According to this VRLA battery - Wikipedia, the free encyclopedia, AGM batteries are supposed to have shorter life than the normal flooded units. What's the typical life observed by Prius owners around here? How do they fail? Does the MID provid a forewarning, since you do not get the warning of weaker cranking performance before a failure occurs with a traditional car. Since there is no aftermarket replacement I am aware of, I want to make sure I have the opportunity to price the replacements, before getting caught with a dead one away from home.
They seem to last maybe 4-6 years. The aftermarket replacement is New Optima 12v Yellow Top D51 battery with Pencil Posts | PriusChat. Prior to the battery being available w/the correct terminal size for the Prius, people (like myself) bought Toyota Prius 12 Volt Auxiliary Battery with install kit for 2004 - 11. I can't speak to the 3rd gen, but the 2nd gen provides no warning other than weird stuff happening (Weird stuff happening? MPGs dropping? Test The Battery | PriusChat). Some of us are proactive and check the voltage ourselves via either a multimeter or the procedure after the car's sat overnight. IIRC, I've heard of people w/their 12 volts down into the 7.xx volt range before...
There's a bit of miss-information or incomplete information in there. The AGM batteries fail sooner because -ALL- lead acid batteries loose water with use. You can't add water to any AGM battery I've seen other than Pearl's, and they don't hold as much water as "flooded cell" batteries. So they fail sooner. If you could add water they would go just as long (proven with Pearl). I added water to Pearl's battery last year, and it's still working this year (that's five years of use, about the average for any vehicle battery here). I've managed up to seven years of life by adding water to some flooded cell vehicle batteries, but that's because it's so much easier to add water to them. Even if they were "sealed" (by a label).
NO warning since the 12v does not crank the engine. The Gen II lasted 5 to 7 years so I would expect the same for the Gen III Prius.
Yup, GII was the same location as the GIII. The GIII is a little easier to get at, but not much difference. I haven't checked Pearl S yet, but with Pearl's battery, to add water I just had to peal off the label and pop off a plastic plate to access the fluid holes. I have found adding distilled water at the 3 yr time will extend the battery life. See, you've triggered one of my "pet peeves". They aren't "Maintenance free" batteries, they are "Maintenance Impossible" batteries! I've worked with batteries most of my working life, particularly "stationary" types. I used to buy "catalytic caps" for stationary cells. They would recombine the H2 and O2 and drip the water back into the cell. Too bad the "Maintenance Free" batteries don't use this technology. It would extend their life!
life seems to be based on treatment and usage. if you live in a climate that doesn't get too hot, and you don't let the battery run down by leaving a lite on or going away for months without a trickle charger, and you didn't get a battery that sat on the dealers lot for a long time and they let it run down, you should get 6 or 7 years out of it. i relaced my 04 battery in 12 and i never had any of the previously mentioned issues.
I have near 20 years experience with spiral cell AGM VRLA batteries built by Optima and Exide Orbital. I will argue that they are NOT shorter lived than a flooded cell battery if the charging system is working correctly so it does not overcharge the battery. I have 20+ Optima and Exide orbital spiral cell AGM batteries in my passenger cars / trucks and farm equipment. I have had only 1 fail, a much abused Optima red top starting battery, and that at 16 years age. Valve regulated means that no electrolyte or gas can escape in normal use, so they do not normally lose any electrolyte. Any hydrogen / oxygen gas produced in a normal discharge / recharge cycle recombines and goes back into the electrolyte. I have been told that when those batteries are turned in on warrenty, the battery is weighed to see if or how much electrolyte is missing and if the relief valves show signs of having opened to relieve pressure caused by overcharging. Warrenty will be denied on units showing signs of overcharging. Optima claims and my experience shows a spiral cell agm battery lasts atleast twice as long as a flooded cell battery . With the flat plate type AGM battery that comes with a Prius, I suspect cycling caused by the " always on " computers, pumps, etc, do more damage to the Prius battery while parked than anything else. The spiral cell AGM batteries are very resistant to vibration damage, the stock flat plate type that comes with a prius may not be as vibration proof.
Glad i read your post as I have 10 years on a prius agm and will not change it till it shows signs of failure. Make sense the agm should last way longer than the lead acid batteries .thanks for your info as its the only one that stated real experience with the life of AGMs
