Battery Maintenance, Part 1: Checking and Adjusting Battery Water Level
Your Batteries are the lifeblood of an off-grid solar system. Without them, you’d have no power when the sun isn’t shining. Batteries are also expensive and deserve your attention to their proper maintenance. Lead acid batteries consume water as part of their normal operation. You need to make sure that the water levels are kept up.
Before you begin, make sure you have safety glasses and a box of baking soda on hand when you start working on your batteries. The baking soda can be used to neutralize any acid that spills on the ground or on your skin. Wear your safety glasses to protect your eyes from any accidental acid splashes. If your skin is especially sensitive, grab a pair of gloves, too.
First, make sure you clean your batteries before you begin. You don’t want dirt or other contaminants getting in them while you have them open. I just sprayed them off with clean water and let them dry. You could also use compressed air if the dirt on your batteries is not stuck on too badly.
You will need some distilled or deionized water to fill your batteries. Never, ever put anything in your batteries except for distilled or deionized water. Anything else can seriously damage them and shorten their lifespan.
If this is your first time adding water to your batteries, pick up several gallons. You don’t want to run short. Once you’ve done this a few times, you will get a better idea of how much water your batteries use over a given time frame.
When filling your batteries, you should first check with the manufacturer to see what they recommend for the fill level. A good rule of thumb is to have the water level about 1/8” below the plastic collar that descends into the battery.
I’ve got a battery filling tool that is specially made for this job. They are available online, or at just about any auto parts store. These tools automatically fill the battery to the proper level. First, rinse out the battery filler. You don’t want to accidentally get contaminants in your batteries. Then, fill it up with distilled water.
Then, take the cap off the battery. Look into each cell to determine whether it needs water or not. Also, you want to make sure that you never let the water level in the cells drop low enough to expose the metal plates. This allows oxidation to occur and can seriously shorten the lifespan of the battery.
Insert the nozzle of the filler into the cell and press down. Make sure that you get a good seal on the top of the battery so that you don’t allow air in. This can cause you to overfill the cell. You will hear the water in the battery filler gurgling a bit as it fills up the battery. When the gurgling stops, the cell is full. Check to make sure that the water level is correct and move on to the next cell.
Continue filling all the cells of your batteries in this way.
Some people skip the special tool and just grab a gallon of distilled water and pour it right in. This is perfectly acceptable. You might want to use a funnel. It’s very easy to spill over and that gives an opportunity for dirt to flow back into the cell if you do. Just make sure that you watch the level carefully while you’re pouring and don’t overfill them.
When your batteries charge, gas bubbles form in the electrolyte that need to escape. If your batteries are too full, this can cause the electrolyte to leak out. This will lead to a slow dilution of the electrolyte in your batteries. When you leak out electrolyte and replace it with water, the strength of the electrolyte will go down. This will negatively impact the lifespan of your batteries.
When I was first getting started with my solar system, I did a great disservice to my batteries by overfilling. Because of this, these batteries will wear out before they should have. This is going to cost me several hundred dollars to buy new batteries earlier than it should have. Make sure you don’t make the same mistakes that I did. That’s part of our mission – to show you the mistakes that we made so that you don’t have to. There’s no sense in me replacing these batteries early and then you going out and making the same expensive mistake.
Once all your batteries are full and the caps are on securely, you’re done!