I keep a "NOCO Genius" battery maintainer on a car that is kept at a vacation home and not used for 8-9 months at a time. I've been using it for two or three years. Works great.

They are designed to be left attached long-term.

quote:

Originally posted by Shifferbrains:
I would recommend that you hook a battery charger to your battery now anyway, there is no chance that your battery is fully charged unless you drove for hours. Newer cars do not charge the battery all of the time, and you will be left with just a surface charge on the battery.

Went and checked to see what I have and noted I still have a well used old Century Model 87151 charger that I'd forgotten about. So I went out and hooked it up to the Sonata as your comment made a lot of sense.


Seems to still be functioning properly so perhaps this is good enough rather than buy a newer Battery Tender. Anyone have thoughts to share?

AFWIW I cancelled my order for the battery disconnect switch now too.

Sounds like you need a new battery to me. Get a load test done at an auto parts store. Otherwise parasitic draw. Check with a DMM. With your ignition off, disconnect positive cable from battery and put meter inline from Batt. + post to positive cable and check your amp draw.

quote:

Originally posted by shiftyvtec:
Sounds like you need a new battery to me. Get a load test done at an auto parts store. Otherwise parasitic draw. Check with a DMM. With your ignition off, disconnect positive cable from battery and put meter inline from Batt. + post to positive cable and check your amp draw.

Battery is less than 2 years old as previously mentioned. It checks out fine.

quote:

Originally posted by bald1:

Went and checked to see what I have and noted I still have a well used old Century Model 87151 charger that I'd forgotten about. So I went out and hooked it up to the Sonata as your comment made a lot of sense.


Seems to still be functioning properly so perhaps this is good enough rather than buy a newer Battery Tender. Anyone have thoughts to share?

AFWIW I cancelled my order for the battery disconnect switch now too.

That will work. I have one similar to yours that I leave hooked to my Lexus. Just keep it at the 2 Amp setting and you should be fine, it should shut down when the battery is fully charged.

I keep a larger Noco in the Jeep. I drive it maybe once a month. If I forget and leave the headlights in the auto position the battery is dead by about 3 weeks. So I try to remember not to leave them on. The Noco works great jumping the 3.0 in the WK.

quote:

Originally posted by RogueJSK:

quote:

Originally posted by 229DAK:

quote:

Tow operator who happened to be the owner told me of new Subaru's using tiny batteries that will die if the car sits more than 3 days.

I have an '18 Outback and have never heard of this. Nothing in the owner's manual. I have left my car sit for over a week and it fired right up and nothing is out of order. I call BS.

BS indeed... There are a half dozen recent production Subarus of various models in my family. I have several other buddies with Subarus. None have any issue with their batteries draining from just sitting for a few days.

Well that's good to know as I really like Subarus and again we still have a '99 Forester running just fine in the family.

quote:

Originally posted by Shifferbrains:
That will work. I have one similar to yours that I leave hooked to my Lexus. Just keep it at the 2 Amp setting and you should be fine, it should shut down when the battery is fully charged.

Thanks! Yup I'm using the 2 amp mode. Frankly can't ever remember using the 15A or 100A modes with this bench unit.

And it should automatically cycle back ON if the battery discharges again.

quote:

Originally posted by bald1:
And it should automatically cycle back ON if the battery discharges again.

Yep

quote:

Originally posted by jimmy123x:
A friend of mine takes care of a 2016 Porsche 911 GTS4, if you don't drive it every 10 days the battery will be dead, happens even with a new battery. Supposedly according to the dealer, it needs to be driven 7 miles just to restore the energy the computers and starter used to start it. If the battery goes dead, you then can't open the hood to get to the battery to charge it, and have to hook 12 volts to these two little tiny posts inside the car and hit the hood button......isn't German engineering great?

Well now, that's gotta be one of the dumbest things I've ever heard about.

quote:

Originally posted by Balzé Halzé:

quote:

Originally posted by jimmy123x:
A friend of mine takes care of a 2016 Porsche 911 GTS4, if you don't drive it every 10 days the battery will be dead, happens even with a new battery. Supposedly according to the dealer, it needs to be driven 7 miles just to restore the energy the computers and starter used to start it. If the battery goes dead, you then can't open the hood to get to the battery to charge it, and have to hook 12 volts to these two little tiny posts inside the car and hit the hood button......isn't German engineering great?

Well now, that's gotta be one of the dumbest things I've ever heard about.

Read what you have to do just to get the hood open with a dead batter, it's absolutely ridiculous on a $100k + car.


https://perryandcoblog.com/200...ocked-hood-solution/

Changing the battery is even better. The dealer charges $800 for the battery and re=programming the computer. LOL I had a friend that sold his 2017 911 Turbo because of these headaches. Most of these cars are only driven once or twice a month.

"Have the battery removed and installed only by your authorized Porsche dealer.
Only use an original Porsche battery, with the correct part number, as a replacement. Only this battery meets the specific requirements of the vehicle.
After you install a new battery, it must be initialised in the control unit.
Please contact your authorized Porsche dealer.
Please observe the disposal instructions for batteries.
Putting vehicle into operation
After the battery is connected or after a fully discharged battery is charged, the PSM warning light lights up on the instrument panel and a message appears on the multi-function display in the instrument panel to indicate a fault."

www.porscheownersmanuals.com/2...l/6/246/Battery-Care


As for the OP, I've had good luck with battery Tender brand on waverunners, on a floating dock (jetdock) with the jet ski covers on them. They lasted years.

This is what I put on my 350z for the winter.

https://www.menards.com/main/t...2337779729139&ipos=5

quote:

Originally posted by black1970:
Too much parasitic draw on new stuff. Most cars and trucks now have 3 computers drawing constantly on the battery. My 07 Tahoe eats up batteries. I slow charge the battery for 24 hours every month. If it ever drops below 12 volts the CD changer will start and run until the battery is dead. This almost always happens during the night. Will not happen of course if being driven. Ah yes modern stuff. Wonderful if working right.

Bought a new 2012 Silverado and needed a new battery every 12-18 months when temps dropped below freezing. OEM is crap, had three replaced under warranty that wouldn't start the truck if temps dropped or it sat 3-5 days. After the third died when one year old I bought an Interestate over two years ago and now it can sit over a week in the cold and starts right up. GM batteries are piss poor crap.

Great thread...making a note to come back and review.

I’ve noticed that my 2014 4Runner is ‘dead’ after a couple weeks of not driving.

 
My wife's Sequoia has parasitic draws, and she doesn't drive it much. I once went on a quest for what was drawing, using a special AT fuse that has blades on both ends. I hooked up my DMM in ammeter mode to the top blades, and began testing the fuses in the main fuse block. I found it was not just one, but several small draws with the key out. Together, they were enough to run the battery down in 2-3 weeks of not driving. A Deltran Battery Tender Plus is the solution. You can leave a battery connected to it indefinitely, as it has smart charging and won't harm the battery, but keeps it topped off. I use them on all of my infrequently used battery devices (tractor, genset, riding mower, ATV, my wife's Sequoia, etc). It comes with two pigtails, one with battery clamps, and the other with ring terminals you can leave permanently attached to the battery, then just plug in the Battery Tender's cord. My tractor gets used sporadically in bursts of activity, but often stays parked for six months at a time. The battery stays healthy, cuts down on sulfation build up on the plates, and has extended the lifetime of my batteries.
 

For those who were curious about my battery. It was bought on 8-20-16 so again just over two years old. Has a 5 year warranty with the first 3 free replacement and the later two prorated.

It had died after 3 months of sitting idle (first week of May to first week of September) but shows "good" after recharging with 741 cranking amps against a rating of 700. The vendor who sold me the battery said if it happens again (dies) they'll replace it.

I have an engineering/design question. Why couldn't the manufacturer install a separate battery who's sole purpose is to keep all these electronics charged when the car is parked? Call it a "Backup Battery", if you will. It gets charged as soon as the car is started and goes into Standby Mode when the car is running. Once the car is turned off, the main battery bus disconnects and those electronics now stay energized from the Backup Battery once again.

That's kinda the system on the ERJ and how I thought of it.

^^^^ That makes too much sense. It's too much like right. A dedicated battery for the use described likely wouldn't even need to be a full-sized battery.

BUT...$200-$300 in parts cost would probably add a few thousand to the vehicle price.

quote:

Originally posted by bald1:
Seems to still be functioning properly so perhaps this is good enough rather than buy a newer Battery Tender. Anyone have thoughts to share?

Many (most) older chargers do not have chip brains to charge a battery in three stages, which is best for the long term health of the battery. After it is bulk charged, then topped off, it goes into "float" mode, which is usually about 13.5V and very low amperage, enough to keep it topped off without overcharging. Newer chargers are 3 stage, such as the Battery Tender Plus, and are not that expensive. 2 amps is really too much for a nearly fully (or fully) charged battery. The Battery Tender Plus is only 1.25 amps at its maximum, and it backs way off the amps in float mode.
 

Thanks once again to SigForum, for teaching me something important I did not know...and I read a lot about cars.

Sure enough the S2000 was dead this morning, the Gooloo got it going with 1 turnover, and I don’t have to bother testing the battery.

Thanks to bald1 for advice on the disconnector terminal, I’ve ordered one from Amazon that is supposedly made of copper.

Anyway I needed an excuse to get the S2000 out of the garage, get the top down, and drive to Costco for gas and tire pressure check.

Now for the moment the garage will be used to get the tandem bike going again—we’re on a new exercise kick.

Thanks, bald1 and SigForum!