2010 prius "check hybrid system" message received today. :(

FYI, the EGR circuit and PCV valve effect fuel efficiency as well..

Posted via the PriusChat mobile app.

 

When the 12v batery is low it draws more current to charge. Causing the hybrid battery to
supply more voltage/current longer to try to charge it up. Causing the hybrid battery to drain
faster which causing the enging to run more to turn the generators to charge up the hybrid battery.
Which uses more fuel. Which effects the mpg.

 

The wattage for a 12V battery charging is less 1% of the wattage for MG2 moving the car. It does not effect much. It is a placebo.

 

It's already been proven, through Prius Chat, that a weak 12v battery causes all kinda of problems
with the hybrid system.
It's an individual's choice to choose to believe or ignore the facts.

 

There are situations where a 12v bad battery draws 75-100 amps of power on a continuous basis, converting it into heat rather than significant stored charge. While still maintaining enough voltage to start the car. You usually see a bulged battery case and it is obvious something is wrong. Clearly a rare event most never personally observe, so for some of those folks it may not exist. It does cause a reduction of mpg that is immediately restored with a new battery.

 

There have been a lot of things "proven, through PriusChat" that aren't the case, too.

This is kind of on the borderline. It is certainly possible for a weak 12v battery to cause some kinda problems.

You can also find all kinda posts pinning all kinda problems on the same cause, and not always, shall we say, to the same level of PriusChat proof. Sometimes the proof level is, it was easier to say that than figure out the problem.

That means that when looking at a post that blames X on a weak 12v battery, whether that is a case of believing the facts or ignoring the facts will often come down to what X is.

 

A battery that is damaged, worn out, whatever you want to call it, but has a weak cell that can't
hold a charge will continue to get as much charge as it can. The charging device will continue to
charge it becaus it's low and will continue because it senses it's not charge.
All this uses more power....which will cost more to continue to try and charge the battery...

 

Curious to know if the code P0101 ever came back since your post in 2020?

Let us know if you have it when you read the codes, also any time you disconnect the 12v you are sort of resetting the codes.

 

A 12-v battery constantly drawing over 75 amperes will have extremely short remaining life, so the energy thus consumed can not be a direct cause of chronic high fuel consumption. That's not to say a failing battery won't cause other problems that might affect consumption indirectly.

 

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I think they may still be made by you yuasa. The micro model it's their top line AGm..use em in lots of powersports engines . As DEKA is no longer .DEKA and VARTA we're the gold I remember