Issues starting Prius in the cold

Well, let's put it another way, "How long is the typical piece of string?"

BTW Welcome to PriusChat! The very best place to learn so much about the amazing Prius!

 

I've just been through this.

Here's the battery I would buy

(it fits Gen III despite the fact that it does not match the OEM code)

The other option is to desulfate the battery (since sulfation is almost certainly what's killing your battery in a cold climate) using a specially designed charger. There are a million products that claim to do this. Some work, some are snake oil. I vouch for this one specifically, which works perfectly, but slowly. 3 weeks of time on charge will make an old (mine is the OEM 2010 battery) work like new. Since the Prius battery is such a PITA to get to, I put a charging pigtail on the battery with ring terminals and just leave the 12V side of the charger plugged into the battery, attaching 110V extension cord whenever convenient.

 

I have not owned a Prius long enough to need a new battery yet.
IF/when I do, I would get the part number from it and call a dealer first.......
Then call auto parts stores and battery shops in the area.
If their prices weren't THAT much different, I'd let the Toyota shop do it.

P.S. Thinking that you are getting a "good deal" on a battery that costs half as much is likely just fooling yourself.

 

Bad advice. BAD, BAD, BAD.
They ALL are snake oil.
Especially with an AGM battery because "suflation" does not form the same way it does with a wet cell.

Your "miracle" won't last long. It never does.

 

I've got 7 years of experience that says you are wrong. It's not a "miracle", it's sound engineering (in this one specific case).

But by all means, make your own decisions, enjoy.

 

Having an AGM battery last 7 years (or more) is not all that unusual.......IF it does not live where it is REALLY hot and you use a tender to keep it charged up when not driven much.
"De-sulfating" likely has nothing to do with it.

Do a quick search for battery sulfation and AGM batteries.
This is not some wild theory I made up.

 

If I decide to write up the full story, I'll put it in its own thread.

The battery in my Prius is original to the car, dated may or june 2010, I purchased the car last November. The car has been owned and operated in Northern New England (cool climate). The battery was end of life, showing 12.0V and barely able to run the brake pump. It now has a resting voltage of 12.6 after three weeks or so on the Pulsetech, works fine.

I've achieved similar results on several flooded automotive batteries since I bought this charger in 2012.

What I would suggest to anyone is what I did: buy the product with healthy skepticism and at least a 30 day return policy. My experience is that you will see positive results starting inside of one week and "worth while" results in 3. We do agree that there is much snake oil being sold.

 

And now we are just a few days into January.

So that means that you have only had the car with it's battery for something like 4 to 7 weeks.
Hardly enough time to draw any valid conclusions.

And it is also possible that keeping it fully charged with most ANY small automatic tender type charger would have yielded similar results.

I'd be interested in how it performs in 6 months or so.......while not being connected to ANY external charger.

 

I can evaluate a battery in 48 hours or less, thanks, and so can anyone else that knows anything about lead acid batteries.

I use the terms "resting" and "at rest" in the conventional sense w.r.t. batteries. It means not charging, not discharging, but commonly "fully charged, then allowed to rest for at least several hours". In this case, I've improved the fully charged/rested voltage from 12.0 to 12.6 (so far). Any conclusions I draw from this are not valid, according to you? I think I can draw a conclusion from your statement that has nothing to do with batteries.

Here's an up to date pic. The car hasn't been started in two days, the charger hasn't been on it in three. May 2010 date code visible if you zoom in. 12.39 does not reflect full charge in this case (the Prius has non-trivial loads when switched off, which is one reason I think owners have so much trouble with the 12v battery). My assessment is that I've restored this battery to about half it's original capacity (so far). I've had to move the charger over to another auto battery for the time being. I'll likely get it back on the Prius in another 3 - 4 weeks. Ideally, I'd like to see a charged/rested voltage around 12.8.

I'll be glad to let anyone know how the battery is doing at any future date.

 

Test it with one of those electronic load testers, Solar BA9 for example, and you'll have a better idea of where it's at.

 

I'm trying to cut down on compulsive tool purchases for 2020

 

Yeah I have to keep coming up with reasons why I don't need that big Milwaukee cordless impact. I'm succeeding, so far.

 

toyota has a headlight load test, but i can never find it

 

That would be meaningful for a Prius. IIRC, the brake pump is said to be about 8 amps. 2 x 55w low beams a bit over 9.

If there's an accepted protocol and way to interpret the the results, I'd be glad to do it.

 

AGM's are still lead-acid category.

What Does AGM Mean on a Battery Charger?

 

AGM is a type of lead acid battery. I am using the Toyota OEM AGM battery from 2010.

 

The charger I use is a 2.5 amp, fully automatic, plug it into 110v sort of charger. I sometimes leave the charger connected to the battery when driving the car (connection is via ring terminals, not clamps!), but we leave the 110v at home .

There are devices that are claimed to desulfate batteries using the car's charging system or even the battery itself as a source of power when parked. I have no idea if any of those things work. I have a lot of skepticism.