We traveled over the holiday weekend, from cool Nebraska to Warm California.
Trip itself was fine.
Upon arriving back in Omaha at 11:15, I volunteered to run ahead to get the car from long term parking while my wife, 2 kids, and M.i.l stayed to get the luggage.
It was a balmy 41 degrees, I wanted the car warm for the very sleepy 7 yr old.
Upon arriving at the car, I discovered a dead battery. So dead I could not unlock the car. AND, the valet key was missing.

1st called wife, no answer
texted wife, no answer
2nd Called 12 yr old no answer
texted 12 year old-- Success!
Wife called me back; evidently the one carryon I had contained her phone (sigh)

Called AAA for locksmith and jump start. ((the airport had guy with jumper cables, but without access to inside of car, I cannot ge tthe $$$$$$ hood up.))
Had wife get rental car to drive home after AAA quoted 30 minute to 2 hour wait.
Waiting outside for 30 minutes, then got in Parking shuttle bus to warm up while waiting AAA.

AAA arrived at 12:15, and I was on the way home by 12:30.

Takeaways;
1) Always have a coat. Golf sweater kept me from freezing, but uncomfortable.
2) replace missing Valet Key- our second set has one, copying it. This would have saved 30-60 minutes; airport could have given me a jump.
3) considering mechanic to look for phantom load in car; checked, no lights left on, nothing plugged in... 2008 Dodge Garnd Caravan, only outside for 7 days, not sure why battery was dead.
4) Are there portable jump start units that would be safe to leave in a car? If so, how long do they last?


Would welcome, comments, feedback.

How old is the battery? My experience has been that at about 5 years old, car batteries start to have problems just like you had---they go flat by themselves and really give problems in cool/cold weather. They just do not hold a charge.

Replaced last winter- we bought the car used, and she could not get it started after taking the kids swimming, so about a year.

Car is parked the the garage at home, no unusual abuse. just kids. and garage doors.

A quick search on Amazon showed a list of Battery Disconnect Switches. Some mount to the battery post, at least one is a panel mount. HTH

I have one of those battery kits that has a Lithium Ion battery, multiple adaptors for cellphones, etc. [Antigravity Batteries AG-XP-10 Multi-Function Power Supply and Jump Starter].

I once had a car battery that got damaged somehow and required several jumpstarts before I could get home and get it replaced. The battery had no problem jumpstarting the car repeatedly without itself being recharged in between jumpstarts. It will also run my my Viar 88p inflator without difficulty. It seems to retain its full charge for at least several months in between topoffs from either the 110V AC or 12V DC.

The included adaptors seem to fit just about everything, and all the pieces come in a decent zippered nylon case. The car battery alligator clamps do have quite short cords, so you need to find a safe spot under the hood near the battery to place the unit if you're by yourself.

Overall, I rate this as a reliable, well designed and very handy kit. The case fits inside a two gallon ziplock bag since it is not waterproof, and I keep it in my car's trunk. I hope that helps.

Jeff

As long as you can access the interior of the car manually without there being any power, to get to the hood release, that seems like a good solution for any car that going into long-term parking or storage. But it would also disable the car's alarm.

Jeff

what do you think of one of those dashboard solar panels?

Sorry, I don't know anything about them. But I'll bet someone else here does!

Jeff

As mentioned above, I recommend something like this: http://thewirecutter.com/reviews/best-gear-for-a-roadside-emergency/#starter (perhaps newer models are available, but this general idea)

Upon further browsing, if I were to buy today, I'd buy this because it charges from Micro USB (very common, vs a dedicated adapter that many such jump start packs require): https://www.amazon.com/dp/B015TKUPIC/ref=psdc_318336011_t2_B00K0VMXDQ