A Simple Off-the-Shelf Solar Power System and Off-Grid Power Tools, by K. in Texas

This article is written for those who have no experience with solar power and would like to set up a simple beginner system. I have been using this system for over a year and have found it to be efficient. My goal was to put together a system which is easy to use and does not require a lot of technical knowledge.

1. BatteryMinder #SCC-015 Solar Charger 12 volt with 15 watt solar panel ($150 from Northern Tool and Supply)
2. BatteryMinder #BC2410 battery clip assembly ($10 from Northern Tool and Supply)
3. Interstate Marine/RV 12 volt battery #27DC-1 ($68 from Sam’s Club)
4. Battery box for group 27 size battery ($10 from Wal-Mart)
5. Vector #VEC005 12 volt battery clips with accessory outlet ($6 from local hardware store)
6. Ryobi #P130 18 volt vehicle battery charger ($40 from Home Depot)
7. Ryobi #P824 18 volt tool starter kit with drill, circular saw, two 18 volt batteries, house current battery charger, and case ($89 from Home Depot)
8. A two or three level heavy duty shelf

Obviously, you can purchase your equipment wherever you like. If you would like to support SurvivalBlog, you can purchase the BatteryMinder solar charger and battery clip assembly from Northern Tool by starting at the “Affiliates” link on the SurvivalBlog main page, left side, third item from the top. Northern Tool also carries a number of battery powered tools. While at the blog’s the “Affiliates” page, you may also want to look at the Allbattery.com site to see what is available in the way of rechargeable batteries and chargers which may be used with this system. The aforementioned equipment reflects the exact hardware that I use, so I know it works. The prices give you an idea of what your system could cost. I have listed Ryobi brand tools because I’ve used them for a number of years and found them to work well. You could use other brands such as DeWalt, Black and Decker, etc. I suggest you purchase tools which use at least 18 volt batteries.

SETUP: Begin by reading and heeding the instructions with all of the listed equipment. Let’s start with the BatteryMinder Solar Charger (item #) and follow the instructions on setup. The instructions are four short pages on how to wire the system, position the solar panel, and how the system works. I leave my system set up 24/7 so that when sunshine is available the system is charging/maintaining the 12 volt deep cycle marine battery and even on a cloudy day some charging activity is going on. I positioned the solar panel near an exterior door of my garage so the wire from the solar panel to the charge controller can be run under the door to a three level shelf just inside the door. This way, the charge controller and the battery condition indicator are not exposed to the weather. I placed the BatteryMinder charge controller and battery condition indicator on the shelf one level above the lowest shelf.

Next, place the Interstate 12 volt marine battery (item #3) into the battery box (item #4) and place both on the bottom level of your shelves. In order to use battery clamps do not place the box top on the battery. The battery comes with two types of posts on the positive and negative sides, one post is larger, smooth sided, and designed for a battery clamp and the other post is threaded. The BatteryMinder’s battery connections are the spade style with holes, these can be fastened onto the threaded posts, remember red to positive, black to negative. Northern Tool offers an optional accessory, item #2 in the Equipment List, which replaces the spade style battery connectors with battery clamps. These make it quicker to disconnect the system from the battery. I use the battery clamps instead of the spade style connectors. I connect the clamps to the large, smooth sided posts, again, red to positive, black to negative.

At this point, you have assembled the BatteryMinder system and hooked it up to the 12 volt deep cycle marine battery. When the sun is shining the battery is being charged/maintained. Now you are ready to hook up the Vector 12 volt battery clamps with accessory outlet jack (item #5). It’s easy, just hook the Vector battery clamps to the unused post on each side of the battery, in my case, I use the threaded posts, again, red to positive, black to negative, I know, it’s getting repetitive!

Last step – place the Ryobi vehicle charger (item #6) on the shelf above the bottom shelf. It needs plenty of space for air circulation because it puts out some heat when in use. Just plug the Ryobi charger male end into the Vector accessory female outlet.

OPERATION: With the Ryobi vehicle charger hooked to the 12 volt deep cycle battery just plug an 18 volt tool battery into the vehicle charger and wait until the green light comes on. Ryobi says a cold tool battery could take about 1 hour to charge. With the 12 volt deep cycle battery at full charge, you will have no problem charging 4 to 6 tool batteries without discharging the 12 volt deep cycle battery too much. That number of fully charged batteries would be able to do more work than I care to do at one time. If you charge a number of 18 volt tool batteries at one time, be sure to use the battery condition indicator to check the 12 volt deep cycle battery. If the indicator says “Good” you are okay, but if the indicator shows “Fair” or “Poor” you should stop charging tool batteries until the BatteryMinder has had time to catch up and fully charge the 12 volt deep cycle battery. On the battery condition indicator “Good” means the 12 volt deep cycle battery is holding a charge of 12.5 to 13.2 volts, “Fair” is 12.0 to 12.5 volts, and “Poor” is 11.5 to 12.0 volts. My BatteryMinder maintains a full charge on the 12 volt deep cycle battery of about 13.1 volts. Be sure to disconnect the Ryobi tool battery charger when not in use, it does use electricity when not charging a tool battery.

Use of tools – I have found that I use the drill the most, followed by the circular saw, reciprocating saw, and jigsaw. With occasional daily usage, the drill battery will last 2-3 weeks on a single charge. I have found these tools so useful I packed away my corded drill and circular saw. Ryobi and others have a number of other tools which use the 18 volt batteries.

Other uses – Of course you can use this charging system for other things besides charging 18 volt tool batteries. Anything that calls for a 12 volt DC car charging source can be charged, i.e. cell phones, rechargeable batteries, laptop computers, MP3 players, etc. You can also use this system to run 12 volt DC gizmos, just remember, use the battery condition indicator so that you don’t too deeply discharge your 12 volt deep cycle battery.

MAINTENANCE: Not much. Other than checking the condition of the 12 volt deep cycle battery the only other thing to check is the level of water. Just fill according to the battery instructions using distilled water. If you were to use a sealed battery you can forget the distilled water. The 18 volt tool batteries last about 2-3 years with fairly steady use so they will have to be replaced. Once this system is placed into use you can stagger your purchases of new 18 volt tool batteries so that all of your tool batteries don’t die at about the same time.

CONCLUSIONS: With careful monitoring, I expect the 12 volt deep cycle marine battery in this system to last seven years or more. There are no moving parts so unless an electronic part fails, the rest of the system should last a long time. BatteryMinder says you can maintain 2 parallel connected medium sized 12 volt batteries at the same time. Also, you could rotate any number of 12 volt deep cycle batteries, one at a time, to maintain a bank of fully charged 12 volt deep cycle batteries. The ability to have power tools available when there is no grid power could prove to be very useful. Even if you have a generator, it is very handy to have fully charged tool batteries available without using the generator to recharge the tool batteries. In the event that there were no new 18 volt tool batteries available, with proper battery management, you could still have the use of power tools for several years.