Dead 2014 Prius battery?

Bad news is that little battery does not enjoy being discharged and may never hold a full charge again.

Prius is an excellent car but has one achilles heel the little 12 volt battery. Its achilles heel is killing that battery and then exposing it to a tow truck driver with little prius experience and confusion on how to hook up the jump points. Many story's here on tow truck drivers causing thousands of dollars of damage to the electrical system by hooking up the jumper cables wrong. Especially using the truck itself to jump the car instead of a jump pack. The truck delivers huge amp capacity that the Prius does not need. This damage would probably not be covered on your gold plan.

2 things a Prius owner must do to have a problem free life.

One is always no matter where the car is turn on the alarm especially in the garage. It will alert you to an open door or hatch causing the interior lights to come on.
Second is always peek at the car before you go to bed and in the dark make sure all the interior lights are off.

 

or off.

 

lol

 

I REALLY don't think that "grounded" is what you mean to say here.
There are two cables that get connected.
Only one of them goes to "ground".
It's the other RED one that you need to know where to connect.

And as mentioned it is hard on a battery to get a full discharge......and even harder if it stays that way very long. After an incident like that, the battery REALLY should be fully charged by an external charger. You can't necessarily count on the built-in charger to do that properly.

 

^ What he said.

The jumpstart solved the immediate problem, of getting the car started, but you've got a seriously depleted battery. When the car's running it will attempt to recharge the battery, but it's normally only expected to maintain a battery in good condition, it's not good at dealing with a depleted battery.

Get yourself an intelligent, 4 amp or under charger (with indicator lights for state of charge), leave it on at least overnight, and/or until it indicates full charge.

I've been using a CTEK 3300 charger for a few years, works fine. It's just one of many chargers available.

And even when it's "back to normal", I would log this event, consider that it's useful lifespan is likely reduced.

 

If the 12V battery was really the problem, it would have been covered 3Y/36,000mi.

 

You and I have to double check!

 

daable check.

 

Ah! Good One!!!

 

Why do you say it has anything to do with mileage? And why continue to top-off since that is exactly what the car does every time you drive it. I've had my car for 12 months and the dealer had it for 6 months before that. I've checked the state of the battery per the instructions in the manual and it's still in the fully charged range.
12-volt batteryOpen voltage at 68 °F (20 °C):
12.6 - 12.8 V Fully charged
12.2 - 12.4 V Half charged
11. 5 - 11.9 V Discharged
(Voltage is checked 20 minutes after the hysystem and all lights are turned off.)

 

The health of the 12 V battery has NOTHING to do with gas mileage.......until it gets so bad that the engine doesn't run right, that is.

And there is no good reason to "top off" the battery unless it is just sitting there unused.

If the car is being driven regularly and the 12 V battery still shows a low state of charge, then the battery is already bad or the charging system is not working right.........or both maybe.

 

To say it has nothing to do with gas mileage is a misnomer. If you have a weak 12V battery, it would put more of a load on the inverter's DC-DC converter or 12V charging circuit. Causing the HV battery to discharge more rapidly, then in turn, causing the ICE to come on sooner and more often. It will not cause a big mpg hit but, can affect mpg.

 

I believe weak batteries take less current, not more. A "weak" battery is like a portion of a "good" battery. They have less capacity (that's why they are weak) so it takes less energy to recharge them to the weak level they will sustain and less current to raise the battery voltage to the "charged" value.

 

The fact that they have less capacity makes them discharge faster causing the system to try to charge it more often and ultimately resulting in a bigger load or draw. Additionally, they get hotter and are less efficient at storing and delivering electricity.

 

Furthermore the weak battery WILL cause the ICE to run more often thus lowering your overall MPG. That is one of the reasons why some folks recommend keeping your battery fully charged. The less energy used to charge the battery with the ICE, the less fuel that is actually burned. It is like a double edged sword.

Another fact concerning 12 volt batteries. Many studies have been made on these. All of them do agree that a fully charged battery has a longer life span that a battery that it is not kept at full charge. As the battery discharges, the plates become sulfated over time. Once sulfation has set in, capacity is reduced. As I said above, it is like a double edged sword.

 

Interesting theories but...........

One of the advantages of an AGM battery is that it doesn't sulphate.......near as much anyway.
Leaving them discharged doesn't cause as much damage, unless it is very deep and very often or it's allowed to sit that way for a LONG time.

As a battery gets "weak" the charging input doesn't really accomplish much and thus it charges more and more often.......but to think that would cause a significant or even detectable drop in MPG is a real stretch.

If it was THAT bad, other more obvious and critical symptoms would probably be present too, like not starting after sitting overnight for instance.

 

many complaints of sudden poor mpg's have been traced to a bad 12v and some as much as 10 mpg's, immediately corrected by replacement.

 

I will have to disagree concerning theory. It is factual about the loss of MPG on the Prius with low voltage levels in the auxiliary battery. Furthermore, ALL of the current 12 volt type batteries do suffer from sulfation regardless if they are "flooded" type, AGM, or Gel. Because of that fact and the fact that the sulfation is directly related to the state of charge in said batteries, it becomes a important factor and should not be dismissed so easily.

Furthermore charging of a battery does help to reduce the sulfation if the voltage levels during charging is handled properly. Many studies have been done on this. Some think the new chargers with the desulfate feature is a gimmick. It is far from it. Again research has proven these things. All of the information stated above can be easily found if you search for it online. It is not myths, but facts that I disclosed above.

Ron (dorunron)

 

Some of your post is "fact" and some of it is opinion based on incomplete information or a bad memory or both.

A true AGM battery does NOT sulphate to any significant degree in normal service.
That is even with "normal" neglect.
They must be severely abused for that to be a factor in the life span of an AGM battery.

And that is my "fact" (opinion) based on a fair amount of research.
If you think you can post any references that says otherwise.......feel free to do that.

P.S. And those chargers that claim to "recover" batteries with sulphation have been debunked over and over again, so much so that it's hard to even find one being advertised anymore.
Whatever good that they do is minor and short lived. The treated battery fails again quickly after treatment.

 

Why do you have to be so negative and attack people personally who are trying to help? Saying things like Ron has a bad memory is a personal attack on him. Lighten up, its only a website.

You want Ron to post references? Where are yours???? Both of you are presumably here to help people. What's the big deal?

If you're here to help people great but, the last thing this blog needs is another antogonist. If you have some info that others don't have, share it please (as others here do).