What's new

How to bring a battery back to life

Squamch

Canadian
Joined
May 19, 2020
Member Number
93
Messages
1,470
Loc
republic of Vancouver island
I screwed up and left the travel trailer battery connected. Its down to 1v. My smart charger says it doesn't exist. Any tricks to bring it back, or did I just throw away $150?
 
Use jumpers to connect another battery to the dead battery. Connect charger to the dead battery until it starts charging. After an hour or 2 disconnect jumpers and let charger do it's job. If you dont have another battery, and you have a charger with a "start" feature to jumpstart a car, sometimes that will energize a battery enough to start charging.
 
(Untitled)

Use jumpers to connect another battery to the dead battery. Connect charger to the dead battery until it starts charging. After an hour or 2 disconnect jumpers and let charger do it's job. If you dont have another battery, and you have a charger with a "start" feature to jumpstart a car, sometimes that will energize a battery enough to start charging.
This was hoing to be my suggestion.
 
Use jumpers to connect another battery to the dead battery. Connect charger to the dead battery until it starts charging. After an hour or 2 disconnect jumpers and let charger do it's job. If you dont have another battery, and you have a charger with a "start" feature to jumpstart a car, sometimes that will energize a battery enough to start charging.

Ok, I'll give that a shot. I don't have a start setting on any of my chargers, but my buddy has one I think. I'll try pulling the battery out of my 4runner tonight and hooking it up that way.
 
Use jumpers to connect another battery to the dead battery. Connect charger to the dead battery until it starts charging. After an hour or 2 disconnect jumpers and let charger do it's job. If you dont have another battery, and you have a charger with a "start" feature to jumpstart a car, sometimes that will energize a battery enough to start charging.

i just had to do exactly that on 2 of my cars, both below 1v charger wouldn't recognize.

After hooking up the "good" battery, let it sit for a minutes before you hook up the charger, at least with my charger it made it easier. then i put it on a low 2amp setting and left it like that for a day. at some point the charger gave me a "timeout" error, so then i disconnected the two batteries and the bad one was up to 12v, hooked it up to just the charger and ran it for another few hours to make sure it was topped off.

no issues.


edit: just for reference, one of my dead batteries is on my van, it sat for 3 years and i did this last year to bring it back to life, then left and it sat for 4 months and died, did this again the other day and it worked again. obviously not a best practice, but it seems to work well and continues to function after being revived.
 
Last edited:
Also I take any old battery I'm trying to salvage and drop it on a concrete floor one time from 2 feet, maybe 18"

old guy trick, in theory it knocks all the corrosion off of the plates to expose fresh lead to take a charge

it made sense, so i do it, some batteries come back, some don't, never able to do a full on "twin study" in my "lab"
 
Got it back up to 12.5 volts using the two batteries and jumpers method, but none of my 3 chargers would recognize it. Gave up and returned to Costco for a new one yesterday. Gonna buy a tender for it this week, or maybe a solar panel if I can find a decent price for one.
 
you just gotta put a dumb charger on it for a while

if you've got a rectifier laying around (dead power supply, a single diode, whatever man) you can just toss 120v DC at it for a while, limit current with a light bulb in series
 
[486 said:
;n286028]you just gotta put a dumb charger on it for a while

if you've got a rectifier laying around (dead power supply, a single diode, whatever man) you can just toss 120v DC at it for a while, limit current with a light bulb in series

I've only got smart ones. Gotta keep an eye out for a dumb one at the flea markets next summer.


Actually, I think the 12v charging feature on my inverter generator for the trailer is a dumb charger. Oh well. Doesn't matter, I have a new one now.
 
Got it back up to 12.5 volts using the two batteries and jumpers method, but none of my 3 chargers would recognize it. Gave up and returned to Costco for a new one yesterday. Gonna buy a tender for it this week, or maybe a solar panel if I can find a decent price for one.

that's weird that it would measure 12 volts but the charger would not recognize it.
 
So dropping from ~2 foot and double charging are the method? I've got two Exide Edge AGMs that are "dead" at about 8V or a bit less. I've had one sitting on a charger for a week. They are about 4 years old with no use at all and not stored on concrete floor.
 
So dropping from ~2 foot and double charging are the method? I've got two Exide Edge AGMs that are "dead" at about 8V or a bit less. I've had one sitting on a charger for a week. They are about 4 years old with no use at all and not stored on concrete floor.

I don't know, but let us know what you do and if it works.

somewhere I also saw somebody say to reverse polarity for a few seconds, if it was totally dead, in theory it "blasts" all the shit off the plates, then trickle charge it as normal. Possibly tagged to another battery if on a smart charger.

I'm ok buying $50 Wal-Mart batteries, but it'd be cool to get some real world battery tech on bringing them back from the dead
 
I've had reasonable luck with ctek chargers being able to bring batteries back, some are hopeless, but quite a few come back and work for another year or two. The battery in my kubota died a couple times, then I sold it to my dad who never replaced the battery. That things has about 4 rounds of recovery and at least 8 years on it.

But its also worth picking up a dumb charger for a couple bucks at a yard sale to have on hand for this stuff. Also can do electrolysis rust removal with it.
 
I don't know, but let us know what you do and if it works.

somewhere I also saw somebody say to reverse polarity for a few seconds, if it was totally dead, in theory it "blasts" all the shit off the plates, then trickle charge it as normal. Possibly tagged to another battery if on a smart charger.

fun fact, if you do this with a real battery charger and the battery ain't totally dead you'll destroy the rectifier

the pussy modern battery chargers sometimes survive, as some of them just output with bigass transistors
 
I use a smart charger and can bring batteries back from the dead usually.

If the cells open make sure to top off battery acid / and or distilled water.

My exboss has used the trick of a 12v 1057 bulb to not overcharge for the past 40 years, taught me that with std chargers 20 years ago.
 
I use a smart charger and can bring batteries back from the dead usually.

If the cells open make sure to top off battery acid / and or distilled water.

My exboss has used the trick of a 12v 1057 bulb to not overcharge for the past 40 years, taught me that with std chargers 20 years ago.

And how does this trick work?
 
The bulb is to limit current once the battery has reached its charge level IE full, at that point it illuminates.
 
I ended up using the drop method and a second battery last night for a flooded cell. Brought it from .09 vdc back to full charge. My charger wouldn't even recognize it. Dropped it from six inches, used a good battery to boil it (in parallel) for about 30 seconds and it took a full charge.
 
Ive rehabbed batteries in the past and heres something I did that worked on a truck battery that i wanted to use for a trolling motor battery when I was too poor to buy one.

I dumped the acid out via drilling a hole in the top of each cell and flushed well with water and added new electrolyte.

Now, the trick is to cycle the battery repeatedly, doesnt matter what the voltage is, fine a motor it will turn and run it down a bit.

I started off with little DC motors, worked up to a starter motor and then to a trolling motor in a keg tub.

After 10-15 cycles it was working like a new battery and was my trolling motor battery for 4 years till I sold the boat.

Not sure I can explain how/why it works without typing out an encyclopedia, but if you know how a lead acid battery operates youll get it.

In short your exercising the battery by making the plates give up and retake the lead.
 
If not sealed. check fluid levels. connect a good battery with cables. Let sit. Charge your partially charged battery. This works for me very often. when a fire truck with 6 batteries goes dead, and the charger will not induce a charge.. It has a dead battery bypass on my charger, but hooking up a booster box and let it feed off of it brings it back every time....so far.
 
Top Back Refresh