Question Battery charge time formula

[Crumm]

My brain must not be working this morning as I can't remember the formula to estimate the time it takes to charge a battery.

After sitting for two months the Battery in our 95' Explorer is low enough that it won't quite start the engine, it will crank a little but too slow to start. Battery is the original 15 year old unit so I suppose it only has 10 or so more years in it I recently purchased a Battery Tender that puts out 1.25 amps. I purchased it for winter battery maintenance for the Camper but I thought why not try it out on the Explorer.

Explorer battery is a standard 845CCA unit and charger puts out 1.25 amps. How do you calculate charge time? 845/1.25/60=11 hours if it was completely dead??

 

[JLDickmon]

Explorer battery is a standard 845CCA unit and charger puts out 1.25 amps. How do you calculate charge time? 845/1.25/60=11 hours if it was completely dead??

works for me..

you're not going to need it fully charged to start the Explorer, either.
I'm thinking 70% or so will probably crank it up... let the alternator do the rest.

so you're looking at like 7 hours @ 1.25 amp per...

 

[Crumm]

I'm thinking 70% or so will probably crank it up... let the alternator do the rest...

I want to fully charge it so I can test it after letting it sit for a week or so. Might be time for a replacement.

 

[BIG JOE]

A 15 year old battery Yep.. you just might half to Break Down and git a New one

 

[Crumm]

A 15 year old battery

Just getting broke in good I still have the 14 year old batteries out of my 96' PSD too although they are in my 75' plow truck.

 

[BIG JOE]

Well.. IF.. they ever Do crap out.. ya shur got yer moneys worth out of'm.. fer shur.