jumped my RAV4 (with a 2 year old battery) on Saturday. Hadn't been driven in 4 weeks, except one for a 3 mile round trip to the supermarket. Our Honda hybrid can't jump another car (per manufacturer).
a neighbor drove over his car, I connected the cables, and jumped it. drove around for 15 minutes. been turning it on for 5 minutes every day and a couple of light revs.
at this point, the gas is 6 weeks old, need to burn off about 5 gallons then get fresh gas. could feel sluggish acceleration and rough idle.
5 minutes of runtime won't even replenish the energy used to start the car! Also a 5 minute run won't get anything up to temp, so you're building up condensation in the crank case and exhaust. This creates a sludge (water/oil mix) and causes corrosion.
The absolute best, cheapest, most reliable thing to do is get a battery maintainer (decent ones can be had very cheaply: $20-30). Plug in or solar.
If you can't do that, you gotta _drive_ the car for at least 30-45 minutes weekly. Idle speeds won't make the alternator put out much juice.
I’m surprised to hear that the engine doesnt’ come up to temperature within 5 minutes. On my dash the engine-temp dial stops climbing and holds steady at 2-3 minutes. Coincides with warm cabin heat.
How long should it take before the whole engine is warm?
I’ll look into getting a battery maintainer for the future. While during non-Covid situations we drive the car at least a few times each week, we often have field work which requires us to be gone for 2-4 weeks. To date the car has always started but with sluggish turnover, though I realizes now that our batteries have never lasted more than 3 winters. I’m guessing that’s why?
The temperature gauge in your car measures the temperature of the cylinder heads (where the combustion is happening). They heat up pretty quick because they are metal and there is burning fuel directly heating them. The temp that matters is the temp of your oil which takes a lot longer to warm up. Oil conducts heat poorly compared to metal (which means it takes more energy to heat it up) and only a tiny bit of your oil circulates through the cylinder heads at a time.
How long should you run a vehicle? Depends on outside temps. In cold weather I wouldn't let your engine run for less than ~20 minutes per start with a good portion of that driving.
And your exhaust also takes a lot longer to warm up than your cylinder heads. The best way to determine if your exhaust is up to temp is if it's still dripping lots of water. You want to get the exhaust warm enough that it evaporates all the water in the lines and muffler. Some exhausts will have several drain points but mufflers don't (can't). Note: water is a byproduct of combustion so that adds to the amount of water in your exhaust.
And yeah, your batteries not lasting very long is definitely due to not keeping them charged. Even in a fairly cold climate (weeks of below freezing temps) a decent, well maintained battery should last at least 6 or 8 years. The reason the average is so low is people don't maintain their batteries. I had a battery last nearly 10 before crapping out in my cold weather/hot weather climate because the car was almost always driven at least 30-40 minutes each way even during the cold months so the battery was always fully charged. You can get similar results with a battery maintainer.