Posted: 4/25/2012 10:45:30 AM EDT
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Ok, here is my entry.
While cleaning out my garage I found 2 Li-ion batteries from my old laptop. They were rated at 14.4V 3800mAh. I tore them apart and found 8 18650 Li-ion cells in each one. One thing I thought was strange was, even though the battery packs were for the same laptop and had the EXACT same model number, they had different cells in them and the circuit boards were completely different. The one with the fluorescent green cells were Panasonic CGR18650 cells, the red ones were completely unmarked. The batteries were connected parallel in pairs, then 4 pairs in series. Like this... 
They were wired parallel in pairs, then 4 pairs in series. I simply cut one pair off the end, soldered a cable to the + and - solder tabs, added an Anderson Power Pole (my first time using them and I'm in love!  ) and some 3" heat shrink tube to make the whole thing a bit less Unibomberish.
Here are the 2 battery packs finished (no pics of the creation  )
Here is one of the packs hooked to my TenTec HB-1B QRP CW transceiver. 
Unfortunately, these do NOT have any over/under-charge protection. The radio does display the voltage it is receiving so, as long as you pay attention and don't let the voltage drop below 10 or so volts, they shouldn't have any problems. The radio also came with a Li-ion charger that I put Power Poles on to charge the battery packs. As long as I don't let them get too low and only use a Li-ion charger, there shouldn't be any problems. Since I cut out 1 series pair of batteries, the capacity should still be 3800 mAh. According to TenTec, this radio draws 800mA on Tx and 60mA on Rx. Theoretically at a 10% duty cycle they should last 28ish hours (RX only ~60 hours!). I'm sure the actual capacity will be somewhat less, but I haven't measured it. I do know that since I finished these last week, I haven't had to recharge them yet. My Father-in-Law (and Elmer) also got us a pair of DCP Miniature iambic paddle kits from American Morse to use with these radios. Now I just need to work on my CW more... |
