Weird stuff happening? MPGs dropping? Test The Battery

No. It is a fine choice, and in many areas it was the first available choice.
12 volt batteries last so long I am unsure if any one has tried more than two batteries. The other choices are so new I would be surprised if anyone had needed replacement yet.

 

I was sorta asking if the emphasis was on 'deep cycle' versus the old typical lead-acid battery.

 

I emphasize three features to be a safe Prius battery

As Toyota has placed the battery in the passenger compartment with you and your passengers, use an AGM battery, as it has less free sulfuric acid to splash on humans.

As Toyota has placed the battery in the passenger compartment with you and your passengers, use an externally vented battery to avoid the build up of noxious or explosive gases inside the car.

As Toyota has used smaller JIS posts rather than the much more common SAE post of most cars, you will want a battery with JIS post in the 'reverse' orientation.

 

I have a 2005 Prius that I’ve owned since last December. The original owners replaced the 12 volt battery at 43.4k miles in March, 2011. The car currently has 70k miles.

While the car shows no signs of battery failure, maintenance mode shows the following values:

Unload: 12.1-12.2
Load: 11.8-11.9
Charge: 14.1

After sitting overnight (not started for at least 12 hours), I tested the battery at the jump point, and my (very cheap) multimeter showed 12.25 volts. The battery has not been drained since I owned the car. What happened before then is anyone’s guess, but the original owners kept the car in a garage and kept up with the maintenance (I have the records).

My MPG is averaging 47 with a mix of short daily trips (~5 miles) and longer trips (~50 miles each way) every 1-2 weeks. On longer trips, my MPG is about 51. I do a good amount of hypermiling, and although I still have lots of room for improvement, I feel like I should be getting a few more MPGs out of this car. With that said, it is very rare that I hit a “sweet spot” during city driving, due to lights, stop signs, and speed limits.

Should I be concerned? I figure I’ve got 3 options at this point:

1. Do nothing
2. Attempt to charge the battery (either by leaving the car on or buying a charger)
3. Go ahead and swap out the battery

My inclination is to charge the battery by leaving the car on for ~9 hours, then continue to test the battery periodically. A part of me wants to just swap out the battery (for peace of mind if nothing else), but I suspect that little or nothing would change as a result. Even if my MPG improved by 10% (which is probably unlikely), I would have to rack up at least 16,000 miles (which would take ~16 months based on past usage) until the improved efficiency added up to $150 in reduced gasoline costs.

Any thoughts/feedback would be appreciated.

Thanks!

 

How much is 9 hours of ICE gasoline consumption? Not as much as a new battery, but I'd simply replace the battery and be done with it.

 

if the car were on for 9 hours with the radio, lights, AC, etcetera off and in ready mode the engine would only run something like 5% of the time and it might use a gallon or so of gas.

I think someone on priuschat did the math once but I'm not sure where the thread is.

The catch is to make sure all accessories are off or unplugged. I also remember threads where someone left the car on accidentally and ran out of gas overnight so the worst case scenario would be several gallons of gas if a radio, fan, or lights were on.

 

I

 

Texaslorraine here...with a 2003 Prius...when I first got this darling, the 12 volt battery kept needing replacing...now this is a 1st gen vehicle and the problem may not be yours, but the mechanic merely tightened the GROUND to the car for the battery charging unit under the left side of the car which I believe is associated also with the wheels. . ..whala, no more problem. I have replaced the battery four times, and realize the extremes in WEATHER may have an effect on the battery. Or the COST of the unit. The first three were $100. or less, this last one was $300. +. ..and has been very sturdy. The battery icon on the dash screen is related to the hybrids under the back seat. For a long while I thought that indicated the starter 12 V battery, so that is not helpful in determining charge of starter battery.

 

I have 2006 Prius with over 200k miles. 50 MPG typical. It is still on the original 12 V battery. Performed the in car battery test and got the following:

Unload: 12.1
Load: 11.9
Charge: 14.2

Also notiecd the audible brake actuator comes on more often than it used to be, once every 2 mintues or so for about 5 sec.

Perhaps it is time to replace the 12 V battery. All suggestions are welcome.

 

so this just happened in the past few days - apparently it's not a good idea to leave your car baking in hot so cali temperatures with the gas cap not fully clicked in.

 

Oh man, it's epidemic now:

Turtle light on - but battery full - engine won't turn off | PriusChat

Ok, see USNavy's fixed it now. It was "wala" at the outset

 

Hi Friends, Yes I am a Newb! Just found the site today GREAT STUFF on here! Thanks for the info, like the 12v battery test on the MFD. But mine was find so I will have to look for other causes for my decreased MPG.

 

Just bought a certified used '09 with 28k miles. I ran this test and the "Vehicle Signal Check" showed voltage to be 11.9 Volts. After pushing the power button once, the voltage dropped to 11.6 Volts. Something to be concerned about? Should I replace the battery? Is this something that should be covered with the certified used warranty? Any insight would be appreciated!!

 

Need to replace the 12 V battery

 

yes it should be covered. a working 12 volt battery is a pretty standard requirement for a car, new or used.

 

Read the warranty carefully. The battery hasn't failed totally yet, so it may be working "good enough" for warranty purposes.

 

Try the test again after the battery is charged (either with a low current charger or after a long drive (it takes several hours to charge the battery at less than 4 amps) and letting the battery sit overnight to dissipate the surface charge. If it doesn't improve to hold above 12v, get it replaced.

JeffD

 

I've had the car about 6 weeks now and I am loving it. My drive to/from work is about 45min-75min each way, depending on traffic. I am guessing that isn't enough time to fully charge my 12V battery? Do you think a trickle charger would be worth the money here, or am I just buying a few months of time before my battery dies anyway? I have run this test probably 10 or 15 times the past month, hoping the charge would rise and hold above 12.0 at some point. My results have been extremely consistent since my previous post above:

Pre-Load (After sitting outside overnight) - 11.8V-11.9V
Post-Load (One push of power button) - 11.5V-11.6V

While I haven't noticed anything funky happening with the car, I get the feeling I shouldn't wait until this comes. I have done a lot of research about current 12V battery options, including the best places to purchase each of them. I have narrowed my choices down to three and looking for some advice on which of these would be best:

1) OEM Toyota Battery: $191 + tax at dealership (one dealer is running a special for $230 installed ) 7 year prorated warranty.
2) Optima Yellow Top: $147 on Amazon or $188 from eLearnAid with full instructions and kit. 3 year warranty.
3) Bosch Premium Performance Part # 51-440BAGM: $125 + tax at PEPBOYS after 35% off code SECRET35 (supposedly this includes installation?) 4 year warranty.

 

My original battery lasted for 28,360 miles (about 2 1/2 years) and was replaced under warranty. About 6 years and 76K miles later I proactively replaced it with a yellowtop from eLearnAid for $180. Replacing the battery is a minor hassle the first time, and a lesser hassle thereafter, so it's tempting to go with the cheapest option (Bosch - generally high quality). Be sure it will fit -- do they supply/offer a kit like yellowtop does, or will it fit in unmodified? I've only got 2 years and 17K miles on the yellowtop, so can't say whether it's good enough to justify the extra expense, but the shorter warranty would caution me. It's highly recommended on the forum, and in theory looks like a better battery, but time will tell; it had better not tell for at least another 4 years . The 7-year dealer warranty looks attractive, and is by far the least hassle, although the total time-to-replace will be much longer, in my experience.