Thursday, September 29, 2011

What is left to save?

Here is an example. The power we are trying to save is the amps along the green line. During the day the system is consuming an average 4 amps. The higher spikes is the oil heater making hot water. If the system was turned off during idle periods, we could be conserving amp hours to stretch into our third day.

Additional note:

4 amps? This isn't 4 amps at 120V but 24V. Our phantom load is 96W or less than 1 amp at 120V (roughly 0.8 amps at 120V). So, at idle times we have a 100W light bulb on all the time. If we shut the house down, the inverter will consume much less.

Tuesday, September 27, 2011

Fall/Winter 2011 Project: More Power System Automation

We are still looking for ways to save energy and money on running the house, primarily during the winter. We are looking at a design that will potentially expand the same battery bank to last for 3 days instead of 2 days. Many of the parts have already been purchased. The one piece I could not find in Fairbanks is a torque wrench that can reasonably show me a torque of 3 1/2 newton meters. The standard torque wrenches from a auto supply store are factors much higher than that.

Why 3 1/2 newton meters (approximately 2+ foot pounds)? That is what is suggested by the inverter manufacturer when tightening the lug nuts for the connection. Higher pressure and you risk breaking the lugs (and voiding the warranty).