Is a fully discharged battery now junk?

[NUTTERDW]

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.

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.

some last 2 years depending on how careful and respectful you are with them. No battery: no tractor is how I respect them.

 

[NUTTERDW]

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?

One thing I have observed is that allowing a battery to run completely down does not hurt it but if I leave them completely discharged for a period of time it usually shortens the life of the battery. I have an old Farmall that I leave at a summer cabin and if I let the battery run down and stay that way for a period of time it may or may not recharge. It is a 12 volt battery and is the same brand of battery I use on my other vehicles.

 

[moosetooth]

Newer "smart" chargers will not charge a battery with zero voltage. The charge cycle just won't begin. The workaround is to hook another battery to the dead one before turning the charger on so the smart charger can "see" the dead battery. Once charging begins you can remove the helper battery. I've had this happen twice and found the solution to it by googling it.

 

[ArlyA]

One thing I have observed is that allowing a battery to run completely down does not hurt it but if I leave them completely discharged for a period of time it usually shortens the life of the battery. I have an old Farmall that I leave at a summer cabin and if I let the battery run down and stay that way for a period of time it may or may not recharge. It is a 12 volt battery and is the same brand of battery I use on my other vehicles.

I believe running a battery down will add solidified crystals to the plates. This does harm the battery much and a desulfation cycle should be done to it.

 

[Riding a Relic]

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.

What kills a lot of batteries is the bottom of the battery collects the contaminates from the plates with constant charging and discharging. This will eventually fill enough to contact the plates, causing shorting between the cells. I like AGM batteries, but they tend to just die a sudden death, instead of getting weaker before death.

 

[Gord Baker]

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?

If it does not 'take' a recharge, hook 2 batteries in parallel and try charging.
+ to + , - to- .

 

[CH4Ohio]

Seems like everyone agrees that running a battery down is NOT a good thing, but may not be fatal.

What is fatal is when you leave something on in the winter and let a dead battery freeze. Even if the case doesn't split open, they never recover from freezing.

 

[coalguy]

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.

I totally agree with you. I am managing many batteries of a few solar only systems, and I worked all my live in International Telecomms where we have large banks of batteries to cover the starting time of generators (my background is Solid State Physic). In addition to what you said, I would add that the longer a battery stay in the discharged mode the greatest the damage, since the sulphation process deteriorates the battery capacity continuously during down times. Also, in cold weather a discharged battery will freeze and be destroyed.

Not all battery are build the same, and some will survive better than others (i.e. deep discharge, some AGM, and those with better build quality). You can bring back some batteries that don't accept charging by applying a small period of over current (100-200 amps), but the total capacity of the battery will never be 100%.

 

[rScotty]

My "smart charger" will not charge a fully discharged battery. It is a batterMINDer model 128CEC2 - and we have several of them. When a battery is left on and gone clear flat, the charger shows an error "polarity reversal" and will not charge at all. It refuses to charge in spite of the "smart, mainenance, and anti-sulfation" features.
So what I do is put hook up my old fashioned $30 battery charger to it for a few hours. Using low charge just to be safe.

Then switch over to the batteryMINDer smart charger for a few days. It may take a week of maintenance charge cycle, but eventually the battery is good again - not 100%, but usable. Although I understand that its ultimate lifespan has been reduced.

For charging a flat battery, my experience is that marine and deep charge type recover best, then AGMs, then the wet cell types with acid caps which are not nearly so good.
rScotty

 

[lcalverson13]

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?

I had a gel mat battery go dead this summer for my RV. I hooked another 12 volt battery to the discharged one and it slow charged to life. The buffer action allowed it to accept the charging. I could not get the Gel Mat to accept power directly from a battery charger.