[time-nuts] HP-105B Battery Replacement?

[Bob Camp]

Hi

A bigger question becomes:

Do batteries inside equipment make much sense anymore?

These days, a UPS is often a standard part of a rack in an outage prone area. Powering
the “whatever” instrument off of the same UPS as the rest of the stuff is one obvious 
answer. 

The other answer is an even older approach. Use a battery bank that is external to all 
the gear in the rack and tend it independently of each box in the rack. That way you have 
a few very large cells to worry about rather than a whole bunch scattered about. Things like
lead acid that are impractical in a piece of gear are more of an option in an independent 
battery box. A single charger / line supply makes it easier to invest in something with real
smarts in it. The advent of dirt cheap isolated switchers makes the conversion to instrument 
voltages a lot easier than it once was. Pick a common voltage like 12, 24, or 48V and run with it. 

My answer to the frequency standard battery pack question has become “don’t do it”. It makes
them a *lot* lighter weight !!!

Bob

> On Sep 15, 2016, at 12:59 PM, Brooke Clarke <brooke at pacific.net> wrote:
> 
> Hi Jeremy:
> 
> I'm currently having fun playing with various rechargeable battery related stuff  which includes Li-Ion cells.
> http://www.prc68.com/I/BatTst.shtml#Resistor
> The cells come in three configurations:
> 1. the raw flat top cell with optional tabs to allow easy soldering into a pack,
> 2. cell plus positive button cap which includes a Positive Temperature Coefficient (PTC) fuse and an over pressure vent,
> 3. fully protected, like 2, plus circuit that turns off the battery if charging and over voltage or loaded and under voltage.  On these you can feel a wire/ribbon running from positive to negative under the shrink wrap and they are slightly longer.
> These configurations are independent of the flavor of Li chemistry.
> 
> To go with any of the above you need a charger specific to the particular Li chemistry (the charging voltage is not the same) and if a pack you also need a either cells like 3 above or a protection circuit for the pack.  For optimum performance in addition a tap between each virtual cell (made of of parallel cells) so that the charge can be balanced and a charger that can do that.  This is not easy, witness the current recall of the Galaxy Note 7s phones.
> 
> I would just use modern Ni-Cad cells mainly because of the ease of charging and maintaining them and use the existing charging circuitry.
> Li chemistry has advantages for portable equipment, but not so much for rack mounted equipment.
> 
> -- 
> Have Fun,
> 
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> The lesser of evils is still evil.
> 
> -------- Original Message --------
>> Thanks, Brooke, I'll price new Ni-Cads. I wasn't thinking of lead-acid (gel
>> cells) but rather lithium rechargeable, providing I can find a type that
>> won't catch fire and will work with the 105B'scircuits.
>> 
>> Jeremy
>> 
>> 
>> On Wednesday, September 14, 2016, Brooke Clarke <brooke at pacific.net> wrote:
>> 
>>> Hi Alex:
>>> 
>>> Yes, I'm recommending Ni-Cad but NOT any acid type.
>>> 
>>> --
>>> Have Fun,
>>> 
>>> Brooke Clarke
>>> http://www.PRC68.com
>>> http://www.end2partygovernment.com/2012Issues.html
>>> The lesser of evils is still evil.
>>> 
>>> -------- Original Message --------
>>> 
>>>> Hi Brooke,
>>>> 
>>>> sorry I have to disappoint you; Ni-Cd batteries do not use any acid, they
>>>> have K-OH  kalium hidrioxid  [potassium hydroxide  for anglophone ] as
>>>> electrolyte and they are normally very air-tide, and widely used in radios.
>>>> 
>>>> 73
>>>> 
>>>> KJ6UHN
>>>> 
>>>> Alex
>>>> 
>>>> On 9/14/2016 4:45 PM, Brooke Clarke wrote:
>>>> 
>>>>> Hi Jeremy:
>>>>> 
>>>>> It's a very bad idea to put any battery with acid in an enclosure that
>>>>> has electronics since if it vents the acid will etch the PCBs.
>>>>> Guess how I learned this.  I got a great price on a Gibbs Frequency
>>>>> Standard because the oven no longer worked.
>>>>> http://prc68.com/I/office_equip.html
>>>>> 
>>>>> 
>>>>> Modern Ni-Cad batteries have much more capacity than older ones and no
>>>>> longer have a memory effect.  They are also very easy to charge, so why not
>>>>> just replace the old cells?
>>>>> 
>>>>> 
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