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????

--------------------------------------------

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??

 

First thing I would do would be to start pulling fuses with the amp meter connected and see when it drops to 0.
Then go from there.

I don't know about the charger stuff other than I use an electronic charger set at 2 amps and if it registers 75% when I hook it up, it usually takes about 2 hours to hit 100%

 

Your practical troubleshooting makes perfect sense. Unfortunately, the theory (in your question) isn't quite there yet...

The confusion comes from the "800 CCA" designator. This doesn't mean that it's an 800 amp-hour battery. Amp-hour is a unit of how many hour a battery can run at one amp. So a 7 amp-hour battery could run at 1 amp for 7 hours, or 7 amps for 1 hour. It's a measure of electrical energy.

CCA stands for "cold crank amps". This means the number of amps the battery can output when your car is started (if it hasn't been for a while). So you have a battery that can use up to 800 amps to start the car. That spec has nothing to do with charging the battery, except (MAYBE) that you couldn't charge it any faster than 800 amps at a time (which would be ridiculous).

So what you need to answer your charging question is the AMP-HOUR rating of your battery. To make matters worse, if your battery is (lets say, even though it's urealistic, it makes the numbers easy) 100 amp-hours, it may not be 70% charge when it has 70 amp-hours of charge. It's not necessarily a linear conversion like that. But it does follow the basic idea.

 

Thanks for the responses!!

Pulling fuses requires a contortionist......I've pulled about 20 of them so far & no change......after my back muscles stop having spasms I'll try the rest.

---------

I was thinking there might be something wrong with the indicator lights on the new Tender......but after your comment......maybe not.....thanks!

 

Not to mention (but I will anyway) if that battery completely discharged, you may have sulfated cells now. A wet cell should never be allowed to sit discharged. You may have to pull it for a load test where you bought it. I also may have misunderstood your post.

 

When the cells are bubbling, that is called out gassing or gassing and is usually an indication of over charging or charging above the batterys needs. You should get the battery checked with a load tester to see its worth, and an INDICATION of its capacity.

Recommend that you get the insulated leads that clip on to the cord of the trickle charger and then go to the battery, and leave the cord exposed under the wiper area so you can leave it in and out at will, I do this with the SRT. A simple battery tester that I use is the one that is about 15 bucks and plugs in the lighter so you can monitor the charging system while driving - Walmart in the car battery section.

The green light on the trickle charger is a relative charge indicator and not the authority. Its in the charged or not charged category, kinda sorta crude reading.

Pulling fuses is a good start but I like to check the glove box light to see if it or the trunk lights are on, vanity mirror also. You check to see if they are hot when you open the door.

Enjoy, WDY

WEEK - END

Yeah

 

Good ideas!!

So, is this the correct way to think about it,

If the battery says 1000 CCA & it's a 100 AH battery.....it's kinda like you had a 100 gallon tank of water & a pump that could pump at a rate of 1000 gallons an hour.....so at full blast the tank would be empty in 6 minutes??

 

The tender has the following indicator light positions

Red flashing = no connection or bad battery

RED SOLID only ....battery less than 80% & charging

RED SOLID & green flashing ......battery is charging & at or over 80%

Red off & Green SOLID .....FULL CHARGE.....then floats......

can be left on indefinely.

 

Read this for info.