How to Maximize Battery Life
I'm often asked about lead-acid batteries and how users can get the best value out of their solar investment. Over 50 years in this business has made me an expert!
Many people ask about battery warranties because places like big box stores and corporate auto parts houses who charge you $89 for a thirty-dollar foreign-made battery will easily give you a new one when the one you bought goes dead. They make you have the original sales receipt, which they know only 20 or so percent of the folks actually retain. It is good marketing on their part and quite profitable as well. You pay dearly for these kinds of “warranties”.
The reality of battery life, however, is that 87% of all batteries die prematurely from some form of abuse, not defects in materials and workmanship from the manufacturer. The actual statistic on defects in materials and workmanship really comes in at just one battery in every 67,000 batteries has a defect that actually qualifies for a warranty. I know that most manufacturers replace more batteries than they need to principally for good customer relations.
I have been working with and selling batteries all my life, at this time that’s 52 years in the battery business. I personally, have seen about 12 actual defective batteries in all that time. It’s always a bad bus connection internally and that complete failure typically happens early on in the life of the battery.
In that time however, I have seen very rare and uncommon circumstances where the abuse has occurred before the battery purchase by the end-user. Batteries that sit in a warehouse or a store for an inordinate amount of time without charge can become hard sulfated and lose capacity.
I have even seen rare instances of tall batteries, like an L-16, that has been tipped over, losing the acid, then filled with water and shipped, making it impossible to charge up. But these circumstances are even more uncommon than actual defects in materials and workmanship.
So, what do I do to get good life from my battery purchase?
In short, maintain your batteries! Battery maintenance takes consistent work and knowledge on the part of the person responsible for the life of the batteries. Although they appear to be forgiving for a while, that apparent forgiveness costs battery life in the end.
Wet-cell, AGM and Gel-cell batteries are all lead-acid batteries with the major difference of how the sulfuric acid interacts with the lead plates.
Wet cell batteries have a mix of H2SO4 and de-ionized water set to a specific acid density, it’s called specific gravity and it is tested with a refractometer or a hydrometer with temperature correction.
AGM and Gel Cell batteries are valve regulated sealed lead acid batteries. In AGM the acid is basically soaked into a fiberglass mat and wrapped around the lead plates. Gel Cells are a mixture of silica “sand” and sulfuric acid making a paste or mud surrounding the plates.
In the end you see they’re all lead acid batteries, and all require maintenance. An equivalent sized and weight battery will have about the same life potential. Only certain characteristics make them different for unique applications.
Wet cell batteries are the most economical to purchase but, they will require the never-ending periodic addition of distilled or deionized water to replace moisture lost thru boiling or off gassing. This off gassing is oxygen and hydrogen, with hydrogen being a concern as it is very explosive and easily ignited by a spark, thus requiring special venting to the outside to dissipate even small concentrations of hydrogen gas.
AGM batteries have lower resistance to charge and can be charged more quickly. Also, they won’t outgas in normal charging operations so their relationship to humans are more friendly. Plus, they have a unique property in that they won’t freeze even when deeply discharged. This attribute recommends them for conditions where they may not be serviced or charged in freezing conditions.
Many people think that they are maintenance free, but the only maintenance difference between them and wet cells are you don’t add moisture back periodically. You still have to regularly maintain and monitor the charging and discharging.
Gel cells are similar to AGM batteries in many respects, but they require a stricter charge protocol and, if not followed, can easily be “cooked” by overcharging. There are some folks who love Gel Cells, but they have the ability to care for their unique properties and tend to get good life from them. We generally don’t recommend them to the typical end user.