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Rechargeable Batteries Print E-mail
Written by KZ1X   
Friday, 17 July 2015 23:08

Recently I have been involved with several side conversations with members revolving around the topic of portable rechargeable batteries.

WalMart sells a 4 pack of 600 mAh 3.2V LiFePo cells that are AA size.  $10.  Yes, WalMart.  They sell these cells as replacements for the little solar rechargeable lawn lights that stop working when the neighbor's dog pees on them.
Lithium Ferro Phosphate. Li-Fe-Po. Many people have never heard of it before. Now you are no longer one of them.
The story is, you can easily charge these inexpensive and lightweight cells to provide a quick and cheap 12V+ power source. Yes,the pack of four cells I am referencing is just 600 milliamp-hour rated.  But, you can put these four cells in a common AA holder and get 12.8V out of them for a LONG time compared to other types.

Also, hams are often about portable stuff.  It would take ELEVEN series connected NiMh cells to get a similar voltage.  Who makes an eleven cell holder?  Nobody.  And that's kind of big anyway.  And decent quality NiMh cells cost too much.  Meh.
If you get these LiFePo cells I am talking about, do NOT EVER mistake them for regular AA cells and put them in something that takes regular AA cells.  Poof.  You have been warned.

RadioShack still sells this 4 AA cell holder item, #270-391:

RadioShack® 4 “AA” Battery Holder,

or you can get similar from a variety of other places on line if you don't already have one.

You can charge this battery pack with a 13.8V current limited source, like the famous OCRA charger kits of some years back.  I still have four of those kits remaining at $8 each if you need one.  Or, just use your existing 13.8V regulated supply with a suitable series resistor.  Since you know Ohm's Law, I will let you do the math.

Here is a link to learn more about the modern battery chemistry that makes this possible:

Here is a link to the WalMart item:

Steve KZ1X

Last Updated on Wednesday, 26 August 2015 09:19