12 volt battery charging voltage when fully charged?

I would check the electrolyte level on conventional batteries, maybe once over the course of the battery's life, say 2~3 year along. It seemed nigh impossible to see properly where the levels were at, till the battery was right out of the car. So I would do that, clean up the posts and clamps while at it. Levels would be a bit uneven, down maybe 1/2" by then.

 

That wasn't the question.
Do you have a Prime ??

But then......that isn't nearly often enough.
While it depends more on mileage, it needs to be checked every 6 months or so.
Certainly at every oil change.

 

Since this thread is still churning back n forth, here's my happy Prime basking in the sun.


Rob43

 

My Prime is basking in the garage, and I checked and the electrolyte levels are normal, just as they have been since I got the car. Tip for those of you checking the electrolyte level - a US quarter is the correct removal tool for the caps. Won't gouge out the very soft plastic and damage the slots.

 

Not charging it so hard once it's leveled off should help keep the electrolyte from boiling off.

 

I haven't had the electrolyte boil off in any vehicle with a properly functioning charging system, so it's not unique to the Prius line.

 

I have had it happen a time or three.

 

does climate matter?

 

I don't understand some of the stuff you say.

Prior to the last couple of years (if what you say about the current "float voltage" turns out to be right), the minimum charging voltage was something around 13.5 volts, with some running as high as 14.5.

That WILL electrolyze the fluid over time and cause the level to fall.
Nothing you can to do stop it.

Is it that you have never owned a car for more than 2 years.
Or is it that you are just blowing smoke ???

 

Some.
Really HOT weather will cause additional water loss due to evaporation......which is different than the electrolysis that occurs from charging.
But both cause the level to go down.

 

the reason i ask is that my dakota 12v is 14 years old and i have never checked the level

 

just wait in a few years when we start having traction battery degradation!!
then the discussions will really get energized.

 

rob, how is the solar panel holding up?

 

It's holding up like the day it was installed, I figure at this point it's good to go. I used Velcro on the top & halfway down the sides with a little extra material to hold it at a slight upward angle, since it's always under compression as the Prime goes faster it stays in place. Maybe someday a large stone nails it, but until then it certainly is working within its parameters.

I have never measured it during the course of a whole day, but when I have measured it from lets say ~4pm to ~7pm in full setting sun I do see a legit 2 to 3 tenths of a volt increase. Most likely based on what I've seen a 0.30 to 0.60 of a volt would be typical if their Prime was parked facing the sun for the day. Is this idea a total winner, I don't know, but for ~$19 bucks my 12v battery will stay within a good enough working range to "most likely" never let me down.


Rob43

 

What I said I said is that a "properly functiioning systemr" should not boil off the electrolyte. If the charger is putting a "normal" charge on the battery, this should not deplete the electroyle significanctly during that charge cycle. If the charger is putting an "equalizer" charge on the battery (not a normal occurence), then the electroyte level would be expected to decrease.

I did not say that that electrolyte levels will not fall. That is normal battery activity. If a charger is malfunctioning, it will rapidly overcharge the battery and quickly boil off the electrolyte. A properly functioning charger will not do this. Over months, you would expect to see the electrolyte level to decrease, not over one or two charges.

 

I ran a test on my 12 volt system with my 2017 Prime today and this is what I saw:
1) 12.1 volts with car in acc. mode (nothing running)
2) 14 volts as soon as I put car in ready mode.
3) 12.8 volts less than a minute down the road and stayed that way on my 10 minute drive.
4) 14 volts after I got home and put the car in park.
5) 12.8 volts as soon as I put it in drive and just keep my foot on the brake and didn’t go anywhere.
6) 12.5 volts after I shut the car down and put it back into acc. mode to see what it would read .

All my results were in EV mode. 10000 miles on the car and 80 degrees today. Also, no hills during this test.

 

^ I'd say that's pretty typical (for a Prime), seems as if you were in my car today doing your tests...


Rob43

 

I agree, I think this is normal for all our Primes.

 

Is it an AGM type ?
If not and it actually has caps to check the level......it probably is now near to bone dry and on the verge of a total failure.

You are lucky.
Who does your routine maintenance....like oil changes ?
Hopefully they are checking it for you.

 

I will be cerebrating my two year anniversary for my PRIME very soon. So far, I am not seeing any degradation other than normal seasonal fluctuations. In fact, so far this year I am doing better than last two summers in terms of displayed and actual EV ranges.