Disconnect Battery or Leave it Be?

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HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
I'm heading to Florida for two months. What are the odds the battery will run down over that period of time? I'd prefer to leave it be so as not to lose the codes and avoid calling AAA for a jump. This is a two year old OEM battery. The car will be garaged in Buffalo cold if that makes any difference.
 

sm1ke

Work In Progress..
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Canada
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'18 CX-9 Signature
Another vote for a Battery Tender. But if you'd prefer not to spend money, I would take the battery out and keep it inside.
 
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2022 CX-5 Turbo
For two months, your car will likely be dead when you come back.
+1 on battery maintainer.

If you have to leave it out in the open, get a Li-ion jump starter when you come back to it.
It is quite useful anyway to keep in the car. (avoid hot heat, though)
 
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CX5 GT
probably disconnect the battery and keep it inside if you are worried and if its the oem one and if the car wont need to be driven for any reason. I would never leave a charger or even tender connected without supervision but thats me. My oem when left for 2months connected was ok-ish but it was severely drained at around 11.9. The car did start though. My current agm lasts 3mo connected without issues or big voltage drop but its deep cycle pure lead agm.
Up to your preference I guess.
 
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2019 CX-5 Signature
A quality "smart" battery tender is the way to go. No worries with over charging, so very safe. I have a pickup truck in my garage that I bought in April 2021. It has 800 miles on it and has been on a tender most of the time.
 

HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
probably disconnect the battery and keep it inside if you are worried and if its the oem one and if the car wont need to be driven for any reason. I would never leave a charger or even tender connected without supervision but thats me. My oem when left for 2months connected was ok-ish but it was severely drained at around 11.9. The car did start though. My current agm lasts 3mo connected without issues or big voltage drop but its deep cycle pure lead agm.
Up to your preference I guess.
I reckoned there's probably enough draw from the electronics to make starting hit or miss after two months. I agree that running a charger or tender while away for two months presents a risk, however minimal. I'm going to disconnect the battery and just leave it in the vehicle--that should suffice. It will be interesting to see how differently it drives after dropping codes. Not much I imagine. Two weeks and a couple of hundred miles ought to get to a reset.

Also washed with undercarriage spray, filled with non-ethanol, and overinflated the tires a couple of pounds. I can't wait to get the h*ll out of here on Sunday, bombogenesis :LOL: permitting.
 
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2018 CX-5 Sport
I think just leave it. My mower sits for 5 months through the winter with a small 12 volt battery and it usually starts in spring. Granted it doesn't have an anti-theft device to power those 5 months.
 
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2019 CX-5 Signature
I think just leave it. My mower sits for 5 months through the winter with a small 12 volt battery and it usually starts in spring. Granted it doesn't have an anti-theft device to power those 5 months.
I have a flashlight that usually sits in a drawer for months at a time, if not longer. It runs on 2 1.5v "D" batteries in series, so 3v. It powers right up when I switch it on, even after 1 year.

What I'm trying to convey, is you can't compare a lawnmower battery to a car battery. Actually, your lawnmower batter has more in common with my flashlight, than it does with a vehicle battery. Neither has any draw when not in use. :)
 
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2016.5 CX-5 GT AWD titanium/black 2016 Miata Club ST MT white
If you're concerned about having a battery tender connected for an extended period of time why not put it on a timer? Have it come on for an hour or two each day, just enough to keep the battery topped up. If you have an Alexa, using that with a remote switch that's controlled by Alexa would be ideal.

I use a tender on all of my vehicles. I move the tender from one to another, leaving it on the vehicle for a week before moving it to the next. When they're all done, I start over.
 
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2019 CX-5 Signature
If you're concerned about having a battery tender connected for an extended period of time why not put it on a timer? Have it come on for an hour or two each day, just enough to keep the battery topped up. If you have an Alexa, using that with a remote switch that's controlled by Alexa would be ideal.
Read up on how smart battery tenders work. They do pretty much what you're asking for, just in a more efficient way.
 
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2016.5 CX-5 GT AWD titanium/black 2016 Miata Club ST MT white
Read up on how smart battery tenders work. They do pretty much what you're asking for, just in a more efficient way.

I was editing my post when you replied. As you can see, I have no concern about leaving the tender connected for an extended period, a week in this case.

I was suggesting the timer in case the OP is concerned about having the tender connected for so long.
 
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2019 CX-5 Signature
I was editing my post when you replied. As you can see, I have no concern about leaving the tender connected for an extended period, a week in this case.

I was suggesting the timer in case the OP is concerned about having the tender connected for so long.
Yeah, and I have no idea why anyone would be concerned with leaving it connected. The majority of time, after it's fully charged, it's off.
 
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2019 Cx-5 sport
I agree , get a deltran battery tender plus or jr... I leave my mower and
motorcycle on them for 4 months without worrying. Been using them
for 15 years without problems..
 
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Phoenix
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2021 signature
There you have it OP, 9 out of 10 of us say, use the Battery Tender Jr. Maybe the one objector is right and we're wrong, who's to say. I suppose one should also unplug all TV's, radios, clocks, refrogerators, etc. when on vacation - yes, I know that's different. Just sayin', one could take this to the nth degree if one so chooses. But, the Battery Tender Jr; is used by auto enthusiasts, mechanics, engineers every day for months at a time.
 

HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
He's a follow-up to my OP:

To recap, I decided to just disconnect the battery (2 year old OEM), fill the tank to minimize the chance of condensation, and pumped the tires to 36 lbs. The vehicle was kept in an unheated garage in the cold north for all of Feb. and March if that matters.

Results:
  • Reconnected the battery and it cranked just a tad slowly and stared right up. After driving 15 miles the start-up is back to normal with some battery recharge.
  • I was surprised to see that my radio pre-sets and bluetooth setup were saved. The clock had to be reset, however.
  • The tires lost 1/2 lb. at most with no detectable flat spots.
  • On an initial 15 mile drive, the brakes started out sounding like like sh*t. The scratching / grinding sound is expected until rotor corrosion is worked off. What I did not expect was the whumpeta-whumpeta from the rear when braking. After a few hard stops there was noticeable improvement, then better from there, and now back to normal on the second short drive. Caliper sticking then unstuck with use? Self-adjustments made? Dunno, don't care at this point.
  • I continue to maintain that claims of the PCM adjusting to driving habits are way overblown. The engine and transmission sound / feel / shift just as I had left it. The only other possible explanations are 1) the adjustment codes are stored in non-volatile memory (as with the PCM and evidently the radio presets) or 2) I've been driving to the Mazda engineers' benchmarks all along. ;) If it's the former, disconnecting / reconnecting the battery will not fix any performance issue if one was of a mind to try it. And I doubt it's the latter.
 
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