I want to spend my money on the best value and right now LifePo4 lithium batteries are the best in several areas: lifetime cycles, cost, and safety.
The safety is incredible. Not only does it work in a way that decreases the likelihood of exploding, it also has things to prevent fire if it should occur. It has been extensively used and tested and withstands abuse that other lithium cells would cause fire. It is the only technology that I feel comfortable using in a space that has gas like an RV or a home.
The lifetime cycles are the number of times that it can be used. Other technologies have cycles of 300, 500 or 1000. That means that if you fully charge and discharge your battery, that counts as one cycle. It is a little more complicated than that, but let’s just assume this is mostly true. So that means that for some batteries it might last a year, two years or even three years of daily cycle use. However it can last between 2000-2500 cycles and this means that it can last for 3-5 times longer than other types. It is common to see 10 year warranties on them, and some companies even have lifetime warranties. Of course all batteries can last longer if you treat them well, so your milage may vary.
The cost is interesting. LifePo4 does have a higher cost than some other lithium technologies but once you factor in the longer lifetime, it clearly is a better value. For example, let us say a lifepo4 battery will last 5 years, and another battery will last two years. The two year battery cost $75, and the lifepo4 cost $100. In another two years you will have to pay for another $75 battery, which means that your lifetime battery cost is now $150 compared to $100. You can see how this doesn’t make sense. In almost every case, buying a lifepo4 battery will save you money over buying another type of battery.
Now there are some really exotic battery technologies that have a better lifespan than Lifepo4 but they are not commercially available and cost doesn’t make sense. Right now Lifepo4 batteries have the best balance of what the average person needs. I have really enjoyed the one I have.