2012 Prius C 2 - 12 Volt Battery replacement

I don't know about the prius, but usually if the red battery light stays on in other cars I've had there is a problem with the charging system (ie alternator is about to go out)

 

what red battery icon indicator light? is this specific to the c?

 

I just depend on the Toyota service people to let me know when the battery needs replacing. They do a battery test when I bring it in for it's routine maintenance.

Of course, the last time I did this they told me the battery was kaput, and gave me the hardcopy tape that came out of the battery tester. The reading was way out of whack with what it had been 6 months earlier, which seemed strange - until I looked a little more closely and saw that they had set the tester to "Toyota Previa". Not surprising that the Prius C's little 12V battery wouldn't be up to the standard required for a Previa. Needless to say, I was not pleased.

 

and, you still depend on them?

 

Since I don't have a battery tester, I'm going to depend on someone. I haven't decided yet whether I'm going to give those guys another chance. Problem is that they're the most convenient for me by a fair margin.

 

a $10. digital volt meter is all you need.

 

For a while, but it's a slippery slope...

 

only if you have ocd.

 

A volt meter is useless to tell you how good the battery is unless you put the battery under load.

 

That's the beginning of the slippery slope: Solar BA5

Clore Automotive

 

not really. in very few instances, a battery may test above 12.3v at rest, and still be bad, but in 99.9% it's a very good indicator. if you read most of the 12v complaints here, (and there are a lot of them) you'll find most bad batteries to be under 12.4 volts at rest.

 

I wonder how much that costs, might be worth getting one...

The problem is that a low battery voltage doesn't necessarily indicate a bad battery - it may just indicate problems with the charging system. A load test is really the definitive way to measure the health of the battery.

The Prius family is a bit different because the battery isn't called upon to produce the same amount of current that's needed by the starter motors of conventional ICE vehicles, so the resting voltage is a little more useful an indication than it would otherwise be. But I'm old school and wouldn't rely simply on voltage if I was concerned about battery health.

 

Checked, mine was $66.10 plus tax through amazon.ca, a few months back. It's gone up a bit now, to $70.89. That's kinda steep I know. It depends: if you consider it (hopefully) will be usable for many years, and you are the "battery guy" for family and friends. Or if you just gotta have it, lol.

It's critical to connect it directly to the battery posts, doesn't read right through the fuse box jump start point. You enter the spec'd CCA (you can also enter CA). This was somewhat difficult with the OEM Yuasa; there's no CCA value on the label. I searched for the battery on the Yuasa site I believe, and came up with 310 for CCA value. I suspect you can enter any CCA value, it's somewhat arbitrary; when testing it'll return the same tested value regardless. The value you enter just colours it's verdict on the battery. I think

You also enter the battery type. The OEM battery I enter as "FLAt" which equates to "traditionally shaped AGM battery". There's a sticker on the back explaining the types, and a manual as well, more in-depth.

So, you hook it up, it immediately shows the volts. You then enter rated CCA, type and then do the test. It returns actual CCA, as measured, and through 3 lights: a verdict, either "OK", "CHARGE" or "FAIL". If you've got a battery that's a bit neglected but it's CCA still measures ok, "CHARGE" is the most likely outcome. After a charge session it should return "OK".

 

That's great info, Mendel - thanks!

 

i have yet to read about a prius with a bad 'charging system'. but i understand your concerns.

 

It is usually the result of jumping the Prius with the +-reversed (blows out the transistors in the charging electronics which are in the "Inverter").

Putting a load on the 12v battery is easy. Just turn on the headlights with the Prius off or. in accessory mode. The voltage should not drop more than 2-4 tenths of a volt.

JeffD

 

right. if your inverter is gone, your 12v is the least of your worries.

 

Yes! At 4.5 years & 18,000 miles, my 2012 Prius c could not be started. The first Geico roadside assistance guy gave up on jumping my car and left me stranded (no kidding, he left in a nasty huff after trying to pull off the cover under the back seat). Another guy came out an hour later, and we still couldn't get it started; but he had a tow truck and took me to my dealer. My dealer replaced the 12V battery for $276 (plus $125 labor). 9 months later (and only 1,000 extra miles), my car again won't start (it's obviously the battery). I've now moved clear across the country, so I'm not able to return to the dealer who replaced my 12V battery. It's most unpleasant when the battery fails unexpectedly (my problems were not the result of leaving lights on), because a jump won't work. I can't believe I've had this twice in a year, I now see the great risk in having a hybrid car when they're still not well understood.

 

Come on Chris, how MANY times are you going to post exactly the same story in different sub-forums ??

I think 5 is more than enough.

Actually it is not good because the resulting discussions just get fractured all over the place and is hard to follow.

Please consider NOT doing that again in the future.