WGSI Solar

How long do solar batteries last?

If you’ve read a few articles on how long solar batteries last, you’ll realize that the answer is “it depends.” However, let me boil it down and skip all the solar geek stuff.

Very few batteries exist for the direct intent of solar power storage. Most people use deep cycle or marine batteries depending on the size and use demands of the system.

Forklift Batteries

If you can get them for a good price or have the money to spend, forklift batteries are one of the best you can get. Some people also use chemistry lead acid that covers flooded gel AGM and few other subcategories, but don’t worry about that if you are new to solar batteries.

Lithium Batteries

Next on the list, we have lithium batteries. This includes lithium ion and lithium iron phosphate. Lithium iron phosphate is the best option for most applications, but no matter what type of battery you get, the design of the battery must be for deep cycle. That means constant regular deep discharging. Having a lot of storage that you should not use is not helpful– although lithium batteries over all tend to take this a bit better than others.

Now if you could find lithium iron phosphate fork lift battery it would likely last 10-20 years in the most demanding system but if you used a regular flooded lead acid starting battery you would likely only get a few months from it.

Different Solar Setups Affect How Long Batteries Last

Bottom line, how long your batteries last depends on the loads you put on it and how large the battery is. Heavy loads and more “recharge” cycles you could eat up a battery in 7 years, but if you aren’t putting heavy loads they can literally last a lifetime.

For example, if you are only powering a dozen LED lawn lights with a single 100 watt panel, the battery would likely last 5 years and still be providing subpar capacity for another 5 or even ten years before it completely quit. (Sub par capacity meaning less then 70 percent of rating but still over double the nightly requirement.)

A solar expert could tell you in detail with a bit of information about your usage and the battery bank you are thinking about buying. But here are some good tips to help you:

  • It is not uncommon to have solar batteries last 18 years or even more.
  • It’s all relevant to their treatment. Two identical sets of batteries will last for starkly different periods of time if one is care for properly and the other is abused.
  • Following the maintenance instructions on your batteries can mean the difference between your battery lasting a few months and 100+ years (for example, with a well maintained NIFE battery).

Here are some different types of solar batteries and how long they have been known to last:

  • If you are using an AGM battery bank it can last over 5 years even if it is heavily abused.
  • A 32 kwh 4×4 6volt L16 lead acid bank has been known to last about ten years.
  • A bank of 16 lead acid batteries lasted over 6 years. Trojan L16RE-B. (using about 20% of its capacity)
  • A golf cart battery using 50% of its capacity daily could last 3 or 4 years. If you only use 10% of its capacity, it might last 8 years.
  • A 10 k lithium battery commonly has a 10 year warranty; that gives you an idea of how long they expect it to last!