roadie13

Right now in the cold weather my car gets exercised about every other week, otherwise it's parked in a shared garage. There is no way to
hook up a trickle charger there, so I've been monitoring the battery charge daily with the amazing Antigravity tracker device. What I found is that during the first week after
driving the car the voltage drops about 0.04V a day. In the second week the car has stopped listening for the key fob and the discharge drops to 0.02V per day. Overall this means there is no problem with a two week rest period
but much longer could lead to a headache. So far so well known.

Now, this week I tried double-locking the car, ie double-clicking the key fob when you shut the car. This deactivates the in-car motion monitoring system. Amazingly, this drops the battery drain to
about 0.01V per day even in the first week! So that's a lot less compared to locking the car normally!
This way I would be confident leaving the car for three weeks and probably a whole month with monitoring.

Of course, to do this your car should be parked in a safe space. Mine is, not least because thieves would have to move my motorcycle first and then figure out that there are chocks under the front wheels

rileyracing1

The next best thing you could do is get a battery power pack and plug your charger into that overnight just to bump up the battery voltage to a decent state rather than being forced to drive or move it when you don't have to .
I too have a battery tracker on my AGM battery and I get about a month before a significant voltage drop ...fortunately I have access to power so it's normally always on the trickle charger.

MrIncredible

I have been battling this too. My battery is fairly new and will not start if I happen to leave the car unplugged for about 2 days. I took the battery back to NAPA to check it and he said it "wasn't great but should be healthy enough". I drove the car around all day last weekend, plugged it into the tender and went to drive it the next day and it didn't want to start... I'm not sure why that made any sense because it was on the tender. I plugged it back in and it seems to be okay now but I can never trust the battery 100% that if I take the car out that it's going to start. I always take a battery jumper with me.

Sporty

Your battery is clearly defective or your charging system is awry - get a new battery for $200 or less or test the charging system- why deal with the anxiety?

roadie13

I like the idea of a battery power pack; maybe that would work for any motorcycle too, though that seems to have almost zero parasitic drain. Fortunately, most of the I don't need to drive the car just to exercise it, like last week I took it to instruct at a winter driving school (except there was no snow..).

MrIncredible

It's a fairly new issue and I'm in the early stages of trying to determine if it is actually the battery or my charging system. I plan to head back to Napa this weekend with it to see if they'll prorate a new battery.

Antigravity

It is a little hard to tell if you battery is bad... sometimes the techs at the places that check you battery look for the ability to handle a load well... and though it diminished they say it still fine. But a more important factor is the batteries ability to maintain its charge which isn't really measureable on the equiptment though they also make a internal resistance tester to try to prove this out, but it isn't always accurate. So you battery , when charged, might have a decent output pulse to handle a load, but then its capacity has been damaged so it doesn't hold a charge well and drains over a few days. My point is just to say the test aren't alway completely accurate. But a test is a good indicator but let that trick you into thinking you don't simply need a new battery.... you just might. These Cars are exceptionally sensative to voltage drops and voltage levels in general from the battery.

911URGE

Do you have slow, sluggish cold starts on a fully charged battery? This could be a symptom of a weak/failing starter as well.