NiCad's are bad news..  They are extremely toxic, and nasty.
I would not use them,   Have a look at
https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery
much better option.

Lachlan



On Thu, May 19, 2016 at 10:38 AM, William Hermans <[email protected]> wrote:

> Oh and for those worried about the LiPO chemistry . . .
> http://www.all-battery.com/15pcsnicdsubc2200mahrechargeablebatteryflattop-90626.aspx?utm_source=GoogleShopping&utm_medium=GDF&gdftrk=gdfV26767_a_7c354_a_7c922_a_7c90626&gclid=CJuytLPW5swCFYaTfgod0bgHeg
>
> Problem is, you need three, maybe four of these. But cost would be ~$6-$8.
> Additionally 2200mah is a bit much if all you're going ot do is shutdown
> right away. So perhaps the AA cell equivelent, and those would cost less.
> SubC is the cell type typically used in cordless drill packs . . .
>
> On Thu, May 19, 2016 at 10:28 AM, Lachlan Audas <[email protected]> wrote:
>
>> It may not be out door's.. the electronics/computer's may be inside near
>> a heat source,
>> I having seen electronics covered up by the end user's many times. (how
>> many routers have you seen under
>> a pile of books..  clothing ? ..etc ) then there is fan's breaking,  air
>> ventilation hole's fill with dust, cat hair etc.
>> it's not just out door's  which may provide and nasty environment.
>> The second problem is super cap's have high internal resistance, which
>> limit's how much current you can pull
>> from them.  Problem there is problem is how much of the capacity of the
>> super cap are you using ?
>> a 5V super cap backing up power to a 5v to 3.3v  switching reg,  or liner
>> reg may only give you 4.3 volts before
>> the reg start's dropping the 3.3v power rail.   So there may be only 0.7V
>> of the super capacity you are using.
>> And to get around that, you need a SEPIC switching reg, and of course
>> your drawing big currents once you start drooping to 1 or 2 volts of the
>> super cap.  So the cost of having a Electro  running at 40 or 50V,  where
>> you will
>> get almost all of it's capacity is not a bad trade off, when you see that
>> you will have even bigger problem with supper caps and extracting there
>> full capacity.   And you will be switch much higher currents to get your
>> 3.3V's from it.
>>
>> Lachlan
>>
>>
>> On Thu, May 19, 2016 at 8:33 AM, Super Twang <[email protected]>
>> wrote:
>>
>>> @Lachlan
>>> Thanks for the info Lachlan.
>>>
>>> Re: Supercap reliability…
>>> My basic understanding is that if you design with supercaps for a
>>> “Everyday” (ie not too hardcore) indoor use case, and keep them within some
>>> pretty obtainable operating conditions they effectively last forever.
>>> Obviously there’s some ambiguity (“everyday” “pretty obtainable”,
>>> “effectively”) in the prior assertion, but...
>>>
>>> My particular use case — indoor temps but in a wall, 5v power — might
>>> see a temp range of 15° - 35°C max I’d guess.  The 70°C - 105°C you’re
>>> talking about would have to be a pretty harsh/industrial environment, no?
>>>
>>> Does anyone (who has done it, or knows how) have a sense of how
>>> straightforward it is to achieve a supercap-based system design that keeps
>>> the components in a range that’d keep them healthy for “Effectively
>>> forever?”  ie 20k+ cycles? (better than bats) 100k+? (effectively forever)
>>> Or, do the requirements we’re looking at for a basic, indoor, power system
>>> really push the supercaps into the “Quickly-used-up” zone?
>>>
>>> Best,
>>> ST
>>>
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