# Is there anything I can do for a dead SLA battery?



## zmoz (Aug 14, 2003)

I have an ~18 amp hour SLA battery that is in one of those portable jump start things. I've had it for about a year and a half, it's been mostly dead for most of that time. It works for a little while if I plug small devices into it, holding maybe 2 amp hours. If I try and jump start with it, it's worse than the battery I am jumping. When I charge it, it shows it's charged up within a few hours, should take around 12 hours. It was never abused very much, I have another one of these things that has just been beat to hell and it still works great. Is there anything I can do to try and "revive" the battery?


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## GJW (Aug 14, 2003)

Usually not but we have had some luck with this:
AccuMate Charger
It's brought a few batteries back from the dead for us.
We bought ours from England but there are US distributors now.


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## zmoz (Aug 14, 2003)

What exactly does that thing do to help the batteries? I'm sure that's a nice charger, but if I had to buy something like that I would just get a new battery. Would it help to do something like give it alot of amps for a short time? Or higher voltage? Or something similar?


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## GJW (Aug 14, 2003)

Nope, nope, and nope.
It's just a charger that's had some luck reviving a few batteries that wouldn't otherwise take a charge.
For 2 batteries it's probably not worth it but here we use hundreds.


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## batterystation (Aug 14, 2003)

What usually happens to SLA batteries is they dry up. They have lost their water. If this is the case, it is shot. SLA batteries also HATE to be stored in the "dead" mode. That will do them in too. If anyone has SLA/gel cell batteries on the shelf, CHARGE THEM while in storage on a monthly basis.


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## zmoz (Aug 14, 2003)

But how could this one have gotten that way in the first place? It wasn't very old when it stopped working, I might have discharged it completely once, and that's it. I have another just like it that is about 5 years old. I used to discharge it completely before charging it because I thought that was good for it. /ubbthreads/images/graemlins/smile.gif I have left it dead for months...overcharged it for days. Still will start up my boat just fine which need 1000 cranking amps minimum.


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## Brock (Aug 15, 2003)

Just unlucky I guess, or I should say lucky with the older one. Heres what I would do before I tossed it. Take in on you boat, once it's started and running connect it to the house or main battery and let it take the full charge from the alternator. It won't get any higher then any of the batteries on the system. Or if your boat is big and has a shore power charger you could turn that on and again connect it to the batteries. You could do this with a car, but it should be connected right at the battery and that is a LOT harder to drive and have it connected under the hood /ubbthreads/images/graemlins/wink.gif

Having said that the battery could leak or crack, or worst case even explode, but I would put odds of exploding about 10,000 to 1. Leaking on the other hand would be about 50 to 1. So if you can put the whole thing in a 5 gal pail, just in case, that is what I would do. Oh the odds that this might bring it back to life are about 1 in 8, maybe. Remember this is just my opinion and just what I would do, do so at your own risk. I will add that I have semi-revived a couple of SLA this way, about 1 in 8 /ubbthreads/images/graemlins/wink.gif


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## zmoz (Aug 15, 2003)

Well...I guess if I've got nothing else to do I can try it. I've got a generator that I made from a lawnmower engine and a car alternator...I'll just hook it up to that. /ubbthreads/images/graemlins/smile.gif


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## snakebite (Aug 15, 2003)

it has sulphated.
you may be able to recover it by float charging at 15v a week or so.if not its time to recycle it.


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## LED_ASAP (Aug 15, 2003)

One thing that worked for me was---scarey as it sounds---charge the battery with low voltage, low current AC power /ubbthreads/images/graemlins/grin.gif

My experience was with a tiny battery used in a Sony walkman, about 2V/1Ah. It won't hold power for more than 10 min playing time and I didn't want to fish out $70 to get a new one. So I hooked it up in series to a small 6V transformer and a ~5V/0.3A bi-pin bulb. Initially the bulb didn't lit at all, but after a few hours it started to glow and eventually got pretty bright. Then it was hooked to the walkman and it charged OK. 

For your 18Ah battery, I think you need to find something that will handle a couple of amps, like the turn-signal bulb for cars, and hook it up to something like 16V AC(assume the battery is 12V). 

Even if you can revive the battery to some extent, it won't perform as well as new batteries. Lead-Acid batteries won't be damaged by slight over charging, but will be seriously damaged if allowed to run flat. So charge them after each use, and once every 6 months or so if sitting on the shelf.


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## snakebite (Aug 16, 2003)

i once recovered a badly sulphated gellcell from a ups that had been left on for 2 years by using 120vac!
used a 1n4007 and a 7w nightlight to charge it.
the higher voltage helped to break down the sulphation.
in your case i would get a new battery for the jump box and play with the old one.starting a car with a dead battery is a pretty demanding application for a small sla.


[ QUOTE ]
*LED mods As Small As Possible said:*
One thing that worked for me was---scarey as it sounds---charge the battery with low voltage, low current AC power /ubbthreads/images/graemlins/grin.gif

My experience was with a tiny battery used in a Sony walkman, about 2V/1Ah. It won't hold power for more than 10 min playing time and I didn't want to fish out $70 to get a new one. So I hooked it up in series to a small 6V transformer and a ~5V/0.3A bi-pin bulb. Initially the bulb didn't lit at all, but after a few hours it started to glow and eventually got pretty bright. Then it was hooked to the walkman and it charged OK. 

For your 18Ah battery, I think you need to find something that will handle a couple of amps, like the turn-signal bulb for cars, and hook it up to something like 16V AC(assume the battery is 12V). 

Even if you can revive the battery to some extent, it won't perform as well as new batteries. Lead-Acid batteries won't be damaged by slight over charging, but will be seriously damaged if allowed to run flat. So charge them after each use, and once every 6 months or so if sitting on the shelf. 

[/ QUOTE ]


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## Ray_of_Light (Aug 16, 2003)

Add some sulphuric acid at 36 Be (Baume degrees, indicated a concentration of about 30 percent) and reverse charge the battery for half hour. (10 percent of battery capacity)
Start a normal charge then, and discharge the battery with a bulb, 12V 20 W.

Repeat the reverse charge up to three times. This should take the lead sulphate off the plates. If, after the third reverse charge, and a subsequent full normal charge, you do not get the full capacity, the plates are irrimediably destroyed ad you should discard the battery.

Anthony


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## Brock (Aug 16, 2003)

The problem with leaving it sit on a charger, or overcharging it, is it is a sealed battery. You can't add acid, so overcharging it will cause it to vent gasses or leak. Once it's gone you can't add any back in. That is why I recommended charging it at a higher voltage, but in parallel with another 12v battery.

zmoz, the lawnmower charger should work, but might not since the SLA might be stable enough for the alternator to work correctly, but it's worth a shot.


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## LED_ASAP (Aug 16, 2003)

[ QUOTE ]
*Brock said:*
That is why I recommended charging it at a higher voltage, but in parallel with another 12v battery.


[/ QUOTE ]

No no, charging it parallel with a good battery will only cause that good battery to sink all the current as that is the lowest resistance pathway.


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## The_LED_Museum (Aug 16, 2003)

If the plates are sulfated, you're probably SOL.
Lead sulfate is a spongy material that is nonreactive (it doesn't produce electricity, and cannot be charged up), and can form on the surface of the plates with as little as 24 hours of "dead" time. That's why you often see admonishments that you should never run a lead acid battery (especially a SLA battery) to the ground, and to charge it fully within 24 hours if you do discharge it significantly. 

Now, I wasn't aware you could dislodge lead sulfate with AC or reverse-charging...usually when a battery becomes sulfated, you throw it away and get a new one.


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## Brock (Aug 17, 2003)

[ QUOTE ]
No no, charging it parallel with a good battery will only cause that good battery to sink all the current as that is the lowest resistance pathway.

[/ QUOTE ]
This is true if you have a small underpowered charger, but it is a car alternator of larger marine alternator, I can assure you it will bring a weak battery up to voltage. It might not be good for the bad battery, but it will get it up to voltage.


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## XploD (Jul 10, 2015)

Sorry for activating an old thread, but I think it's better than opening a new one. I have a one year old SLA 12V 7.5 Ah battery. I use it only during summer to power up a portable audio system with car radio and speakers on the beach. So, during winter, it was not used. Today I tried to charge it but it won't charge. I meassured a 5.5V voltage on it (instead 12V) and when I connect it to power source (up to 21 V) with ampermeter in series, it meassures 0.00 A. Is there anything I can do to recover it!? It's only 1 year old and it served only 1 summer.

I have another SLA 12V 4.5 Ah for 4-5 years now which I was using for that same purpouse and it's still alive! It was not used during winter as well and it was barely used last summer since I had this 7.5 Ah one and today I connected it to car radio and it works. I'm charging it currently. So how is this possible that a 4-5 years old battery still works and this new one is already dead? Both batteries have been used on the same way.

I read all posts in this topic but there are different and oposite advices so I don't know what to do now. Any advice is welcome. I found this video: http://makezine.com/2013/03/27/how-to-recover-a-sealed-lead-acid-battery/ and my battery looks the same as this one in the video, but from another manufacturer. Will this work?

I saw that there are some chargers that can recover batteries but buying them is not profitable since the battery costed less than 20$. Is cheaper to buy a new one. So my question is mostly related to a way of recovering it without buying an aditional equipment.

EDIT: I tried to keep it connected on the power source and it's voltage vent from 4.83 to 6 V but all that time, there was NO current flowing to the battery. I put ammeter to micro ampers but there is still a big zero standing. I tried ammeter with another battery, it works. I tried to connect a LED diode to the battery and it's barely working, while it's connected, the voltage of the battery drops to 1.6 V and when I remove the LED, it went back to 5.6 V.


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## more_vampires (Jul 10, 2015)

XploD said:


> So how is this possible that a 4-5 years old battery still works and this new one is already dead? Both batteries have been used on the same way.



Storage condition and maintenance. Example: Store the battery touching the ground = killed battery. ...so don't put the battery onto the floor or ground. Lots of one-off situations that can do it. Excessive temperature extremes, thermal cycling, on and on...

Also, you don't know how long a *recently purchased battery* has been on the shelf. Big difference from "actually new."


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## WalkIntoTheLight (Jul 10, 2015)

more_vampires said:


> Storage condition and maintenance. Example: Store the battery touching the ground = killed battery. ...so don't put the battery onto the floor or ground.



They come in a plastic housing. How is putting it on the ground going to drain it?


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## more_vampires (Jul 10, 2015)

Old mechanics with gray hair told me about this. Apparently, it's a bad practice according to the old heads. The conventional wisdom says you can put a NON FILLED battery on the floor, no problem. I've been yelled at about this in various shops over the past 20 years.

Electrical continuity is one thing, but magnetic fields are another issue. From what I understand, magnetic fields can mess with a battery as well over long term periods. The Earth is the ultimate grounding force. Burying a battery will kill the crap out of it, afaik.

It's quite possible all of these old mechanics with gray hair are full of it, repeating an "old mechanic's superstition tale." It's been drilled into my head, however.

Wonder if it's actually true or a load of BS? Can anyone confirm or deny? I'd actually like an authoritative confirmation or denial.


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## Mr Floppy (Jul 10, 2015)

WalkIntoTheLight said:


> They come in a plastic housing. How is putting it on the ground going to drain it?



It is part myth and part true but does not apply to modern lead acid batteries. Don't remember the actual explanation though 

The thing most likely is that lead acid batteries need to be maintained. They have a high self discharge and if they are left too long with no charge, that will damage it.


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## WalkIntoTheLight (Jul 10, 2015)

Okay, snopes says it's a myth.

http://www.snopes.com/autos/techno/battery.asp

Apparently, it might have been true a long time ago, when porous rubber was used as the housing.


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## more_vampires (Jul 10, 2015)

> Car batteries used to be encased in hard rubber, a substance that was porous enough that battery acid could seep through it and create a conductive path through the damp concrete, draining the battery.



Those are still available, often with the top sealed with tar. I sell them for antique vehicles. They are the old fashioned "fill with acid, top up later with distilled water" kinds.

So:
1. Valid, not a myth.
2. Still applicable to my shop.
3. The old guys were right.

Cool. Old guys, old vehicles, old superstitions. Just because the stone age ended, doesn't mean it is invalid now.


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## SemiMan (Jul 10, 2015)

more_vampires said:


> From what I understand, magnetic fields can mess with a battery as well over long term periods. The Earth is the ultimate grounding force. Burying a battery will kill the crap out of it, afaik.



This would fall into the BS category. Batteries are buried all the time, especially for lead acid. It keeps the temperature much more stable and they last longer.


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## more_vampires (Jul 10, 2015)

Never heard anyone advocate that before, just a cool dry temp-stable place. Tons of battery superstitions out there. Weird.

Thanks for the discussion, everyone. This thread applies to my work.


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## WarRaven (Jul 10, 2015)

I've read about some hundred thousand gallon or better lead acid batteries used by US government for back up power long time ago.

Yup, swimming pool sized, built in ground.

In NAIT, my local trade tech school, it was like quantum mechanics, it shouldn't effect any but has been known to cause damage being stored on ground.
However, by our standards at that time, to complete a full charge on a Lead Acid, if it didn't slow boil, it didn't/couldn't reach max capacity.
Thus negating ground storage effect of sludge on bottom of cells.
All of this is also about batteries that can be opened during charging, does not apply to sealed lead acid. 

Yes, more yes and no, danger to boil, high soc, why, the venting gases. Otherwise, that is what stirs up the sulfated material that collects at bottom of cells allowing it to rebond/coalesce to plates.
Though, we used vented charging stations when I first started pulling wrenches, rare to charge in car, just smoked further away.


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## more_vampires (Jul 10, 2015)

I have made a fortune on body work and paint jobs due to old fashioned boiling batteries. 

I guess I should be grateful for this design "feature."


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## WarRaven (Jul 10, 2015)

6 volt batteries really gassed.

No doubt.


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## XploD (Jul 11, 2015)

more_vampires said:


> Storage condition and maintenance. Example: Store the battery touching the ground = killed battery. ...so don't put the battery onto the floor or ground. Lots of one-off situations that can do it. Excessive temperature extremes, thermal cycling, on and on...
> 
> Also, you don't know how long a *recently purchased battery* has been on the shelf. Big difference from "actually new."



It was stored in basement garage, but both batteries were one next to another on a 2m high shelf. And during summer, I keep it in my flat and I live on a third floor. That last statement is probably true, since this shop where I bought it sells lots of these batteries but I don't think that often people buy this so they probably are there for longer periods.

Btw you mentioned magnetic field? I kept all my electronics, devices and parts in one place in garage and I have a lot of loudspeakers, most of them stored on a shelf under the one where batteries were. Is it possible that they caused damage to the battery?

So, what should I try to do before ordering a new one (which will probably end dead like this again during winter)?


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## Mr Floppy (Jul 11, 2015)

XploD said:


> So, what should I try to do before ordering a new one (which will probably end dead like this again during winter)?



Don't buy a cheap one. Most of the cheap ones I have got seems to self discharge rather quickly


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## XploD (Jul 11, 2015)

Mr Floppy said:


> Don't buy a cheap one. Most of the cheap ones I have got seems to self discharge rather quickly



I know, but if I buy an expensive one, there are still high chances that it will die because not using it during winter and because over-discharging it, but the price (damage) will be bigger. I don't know if these batteries have some kind of protection, but I don't think so. When we use the battery, I never care about over-discharging since we're usually drunk somewhere on the beach  We crank the car radio to the maximum and it can play for few hours untill the radio starts powering off everytime the bass kicks due to voltage dropping to low. Then we decrease the volume and continue to listen to music until this starts happening again, and then we decrease the volume again and we continue doing that until it's unable to work even on the lowest volume. At this point, the battery is totally empty, I never meassured the voltage but it's probably 10V at max since car radio is unable to work (it' possible to turn it on but when the music starts, it goes off). I know that this is damaging the battery but while drunk, I can't think about the battery, I just want my music  But we use that other much older battery like this and it still works after 4-5 years. Maybe I should construct a cheap DIY protection or even a whole electronic circuit for protecting and charging the battery, including float charge, and built the circuit within the battery. And then, I could left it float-charging during winter.


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## WalkIntoTheLight (Jul 11, 2015)

As long as the battery isn't hooked up to anything, a good battery shouldn't self-discharge down to bad levels over the winter. Just charge it up in the fall, and again in the spring, and it should be fine.


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## WarRaven (Jul 11, 2015)

Lead acid batteries do not like to be drained down to dead. 



Need a bigger battery and treat it better honestly.


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## Mr Floppy (Jul 11, 2015)

XploD said:


> I know, but if I buy an expensive one, there are still high chances that it will die



Ok, cheap may not be the right word, perhaps reputable brand in your country?

There is sort of a reason as to why the cheap batteries don't last as long. They skimp on plates. The more reputable ones have thicker plates. It is a lottery with the cheaper ones. There are often warranties with the reputable ones of two or more years. Mind you constantly over discharging may void that.


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## SemiMan (Jul 11, 2015)

Floody batteries can fail a winter ... If you keep them inside. Outside where cold or at least in unheated storage they hold charge much longer. Gel and AGM batteries have slower self discharge, but be careful. If stored hot, they can self discharge quick.


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## XploD (Jul 11, 2015)

During winter it's pretty cold in garage, it's not heated.

In that shop, I can get a few manufacturers: Fiamm, Multipower, Focus, Emos. Is any of them trustable or quality? The dead one is Multipower, and that older one is Fiamm. Fiamm is more expensive.


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## more_vampires (Jul 11, 2015)

XploD said:


> It was stored in basement garage, but both batteries were one next to another on a 2m high shelf. And during summer, I keep it in my flat and I live on a third floor. That last statement is probably true, since this shop where I bought it sells lots of these batteries but I don't think that often people buy this so they probably are there for longer periods.
> 
> Btw you mentioned magnetic field? I kept all my electronics, devices and parts in one place in garage and I have a lot of loudspeakers, most of them stored on a shelf under the one where batteries were. Is it possible that they caused damage to the battery?
> 
> So, what should I try to do before ordering a new one (which will probably end dead like this again during winter)?



Hard to say. A magnetic field that can jerk the antique metal fillings out of your teeth also explodes batteries (yes, wrong word, not actually an explosion.) A speaker magnet "over there" isn't so big a deal. Recall, field strength typically falls off by inverse square of distance. New kids have it lucky with that UV conversion white filling stuff in their teeth. Also, I'm totally glad that I don't do that sort of work anymore.

My best advice is a computer-chipped "smart charger" constantly hooked up for maintenance. It seems to add years to a SLA.

I use the "Battery Tender" in bulk all over the place. It was a net savings in the $$$$. When you have more than a couple of vehicles that you tend to, this totally adds up fast.

My 2 cents.


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## WarRaven (Jul 11, 2015)

The battery, and its composition of cells, is a small emf generator. 
When the electrons flow along non twisted pair wiring. 

Minute, but it is what it is. 

As More-Vampires suggested, a battery tender goes a long way to prolonging lead acid battery storage life. Without, at best two years.
+1


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## XploD (Jul 11, 2015)

Now I need to find a good electronic circuit. I would like to build it myself (even better, a all-in-one device: tender, charger and protection) because it will be very cheap comparing to buying one. I have lots of transformers, power supplies, cases, coolers etc. at home, I would only need to buy discrete components from eBay.

Also, I currently don't have even a charger. I charge my batteries with an ordinary regulated power supply (2 - 20V up to 2A).


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## more_vampires (Jul 11, 2015)

XploD said:


> Now I need to find a good electronic circuit. I would like to build it myself (even better, a all-in-one device: tender, charger and protection) because it will be very cheap comparing to buying one. I have lots of transformers, power supplies, cases, coolers etc. at home, I would only need to buy discrete components from eBay.
> 
> Also, I currently don't have even a charger. I charge my batteries with an ordinary regulated power supply (2 - 20V up to 2A).



I sell these things. Deltran Battery Tender 12v. $39. Tell me CPF and you get free ship. It knows when to stop, when to start, when to float. If you plug it into the battery and you get red blinky light, that means your battery or charger are screwed.

Great stuff, almost zero effort. The best I've found/tested yet. I've been maintaining antique vehicles with the 12v and 6v versions for well over a decade.

The only time I've ever burst/boiled a battery was accidentally hooking a 12v charger to a 6v system. (Yes, I have both.)


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## Mr Floppy (Jul 12, 2015)

XploD said:


> In that shop, I can get a few manufacturers: Fiamm, Multipower, Focus, Emos. Is any of them trustable or quality? The dead one is Multipower, and that older one is Fiamm. Fiamm is more expensive.



Wow, I have never heard of any of them but I am guessing that SLA battery makers vary from country to country. Guess with the weight it is not worth the shipping


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## more_vampires (Jul 12, 2015)

Mr F, when you fill any lead acid battery of any stripe, "the clock starts ticking."

Computer chipped smart chargers expand the life time before you're throwing down money for another one. It pays for itself. Big time!

Country to country? Try shop to shop! Mine is legit and I rotate the SLA cells and never let an old one sit around. As I buy straight from a manufacturer, trust me.... you have no idea how long they have been on the shelf.

If a filled battery (SLA) is on the shelf, it's anyone's guess how long it will last. An old fashioned battery (unfilled) has a far, far, far better shelf life and will (normally) work as expected once filled.

It's my primary beef with prefilled SLA. You simply don't know how long the clock has been ticking.


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## SemiMan (Jul 12, 2015)

Most quality mfrs stamp the mfr date on the battery when made.


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## Kouryu (Jul 12, 2015)

All batteries self discharge, just the matter of how much in a given time... for any kind of lead acid battery, long term self discharge causes the cells to sulfate... given time, this effect is permanent and considered "damage"... to prevent this, you need to have a float (not trickle!) charger... temporary battery sulfation can be reversed with a good pulsing charger, such as ctek, battery tender, accumate

I've kept my weekend hot rod on a ctek charger for years, and the very old battery still works very good, like it hasn't really aged
If you don't do this, even with the battery disconnected, you'll kill the battery within months!

For these very reasons, this is why I've kept my unused UPS's plugged in, so that their charges are maintained... I also have spare alarm batteries (got them free) I have to keep on a float charger, otherwise they become boat anchors!


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## wrcsixeight (Jul 13, 2015)

The chargers in these jumperpacks/included with are simple wall wart single voltage power supplies. Usually 13.6 to 13.8 volts and they max out at 1.5 amps or so.

They are very poor at actually full charging a battery, especially one which has been mistreated by being stored in a discharged state.

Any automatic charger that sees a battery depleted below 10.5 volts, which is considered completely dead for a 12v battery, will not attempt to charge the battery. To trick an Automatic charger into charging it, one must hook the charger to a known good 12v battery, and parallel the sub 10.5 volt battery to the good battery. After some time the charger can be removed from the better battery and all the amperage will now flow into the bad battery.

AGM batteries enjoy higher charging currents than wet/flooded batteries. The Asian AGMs that are so popular in these jumper packs typically have a 30% maximum recharge rate, but still benefit from rates upto 30%. 30 amps for a 100AH battery.

The included charger with a jumper pack is more like a 5% rate, if that, and if one actually tests the wall warts power output it usually is not even close to the specs listed on it, and when applied to a depleted battery, which should max out the power supply, it maxes out at less than the rating stamped onto the charger or in its sticker.

Junk.

Trying to revive a battery slowly depleted below 10.5 volts is usually a fools errand, but sometimes it does seem to respond, and usually it responds to higher recharge rates which actually cause the battery to heat up. Do not let it exceed 120F. If one can hold voltages in the mid 15's and keep temps below 120F this stands the best chance of returning the battery to some function.

It is quite simple to open up these jumper packs and replace the battery with another AGM. An 18 AH Asian AGM can be had for as little as 35$ or so online with free shipping.

These asian AGMs do not have the super low self discharge rates of high quality AGMS like Odyssey, Lifeline and Northstar.

One need not worry about a concrete floor discharging a flooded battery, however the concrete floor can increase acid stratification as it is generally cooler and the more dense acid sinks to the bottom and eats the plates faster.

My recommendations with these jumper packs is to not use the provided wall wart charger, Use an automatic charger capable of bringing the battery to 14.5 to 14.9 volts at a 20 to 30% charge rate in relation to the amp hour capacity measured at the 20 hour rate. Hold Absorption voltage of 14,5 to 14.9 volts for 2 to 4 hours or until amperage required to hold absorption voltage decreases to 0.5% of battery capacity, or 0.5 amps for a 100 AH battery.

Recharge monthly if unused, and recharge ASAP after use.

One can leave the jumper cables hooked to the Idling engine battery and return some charge to the battery, but this can easily exceed the 30% rate these batteries generally say not to exceed, so Do not do it for long.

Temperature has a huge effect on correct charging voltages. All recommended charging voltages are for 77F battery temperature. Increase voltages for lower temps and reduce them at higher temps.

No product recommendations from me. I use an adjustable voltage power supply for charging my Lead acid batteries, and it can provide upto 40 amps. I keep a current meter on it, and when I fire it up on a battery which is warm from an 'automatic charger' I find the battery is usually only about 90% charged and I can shoehorn in much more juice before amps drop to acceptable levels at absorption voltage, or on a flooded battery, before Specific gravity maxes out in the 1.275 range.

I release flatulence in the general direction of Automatic chargers. Their blinking green full charge indicator lights are simple liars. Soothing liars whose soothed owners have complete and utter chest pounding confidence in. Those chargers with float stages can eventually get a battery to full charge if left plugged in long enough, but when they first flash the full charge light and drop to float voltage, they are wrong.

If you do not have an Ammeter on an AGM battery or do not use a Hydrometer on a flooded battery, you simply do not know if the battery is indeed fully charged.

Voltage can be extremely misleading. I've had a battery hold 12.86 volts for a week and measure 1.225 specific gravity, which is very poor. 3 hours held at 14.5v on this battery pushed Sg back upto 1.280, and a week later the rested voltage still read 12.86.


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## WarRaven (Jul 13, 2015)

Great information thank you.

Always a good thing for refresher.

All of my rides, are powered by AGM, cylindrical and flat styles.
Tough and robust, loves high soc, perfect for old GMs.

I've yet to see a broken plate in a AGM and leave a guy stranded.

Again thanks.

Ooh, manual chargers to the end for me on LA.
Use it or lose it.


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## SemiMan (Jul 13, 2015)

In cars at least, in warm climates, AGM batteries are somewhat of a waste of money. Rapid degradation at high temps is likely to kill them before any benefit of AGM come into play. Lower cost long life flooded are better value.


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