The Off Grid Journey to Self Sufficiency Part 2 Batteries

 

Battery Repaired with silicone and new acid. Rebuilt Battery

In the first installment of “The Off Grid Journey to Self Sufficiency”  we touched briefly on Batteries and Battery Banks. In this installment we will go into more detail including sourcing batteries for cheap, restoring batteries, and building the battery bank.

You could alway get your batteries new, but if you are like me you are either too thrifty or cannot afford to put out thousands of dollars on batteries for your off grid project. Where then do you find the batteries you need? There are several sources I use. The local landfill is probably my best source for used batteries. Many people discard batteries that have been boiled dry of the electrolyte/acid as they don’t realize how easy it is to top them up or can’t be bothered. Most landfills don’t mind you taking these batteries as they are a pain for them to deal with. The second source is the online buy/sell pages such as Kijiji or Facebook. Usually these batteries will cost you a few dollars, but they are most likely in better condition than the landfill batteries and won’t take as much effort to bring them back to full potential. The third and most expensive option is to find a local battery rebuilder. Going this route is the most expensive choice for used batteries because the rebuilder has already done the work of bringing the battery back to life for you.

Restoring batteries can get quite complicated as a rebuilder with the right equipment can remove the lead plates from the old case, clean the cells, replace damaged cells, and finally place the cells into a new case. As most of us don’t have the equipment to do this, nor do we want the exposure to the lead, we will concentrate on the simplest method of restoring batteries. With this method only about 50% of the batteries you find will be restorable, but the cost is minimal and those batteries that are restorable should function for a long time. In the below video I take you through the process.

Now that we have our batteries we will need to put them together to form a battery bank. A battery bank can be hooked up in either a serial configuration, a parallel configuration, or a combination of the two.

The system I use is a 12 volt, so if I found two 6 volt golf cart batteries the would not be useable in my system at their current voltage. To make them useable in my system they need to be 12 volt and to get this they will need to be connected in series. To accomplish this connect the Positive terminal of one battery to the Negative of the second battery as shown below.

Series Connection Connecting in series doubles the voltage, but the storage capacity stays the same.

Parallel Connections on the other hand allow you to keep the same voltage, but increase the storage capacity of your battery bank. To accomplish this the Positives need to be connected together and the Negatives connected together as pictured below.

Parallel Connection

Now in the system I started out explaining we want 12 volts, but we need increased storage as well. To accomplish this a combination of Serial and Parallel connections can be used as pictured below.

Combination Connection

 This allows the increase in voltage and the increase in storage.

The experts will tell you that when connecting batteries to make a battery bank that you shouldn’t mix batteries with different storage capacities as this can shorten the life of your bank. While this is true it is not very practical when dealing with rebuilt batteries that were salvaged. To minimize the potential damage though try to keep the storage capacities close to each other. For example don’t use a 100 AH(Amp Hour) battery in the same bank as a 20 AH battery. In my setup I try to keep batteries that are closer than 20 AH difference together. One of my banks is made up of 15 to 32 AH Deep Cycle SLA (Sealed Lead Acid) batteries. Using this method is a good compromise between best practise and practicality.

In the next installment we will discuss power distribution.

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