[GeoStL] Re: Rechargeable Batteries

  • From: Mike Lusicic <lusicic@xxxxxxxxxxxxx>
  • To: geocaching@xxxxxxxxxxxxx
  • Date: Sat, 14 Jul 2007 13:49:49 -0500

- The secret to long rechargeable battery life is the charger itself. You need one that is designed for the type of battery you are using. Not all rechargeable batteries are the same, and the voltage varies. That is why the rechargeable batteries may not last as long. They have slightly lower voltage, so for the same power output, they have to make it with more current.

Anyway, all rechargeable batteries have to have some sort of vent. It is usually a one way job. That is because when you charge a battery, it creates heat. That creates pressure inside the battery case. Too much pressure and the battery will explode. Thus they have a vent to prevent such a catastrophic event.

If the battery gets hot and does vent some gas, the gas that it is venting is actually part of the electrolyte inside the battery. You lose too much, and the battery loses capacity. The most heat is produced after the battery is done charging and you keep it on the charger. If the charger "knows" what voltage represents a full charge, it can stop charging the battery, or only feed it a tiny current to keep it from heating up. Dumb chargers, or ones made for different battery types with different fully charged voltage levels can overcharge and overheat the battery. That is when you shorten the life of the battery.

I hope this helps.

Roger Barnes wrote: 
-
My experience is that some last a year or two and some last several
years.  I did not mark my batteries so I could pair the same two
together all the time. I think that helps.  The next time I open new
ones, I will do that.  The ones that last several years have been
recharged dozens of times, even the ones that haven't lasted as long
have been recharged maybe a dozen time or more.  They charge OK, they
just don't last very long.  Anyway, I think they have been well worth
it.  Of course, YMMV.

Roger

ps - YMMV = Your Mileage May Very, in case anyone is wondering.


  
Andrew Senger wrote:

Thanks everyone for your information.  I have a couple of follow-up
questions.

Have you ever had the batteries go "dead" (i.e. won't recharge, or
won't stay charged for long)?  If so, approx how long did that take
(in recharges or months/years)?

At Sam's, I bought a recharge kit with 8 AA batteries and 4 AAA
batteries.  It was the same price as (I believe) a 32-count AA case.

Eric mentioned that he was getting about 3/4 of the time with
rechargeables, so I would need at least 5 recharges to be worth the
value.  Will the 8 batteries will last 5 times longer than a typical
AA over its life?  If so, is the charge still good after that 5th use?

Thanks again!

Andrew
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