Today I have the privilege of bringing a great article to you from one of our own readers. Lux17 has written several instructables and has some great ideas on how to enhance some items that you may already have. The article below is a great example of this; in it Lux17 has taken some old “dead” car batteries and brought them back to life with a new purpose.
Uses For Dead Car Batteries And Sealed Lead Acid Batteries
Many “dead” car batteries are actually perfectly good batteries. They just can no longer provide the hundreds of amps needed to start a car. Many “dead” sealed lead acid batteries are actually un-dead batteries that can no longer reliably provide a couple of hundred watts of power needed to keep a computer running in a power outage.
A couple of years ago I decided to add another small solar panel to the collection I have on my roof. I have a 5 and 10 watt. This new one is a 20 watt. It is dedicated to providing emergency power for lighting, a small fan and other misc. small low voltage devices.
For this setup I needed a battery since it would need to be able to provide power 24 hours a day. I decided an un-dead car battery would be perfect since the largest load it would need to power for any extended period of time would be less than one half an amp. There is quite a difference between 200 – 600 amps and a half an amp.
The battery pictured was one I replaced when it would no longer start my car.
Charging The Battery
I could have used a linear regulator to charge the battery with the solar panel. The cost of a linear regulator is typically less than a dollar. I decided to go with a charge controller instead because they more efficiently use the available power to charge the battery. You get more run time at night when you use a charge controller.
The Test Fan
I did some extensive testing to make sure I knew how well the system would work in an extended power outage. I ran the fan for several weeks, 24 hours a day a couple of summers ago. The system worked fine. Since then I have been running LED lighting out on the patio 24 hours a day for about 2 years.
The fan pictured is a 10” 12 volt, 5 watt, 2 speed fan that was on clearance at Walmart. They still sell them but it was the end of the season. I have 3 or 4 of them.
The LED board has 16 leds. The battery is not even hardly trying to power this tiny 1 watt load.
Click here to view the full instructable with images and diagrams