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This article was published after a number of people were coming in to replace bloated batteries. This situation didn't look safe and they wondered what happened.
What happened to my battery?!
 This battery has been catastrophically overcharged. We recommend unplugging the charger from the wall before unhooking the battery’s terminals. The battery may contain volatile gasses that could react badly to a spark near the battery’s vent. When a battery is charged it creates gasses that re-combine into solution; however, when the charge creates gasses faster than they can re-combine, that gas creates pressure inside the battery.
So what happened to the battery in the picture? Typically, a battery’s vents will expel any gas pressure that builds up faster than the gas can re-combine. The battery pictured above, however, collected gasses faster than the vents could remove them, allowing pressure to build up internally. Luckily for the customer, the additional safety features in the battery limited the damage to the battery only—sparing the charger and the charging environment. The malleable plastic design of this sealed lead acid battery allowed it to balloon without breaking, and an internal shorting design ceased the collection of more gasses. Furthermore, these batteries are designed with the electrolyte, an acid, to be absorbed in a glass mat, preventing the spilling of acid even in the instance of a broken casing. Our best guess is that a large 12V charger was used on this relatively small 6V battery.
How can you prevent overcharging your battery?
The most common overcharging error we see is matching a battery to a charger that is not designed for use with that battery’s capacity even if the voltage is the same. For instance, our 12 volt 3 Amp charger should not, in general, be used on 12 volt batteries that have a capacity below 10Ah. A capacity miss-match will result in a charge that may be harder on a battery than it should be, shortening the battery’s life. As batteries are used, their chemical properties degrade. They will hold less and less energy as time goes by, meaning their capacity decreases over time. If a battery degrades to a level below the range a charger was designed for, the charger may begin to overcharge that battery. In that case, the battery will wear out faster and faster each time it is charged. Of course, if a charger was designed for higher voltage batteries, hooking up a lower voltage battery will overcharge that battery.
Chargers are often engineered with built-in overcharge protection; they charge in stages, stopping or reducing the energy going into the battery when it is full. Yet there are some models that are not designed to stop charging after a battery is full which will shorten the life of the battery, sometimes severely. This will often cause customers to believe they have a defective battery rather than a defective charger and they end up overcharging battery after battery.
These instances will rarely result in the kind of swelling you see in the photo, but it will shorten the life of your battery or render the battery unusable.
So pay attention to the charger you use on a battery. Don’t use a car charger with small sealed lead acid batteries (or, in general, any batteries that use a glass mat to absorb the electrolyte). If you aren’t sure a charger is slowing down its charge after a battery is full, take the battery off the charger when it’s fully charged. A rule of thumb is to not leave a battery on a charger that you are sure will charge the battery in about 10 hours. And last, but not least, pay attention to the voltage the charger was designed for and the voltage of the battery you are charging.
A number of people have asked what is on the test bench at Zbattery.
The simple answer is 1 battery analyzer and 3 variable power supplies.
That is what is used the most. The variable power supplies charge the batteries, which can be monitored by the analyzer if needed. And the analyzer also records any discharge.
The analyzer can handle 48V, or 150W, or 40A. That's not too bad in most cases. Sometimes with very large or very small batteries, we have to either split the supply or amplify it. That makes a test less accurate, but it doesn't happen often and the result is usually close enough.
The analyzer is really the center of the test bench.
And we've found the best chargers are the variable power supplies for these reasons.
- They are accurate to a hundredth of a volt and charge almost any cell and pack.
- Variable smart chargers are limited to a range of batteries and packs and we'd need other smart chargers to do as wide a range as the power supplies do.
- We can "rig" up a charging protocol with power supplies if a pack/cell falls outside the immediate range of what they can do natively while smart chargers can only do their native range of cells/packs.
- And sometimes we want to know exactly what the charger is doing - voltage and amperage wise - which only the most expensive of variable chargers will let us do.
It's not to say we don't have smart chargers. We have them for some more common cells/packs. Also, we sometimes need to charge something faster than a variable power supply method will allow which a smart charger does.
Testing is something we love doing. One of the most popular articles is about testing AA alkaline batteries. Who doesn't want to know what the best AA alkaline battery is? Although that set of tests is getting rather old because the latest in alkaline battery technology is a little better than they show. I'll work to update that information and I'll republish the old article here as well.
If there is any question about battery testing, or if there is a specific test you haven't seen, just let me know.
Someone was nice enough to tell us what they learned from a part of the EZ Battery Reconditioning guide. Sure, the EZ Battery people got their money, but at least we can give the person that asked an honest opinion on what they bought.
One of the supplementary guides is titled "How To Revive A Dead Phone Battery", and I made sure to ask if the word Dead was in quotes. There is supposedly more information on how to recondition li-ion batteries beyond the supplement. But we'll start with the supplement.
The word Dead is not in quotes. They supposedly put it in quotes later in the document.
Wow... If I had the chutzpah to pull off publishing something like this for money I'd probably be richer in my bank account. Fortunately, I value my soul more than my bank account.
The method they propose is to "jump start" a good battery that has gone below what we call the "threshold voltage".
I'll explain what a threshold voltage is. Every cell phone has a charger in it that takes a 5V USB signal and modifies it to properly charge the li-ion battery. If the voltage of the battery goes below a certain level (the threshold voltage) the electronics in the phone will not recognize the battery and thus won't charge it. The solution COULD be to raise the voltage of the cell just a little so it reaches the threshold voltage and the phone can recognize the battery and charge it. This, again, only works if the battery is actually a good battery that happens to have a low voltage.
Please note, every smart charger has a threshold voltage regardless of chemistry the charger works with. The solution in cases like this, whether it be Lead Acid, NiCd, NiMH, or even Li-Ion is to charge the battery with what we call a "dumb" charger. A dumb charger is just a power supply that delivers a certain voltage whenever electrically possible and thus a threshold voltage is not applicable.
That power supply could be any DC power source in a certain voltage range above the threshold voltage. Even another battery of the same type that has enough charge in it to give a low battery a higher voltage would work.
So the guide says that to revive a DEAD PHONE BATTERY one should apply a straight 5VDC from a USB supply by cutting a USB cable, expose the bare leads, and touch them to the + and - of the battery in the right order.
Doing that CAN raise the voltage of a single cell li-ion battery enough for the charger to start working. Don't hold it on the battery too long, though, because the battery will be taking in the full Amperage that the USB supply will deliver. And it will take that Amperage for as long as the wires are touching the contacts - even after the battery is fully charged. And overcharging a li-ion battery is a bad idea. As far as I understand, the supplemental guide does not give a time limit, but I wouldn't want to hold those wires on there for more than a few seconds. If this trick is going to work, that's all the time it should need.
But is that the kind of dead phone battery that 99.999% of us run into? The kind of battery that is good but just happens to be below the threshold voltage of the phone? No. The dead phone batteries we encounter are ones that have been in use for a year or three and need to be charged at lunch just to make it through the day.
This EZ Battery Reconditioning trick won't work for a battery like that.
I realize the title of the guide and the supplement and all their advertising might lead you to believe that a normal dead battery that you get after using your phone for 3 years can be reconditioned. And perhaps there are other parts of the guide that go into that. But nothing about it has been told to me yet.
Perhaps people can ask me more questions about the methods in the guides and I'll keep giving my opinion on their effectiveness.
Do you have a EZ Battery Reconditioning guide? Have a question about it? Feel free to ask in the comments!
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