Is a fully discharged battery now junk?

[Rockbadchild]

Also the length of time the battery was totally dead has a impact on the likely hood of its ability of charging or not.

 

[MRTOES]

You guys have taught me something today. These new automatic chargers are just as finicky as a lithium ion charger. I went through a couple of them from Harbor Freight before I went back to the Schumacher old fashioned ones and never ran across trying to charge a regular dead lead acid battery with an automatic charger.

 

[John_Mc]

All electronic schumacher chargers have a desulfation cycle built into them. I have several and they seem to work.

I'm not seeing desulfation mentioned in the documentation for Shumacher chargers on their website or in any of the several of their operators manuals I downloaded.

 

[ArlyA]

I'm not seeing desulfation mentioned in the documentation for Shumacher chargers on their website or in any of the several of their operators manuals I downloaded.

I found that's pasted below via google. I emailed the company some years ago who then stated that all there electronic chargers will automatically do a desulfation. Sorry I can't find something more specific.

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Schumacher
Blowing all the competitors out of the water with 15.0-amp rapid charging, this massive current will quickly bring your battery back to usable health—if you can wait patiently for the initial desulfation mode.Aug 15, 2023

 

[AnotherBueller]

My understanding is it actually can be good for them to be discharged then charged fully back up. Try it and see.

When a lead acid battery is completely discharged it may be able to be recharged, but you will loos some of it's capacity (CCA & reserve). So it will probability work but if you ever needed ALL the CCA in the winter you should either replace it or be prepared to jump it whenever it gets cold enough. Either way you'll a lesson ie: cash now or PITA in the winter.

 

[RjCorazza]

...
Last suggestion, if you want a really good analysis of battery condition(s), you might buy a Midtronics (or clone) tester. Yes, I have load testers and old fashioned (but accurate) hydrometers - if you can get to the electrolyte... But, I kinda like the Midtronics solution.

I use a Midtronics tester also. They are particularly good at tracking the overall decline of a battery so that a failure doesn't come as a surprise.

 

[AnotherBueller]

I left the radio on on my Kawi Voyager, the battery, a 2 yr old AGM was dead to the point that it wouldn't even turn on my maintainer. Hooked it up to my booster pack with the maintainer on it to give it a nudge to start charging which it did. Battery finally gave up the ghost this year 4-5 years after killing it.

That is battery maintainer (1 amp) not a charger

Maybe he meant this one. Its a 10 amp smart charger and a maintainer.

Amazon.com

 

[AnotherBueller]

From what I understand, regular lead acid batteries used for starting an ICE are not ever SUPPOSED to be fully discharged - which is why engines are equipped with an alternator to replace the amount of power used to start the engine in the first place and keep the battery "topped up" while it's working. There is another type of lead acid battery called a "deep cycle" battery that is designed to be fully drained then recharged, drained and recharged without damaging the cells. These are often used in marine environments with trolling motors or to power electrical "devices" with no alternator till empty and then be fully recharged.

Not true. A regular battery can be discharged to the low 80s% without much damage, a deep discharge battery can go down into the 40% range without significant damage.

 

[AnotherBueller]

You guys have taught me something today. These new automatic chargers are just as finicky as a lithium ion charger. I went through a couple of them from Harbor Freight before I went back to the Schumacher old fashioned ones and never ran across trying to charge a regular dead lead acid battery with an automatic charger.

Excuse me, but did you say HF? Somethings you get what you paid.

 

[1Mech]

Excuse me, but did you say HF? Somethings you get what you paid.

Very true, I bought one of their chargers and never have been satisfied with it. Should have returned it. It still works, but only on the slower rate.