made and most went to the factory and some went into the supply system for the dealers.

If it was in wiring when the car was bulit, it would most likely be happening to large number of owners. I did not see any postings about problem after the 12 volt battery was replaced and at least one posting told of twice on the same car and it need two new batterys.

[jayman]

Originally Posted by SageBrush

Jayman posted in another thread that he uses a trickle charger -- presumably related to living in the frozen tundra.

Somebody emailed me about this, so I thought I would offer some comments

First, never use a conventional trickle charger on a battery, as it will overcharge and ruin the battery. I use a battery tender, this model from VDC

BatteryMINDer® Plus 12 Volt 1.33 Amp Charger-Maintainer-Conditioner (Desulfator) :: All :: Battery Chargers by BatteryMINDers.com

I had problems the first winter with my Prius. Even though at the time I had a condo with heated underground parking, my commute was under 15 minutes in temps down to -40

With constant use of electric rear defrost, headlights, max heat, and short commutes, the battery drained. Using the Battery Minder overnight solved that problem

The Prius taxis here don't have a problem as they are usually left in Ready 24x7

I sometimes have to be away for upwards of 3 weeks on business, and have also noticed the Battery Minders make a big difference in how long the batteries last. Nothing worse for a battery than being allowed to sit and slowly discharge

[richwiller]

I have an 05 with 77,xxx that lost the 12 volt bat. at the end of a week of really bad heat wave here in St. Louis, but it was just a syphtom of my problem which actually was a result of the engine not running at idle when it should have. The mass air flow sensor wouldn't let it, so just 2000 over my extended warrenty I dropped about $425 on the sensor and $150 on the overstressed battery. I doubt that the battery would have recovered from the 10 volts it was reading at anyway since it was 4 1/2 years old. The extended warrenty was a waste of $1100 with no other issues covered.

[jayman]

Originally Posted by richwiller

The mass air flow sensor wouldn't let it, so just 2000 over my extended warrenty I dropped about $425 on the sensor and $150 on the overstressed battery.

I'm sorry to hear that. Was the MAF really kaput, or was it just dirty? Unless a definite code was thrown for the MAF, I would have tried cleaning it first

This is the MAF before cleaning



This is the MAF after cleaning. The bulb thing is the IAT sensor, which is part of the MAF



Inside the MAF barrel are the two hot wires, which are cleaned with the appropriate MAF cleaner. You can barely see them here



I'd also wonder if the TB needed cleaning, older Prius cars can have sticky TB blades, which cause problems

[socaldano]

Don't believe it...If you drive your car once a week then you are fine.
If it keeps going dead. Are you sitting in the car with it powered off? Then the lights are staying on.
If you dont drive it for 5 days, and it goes dead and you have the remote keyswitch special dobber, turn it off under the steering wheel. Then just use the button to unlock the car.
The 12volt battery is very small in amps, and is only used to boot the computer and run the 12v stuff. unlike a regular car which needs a powerful battery to run the starter.

Dealers often say things they know nothing about...salesmen are the worst. Often they are uneducated and rude and crass. Ever here them talk trash about thier customers after work? Service writers are second worse. There job is to write money tickets, not solve your piddly little problem.

Originally Posted by datura

i bought a new prius in aug 2007. in dec the battery was dead. i called the dealer and after AAA came, brought car in for check up. no problems found. i was told then that this car was not the right one for me to use, considering my driving habits. (i have an 87 camry with 125,000 miles on it) i only use the car 1-3 times a week. when i bought the car, i discussed this with the salesman. he told me, no problem. but after the battery died, i was told the car was meant to be driven regularly. i was flabbergasted! a brand new car, and if i dont drive it every other day or so (as they said) i could not rely on it. hmmmmm
so i let a carless friend use the car so it was driven at least twice a week. then in feb after 4 days the battery was again dead. off i go to toyota after AAA came and again, no problem with the car. after some pressure on my part they offered me a small rechargable portable battery to keep in the car for when it happens again.
anyone else encounter this problem?
help!