[aprssig] backup pwr systems

VE7GDH ve7gdh at rac.ca
Sat Dec 9 13:15:17 CST 2006

Charles N5EXY wrote...

> FWIW I had two "smart" chargers (different brands)
> fail and boil two relatively new deep cycle batteries
> dry. Even the smart ones need to be monitored a bit.

What make and model were the "smart" chargers? Yes, if it isn't a 
"maintenance free" battery such as AGM or gel, you do need to keep the level 
up by topping it up with distilled water, but the levels shouldn't go down 
much unless you are deeply discharging the battery and then charging it a 
high rate all of the time. A true "3 stage charger" should charge the 
battery at the (bulk) maximum rate, and then change to a fixed voltage at a 
certain point, and then it should switch again to a lower voltage to trickle 
charge the battery for maintenance. The charger type should match the 
battery chemistry. Some batteries (flooded lead acid) should get the 
occasional equalization charge at a higher rate to shake things up. With the 
wrong charger, or one that isn't as "smart" as advertised, battery life will 
be impacted. I've actually got a large battery bank that is down in capacity 
right now. I'm playing around with a battery desulfator to see if it can 
recover some capacity.

My backup power system is to keep computers (and other things) running. Just 
to keep it on topic, it also powers a digi / IGate / IRLP node and other 
things. Disasters like Katrina show how important it is to have a backup 
power system. However, that was on such a massive scale that most backup 
power systems would be severely taxed, but having some backup capability is 
better than no capability. Most of my power outages are from wind or snow in 
winter. Most are of short duration... less than 3 hours. However, an outage 
of nearly a week is not unheard of. Here in southwest BC, we had nearly two 
weeks of high winds and heavy rain, followed by a week and a half of snow 
(OK, two days of snow, but it hung around a while) and cool temperatures 
with some lengthy outages for some areas. Each individual should decide how 
much of a "backup power system" they need and go from there. Some will opt 
for none. Others will have a 60-100 Ah battery and a smart charger and 
connect it when needed. Others will go for a lot more capacity and automatic 
changeover. Some will have solar power and/or generator backup as well. 
There are lots of options to choose from. Looking at it from the APRS 
perspective, keeping digis and IGates running during power failures could 
really make the difference between having no communications and some 
communications. Of course, voice repeaters would certainly benefit from 
backup power capability as well, as would HF stations.

73 es cul - Keith VE7GDH
"I may be lost, but I know exactly where I am!" 

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