[time-nuts] HP 5065A battery pack

Bob Camp kb8tq at n1k.org
Sat Nov 21 21:20:40 EST 2015


If you are running inside a facility with backup power, the couple of seconds between lights out
and generators on is something that does need to be handled. If the frequency standard cruises 
through the event, it’s probably ok for the rest of the gear here and there to restart. Waiting for another
hour or three while a standard gets running again is what you want to avoid. 

In that sort of situation, a 10 minute run time is way more than you likely will need. 


> On Nov 21, 2015, at 4:49 PM, Dan Rae <danrae at verizon.net> wrote:
> On 11/21/2015 6:13 AM, Bob Camp wrote:
>> Hi
>> The key issue is that there has been a lot learned about charging batteries
>> since the 5065A was designed. Just as other parts of the 5065 can be improved
>> with some work, so can the battery charger. Given that NiCad’s aren’t cheap,
>> it’s worth noting that the circuit could be worked on *before* somebody buys
>> a bunch of batteries to re-cell one.
>> Moving a bit further off topic and back to our original conversation when you re-did
>> yours (2 years ago?) - you don’t get a lot of standby time even with the full load of
>> NiCads in there.
> Bob, I stopped writing dates on the chart thing inside the pull down cover in August 2004 since the numbers had not changed significantly since 2002 (and still haven't) which in fact must have been when I did the battery.  Time flies... A bit more than my guess of 5 years!   It got a check recently when we had an outage that lasted for a good twenty minutes and the green light stayed lit.  -hp- spec is for more than ten minutes.
> And incidentally the schematic shows the battery as 25.2 Volts which might indicate 21 cells, although I'm sure it would work with 20 and maybe there have been early versions that did have 20; mine is late, the last but one serial prefix.
> It's certainly possible that the circuit might be improved but it does seem to perform as advertised as is.  For extended periods than there is always the DC input as has been pointed out.  I suspect this option was more for moving the thing from one lab to another adjacent rather that flying clock trips or mountain climbing :^)
> Dan
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