So we've got this 2003 T-Bird my wife inherited ......her mother acquired it about 3 years ago & it always had problems with the battery going dead.....kinda always chalked it up to not being driven much. I put a new battery in it less than a year ago......problem still persists. It gets driven maybe 200 miles / month.

So, a little research indicates it could be a software problem FORD was aware of a long time ago.....or an even much more expensive part issue.

OK, six weeks ago it wouldn't start. I charged the battery till it started to bubble. Now I'm under the impression when a battery starts to bubble....that means it's in the 80-85% fully charged range.

A few days ago ......no start. I charge till bubbles can be heard.

Yesterday I acquired a "Battery Tender Plus", ( +an optional cigarette lighter plug adapter that hasn't arrived yet).....supposedly if your car's cigarette lighter works when the key is not turned on then you can use this device to maintain a battery through the lighter socket. This would be a lot more convenient than getting in the trunk & removing the floorboard to get to the battery.....I figure just roll the window down once a month & connect to the drop light & cigarette lighter.

So, the multimeter indicates that the car is always pulling at least 0.7 amps....way more than it should just sitting there. Maybe after I contact Ford they will do the software update for free????

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Down to the battery science issue now;

Monday I use the big (10 amp) charger till it bubbles....assume just over 80% charged.

Thursday I get the " Battery Tender Plus" .....disconnect the battery from the car and attach the tender. 6 pm
Indicator lights indicate battery is charging & battery is at less than 80% ......10 pm last night indicator lights imply it has reached 80%.......& at 6 am this morning the Tender indicates FULL CHARGE.

My confusion is; This is a battery that says its 800 CCA. If it just got to 80% last night at 10 pm & the tender is a 1.25 amp device.....how could the battery go from 80% (=640 amp) at 10 pm to 100% (800 amp) using a 1.25 amp charger???? I would have thought it would take well over a 100 hours to juice up that last 20% of an 800 amp battery?

How does the Tender even know what the capacity of a specific battery is ?

Note; I disconnected the battery from the car during this recharge cause I figured if it was pulling 0.7
amp at the same time I was trying to put in 1.25 amp.....that that would be like trying to pour water into a cup that had a hole in the bottom.

Thoughts??