Sent: 12 Aug 07
Subject: Battery lesson learned the hard way.

From time to time measure the current flow with everything turned off for the 12 volt battery supply at your survival site.   Things can creep into use that draw power even when turned off.   We recently found that a 12 volt TV will use about 1 watt (.08amp) all the time, even when off.  This is the sensor circuit that is constantly listening to the wireless remote.  If you purchase any 12 Volt items with infrared remotes it will draw current while turned off.  Avoid this.  Measuring the current flow with everything turned off once in a while will point out the power wasters for you.  

A simple low cost amp meter can be made from a $3 digital voltmeter item 90899 from http://www.harborfreight.com/ and alligator clips a given distance (see below) apart clipped onto your existing 12 volt feed wire.  See: “How to Make High Amperage DC Current Meter” sent in May 7, 07.
 http://home1.gte.net/ob/Make_Your_Own_DC-Current_Shunt_Meter.pdf
It shows that input wire with following sizes can be used
AWG
Gauge   Inches of wire with clip at each end measuring voltage
 2         76.7
 4         48.3
 6         30.3
 8         19.1
10         12.0
12          7.5
The electricity passes through this feed wire to your site from the batteries. Larger wires are noted in the report. 



