Wednesday, October 22, 2014

DIY: RV Alternate Power Souces Including Generators and Solar

We hope to create a live discussion on the different sources of power for your RV/Trailer/Boat, or "off grid" living.

Offered initially to get the discussion going is a simplified block diagram.  This shows the following power sources:

Generator source 110V AC
Shore/RV Park/Commercial Power source 110V AC
Solar Collector source Unregulated DC
Vehicle source 12V DC
Wind/Water Turbine source (are other options not shown)

The diagram also shows the placement of components to produce usable regulated 110V AC, as well as regulated 12V DC.  Some of the components are:

Transfer Switches (Can be manual or automated)
110V AC to 12V DC Converter+Charger
Battery Isolators
Solar Panel Combiner
Solar Controllers
Power Distribution and fuses/breakers
12V DC to 110V AC Inverter 

The rule of thumb in calculating solar requirements is "one 80 Watt panel and one 105 AH rated (or better) battery per person".  This compensates for fact the panels do not always operate at 100% of their rating.  This is overkill for minimalists or frugal power users, but will also be under the requirements of others that have more requirements.  Remember you can only take as much out of a battery, that has been stored into it.

Many devices consume your power.  Propane and CO2 detectors as well as electronic devices, even though turned off, have circuitry still working and consuming power to provide "instant on" or to hold memory.

Follow this link to My First Venture into Solar.  We hope to show project steps of design, ordering, layout, mounting, and bringing a small system into operation.


Another option for about $100 is to use one of the portable jump start units that are starting to show up on the market.  Some now have built in 110V AC inverters.


I used and tested a Schumacher XP2260 portable jump start unit. It has a built in 110V AC Inverter rated at 600watts/1200watt peak surge. It also has a couple 12V DC connectors and a couple USB Charging ports. In addition it has a compressor, emergency LED white light, and digital monitoring of the power.  Not to mention its main purpose of being able to jump start a vehicle (If the charge is full)

The XP2260 is rated at 22 AH (Amp hours) which is about one forth the rule of thumb for a 80 watt solar panel and one battery solar set up. While this device can't power a microwave it can do many other things. I recently ran my laptop playing a DVD. It played the whole movie. The meter said I had 54% of a charge left. I am not sure it was fully charged when I started so more testing is needed. This device easily charges off a 400Watt inverter I have plugged into the cigarette lighter of my tow vehicle while I am driving. I am thinking this XP2260 could probably power a DVD and a newer Flat screen TV (they use less power) through at least one movie. I am planning on testing this theory out on one of my next outings in which I am unable to sit around a campfire. 

Please note:  We do not believe the Inverter is a pure sine type.  It may burn up sensitive electronics.  Proceed with use at your own risk.

Another fun test on the XP2260 would be to connect a solar panel and controller that outputs 12V DC to the input of an inverter, say a cheap 400 Watt type.  That also would require a battery in between the solar controller and the inverter input for best results.  Then plug the XP2260 into the inverter 110V AC output to charge the XP2260.   You then have portable power to use through the night to charge up digital devices via its USB ports, use the 12V sockets to power those types of devices, and with the built in 400 Watt inverter also have 110V AC for lower load type household devices.  

TESTING OF THE XP2269   10/24/14 

We performed a Test of the XP2260 in powering a 110V AC TV, and a 110V AC DVD player.  The XP2260 was fully charged (13.6 Volts) just prior to commencing with the test.  We wanted to prove the XP2260 would power both devices that are normal household voltage (110V AC).  The XP2260 was used in the “Inverter” mode and not connected to any other power source during testing.  We took the ratings off the sticker on the back of both the TV and the DVD player.

32 inch Flat Screen rated at           1 AMP  (Note 1:We fried this TV the third time out)
Blue Ray DVD Player rated at         3 AMP
Total Calculated AMPs per hours     4 AMP

Estimate length of Play time         3 hours

We ran the TV and DVD continuously to watch a movie for 3 hours.  We found an Actual AMP meter fluctuated between 2.8 and 3.4 AMPs during play.  Our findings are the actual AMP hours used, was more like an average of 3 AMPs per hour.  Not at the sticker rated values that indicated it would be 4 AMPs per hour.   We were pleased with that fact.  

We further calculate the numbers for the 3 hours of play time

Calculated AMP usage for 3 hours X 4 AMPs = 12 AMPs
Actual AMP usage for 3 hours X 3 AMPS       =   9 AMPS

After disconnecting all load devices from the XP2260 at the end of the 3 hour movie play, the XP2260 meter indicated there was still an 80% charge. The fully charged voltage of 13.6 volts was now down to 12.5 volts. Since the XP2260 is rated at a maximum storage of 22 AMPs, we were surprised the reading wasn’t closer to 50%.  It is quite possible the depletion rate when using the built in inverter, under load, accelerates faster toward the end of discharge?   We plan further testing on a longer duration to provide those results as well.

The conclusion of the test we set out to satisfy is this.  The XP2260 is quite capable of providing enough stored energy to power both the TV and DVD we used, play for 3 hours, and have plenty of power left over.

XP2260 our 3rd camping trip out.  We suspect the Inverter is not pure sine.  This TV did not have a transformer built into its cord to drop or convert the AC Volt and act as a filter.   We suspect the TV's internal power supply was damaged.  Our laptop does have a transformer/power supply as part of the cord and has never shown any trouble.


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