Proactively replacing 12v

Woops meant to say I didn't know this. @Raytheeagle is hitting 8 years on his with a battery tender. I think I'm stupid enough to challenge him for the record.

 

It will be 8 years in my possession on August 9th.

I welcome the competition .

 

Amazon for Optima designed for Prius only. $162. Cheaper than the dealer.


iPhone ?

 

i think the map is probably generally correct, but the corresponding years are more varied. if you abuse the battery, they will be shorter. if it's garaged vs outside, that might matter a lot.

 

When I lived in the East Coast, batteries always died in the winter, not in the summer. That's what I remember.

 

agreed. even though heat may shorten the lifespan, a weak battery freezes on a cold day.

 

Bzzzzz. Wrong.
Either the battery has to be VERY weak to start with OR it has to be VERY cold for that to happen.

As the temperature goes down, that battery CAPACITY goes down too.
In a conventional system with a high current starter, that "load test" finds a marginal battery when it's cold......that might still work when it's warmer and the capacity recovers.

 

i'm wrong because i left out an adjective? or is it an adverb.

 

How reliable is using the resting voltage on the Plug-in Prius 12v battery as a predictor of when it needs to be replaced, assuming the battery has never been run down?

If the resting voltage is reliable indicator, what voltage would then be a reasonable cutoff to determine that it's time to replace the battery?

 

Resting voltage only tells you state of charge or SoC at time of measurement. It has no bearing on capacity. So you could have a weak battery that would go dead if you left the door open for 5 minutes, and it would read the same voltage as a good battery if they were both fully charged.


iPhone ?

 

What would be a reasonable load test in the Plug-in Prius?

 

I would say one of three things: a battery charger/tester like we have at the dealer for warranty battery tests, letting the car sit without plugging in for let's say a month for example, or letting the headlights on and/or door open for a preset amount of time lets say half an hour or 15 minutes. Then checking for voltage/if the car will power up after the last two. Obviously I prefer the first option because I have access to it.


iPhone ?

 

Ours was built in August 2009. Languished on dealership (or dealerships?) lot till we asked them to dig it out from the back of display shed, in November 2010. Had about 10km on the odo when we took it for a test drive. OEM 12 volt battery was dead, dead, dead. They "had it running for us" when we showed up...

 

The dealer nearest us has five 2015s still on the lot.

I bet their 12v batteries leave something to be desired .

 

i have been using the resting 12v measurement for 13 years. it is reliable if you monitor it regularly, and haven't run the battery down. if you have run the battery down, i would just replace it, it has no integrity after that.

 

What resting voltage are you getting and what would you consider the cutoff voltage for time to replace?