[ARC5] adventures in battery ops

[Bill Cromwell]

Hi,

I have been running my command receivers on pure DC battery power. For 
the heater strings I have been running a pair of '12 volt' gel cells - 
7.5 A-H - in series to give me the required voltage. I periodically 
measure the terminal voltages and a couple of days ago I thought I was 
getting close to needing a charge cycle. This morning I went in to turn 
the radio on (BC-455) to play with it a little more and it wouldn't come 
up. I shut everything down and applied the voltmeter again. One battery 
was dead! That is not good. The remaining battery can force the weaker 
one into reverse. The battery in question seems to be okay.

This incident set me to thinking that I should rewire all my 24 volt 
heater strings to 12 volts so there won't be this possibility of a 
reversed battery. I think I would rather setup an Arduino to monitor the 
battery voltage and give me a warning when it gets to the minimum 
useable point. The same thing can happen to a single 12 volt battery 
when one cell get discharged before the rest.

By the way, using batteries has kept the crap that can be conducted into 
the radio via the power line *OUT* of my radios. That's why I initially 
tried it. I'm working to make the AC line operated power supplies 
cleaner but meanwhile the battery operation has been an eye opener. 
Besides cleaner power I can take the radios out to the park for field 
operations. Sealed lead-acid batteries on the heaters and ten 9-volt 
batteries in series for the B+. The little 9-volt batteries have 
surprised me by how long they last. I use the cheapest alkaline 
batteries I can get and I'm paying just under a dollar each in six packs.

73,

Bill  KU8H