[aprssig] NiCd Lessons relearned

Glenn Little WB4UIV glennmaillist at bellsouth.net
Fri Jul 14 18:17:40 CDT 2017

Nicads are current charged.
SLA are voltage charged.


On 7/14/2017 5:06 PM, Robert Bruninga wrote:
> Lesson relearned on NiCd charging:  Several years ago I made three 12v 
> batteries from D cell NiCd’s.
> They have been a huge disappointment.  They are only used once or twice 
> a year on critical field work and always fail far earlier than 
> estimates.  But I always just charge them the night before with a fixed 
> voltage charge of 14 volts since I most often forget about batteries I 
> put on charge and end up ruining most of them.  Charging at fixed 
> voltage is safe…
> For the AT Golden Packet event tomorrow, last night I left them on my 
> usual 14 volt overnight charge and they were “fully charged” by morning, 
> only drawing a 50 mAh each in the morning at 14 volts..
> Put them on a battery analyzer and their capacities came in at 10%, 8% 
> and 3%.  Then the battery analyzer quick charged them at 1C rate for 1 
> hour with them getting up to 16 or 18 volts, then a 4 hour equalization 
> charge of 0.1C or 400 mA.
> Then it retested them and got 75%, 65% and 85% of rated capacity!
> So, Apparently little-used NiCd’s are not going to get a good charge 
> from a FIXED voltage charge!
> Wish I had time to cycle them two more times.  On batteries at work we 
> see huge recoveries from little used NiCd’s when “rejuvenated” which is 
> the 3 cycles of charge and discharge I started with above.
> Bob
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Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv at arrl.net    AMSAT LM 2178
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

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