Question re: 12-volt battery, please?

I too agree that the battery is simply not up to full charge yet like Patrick is saying. It would not surprise me if it takes a good 12 to 24 hours of charging to bring it up to 100% charge.

Sitting on a shelf for 30 days idle in the heat (80 F. or higher) can essentially reduce the charge of a new fully charged battery a good 40% when you consider a 12V battery is considered 60% discharged @ 11.9V and fully charged at 12.6V or higher. Furthermore, when a battery gets discharged, the plates tend to sulfate. Unless you get a desulfator, you may not be able to achieve a complete 100% charge with a regular battery charger.

Read the following about the sulfation of 12 volt batteries, then you will understand one of the problems with 12 volt batteries. Not all battery charger's will desulfate, only some of them. If you are interested in getting maximum life span and 100% charge out of your 12 volt battery, you might want to consider a charger that also desulfates.

http://rollsbatteryne.com/docs/A%20Sulfated%20Battery.pdf

Two chargers that desulfate have been mentioned here on PC

Amazon.com: Pulse Tech XC100-P Xtreme Charge 12V Battery Maintenance Charger Desulfator: Automotive and BatteryMINDer Battery Charger / Maintainer with Desulphator — 12 Volt 2/4/8 Amp, Model# 12248 | Battery Maintainers| Northern Tool + Equipment. Both of these units will charge and desulfate a battery.

Ron

 

I'd also mention that many battery chargers cut off before taking the battery to 100% charge as they can't accurately tell when to stop. If you leave the charger plugged up after it says the battery is full a better charger will continue to top up the battery at a much slower rate. Eventually after a day or two on the charger you might get the battery fully charged.

On a dumb charger you may have to charge it to "full", take it off and let it sit a while then charge it again.

 

Good point. This is why I like using a lab power supply to charge 12V batteries, as I can set the charging voltage and maximum current, and monitor the decrease in current over time.

 

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Thanks for the info dhanson865.

BTW. Now that your battery is just being charged and maintained by the Prius, have you re-measured the (service menu displayed) voltages in "acc" and ig-on" modes? It would be really interesting to see how a random measurement now compares to the values you noted previously for when the battery had just been charged externally.

 

julia, is your car starting and running okay?

 

Julia,

You may find that if and when you get your next battery, you will have better results if you do a couple of things before installation.

Try these steps the next time, and you might have better luck. First and foremost, never place a battery on concrete, as that will kill a battery quick. If you have to put the battery down, place it on a metal shelf or a block of wood. Do not set it on concrete at any time.

Check the voltage of the new battery, and if it is not fully charged place the battery on a charger and charge it until the battery is fully charged, usually overnight. Then let it rest twelve hours. After that check the voltage again. A 100% fully charged 12 volt battery should show at least 12.6 Volts or more. If the battery was severely discharged (new), it may require more than one charging session to achieve the 12.6 desired volts. Have patience with battery charging as it is a slow process overall.

Once the battery is fully charged, proceed to clean all connections. Use a battery post cleaner, and clean both the post's on the battery and the terminal clamps that go on the post. The prius battery has small posts, so you will find it tricky to clean them with a standard brush from your auto parts store. A wire brush like a welder uses is very helpful when cleaning the post and the standard brush from the auto parts store will clean up the clamps. Once all connections are clean, and the battery is charged to 12.6 Volts, then proceed to install the battery.

I think if you will try these things the next time you go thru changing a battery, you might have better end results.

I am sorry to hear you think the Optima is bad, it could very well be. I do understand your agravation, I too would be unhappy if I were in your shoes.

Finally, if I were you I would invest in a good battery charger for future use. You seem to know about the sulfation already, therefore you might consider getting a charger that also desulfates.

Good luck and I hope the sun shines a little brighter for you.

Ron

 

Julia,
Sorry you feel that way. I see this as a situation where too many hands spoiled the soup. I wanted to tell you to keep your old battery and not buy a new one but, I really didn't think I would be heard. There were so many people tripping over each other to help (which is great on one hand) that it would have been impossible to decipher who had the best advice. I just felt like it would have just added to the confusion to post my $0.02. I would never have predicted this would have happened. Keep your chin up and don't spend any more money on this battery. If it fails w/in the warranty (which I don't think it will), take it back. I wouldn't buy a minder, charger or anything else. Let it fail and get some warranty coverage.

 

Come oooooooon Ron. Seriously, if you look up "old wives tales" in the dictionary that's probably the definition. There is no harm at all in placing a battery on concrete .

The only merit at all to that story is in extreme cold conditions, where placing the battery on a piece of wood will somewhat help in preventing it from freezing.

 

it won't start or run any better if your old battery was okay, so i would say this one is okay too. but if it's not upto specs for a new battery, i suppose optima should replace it under warranty. advice about replacing good batteries after 4-5 years is to prevent sudden failure. the life of any battery is unpredictable at best. i still think replacing it was a good idea, just not the best results.

 

Hi Julia,

Before you go to the trouble associated with removing and installing yet another battery, I strongly suggest that you fully-charge your current battery and see what happens. If your battery shows good voltage at that point then why worry?

Suppose your retailer had checked the battery voltage and charged the battery as you had requested, before selling it to you. You would have no idea what the voltage was prior to its being charged.

If you ask for a replacement battery, the retailer will put the replacement on a charger, before giving it to you. What is the difference with that process compared to working with the battery you have installed in your car and charging it after the fact?