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Battery Headaches

I have a 2008 Ford Mustang Bullitt which I bought brand new and love to drive. Since I live in Minneapolis I don’t drive it much after October until April or May. The problem I have is that if I leave it for more than a week without starting the engine the battery is completely dead. I have ahd the battery replaced once already. Everything is turned off while it’s parked, radio , fan everything. The car is parked in an underground garage though not heated is protected from the elements. My question is why would the battery drain completely after such s short period of time?

You need to check for excessive load while the car is off and sleeping. Connect an ampmeter between the ground cable and the ground post on the battery. Wait until the car goes to sleep (about 30 minutes after you connect the meter), and see if the current drain is over 50 mA. If so, there’s a problem with one of the electronic modules.

There is always some drain on the battery. The car’s computers and its radio require small amounts of power to maintain their memories.

But this small drain should not kill a battery in a week. You should be able to park the car for at least several weeks, or even longer, with no problems.

I suspect there is an additional drain that is not supposed to be there. Has anyone tested the circuits looking for an unexplained current drain?

It should last longer than a week, as others have said. However, it sounds like you might be expecting it to last from October until April. There’s no chance of that. You need to either hook up a battery tender or disconnect the battery.

How long do you drive it on a typical trip?
How much charging time does the battery get after it’s revived from dead?

It takes about 8 hours of slow charging to thoroughly charge a dead battery.
A car battery also takes a charge more slowly when cold.

My advice to you is to get a “battery tender” or other small (~5 amps) automatic battery charger and charge the battery overnight once a month during the winter.

p.s. Is your “handle” a nod to Coltrane?

I used a Battery Tender to keep the battery charged on my last motorcycle during winter storage. Although expensive, it was cheaper than replacing a $110 battery every spring.

Specifically the Battery Tender Plus

I still use it today to maintain my car batteries.

Ed B.

Thank you all for your responses. I’ve read in other places that the radio, in this case the Shaker 500 system, may be part of the problem in causing excessive drain eventhough its off. Some folks swapped out their system entirely nad fixed the problem. I’ve also read that swapping out the OEM battery for aanother brend of battery might be the trick. Since it’s under the warranty still I’ll talk to the service guy about it. I will purchase the battery tender though. There is only 18,000 miles on it so I don’t drive it very far distances. @ Circuitsmith,yes, my “handle” is a nod to John Coltrane.musical giant of the 20th Century. Thanks again

As was already suggested I would have the current drain checked to see what the real amount is. Unless the battery isn’t at full charge capacity it does sound like there is a problem somewhere even though the battery tender would cover that. When things are in the sleep mode I think the normal current drain should be less than 30ma…