Discharged 12 volt - advice

yes ... to answer the original question before all the great replacement battery advice started ... yes - even if you had a fresh oem ... when you give the poor little thing a major drain - it becomes mortally wounded
Oh, you can bring it back to life a little bit ... but its still on borrowed time & mortally wounded.
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If driving you'd be reading the voltage of the charging system right?

If I was in southern Ontario closer to the big CTC distribution centers then most likely I'd have gone with the Exide/Motormaster Ultra AGM. Even if Exide and Yuasa are the same company.

My Optima does have local distributors here oddly enough, just that they charge more than Optima.ca... go figure.

When I ordered early one Saturday morning asking about shipping methods, manufactured dates and a bunch of what if's, it was minus 53 with the windchill in Regina and Mark said the soc was a little lower than he usually saw. My Optima was made in January, and about 7 weeks old by the time it reached me. Better than what I saw at CTC locally with the Exide.

So for that reason, along with the belief that the spiral wound plate makes some sense in terms of vibration resistance and plate to plate separation I went with the Johnson Controls folks.

Roland

 

As someone else pointed out, while driving you would be looking at the charge voltage going TO the battery which is typically 14.7 volts for the first few minutes before dropping down to about 13.6V, unless you have the headlights and such on or your 12V battery SOC is too low.

What I would recommend is to plug something like the following into the cigarette lighter port under the dash and at the beginning of every month, get into the car from the passenger side, and switch the car on into Accessory mode and see what voltage is displayed. This would be a reasonably good way to monitor the 12V SOC without much hassle, particularly if your wife would be the one to do the monitoring.

 

Also you can leave it plugged in. The Cigarette port is only alive when the you enter accessory mode or otherwise the car is "on". It's NOT going to put a parasitic drain on the 12V when the car is totally off.

The minutes quoted is with you drawing 25 Amps from the battery. In reality, a dome light may only draw a few milli-Amps or so (is what my impression is), so we are really talking proportionately big differences in how long your battery will be alive. Please see:

Deep Cycle Battery FAQ

DS46B24R YELLOWTOP® Prius® Auxiliary Battery 8171-767 | OPTIMABATTERIES

http://www.exideworld.com/Media/files/Downloads/TransAmer/Products/Edge%204%20page%20booklet%20non%20spread.pdf

Agreed, but wouldn't you want a greater insurance in the event of an inadvertent drain such as the dome light left on?

Fall it does with the battery Toyota shipped the cars with. But Toyota have since upgraded the replacement to a 45AH battery with a 2 year free replacement followed by 5 year pro-rata warranty. It's still made by Yuasa if you peel the sticker off. While I think Toyota or Yuasa learned some from the failures, I am still disappointed that the new offering still says to NOT exceed 4.2 Amps for charging. Not sure if this is just an old sticker design they carried onto the new battery or if the battery can in reality take higher charging currents without significant degradation.

"Few minutes" is a misnomer as you can see from my earlier comment.

You are getting into battery construction here and I am particularly intrigued by "which lessens the need for alloys or add ons like graphite on the plates". Exide has been touting this Graphite addition all over its marketing materials as extending the longevity, etc., of the battery. Granted marketing hype is usually suspect, are you intimately familiar with AGM battery construction to make the supposed positive with the Exide a necessity, that too a drawback?

Per the below 2-3 million of the Exide AGMs have been sold in Europe before they setup a plant in USA to make them here.

Exide takes the lead-acid battery in a new direction - SAE International

I am again confused. Considering the Optima charge current should be below 10 Amps, while the Exide in theory can be charged at much higher currents (25 Amps or more), it would seem to me the Exide can be charged much quicker.

You already have experience that the OEM at 302 cca was able to handle the job just fine, so CCA ceases to be a factor above that number IMHO. It's capacity that has been time and again emphasized if you look on the Gen II forum.

Good luck with the Optima. You can find some tips for recharging if you ever leave the car not running for a long time here:

Odd (and alarming) failure mode of Optima 12V battery | PriusChat

This can be the case even with inadvertent drains such as the dome light. I would carry a jumpstarter in the car so you can get going in less than 5 minutes regardless of how your battery has died.

Good thing you didn't get the aged Exide. Perhaps you would have had better luck finding a new Exide online, but I think you will be fine with the Optima. What I shared above is mostly for future reference and for others on this forum that need to consider those things for making their own choices.

 

All great points and I believe a timely conversation as more and more GenIII owners are reaching the time when they should be thinking about 12v battery replacement.

Until now, I have never left a dome light on by accident, and if I did, I have to wonder if I would discover the problem before any replacement battery gave up the ghost. While I hope to never have the issue, it is true that I did buy a battery jumper box/booster years ago before my first leg operation. I was worried at the time that the car would sit for a month or two and be unable to start. Although it was winter, and most likely many people walked past the car carrying what ever version of smart keys they used with their own cars, I had no problems.

I may either buy a cheap set of booster cables or make up a set using small clamps and lamp wire to save space in the truck, but never needed them with this car or any previous and I've been driving for over 40 years. With this Toyota though, the discussion of the day before I bought that booster battery pack was that people had the cars go dead after being parked at an airport for only a week or something like that. turns out to have been something I've never used, despite getting a model with usb port and an a/c port in case of a power failure at home. Waste of money.

Some folks have reported a long service life with the Optima battery, others as in the link you have provided and elsewhere have had issues. One member blamed the battery for problems but apparently parked outside the bedroom wall in range of the smart key. Those comments seem to have been removed, but some negative comments concerning the car battery seem to remain. It would have been nice if Toyota had thought to include a fail safe cut off switch for the interior lights, but it has not been something I've missed yet.

While my car sat unused for abnormal amounts of time, I always had the SKS system active, and the lights on auto. This may have caused an increase in the rate of discharge while parked, but again, I got 5 years out of the OEM and it is still good by most measures. I was aware that the SKS system did in fact go to sleep after days of not being accessed by me, as evidenced by the wake up behaviour when placing my hand on the door handle after these prolonged periods.

So I agree with you, the Optima battery for me, is likely a fine choice. It was cheaper than the Toyota replacement by $42 and a perfect fit. If I keep the car for more than another 5 years it could be an even better buy should it appear to last longer than the OEM that while still good, no longer provided the level of trust. I was prepared to buy the Exide made battery but decided not to when I looked at the date of manufacture and time since it should have been charged by the retailer. Anyone with a history of leaving doors open or interior lights on might be better to buy a battery with a greater AH rating... but I`m good here.

Roland

 

...but as I noted before, I discharged my OEM battery nearly 4 years ago, and the SoC (as measured by at-rest voltage) is still pretty much the same, and the battery doesn't seem to be in need of replacement for a while yet. Considering that a decent number of people who *haven't* drained their batteries are finding them in need of replacement at 4 or 5 years, I'd say that a single discharge event isn't necessarily that catastrophic.

 

It isn't THAT catastrophic but it depends on the situation.
How old the battery was to begin with and how long it stayed dead mostly.

The contention that one deep discharge on a new(er) battery that lasts just overnight as a fatal event is
not representing the "normal" outcome. Most of the time, it is just fine. Better if it is charged slowly and completely before being used again though.

 

I've had my Prius Plug-in for about 10 days now, and I'm still not sure why the auxiliary battery has to go dead at all, and when it does, why doesn't the computer remedy the situation by shunting over a bit of power from the main hybrid battery?

 

I have a 2011 Prius. It will soon be 3 years old and will have about 50,000 miles on it. I was thinking of changing the 12 volt battery at that time. Anyone have any comments?

 

Better get a Jumpstarter pack and carry it with you, if you are so concerned about getting stuck somewhere when the 12V does die at some point. This will also save you if your 12V (even a new one) gets drained inadvertently (such as when a dome light is left on and such).

I still have the original 12V (drained once) in my 2010 Prius as well as my 2007 Camry Hybrid.

ADDITION: My Prius was manufactured 09/09 and Camry 06/2006.

 

I wouldn't use the calendar to decide when to replace a car battery. If the battery has experienced light loads and shallow charge cycles, as well as being made out of good materials, there's no real need to replace it, if your mechanic has given it a clean bill of health. Cheaper batteries, that use inferior electrodes can fail sooner than 3 years, but that's not a good yardstick by which to judge the Toyota-supplied battery.

 

I was concerned about sudden battery death in my Dodge Ram, particularly since I was using it year-round for work in some very remote regions, so I installed a deep-cycle AGM battery, which had a much better life expectancy than the OEM's battery. For my Prius however, I'll be content to carry a booster battery pack in case I have dead battery issues.

 

Thanks for your comments guys. I haven't had any issues with the battery so I'll keep driving it. Sometimes I worry too much, besides I have AAA to come to my rescue in case I have a problem.

 

The battery in a Prius goes dead for the same reasons that they do in any other cars.

Defective battery.
Owner leaves lights on overnight.
Loose connections.
Charging system fails.
OLD battery that is just worn out.

 

Loose connections don't generally cause batteries and alternators to fail.

But it makes for a great excuse to sell you new ones!

 

Loose connections can make a battery go bad IF it causes the battery to be chronically low on charge.
You are probably right about alternators but these cars don't HAVE an alternator, not in the conventional sense anyway.

 

To me, chronically low on charge, means sitting at low voltage for weeks at a time, causing sulfation to occur. If it's that low, you wouldn't be starting it, and would have had it repaired.

BTW, I would love to find out how the charging system on a PIP works. Seems to me the simplest way would be to shunt some of the power over from the main traction electrical system. I have heard that the smaller motor-generator (MG1) functions as both a starter and an alternator, but that doesn't quite add up for me.

 

First, a wet cell battery doesn't have to be dead for the rate of sulfation to increase.

As for the charging, a little more than "shunting" is involved because the main traction system runs on a much higher voltage. The voltage is stepped down AND some sensing is done to know how much the 12 Volt side needs.
That is the electronic replacement for the alternator and regulator.

 

That's well and good, but how is it that you can have a dead auxiliary battery while your hybrid battery is fully charged?

Mine was plugged in while it was in the showroom, but it wouldn't start until it was boosted. The salesman said all their showroom cars have the batteries going dead all the time, due to things being left on.