[aprssig] NiCd Lessons relearned

Scott Miller scott at opentrac.org
Fri Jul 14 17:33:33 CDT 2017


Lithium ion is hard to beat for rechargeable tools.  We've switched to 
Milwaukee M12 tools in the shop and they've been great.  I think NiCd 
can manage higher currents easier, but the self-discharge rate is 
ridiculous.

I use non-rechargeable lithium metal batteries for anything I'm going to 
keep packed away for an emergency.  They'll last 20 years on the shelf 
and won't leak, and they last 3x as long as alkalines. I don't use 
anything else in flashlights anymore.

Scott
N1VG

On 7/14/2017 3:16 PM, Michael Barnes wrote:
> I have experienced so much grief from NiCd batteries over the years, I 
> will never use them again if I can help it. I got a real nice screw 
> gun a couple years ago for Christmas that has NiCd batteries. Every 
> time I go to use it, the batteries are dead and I have to wait a 
> couple hours to charge one. I have a small electric screwdriver with 
> lithium batteries that was in storage for almost a year. When I 
> unpacked it, I used it heavily for a week before I had to charge it. 
> It held its charge all that time in storage. When I can, I'm going to 
> have my remaining NiCd packs converted to lithium cells.
>
> Michael WA7SKG
>
>
> On Jul 14, 2017 16:14, "Robert Bruninga" <bruninga at usna.edu 
> <mailto:bruninga at usna.edu>> 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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