Sunday, September 15, 2013

"Yeah, but how do you....?"

I got a question from a reader that came in probably because I didn't do a good job of explaining the Tank's solar power setup in my most recent blog post.  The reader asked if I hooked my cell phone up to my solar panels to charge it when I'm boon docking.

The Tank's hard working solar panels.

The easiest way to conceptualize the Tank's solar setup is to think of the house battery as a "sun dollar" bank account.  The difference between the battery and your bank account is that the battery can only hold 100 sun dollars max. (I hope your bank account has more!)

Battery and solar controller (silver thing) from above.
The two solar panels on the roof of the Tank "deposit" sun dollars into the battery until the battery gets to 100 (percent capacity) then the silver solar controller in the picture above cuts the circuit from the panels to the battery to prevent overcharging the battery, which could boil off all the liquid in the battery and ruin it.  One other thing the solar controller does is to convert the 18 volt DC current that comes our of the solar panels down to about 14.5 volts DC.  The battery is a deep cycle 12 volt DC battery but you need more than 12 volts DC to charge a 12 volt DC battery thus the need for conversion to 14.5 volt current by the solar controller.  From the battery going into the Tank the voltage is now 12 volts (out of the battery) and the next point of concern is how do you run 120 volt AC appliances (like your cell phone charger) off 12 volt DC power?  The answer is a device called an inverter.  The inverter converts 12 volt DC power to 120 volt AC power like you're used to in your house.

The Tank's inverter.  Note it can plug into a cigarette outlet in a vehicle.
On the left end of the inverter pictured above is a normal three pronged outlet that devices can plug into.  When you plug into the inverter sun dollar "withdrawals" are taken from the battery bank account and it dips below 100 based upon the electric current the appliance plugged in draws.

With-drawers: LCD TV, laptop, tablet, phone, music player.....
The silver solar controller constantly monitors the charge in the battery and when it dips below 100 the solar controller reestablishes the circuit to the solar panels and new "deposits" of sun dollars go into the battery until it gets back up to 100 again.  This process continues throughout the day with no owner (me) oversight whatsoever required which is very cool!

So, yes, I charge my cell phone with solar energy sun dollars from the solar panels but there are a few additional steps involved.

Thanks for reading!