[aprssig] NiCd Lessons relearned

Brian D Heaton ky9k-lists at ky9k.org
Sun Jul 16 23:46:43 CDT 2017


OH8STN has built a couple of different Lithium Ion packs, including a 
more recent 10Ah LiFePo4 pack. There are very good writeups on his web site.

http://oh8stn.org/blog/2017/06/08/diy-34s-li-ion-qrp-battery-pack/

This link is the full series on his off-grid portable setup -

http://oh8stn.org/blog/2017/07/05/man-portable-off-grid-power-for-amateur-radio-introduction/

Newer and better tech. Time to retire the old NiCd and NiMH portal packs.

73-KY9K/Brian

On 7/14/2017 16:17, Glenn Little WB4UIV wrote:
> Nicads are current charged.
> SLA are voltage charged.
>
> 73
> Glenn
> WB4UIV
>
> 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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>



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