[time-nuts] UPS for my time rack

Mark Spencer mark at alignedsolutions.com
Sun Oct 11 16:22:07 EDT 2015

I'm fortunate that several of pieces of my time nuts gear (including two of my ocxo's) feature backup 24 volt dc power inputs.   They were the only things in my house that stayed running during a recent 2 day power outage while I was away.

I have two large 12 volt gel cells in series that I re charge from time to time with a power supply via a blocking diode.

I agree about the importance of the fusing.  I've also found it's easy to buy fuses rated to work on 12 and 24 volt dc systems, fuses for 48 volt and higher dc systems are harder to find.

I also bolt the fuses directly to the battery terminals.

Sent from my iPhone

> On Oct 10, 2015, at 9:31 AM, Alex Pummer <alex at pcscons.com> wrote:
> for a very similar application I am using a solar panel to charge the battery, but I have a vented NiFe battery, which is not sensitive of over charging or deep discharging, and has almost unlimited life time -- I have seen some in forklifts which were 60 years old and working...
> 73
> Alex
>> On 10/10/2015 7:14 AM, Poul-Henning Kamp wrote:
>> --------
>> In message <1444483218108.6a07c91c at Nodemailer>, "Chris Waldrup" writes:
>>> Has anyone had bad experience noise wise with the APC brand units
>>> like are available on Amazon and at Staples? I'd like to get one
>>> that doesn't generate lots of RFI. Thank you.
>> Then don't.
>> Instead get 12 or 24 Volt sealed lead-acid batteries and a good
>> float-charger, and run your stuff from that.
>> You avoid a lot of conversion losses, and you get to decide what
>> quality batteries you want (As opposed to "the cheapest we can get
>> away with") and you get to decide how long hold-up time you want.
>> The important tricks are:
>>   1. ATO Fuse *RIGHT NEXT TO THE BATTERY*.  Not a meter away, but
>>      quite literally bolted right onto the terminal.
>>   2. Don't buy a shit charger, it will cost you battery life.
>>   3. Suitably sized fuse/polyfuses on all loads.
>>   4. Either put 0.010 Ohm current shunts in all over the place
>>      or buy a 1mA resolution clamp meter and prepare the wiring
>>      for measurement.
>> And that's it really...
>> I run all the always-on stuff in my lab from two 12V/105Ah telco-grade
>> sealed lead-acid batteries, and I'll never look back.
>> Presenty the load is 6.7A @ 24V, and that powers my ADSL lines,
>> firewalls (soekris), home server (ITX with mini-box.com PSU),
>> emergency lights (LED strips), GPS, GPSDO, HP5065 etc. etc.
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