So I only drive my car about once every two weeks, and I am finding that my battery is starting to no longer hold its charge even after fully charging it with my Battery Tender in between drives. The battery is only about 1.5 years old so I think my bike commuting is killing it. I don't like having my BT hooked up all the time because it is essentially entirely outside my condo except for the extension cord and theft is pretty frequent in my city.

Are there any good car batteries that are spec'd to hold their charge for a long time with infrequent charges? I'm willing to juice it all the way up like once or twice a month with the BT if needed. It's just annoying that the rare times I need to use my car, it hasn't been available to be driven until I charge it up overnight.

Just reinstall your battery whenever you get ready to drive...

Problem solved! No recharging!

BTW

That's also a car theft deterrent...

Your car has a "draw" pulling the battery down.
I would put a battery cutoff switch. We use them at work on equipment that doesn't get used much.

A deep cycle dry-cell battery like from Optima could be the answer.

Since you drive your car so little it may not matter, but just remember that always cutting the battery connection will make all the radio presets go away, clock reset, etc. But like I said you may not care about that.

My car often sits for a week or two and it does not have a problem starting... seems that your vehicle is drawing power when it should not be.

Batteries will discharge over time but 2 weeks is a 4% loss per day which is extreme.

Maybe the battery itself is defective.

+1 ^ I think Sixty has nailed it!

+2

Don't tell anyone that I can fix cars... some people are still stunned to realize that I own a car and can drive.



For longer term storage or minimal use a solar charger can be purchased relatively cheaply to maintain a battery... they plug in through the lighter / power socket and nothing on them is external so theft really is not an issue.

I put a new 850 amp battery in my Nissan this spring... if the OP has a realtively new battery it should be covered under a waranty and most shops will test them for free to make sure they are 100%.

Is it a Volkswagen?

A friend of mine had the same problem with a new-ish Golf. He went to the dealer and they said it was "normal", and tried to sell him on plug-in thingy to keep the battery charged. Not particularly useful information, but there it is.

One thing I would check is if there's any single device draining power. Sometimes just leaving a cell phone charge cable plugged in can do it, or maybe an aftermarket stereo.

Another drawback to removing the battery on a regular basis (on a newer car) is that the ECU will reset. Gas mileage won't be as good. Car won't pass SMOG (if applicable) until you drive at least a couple hundred miles. Clock and radio are minor inconveniences, in comparison.

I use Interstate Megatron batteries in my car & truck, and have been very happy with them...but they usually don't sit unused for more than 5-6 days at a time.

How long do you drive when you do drive? If it's less than 1/2 an hour (just guessing), it might not be enough to top off the battery.

I had a truck that I didn't drive for at least a month at a time, but when I did I would drive it for at least an hour. Never had a problem with the battery (except when the accessory switch was accidentally left on).

I'll second the solar charger.

Not applicable...

From the OP:

Or the car has developed a minor short, which could be the cause for the drain.

You assume it works properly, or that it's capable of actually charging a battery, and not just keeping a battery for self-discharging.

I suspect there's a large draw somewhere, like an aftermarket radio, alarm, or such. Or the battery has failed. I also suspect asking a bunch of bike commuters about fixing your car isn't the best way of doing things.

You're right, there are a lot of assumptions when it comes to diagnosing a vehicle across the internet without sufficient details. We don't even know the year/make/model. It could actually be a problem with the alternator, maybe a bad ground...who knows?

At least he didn't ask the question in the "Living Car-Free" forum.

It could be so many things... starting with the battery is the first and easiest step before one tries to trace the wiring for a short or find what is drawing down the battery. If it is starting and then running well I would assume the alternator function is good.

I grew up with a father who ran his own auto repair shop... was turning wrenches on cars just about as early as I was turning them on my bike.

Now the new cars have reached a point where self service can be really difficult due to all the technology under the hood.

One should also check to make sure the dome light... interesting note on these is that my friend's father invented the automatic dome light when he worked for Packard.

+1
If the battery is already out of warranty, and you find it is defective, get a new one with a longer warranty.

Get a marine grade deep cycle battery that fits in you car.
Wal-Mart has em for about $75.

The optima is a good battery. Got one in the Xterra and I only take it out 1 or twice a month. I just drive it to the store once a month and it keep it charged.

I start my car once every 6 weeks and it's fine. It never hesitates to start.

It's a 95 Audi A4 with the original battery.

Can't go wrong with VW/Audi OEM

It's a 90's camry for those that are wondering. I bought a battery quick disconnect off of eBay for $3.50, so maybe that will solve my woes. The battery was completely fine until I started bike commuting 100%, so I don't think it's defective. I likely have a phantom draw somewhere, the electrical in this car has never been real great.

I had a friend with the same issue in a late-80s camry. it was an excellent car otherwise. they traced the draw to somewhere behind the dash, but found that a quick disconnect was the easiest way to handle the problem!