How much driving to fully charge the 12V?

Here is an 8 month old AGM, sitting after a 100ma trickle charge.

 

Fact: OEM battery is not made by Toyota. Try Yuasa. Fact: Toyota service bulletin is not fact? Toyota dealer approved battery charger manual is not fact?

So I’m to ignore my vehicle battery manufacturer recommendations for charging, and follow your recommendations.

Maybe take your own advice. What? You didn’t like being corrected?

 

Are the Owners Manual recommendations to be ignored then?

 

Looks like Toyota has suggested otherwise to the dealers, so why is the battery dealer service bulletin specific to Prius to be ignored, or the dealer recommended battery charger manual for the Prius battery?

 

Just some random thoughts, as those who have been here awhile know, I am no expert, but I think I may have a valid point or two (or not).

I believe, depending on your region, the 12v battery I buy in Seattle from a Toyota dealer well might be a different battery than someone who buys a battery from a dealer in Akron. I have only replaced my 12v once and I received a YUASA from the Toyota dealership near me. Seems people in other parts of the country had received different batteries from their local Toyota dealer.

Makes sense. Batteries are heavy, bulky and considered hazardous material. I would assume they like to keep the supply route as short as possible.

The whole four amps thing:

Is it not possible that originally, the four amps charge was needed and necessary, but is it possible that battery technology has changed in the past decade and the "new replacement" batteries bought from Toyota don't have that restriction, while the batteries shipped with the original new car could not handle more than four amps?

Meh, I am going to stick with Sam and the four amps -- not risking frying a $200 battery. But, then, I have never had to charge my battery. IIRC, when I bought the replacement from the Toy dealer about five years ago, it tested 12.4v on the bench before I brought it home.

 

For the record, 4 amp is the 3rd gen and up OM recommendation, and for 2nd gen, OM I believe says 3.5.

FWIW, it does NOT take tediously long, charging with a smart charger in the 3.5~4.0 amp range, anywhere between 4 and 10 hours, depending on battery condition. And it’s maybe easier on the battery.

 

Thanks for the correction to 3.5 amps. My memory is hazy, but since you mentioned it you may have shaken loose some brain cells and NOW, I seem to remember someone saying not to worry about the difference between 3.5 or 4 amps.....but ....I am not going to contradict Toyota.

 

2018 Prius manual 5 amp

Manual also says only charge in an open area, not in a closed garage. Then the next page says if you are charging battery in the car, remove ground cable.

Manual also says don’t spill water in floor or battery compartment. No recall for leaking hatch welds.

 

Yeah thanks for that check. I’m hammering away on an iPhone, and downloading the OM’s is nigh impossible. I had a vague recollection that 4th gen might have revised the max charging amps once again; but figured I’d just bluff my way through...

To recap:

2nd gen: 3.5
3rd gen: 4.2
4th gen: 5.0

 

My 2010 Owner's Manual says 4.2 amps

 

Thanks, revd my earlier entry. I’m currently hobbled by limited access, mostly just iPhone.

 

Haha, iPhone in northern Sask as well.

 

I can imagine a couple things going on here. One, maybe specs getting upgraded, updates published in TSBs and tech literature, not getting updated in owners' manuals. Two, maybe audience considerations: "give those owners the 4 amp figure, keep them way out of any trouble." Or some combination of the two.

If the roughly 45 amp-hour battery could be recharged with no losses, that would be about 11 hours at a 4 amp rate, 13 hours at 3.5, to recharge from a full discharge. But it can't be; the time required can be pushing 50% higher, so 16 to 19 or so. (That 50% higher comes from very old experience of mine; possibly newer batteries have brought that down some.)

Also, the car itself is not very fastidious about the charging current. They may be more careful starting with Gen 4, which has a much richer collection of sensors at the battery clamp, but a Gen 3, for example, may just supply constant 14.6 or 14.7 volts for a significant time, and the current going into the battery then is whatever it accepts at 14.7 volts.

 

Gen 3 (but not Gen 2 or Gen 1) has a temperature sensor mounted on the hold-down bracket above the battery. It doesn't seem like a good position to try to charge according to the battery's own temperature, but it is taking the temperature of the area around the battery, and there are some mentions in the manual about the Power Management Control ECU using that information to send output voltage requests to the DC/DC converter.

Gen 4 has a whole all-singing, all-dancing battery state sensor assembly.

 

While driving, I have seen all of those voltages regularly on my in-car permanently wired voltmeter, as well as 13.2V and a very rare 12.9V, and if I recall, that was a few hours into a long trip.

 

It's messier than that, it looks like it changed mid-generation. From my 2010 Prius OM:



From my 2012 Prius OM:

 

Guess you can take 5 amp to the bank.