12V battery replacement as preventive maintenance?

JimboK,

I have been watching reports of 12V battery failure closely since I joined
in Jan '08.

Four years is the generally repeated, if not actually recommended, period
for considering replacement -- check voltage w/ ScanGuage on shutdown,
be sensative for weird happenings in the warning lights, random turning
on/off of wipers, etc

I'm sure the e-smart posters can add further clarity.

 

3 years on mine and no problems. If it does go, I'll call you for a jump.

 

Since the life of a battery is unknown (precisely) I have quit worrying about it, especially in a preventive service angle. I keep a small block battery in my trunk, charge off the cars system from time to time. When I have a no start problem I can easily switch to this block battery, then solve the larger problem of a new replacement battery. A couple of years ago, I ran the car only with the block battery and it worked great!

 

I replaced the battery in my 2001 when it was six years old, as a preventive measure. However I live in an area with moderate climate and drove the car daily, hence the battery was kept in a highly-charged state.

If you live in an area that gets snow in the winter, if you don't drive the car much and hence the battery has a chance to discharge, and if you would be highly inconvenienced when the battery fails unexpectedly, then I suggest you consider replacing the battery at 4 year intervals.

 

I just did mine, replacing the original '04 [non smartkey] unit
with the yellowtop kit from elearnaid. The old one was still
mostly fine although its base light-load voltage seemed to be
a little shy of 12V and definitely dipped a bit during the process
of pre-booting the car, i.e. bringing ECUs online and running the
brake pump and all. Rather than watch its slow demise I decided
to get a new one, also giving more assurance of being able to
hold up the fan hack overnight on road-trips. I've still got
the old battery and will come up with something it can help
to power at home.
.
_H*

 

The 08 Silver Prius I selected was dead on the dealer lot. I had to stop the dumb salesman from attempting a jump start. He did not even know how to power up the vehicle. He held the power button down forever and waited for the ICE to start before releasing it on several other cars. I requested that he summon a Prius tech who jumped the vehicle and then put it on the charger for 3 hours. Because of the improper storage (car was on the lot for 3+ months), I chose to upgrade the battery to an Optima at 800 miles. I am using the original for a UPS in the house. The neg terminal was already starting to corrode (green fuzz) due to slight acid wicking around the post. On a brighter note, the tech who came to repair my car was a graduate from the tech college where I previously instructed (automotive technology). He was one of my better students in electrical and engine performance classes.

 

I think most of us universally detest stupid car salesmen! The battery seems to be less stressed on the Pri than on most cars methinks. Else why would it be so small!

 

heya jim-

we're at just over 3 years with no indication of trouble. DH says a reasonable preventive interval is 4 years. a jump pack is cheap insurance if you're worried about getting stranded, and you've got 1.5 years to stuff away the money for the battery.

 

This is a really good question. If you think about it, the function of the 12V battery in the Prius is different than in conventional cars. Most cars require a "starting" battery, which means they need a large amount of current for a short amount of time (to push the starter motor around). Starting batteries are specifically designed for this function (thin plates for maximum surface area, but bad for deep cycling.) See: Deep Cycle Battery FAQ (and scroll down the section titled "Starting, Marine, and Deep-Cycle Batteries")
But I don't believe the Prius uses the 12V battery for pushing the starter motor around. It seems to me that it just powers up the electronics, and once they are powered up and the HV battery is brought online it doesn't need to do very much, and is just part of the 12V electrical system. Assuming that bringing up the electronics doesn't require much in the way of amperage, wouldn't it make sense that the 12V battery should be more like a deep cycle or marine battery than a starting battery? Anyone know anything about this, and specifically about what type of battery the 12V battery really is?

 

I don't know what it is, but yes, it makes sense it is not a "starting battery" that needs to be rated by CCA (Cold Cranking Amps).

I think it might make financial sense for Toyota to just use a normal. less expensive lead acid battery.

Given the issues some people have had with stock 12v batteries, I'm thinking of some sort of upgrade for the 2008 I'm hoping to pick up on Thursday. Perhaps an AGM battery.

I'm planning to use a big marine battery as a buffer battery for the 12v Priups project I'm doing.

 

AGM is OEM in the 08. All automotive batteries are required to have a CCA and a RC (reserve capacity) rating. They help when selecting a replacement of greater or equal capacity. In the Prius, the only real upgrade is an Optima Yellow Top when replacing the original.

 

As the battery on my early 04 was approaching 5 years of age I also did the replacement with an Optima "yellow top". It was a tougher job than any other battery replacement I've ever done, but it got done in under an hour.

 

this is what im doing next week. i need more power for my 12v 1000w convertor.....i like my coffee when i camp out

 

4.3 years and 127K miles on my 2004 Prius, and the battery seems fine. My dad got 7 years out of his 2000 Camry OEM battery.

 

Since it was dead to the point the car wouldn't power up, I would have required them to replace it BEFORE I took the car. If it was that dead, it was also probably damaged. There is no reason you should have to pay for a new battery for your peace of mind.

I am more in the camp of "if it ain't broke, don't fix it". It is true that unlike most cars that use the 12V to crank a starter motor, a weak 12V in a Prius may not be as obvious. I like Dr. Fusco's thoughts. If you are using the 12V with IgOn (listening to the radio while waiting for your kids ) and that seems to drain the battery fairly quickly, it is time to get it checked and possibly replaced. Earlier than necessary is just wasted money on your part and more stuff in the dump (after recycling the reusable stuff).

 

I can see your point, but...

Batteries tend to fail at the most inconvenient time. So, you have to factor in (what you pointed out) how much your "peace of mind" is worth.

What I do is the _FIRST_ sign that the battery is going south (dim lights, slow cranking (on a non-hybrid)), I replace it. No screwing around, no wondering how much longer it will last. I've _NEVER_ had good luck "reconditioning" a battery in any way. If it acts up, out it goes.

As for the environmental impact of replacing a car battery, as long as you return the dead battery to be recycled, you don't have much to worry about. Almost all of the lead from a battery is recycled. There is some plastic, most gets recycled, some gets thrown out, but plastic is not a big deal. Sulphuric acid is cheap and made of commonly available stuff. They probably just neutralize it with something like baking soda or lye and then get rid of it - various suphate salts aren't a big deal either.

 

My 2006 is quickly approaching its 2nd birthday and if the battery makes it through the rest of the summer I'll be changing it out this fall/winter. This isn't just a Prius thing, I've done that with every car I've owned since moving here in the '80s. Anything over 2 years and you are on borrowed time as the desert heat is murder on lead/acid batteries. The problem is you never know when it will go and I would rather have the peace of mind than be stranded with a dead battery which always seems to happen at the most inopportune time.