Dying Battery Extender
When we purchased our new (to us) homestead, it came with an old dilapidated off-grid power system.
It didn’t take much expertise to see the writing on the wall—this power system was a relic from the past and was on its last leg. We would need to replace it soon...
But purchasing a homestead can tend to stretch one’s finances, so we decided to try and make the old power system “stretch” for a year or two while we saved for a “real” solar power system. We’ve been slowly whittling away at replacing one component after the next. But still, the batteries kept cruising. One year…two years…three years. Finally, they are officially biting the dust.
My initial assessment was that the batteries wouldn’t even last one year, but with some careful management and a few tricks up my sleeve, we managed to squeak another 3 years of life out of an almost dead bank of batteries.
Our "Dying Battery Extender" Strategy
So, how did we do it? What are those tips for stretching more life out of a dying battery bank?
Our strategy wasn’t all that revolutionary, but I think you’ll find it really helpful to see what we did—in case you find yourself in this position.
Here’s a quick video I just shot that walks you through it all…
No Actually 5 Options For Extending Dying Batteries
There are 5 things we did to squeak extra life out of our dying battery bank. Be sure to check out #5 especially as I forgot to mention it in the video. PLEASE NOTE: This list is NOT for maintenance of a healthy battery bank. It is for dying batteries that would otherwise be unusable.
- Triage - Don’t assume that a battery bank is entirely dead just because it is misbehaving. Investigate whenever strange things happen. How? Your primary tool is a hydrometer (which measures the specific gravity of each cell). Check each cell, looking for particular cells that are reading dramatically lower than the rest. Remove each battery that has even one dead cell.
How many do you have left? Based on that, reconfigure your battery layout. Remember that it takes four 6-volt batteries to equal 24 volts (or eight of them to equal 48 volts). If you are dealing with industrial type 2 volt batteries, it will be strings of 12 (for a 24 volt system) or 24 (for a 48 volt system). Removing the dead cells will save the good ones from being killed by it, and will dramatically improve the overall performance of the battery bank.
We whittled our old battery bank from 12 down to 8 and then to 4 batteries. Now that the last 4 batteries are spent, we have reached the end of our rope :-).
- Use a desulfator - This is a little device that helps to dissolve the sulfate crystals that can form on the plates of a battery and greatly impair the performance and capacity of it. But not all desolators are created equal. My favorite brand is Battery Life Saver. We’ve been using it for many years as preventative maintenance. I think it is one of the factors that caused this old battery bank to last as long as it did. I have heard of some folks having success with rejuvenating old sulfated batteries with it also, but there is some debate about this. It’s best used for preventative maintenance.
Battery Life Saver makes a number of models, but I’d suggest this one for 12/24 volts systems (with an overall capacity of less than 1,000 amp hours), this one for 48 volt systems (less than 1,000 amp hours), this one for large 24 volt systems (larger than 1,000 amp hours), and this one for large 48 volt systems (larger than 1,000 amp hours) [those are affiliate links to reasonably priced options]. I don't suggest going with a different brand for your desulfator as I have heard mostly poor feedback about the others I've heard of. Battery Life Saver is what we have used personally for years.
- Equalize more frequently? - When trying to stretch another year out of a dying battery bank, most of the rules are out the window. So you might find that the only way to get a decent charge into the old batteries is to equalize them more frequently than typical. Equalizing is a controlled overcharge. You definitely don’t want to do this too frequently with a functional battery bank, but you may have to do it a lot more frequently when batteries are dying.
You'll notice that I put a question mark at the end of this subheading. That's because equalizing an old battery does not come without risks. If you have used the batteries hard and worn the lead plates thin, then equalizing a lot could finish them off. Also, equalizing knocks sulfate crystals off the leads plates, adding to the sediment piling up in the bottom of an old battery. When the sediment gets high enough, it can short out the cells. So there are risks to this, but if you are unable to get a decent charge with the typical settings, then you really have nothing to lose, right?
- Keep them watered - You’ll likely find that worn out batteries use more water than new ones. This is especially true if you are equalizing more frequently.
- Kill any corrosion - Corrosion is the enemy of free-flowing electrons. In the highly corrosive air present in a battery bank, almost any piece of metal is at risk, especially any electrical connection (where wires or cables connect together). This is especially true with old batteries. You will often find that old batteries are dealing with serious corrosion issues. Since the symptoms of corrosion issues and dying batteries are sometimes similar, it can be difficult to tell one from the other. But here's how to do it...
Use a wrench to take apart EVERY cable and wire connection in the battery box (specifically, the battery interconnect cables and the main cable that connects the battery bank to your inverter or power center). Then you'll want to use a wire brush to clean all of those connections and battery terminals. Then put it all back together and tighten them down. You probably don't have to worry about wire brushing connectors that are outside of the battery box, but it never hurts to snug up those connections with a wrench. Anytime you have heating and cooling occurring frequently, it's possible for the nut to work its way loose.
After you have cleaned and tightened everything, apply a liberal dose of battery terminal protectant. My favorites are generally a gel or grease type consistency and have additives that neutralize battery acid. I have used this one with great results, and this is another great option.
That's about it. As you can see, this is not some revolutionary new method. It's pretty common sense if you understand how batteries work. It worked well for us and bought us a significant amount of extra time. Hopefully, you won't be in that position, but if you are, I hope this helps!