New auxiliary battery: how long do I need to drive it? (2005)

Each drive should be a minimum of 20 minutes – 30 minutes would be better – and you should aim to do a minimum of 2 drives per week – 3 or more would be better. You could intersperse shorter drives between the longer drives.

If you can't do the longer drives and/or have no need to do longer drives, purchase a fully automatic 4 Amp multi-stage charger that also will ramp down to a trickle charge after completing the main charge. For convenience, get a charge with a "quick connect" pigtail. Use the charger any time the car is not driven for three or more days.

Make a sign for the steering wheel that says BATTERY ON CHARGE – REMOVE BEFORE DRIVING

I hope this helps.

 

Well first you have to make sure the 12 volt battery is what will allow the car to run again depending upon how long it's been sitting I would imagine you're going to get a a bunch of lights and hybrid battery signals here in just any minute.

 

You don't need to drive it after putting the new battery in.

If you don't plan to use the car often, disable SKS and make sure you drive it around a half hour once every week or two.

 

BUT you should make sure that the new battery is fully charged before or immediately after being
installed. This is best accomplished with an automatic external charger.
The battery store usually does this for you........but you should not ASSume.

 

If you're buying a Prius or have a Prius and leave it parked give the Prius to your kid and take his Corolla or whatever it is you got to do You don't need the Prius it's parked that's part of the clue. Get the granddaughter's Yaris and give her the Prius something It just makes sense The kids going to be driving and y'all very rarely a Prius is not made for very rarely

 

With older cars, sometimes you needed to go drive the car, as the 12 volt battery would not be charged as effectively if you just sat with the engine idling.

In a Prius, that's not the case: the 12 volt battery is being charged any time the READY light on the dash is on, even if you're just sitting there in your driveway catching up on the news.

So the main thing is just arranging to have the car READY enough of the time to keep that battery charged, whether you drive it or not. (For other things, like tire flat spots or rusting brakes, it's still a good idea to actually drive now and then.)

To fully charge the battery if it is deeply discharged takes about 15 hours in READY. Just keeping it topped off does not take that long.

 

How old was the bad battery? They don’t last forever

 

With both me and my wife retired, doing a little belt tightening, and with the advent of COVID, I found I was looking for excuses to drive, purely to keep the 12 volt battery healthy. Which seemed a little nuts.

After a while I came around to "this is the tail wagging the dog", got a smart charger*, installed it in our garage, installed a quick-connect (came with the charger) to make it more convenient.

Now we have the car on the charger any time it's idle, drive once or twice a week, consolidate trips as much as possible, and zero worries about battery running down. Current battery was installed Sept of 2015, still tests like new.

* The charger's current equiv would be a CTEK 5, good charger, no problems.

 

Now you might want to add into Mendel Leisk equation the tendency to leave the rear hatch open for extended periods of time due to forgetfulness.

 

I began to be concerned about this when I first joined PC, so after buying my ‘22 in February of that year I began monitoring the 12 volt battery because my wife and I AVERAGE only a messily 250 miles a month. Being convinced that “the sky was falling” by the Chicken Littles on PC, I thought it was prudent. Bottom line, we use the car like every other car we have ever owned and sometimes it sits for a few days, sometimes it sits for a week or two. HOWEVER, we don’t leave our doors or hatch open, don’t leave our lights on, or hook up battery monitors to the OBD terminal (in short, we don’t come up with ways to drain the battery) and after 17.5 months of not being stupid, the battery is doing fine and the sky hasn’t fallen. FWIW

You might ask how I know it is doing fine, well I bought a battery tester that when testing the battery checks for Battery Internal Resistance (a way to measure the resistance to current flow through the battery (a simplified explanation that helps non engineers to understand it)). And over this period of time the IR ( Internal Resistance) is the same as it was when I first tested it.

 

Based on diff between the last two spring oil change odo readings, we did roughly 3000 kms in the last year (2977). Divided by 12, times 5 and divided by 8, about 150 miles a month for us.

 

If it is fully charged, zero miles. Actually I would measure the voltage before attaching it. The battery really should be fully charged, or close to it. If somebody sells you a battery that is heavily discharged, take it back and go elsewhere.

I seem to recall that sometimes when the 12V is reattached to my car the vehicle won't go to "ready" on the first attempt and warning lights may be lit. Power it off and then back on again and all will be good.

 

Of all the things to worry about, a new 12 V battery is the least of your potential future problems. Which remaind true as long as you drive it once or more every two weeks and the battery is still five years or younger.

It is much more likely that the next major expense will be a $2000 Hybrid Battery or the $2500 brake booster system.

 

HELLO????? Earthlings we have a problem? WOEAYTA??????

 

However, the REAL question is “what is the likelihood of either of those being a problem in the real world?”
Answer: NOT LIKELY (unless you just insist on ignoring your Prius and try to destroy it (or use pop cycle sticks as feeler gauges)

Didn’t you just recently announce that you no longer believe you should abide by Toyota’s recommendation to change your oil every 6 months (since you don’t drive it enough to justify it in your opinion)? The point goes towards credibility.

 

(referring to pack and brake problems)

Signs of failure will usually be apparent for both of those components well before they kick the bucket. The more of those signs which appear the higher the likelihood that a new component is going to be needed soon. Let's add another - the A/C evaporator. I don't have access to statistics, but my impression is that a significant number of 2nd Gen Prius's have had that start leaking refrigerant and need to be replaced. Ours did that a couple of years ago. (I think the problem is actually a valve mounted in the evaporator, but the whole thing has to come out to get to it, and I'm not even sure that they sell the valve as a separate part.)

For the pack having the SOC dropping rapidly, or recovering too rapidly, or the motor starting too often, are signs things are going south. One can also use the Dr. Prius app to test the pack. Our 2007 will need a pack "soon" based on some SOC collapses and the Dr. Prius tests. I cannot tell though if "soon" is next week, next month, or next year. It certainly will not be another 15 years though! The sky may not be falling, but these cars are getting on in years and parts are going to fail.

 

(1) Install a fully charged battery, or purchase a battery charger/maintainer, and charge it yourself. Will take 5-6 hours to fully charge.

(2) Having a charger/maintainer will allow the vehicle to sit "forever", without any 12v battery issues. See post #9.

 

I used them to make rudimentary thickness gauges for brake pad thickness; accurate enough for that application. There are similar plastic gauges available commercially, and they are definitely not “feeler gauges”.

I think I’m beginning to understand your motivation.

 

you think?