Is a fully discharged battery now junk?

   / Is a fully discharged battery now junk? #1  

sixdogs

Super Star Member
Joined
Dec 8, 2007
Messages
13,776
Location
Ohio
Tractor
Kubota M7040, Kubota MX5100, Deere 790 TLB, Farmall Super C
I mistakenly fully discharged the battery in my MX 5100 Kubota. It was a replacement likely made by Interstate. The battery was so dead it even tripped the 50 amp main fuse and I didn't know it could do that.

Anyway, I've been slow charging that battery but I have the feeling it's no good after a full discharge like that. Anyone know about this?
 
   / Is a fully discharged battery now junk? #2  
My understanding is it actually can be good for them to be discharged then charged fully back up. Try it and see.
 
   / Is a fully discharged battery now junk? #3  
Ive fully discharged batteries-even 2 of them- in larger tractors and they always recharged for me.
 
   / Is a fully discharged battery now junk? #4  
I've discharged a new battery, charged it back up and it came back full. Been lasting 5 years now
 
   / Is a fully discharged battery now junk?
  • Thread Starter
#5  
Wow, thank you all for the voice of optimism.I've bought a lot of batteries this year and don't need any more.

It must be an old wive's tale that fully discharged ruins a battery. Or maybe that was in the olden days. These days I charge batteries just before the cold starts and I've had great luck with longevity.
 
   / Is a fully discharged battery now junk? #7  
Fully discharged from slow leak is ok 1ce or twice & maybe 3 times. High discharge can swell/ruin the plates, especially if water level is way down. Using distilled water is best but hardly anyone pays any attention. Mineral water == slow short circuit. Plus, high charge rate bubbling puts acid on the case top so another slow death/drain. Some batteries can last 20 years. some last 2 years depending on how careful and respectful you are with them. No battery: no tractor is how I respect them.
 
   / Is a fully discharged battery now junk? #8  
Only one real way to find out, charge or jump it and see what happens.
 
   / Is a fully discharged battery now junk?
  • Thread Starter
#9  
Only one real way to find out, charge or jump it and see what happens.
I needed the tractor so put a spare in and the discharged battery is on a 3 amp slow charge "smart" modern charger. I never understood boiling the cr*p out of them with a high amp fast charger.

I'll let it slow charge longer and then see what happens. All good to know.
 
   / Is a fully discharged battery now junk? #10  
Discharged batteries start to oxidize the lead plates. Leaving batteries discharged for extended periods is definitely bad.

Single time and it was charged fairly quickly….may not be a certain death sentence.
 

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