May be minor, but I cant figure it out. I went on a three day trip, the 8 parked in my garage, and came back this morning to a dead battery. I jumped it with my wifes Tahoe, went to work, and when I went out to leave for lunch, dead battery again.

Trying to think what is on to make the battery keep going dead. I have a 10 minute highway commute to work so I would have thought this would be ample time to charge it up.

Any ideas?????????????????

 

Its not the cold. The same thing happened to mine and it was 70 degrees. Take it to Mazda and make them replace the battery and do a diagnostic check. There is another thread here where an 8's nav system was drawing too much power from the battery. MAKE SURE THEY DO IT. They will try to get out of it!!!

 

Assuming your alternator is charging the battery, then it sounds as if you've got a battery that won't hold a charge. Probably some internal damage. The only other explanation that comes to mind is a dead-short somewhere in the electical system. But a dead-short that can drain a battery in 3 hours or so would probably be bad enough to cause the battery to heat to the point of melt-down. I'm going on the only dead-short-battery experience I've ever had. It was a work-truck with a hoist and the hoist motor shorted out. The dang battery exploded under the hood as I was rolling down the road. Insulation was melted off the wires from the battery to the hoist. Perhaps more mechanical minds than mine can give you a better feel for what's going on....

 

Take it in. I had the same exact problem. They replaced the battery and did a few other things and for now it is working great.

 

Isn't there a TSB on the battery? And I know that there was a thread about this in the Tech garage at one point so a search might help.

 

If a battery is dead, how long do you need to run a vehicle to fully charge it?

Also, do I need to jump it, or can I just push start it?

 

I would jump it and a good hour long trip should charge it enough. Like you needed an excuse to drive the car . But from the sounds of it you had already taken it on a long trip the day before it died. If that is the case then you should have charged it just fine while driving. Unless you left the interior light or something else on over night I would recommend that you take it back to the dealer and have them check it out.

 

Thanks for all the input. Just got back from the dealership and they replaced the battery saying it was faulty. He said he has had to replace the battery of several 8's and that it seems to be more of a problem than it should be.