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FREE Li-Ion Battery for your transceivers

It becomes very easy to recover junk batteries coming from dead laptop  computer or considered as dead by their owner .Very often these batteries are not completely junked  component and some elements can be recovered to power  the various electric devices you own like VHF transceiver , audio preamplifier ..... The first thing is to check whether the battery is ok  , dead or in between .You will  have to locate the + and minus terminal using a voltmeter ..

various lap top battery

Sometimes this is not an easy task as the  battery as a more or less sophisticated protection system  to prevent overcharging the battery .If you are not able to locate the output pins the only way is to open the battery  using a cutter And remove the regulator system which is tied to the parent computer .with various gold contactsvarious regulators

When this is done is becomes easy to located the various lead  and to check each battery to determine  the ones which can be recovered..Very often only one element is out of order , the others being  good  .It is sure that   their capacity can be a little bit lower than the nominal capacity  but this is not genrally  a problem .After removing the dead element you will have to proceed to a charge at an amperage anywhere between  C/10 and C/3 (assuming the nominal capactiy written outside the battery is 4 amp.h the charging current can be between .4 amp during 10 hours or 1.3amp during 3 hours )     an opened battery

As you will see by opening of a battery the elements are both in serie and in parallel  to reach the design voltage and capacity .As an example , to get  a nominal voltage of 10.8 volt you will see that the battery has 3 packs in serie each pack made of 2 or 3 elements in parallel ..Very often a visual inspection of the external aspect is enough to find out which elements are bad .

The discharge voltage of a Li-Ion battery is far to be constant during its useful service , this is not a problem for the switching power supply of the computer which was using the battery  but this can be a different story when using it  to power you transceiver.As an example a battery with a rated voltage of 10.8 volt see its output varying from 12.0 volt at the begining going down to 9 volt at the end  as shown on the curve on the left  showing a CHARGE/DISCHARGE/CHARGE cycle  .

As you probably know some care has to be taken when charging Li-Ion battery .especially  in trying  not to overcharge the elements .A lot of information is available on the subject over the internet .
charging discharging Li-ion battery

See a full size diagram

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