Avoiding the dreaded "short trips"
January 5, 2012 12:33 PM   Subscribe

How far does a car need to be driven to charge the battery?

Mrs. VTX and I bought our first house (yay!) six months ago and one of the benefits is that it is MUCH closer to where she works. Recently, the battery in her car (a 2006 Mazda 3s) died after the car had sat around for four days. The battery was original so it probably needed to be replaced anyways but I'm worried that my wife's short commute will start burning up batteries.

She drives 3.8 miles to work, the car sits in a covered but otherwise open parking ramp for 8 hours then she drives 3.8 miles home all on side streets, never faster than 40 mph. Other than that, we take my car everywhere else so it almost never gets driven anywhere other than to and from work. We're in Minnesota in case the cold of winter is relevant.

Is this a long enough drive that the battery will get charged regularly?

Are there any other issues that this sort of use will cause?

Are these trips long enough to avoid being "short trips"?
posted by VTX to Travel & Transportation (15 answers total) 1 user marked this as a favorite
Yes, that should be plenty of time to keep the battery charged. If you notice that the battery starts causing a slow turnover when starting, I'd get the alternator checked also. Autozone (or another big-box parts store) can do this for you.
posted by chrisfromthelc at 12:36 PM on January 5, 2012 [1 favorite]

Additionally, you're probably letting the car heat up before driving, right? That should also negate any 'short-trip' issue with the charging system.
posted by chrisfromthelc at 12:36 PM on January 5, 2012

Seconding yes that's plenty. The only situation I've expereinced/heard of this being a problem was with older cars (such as a vintage VW Beetle) that has a generator instead of an alternator. The only other situation where it might be a problem is if you have alot of periphrials or a massive stereo/subwoofer setup installed in the vehicle and overloading the charging/battery system.

You probably had a bad battery, failing alternator, loose belt, not totally closed door/device left on, or electrical short cause the battery to be dead/fail.
posted by RolandOfEld at 12:41 PM on January 5, 2012 [1 favorite]

I believe the car talk guys answered a similar question about the exhaust rusting out because the car wasn't driven long/far enough to get all the condensate out. Their answer was something along the lines of "take it for a 40 mile drive on the weekend" (can't recall if they meant every weekend, or somesuch..) So be aware the exhaust/muffler may also rust out on you.
posted by k5.user at 12:46 PM on January 5, 2012

With a new battery that should be fine. As the battery ages it might have a harder time holding a charge, but you can always plug it into a trickle charger if that becomes a problem again. Trickle chargers can be had pretty cheaply online.
posted by ambrosia at 1:27 PM on January 5, 2012

That should be plenty to keep the battery topped-up, particularly if the commuting is done in daylight. Five years is pretty good for a battery these days, so i wouldn't worry about something being wrong.

Unrelated to your question, but do you really need a second car at all for such a small commute? We got rid of our second car recently and the savings are surprisingly high.
posted by dg at 1:42 PM on January 5, 2012

I'm Mrs. VTX - thanks for all the great responses!

We have definitely talked about getting rid of one of our two cars, since my commute is so short and VTX takes the bus. What's stopping us? A couple of things:
* VTX just started a new job and while he's able to take the bus now, he might be moving to a different office.
* Point-to-point transit in our area (Bloomington/Edina MN) is terrible! It's great for getting into downtown in the AM and back out to the suburbs in the PM, but for me to get from home in one suburb to my office in another, it would take almost an hour and involve 3 transfers and a 1/2 mile walk.

Plus we're planning to have kids soon and we're not sure what the pickup/dropoff situation will be like.

We figure that by moving and cutting down from two 20-mile (each way) car commutes to one 4-mile car commute and one bus commute we're still way ahead of where we were.
posted by Coffeemate at 2:16 PM on January 5, 2012 [1 favorite]

I've always taken it that 30 minutes is the right length to charge a car battery from dead.

Also, people with exceptionally short commutes should, at least once every week or two, take the car for a 20-mile-ish drive to keep it in good shape. My source, too, is Car Talk, but I don't think 3.8 miles quite counts as exceptionally short, <1-mile commutes and such are what usually cause Click and Clack to recommend a leg-stretching drive on the weekends, just so the car can get properly warmed up, get all the fluids circulating, exercise the cup-holders, and so-on.
posted by Sunburnt at 2:40 PM on January 5, 2012

Let's just remember that charging a battery is a matter of time, not distance. Unless your car is experience a slow turnover when you start it (as mentioned above) due to an alternator issue, then the new battery is gonna be just fine. If it really worries you, let the car run in the driveway for a bit on the weekend, but that seems like a waste of gas to me.

Given minnesota winters, you might want to consider a car engine warmer?
posted by matty at 2:55 PM on January 5, 2012

I don't think you need to worry about taking the car for longer drives to 'blow out the cobwebs' - it's just burning fuel and adding wear and tear for no reason. Cars that predominantly take very short journeys do tend to wear our engines more quickly (in mileage terms), but only because a significant proportion of the wear happens on start-up, when oil has settled and needs to be circulated around the engine for optimum lubrication. Driving it more won't make it wear out less. As long as the car is serviced regularly and a quality synthetic oil is used and changed regularly, this is not even such a problem these days, anyway. As a data point, my mother has a 1997 Ford Festiva that she bought new and it has a fairly similar usage pattern to what you describe - it's still in perfect condition and drives like a new car.

One thing you may want to watch is the oil level if you do take the car for a long drive (ie hundreds of miles), as all cars use some oil and, for cars that never get really warmed-up, that is naturally replaced by condensation, so the oil level looks the same. A long trip will evaporate that condensation, resulting in a sudden drop in the oil level. Again, regular oil changes will mostly stop this.
posted by dg at 3:00 PM on January 5, 2012 [1 favorite]

I don't think you need to worry about taking the car for longer drives to 'blow out the cobwebs' - it's just burning fuel and adding wear and tear for no reason.

Conversely, running the car through to a full heat cycle with some running at fully warm (ie a drive of 20 minutes or so) will have beneficial effects in terms of preventing condensation build up or deposits in your engine. Only when the car is fully warm is the engine running at best efficiency and it needs a period of running at that temperature to burn off the effects of the warm up cycle and to clear out any moisture fully out of the system and exhaust.

The additional wear is minimal (as noted they are mostly during cold starts) and the benefits tangible and important.
posted by Brockles at 4:40 PM on January 5, 2012

I had a Mercedes 500 that I drove about 20 miles a week in Chicago area, and went through a 3 batteries in 5 years. In each case, the battery died without any telltale signs of trouble. Have a plan if the car won't start.
posted by Land Ho at 8:08 PM on January 5, 2012

You've done well, getting five years of service out of a car battery. Most of them start being pretty useless at four.

Get a new battery, then listen to Brockles.
posted by flabdablet at 11:11 PM on January 5, 2012

After paying close attention this morning on her way to work, I'm told that the car does in fact reach normal operating temperatures by the time she gets to work so I think we'll be able to avoid any other battery or short trip issues.

Thanks everyone!
posted by VTX at 8:00 AM on January 6, 2012

Get an idea of how long it is at full operating temp for. While you may be able to establish no battery charging issues if it gets to full temp, but it needs to spend some time at full temp to burn off the effects of a cold start. 5-10 minutes after full temp would be where I'd think you could stop calling it a 'short trip' from that perspective.
posted by Brockles at 9:18 AM on January 6, 2012

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