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Posted on 08/21/2012 8:52:53 AM PDT by djf
I have a flashlight that takes the tallish 6V alkaline batteries, the ones that are 3inX3inX6in or so.
The light started getting dimmer, so I got curiour - always a bad move!
I have 2 spare batteries, but they are totally fresh and I prefer to keep them that way so that if I need them during winter storms or whatever they are there.
So! I did some Googling and came up with basically tons of conflicting info about whether or not they can be re-charge, it amounted to about zero help.
I took my auto battery charger. This can operate at either 12V or 6V, set up the whole mess outside, and hooked it up. I NEVER left it hooked up for more than ten minutes at a time.
Put the battery in the flashlight and VOILA!! it was full brightness as if the battery was new. Now I left the light on and after a while, (1/2 hour or so), it pretty much started to dim.
I tried it again, but for a shorter period, and instead of leaving it on longer, I figured repeated cycles of charge would bring it back at least as much as the first time.
The battery so far has not leaked or exploded or ever gotten hot to the touch, an I'm curious if any other FReepers have had experience with recharging alkaline cells and have any hints or tips.
One thing I know is to NEVER try to recharge a completely dead croaked battery.
TIA!
Not true.
Common batteries CAN be recharged.
My father bought a cheap charger for flashlight batteries back in the 1960s at Rinks.I still have it.Simple and works.It has a current limiter in the form of a small light bulb and a diode to rectify the AC so the batteries “see” a pulsating DC current .It works on flashlight cells and 9v batteries. Ordinary carbon-zinc flashlight batteries could/can be recharged about a dozen times.The important thing is to not run them completely dead and the battery should not get hot.If it gets hot it also means the liquid inside will boil out and the battery will fail.
Excessive charging current will heat a battery and can then cause it to rupture.
Fast charges kill batteries;a battery that receives its charge over 16 hours and gets barely warm to touch will last many times longer than one cooked in a 15 minute charger.
As for what “they” tell you not to do,the reason is as likely to be their concerns about lawsuits and selling more product.
I have lots of chargers.Pick them up at yard sales for cheap.I had the same GE nicads in a 2-way radio for 10 years.Many people can’t seem to discipline their battery use and keep batteries sorted.They would rather buy new and throw away.Of course our whole CONSUMER society is based on constantly replacing usable goods .
Several years ago when the alkaline rechargeable batteries came out they were rechargeable only in special recharger’s. The recharger’s were intermittent chargers. They would shoot a little voltage into the battery and then stop and then do it again and again. They would read the voltage and temperature of the battery as they charged. It used to be a popular science to charge them but now with the advent of all the special rechargeable batteries that really do work most people have ignored recharging alkaline batteries. I still have a charger that has an alkaline setting.
Not worth the hassle to attempt recharging one IMHO; 6V latern batteries only cost about $6 new on Amazon or less than $10 if you want to buy one at a brick and mortar store like Walmart or Home Depot.
“Ok, so I have the auto-battery charger hooked up and charging. Now what?”
I’m telling on you! Where do you live? You, you, you auto battery charger using non-conformist, you!
LOL! Exactly.
“Look, I’m running with scissors!”
This one does 6 Amps at 6V. That’s why I have always watched it closely and never left it on for long.
But the way the auto chargers work is as the battery charges, the amps drop. So if you hooked the leads up to a completely dead battery with infinite resistance, it would read as fully charged on the charger and no current would flow.
Zinc-carbon batteries are rechargeable but alkalines are tricky because of the risks described in this thread.
We did too. I think my dad got his charger at a hardware store.
Many hobby shops sell high-capacity D cells (~6AH). Open up the dead battery, replace the cells and you’re good for at least 1,000 charge cycles. As a bonus the capacity will be at least double what you’d get from fresh alkalines.
“I know as a kid in the 70s, we recharged in a regular battery charger all kinds of batteries”
Same here. It was the only way to get any life out of those old dry-cell batteries.
The reason is that the chemical reaction is not 100% reversible; when charging some of the electrolyte is broken down into gases that can cause the casing to burst. At low charging current the casing will swell and leak but at higher levels it can explode.
Those LED flashlights when they first came out, something about their spectrum really, really bugged my eyes.
But they have gotten alot better lately, at least as far as how they are on the eyes.
"After your nap you will be fresh and awake and should be able to locate your fire extinguisher quickly.."
THANKS SO MUCH
You get the "chukle of the day award".
I remember those, the only advantages they had wers that they could hold a charge for more than a year and had a higher capacity than NiCds. The downside was that they were only good for ~100 cycles. Those advantages were wiped out first by NiMH cells with more than double the capacity and more recently with the advent of NiMH batteries that hold a charge for more than a year.
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