Weird stuff happening? MPGs dropping? Test The Battery

Agreed, but I think both of those failure modes are extremes. The most common is a battery whose internal resistance is slowly increasing (that is in fact the "quietly dieing" process), limiting both the ability to charge and discharge. The ICE will run more often in an attempt to maintain the charge level, thus burning more fuel, giving the illusion of lower mileage. Eventually the quiet death is reached. The more dramatic death, and, thankfully, much less likely, is the internal-short scenario, where the battery has turned into a heater or, if you're very unlucky, a bomb.

 

It's not an illusion of lower mileage; it's actually causes lower mileage.

The bomb scenario is usually limited by the ability to power the 12V bus. Thankfully, a shorted battery will usually crowbar the bus, preventing the Prius from running. While inconvenient, it's a heck of lot better than a battery fire.

Tom

 

I had my first Prius fail last Friday morning when the doors wouldn't unlock. I had had the car for 1 week and hadn't driven it for several days, however I had been in and out of it presetting the radio, pairing phones etc. and I had left a light on for a short time.

So on Friday and in the rain I had to scramble. My lease is so new I didn't even have a roadside assist card.

RA tested the battery at 3.16v (no, I haven't put the "1" in the wrong spot). Jump from the front worked and we soon saw 13-14 volts. I drove in PWR mode (thinking that would keep the engine running more) and took a 45 minute drive (I was late for work, but I had a long drive the next day so I had little choice). Despite the rain, where I was running A/C, lights and wipers the battery seems to be OK. My Garmin ecoroute HD reported 14.6V with the engine off, but this displays only after switching to ON so it may be an artefact and not as accurate as a proper load tester. But I didn't need to call the RA again.

By rights that battery should be toast, but it has started fine since then.
The car is a 2009 NVW30 (aka 2010 Prius) and it appears to be the original 2009 battery. It wouldn't have had too many cold winters in its past life but now that it is in Canberra it will be different. I think that I'll replace it before it starts to get cold.

Is it possible to use a battery charger to jump start the car? Is any 12v source as good as another?

 

[delete duplicate]

 

I couldn't be bothered to read through the whole listing but i have a few weird things happening. Occasionally at random on the display screen it will display the outside temp. Not the normal display that's always in the corner. A drop down display like when it tells you your bluetooth connected successfully.

Also, whenever i hit the info button it always goes to the navigation... always. Kinda weird. So could these few possible quirks have something to do with a 12v battery going bad?

 

fwiw from http://priuschat.com/forums/gen-ii-...y-doa-almost-getting-worse-2.html#post1493405

HTML:

At Battery   vs  MFD
12.52            N.A.   out of box charge level

12.94            N.A.   after 18 hours on charger
12.72            ??.?   connected to car (SKS load)
??.??            12.5   accessory mode (SKS + display and such)
12.45            12.25  IG-ON (SKS plus a ton of other systems)

12.59            N.A.   car off after first round of testing

??.??            11.9   IG-ON plus headlights on

oh, and contrary to the thread title this is a presumably perfectly good brand new battery.

 

Re: Weird stuff happening? Test The Battery: Here's How

I just bought my Prius used last Wednesday. It's an 08 with 84500 miles, smart key, nav, bluetooth etc. I think it is a package 8.

When we went to test drive the car I had called ahead so the sales person had it waiting for me when I got there. He said that we would need to wait a minute or two to drive the car because it had been sitting without a test drive for a while and it needed to charge. It drove well and looks as if someone took immaculate care of it. I don't think they were bringing it to a Toyota dealership for maintenance as there weren't many maintenance records on the car fax report.

So I have only been driving it a few days and I don't really have much of a commute. So far I have driven it home from the dealership (12 city miles as it was rush hour and I took back roads), driven it to and from work twice (work is only 0.5 miles away, when I close my store I have a 3 mile round trip to and from the bank for deposits). My longest trip so far is up to my sisters house and back (about 15 miles each way).

Total I have around 65 miles on it from purchase and am averaging 42 MPG. Given my type of driving I find that MPG to be acceptable. What I have noticed is that my car doesn't even run at low speeds, sub 15 mph, on the electric motor. It engages both motors at these low speeds. Certainly once I have warmed it up it seems that it does engage only the electric motor sometimes but very infrequently. When I first turn the car on it is very quick to have the ICE charge the battery before I even get moving. When I did the maintenance test this is what I found;

12.1
11.8
14.2

Certainly after reading this entire thread I would be lead to believe that I am in fact in need of a battery replacement. It is very possible to think that it is still on it's original battery. The car was manufactured in Sept 08 so it is about 3.5 years old, and as mentioned has 85000 miles on it. Can I be sure at this point that the 12Volt needs replacing? Or do I need to get it out for a longer trip or two prior to making that conclusion? I might get it out on the highway for 45 minutes or so today. My test numbers by the way are from having it sit overnight and coming out and doing the test before even turning it on this morning.

Thanks so much for the guidance. I am really glad to have found this forum. You all seem awesome!

 

I think it's a little early to tell, but the timing is about right for battery replacement -- mine went at 58,000 miles and was replaced under warranty. But I'd drive it for a while, and put a couple of hour-long trips on it first. Sitting on a dealer lot for a while isn't healthy. Can you contact the previous owner?

 

You battery is not new, but it still seem s to be working. The longer term issue is how long can it sit without discharging to too low a voltage.

JeffD

 

Well the dealership did not give me contact info from the original owner but I noticed that in the leather case for the owners manual the owner's registration is there with the full name and address of the couple who owned it. Also there are lots of speed dial presets in the car already so theoretically I could contact the owner. I was thinking that would be a bit creepyish since the dealer doesn't disclose that info. But I would love to talk to the owner and if whoever get's there hands on my old beater civic wanted to contact me I wouldn't feel weird about it. Anyone else have any thoughts? Is it weird and stalkerish to just call them?

 

Well, there is always 'carfax'. A little less creepy and should give you a history of the car.

 

Thanks. Have the car fax, as mentioned it doesn't show many service records. So either the dealer they were using did not log them appropriately or they weren't taking it to a dealer.

 

Even then, if they were taking it to a mechanic or service center (Not Dealer) the car has a 'record'. This might suggest said user might have done his own servicing for oil.

 

Call them. The worst they can do is say no.

 

So would it make sense to replace now with the optima or wait it out?

 

Tried both methods. This new method read 14 volts on my 2005 but the headlight method showed the battery at 12 volts

 

Would something like this work in a Prius to provide power so that I don't lose settings, etc: INC-12V-OBD: