[reasoner@dimensional.com: d7 power source]

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From: Doug Faunt N6TQS +1-510-655-8604 (faunt@netcom.com)
Date: Sun Dec 31 1995 - 02:31:17 EST


This was posted on another mailing list, but the batteries sound
interesting for portable QRP operation.

73, doug

To: dat-heads@fedney.near.net
From: Marc Reasoner <reasoner@dimensional.com>
Subject: d7 power source
Date: Sat, 30 Dec 1995 11:01:33 -0700 (MST)

<text deleted>

then came my "discovery" of sony's 7.2v, 1350mah lithium-ion pack, the
np-500h (later replaced by the np-520h). sony sells it for use in their
palm-sized camcorders. i bought one on a lark for $50 and have
not used anything since. this pack is about the size and weight of a
large pack of gum, and powers the d7 for about 6 hours or
recording. i use a 9v 500mah wall cube to charge it and, at first, was
concerned about the overcharging properties of li-ion... they get very hot
and can melt things around it (or explode!) not a very nice thing.
this is what happened in the now infamous apple powerbook li-ion fiasco.
well, no worries...sony designed into these little gems
some recharging "intelligence" (my guess is a couple
resistors, caps, and op amps) to avoid overcharging. the bottom line is
they are *wonderful*. i will never again use another nicad or lead-acid
(gelcel). the li-ion's don't have any of the so-called "memory effects"
(often misunderstood in nicads), they don't get hot when draining
heavy loads (unlike nicads), they are extremely small and light weight
(unlike nicads and gelcels), and they are very easy to
charge. please note that i am not refering to the lithium cylinder batteries
such as the aa-size lithiums that everyready makes. i would strongly advise
not even experimenting with recharging these. i'm refering only to the sony
np-500h and np-520h li-ion packs. i've built 2 for myself and 2 for friends.
for around $65 ($50 for the pack, $2 for the power cord, $10 for a good
9v wallcube, and $3 for some molex-style power connectors), you've got
the best on the market (imho, of course). it's interesting to note that
aiwa's new portable dat uses a li-ion pack, probably very similar to
the one i've describled. btw, most sony outlet stores carry these packs.

a couple cautionary words (of course ;^) the solder points on the battery
packs are recessed metal holes surrounded by the plastic battery
housing. *please* be very careful when soldering to these points.
if you're not comfortable with soldering, have someone else do it
who is, and wear eye protection. also, these are 7.2v packs, so you
denon owners might want to investigate further. but like i said,
i've built 4 of these babies and haven't had a single problem or worry
in at least 1000 hours of use, but your mileage may vary. i also use 'em to
power other portable products, including cd players and vistalite
10 watt bicycle lighting systems! sorry for the lengthy post, but
within a couple of years, rechargable li-ion is gonna be a significant
portable power source, so ya might as well jump on the bandwagon a
little sooner ;^)

regards,
marc. (please note my new email address)

-- 
marc reasoner                       <reasoner@dimensional.com>


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