“Oils ain’t Oils” well neither are battery warranties.
Governments, large energy companies as well as small homeowners have been fooled into thinking they have a 10-year warranty (guarantee) that their battery will last 10 years. And in many cases is just not true. READ THE FINE PRINT!
Battery suppliers have a problem. Its to do with the chemistry they are using. By far the most common chemistries used in home or large-scale storage are LFP (Lithium iron phosphate also known as LIPO) or NMC (Lithium nickel manganese cobalt oxide) chemistry cells. These are the actual storage parts of a battery and when you charge or discharge them, they deteriorate to a greater or lesser extent depending on the actual chemistry. LFP and NMC cells are very similar in how fast they deteriorate.
The greatest deterioration happens when the battery nears it highest voltage when it is charging and its lowest voltage when it is fully discharged. Also effecting the battery and how quickly it deteriorates is how often it is charged and discharged. Each charge and discharge is known as a cycle and the so called cycle life of the battery is a critical component of how long a battery will last. Yet another factor effecting the deterioration rate is how quickly the battery is charged and discharge which is known as its C rate. Finally, temperature in which the battery operates has an effect on how the battery deteriorates.
Above: a sweet Zenaji Aeon set-up in a dedicated battery room. Install by Total Solar Solutions Australia
LFP and NMC cells have a cycle life of approximately 3000 to 4000 full cycles before they become liable to stop working effectively. No matter what the customer wants or thinks none of the battery manufacturers can change how this chemistry works and can guarantee their batteries for longer than this. So, it begs the question how are manufacturers getting around the problem and offering 10-year warranties and 6000 cycles?
The answer is in the fine print of these warranties and here are some of their tricks which you should be very wary of.
Commonly they offer a 5-year warranty but will extend it to 10 years if you give them access to your battery and its settings. They then go into your battery settings and stop it either charging or discharging to the batteries highest or lowest voltage. Of course, this lowers the actual capacity of the battery so you don’t have as much storage as you actually paid for but most people are not aware of this.
Brand names are no guarantee here either. No matter how good you think the company behind the warranty is, remember it’s the chemistry of the cells which dictates the life of the battery. Its true the battery manufacturer can do things to help maximise this life but predominantly it’s the chemistry and not the brand name behind it or the clever lawyer who wrote the warranty.
Another trick, though usually not found in their warranty, is to define a cycle in a way that a partial discharge and charge is a cycle. So, a small amount of current flowing in and out of the battery on say a cloudy day, is still a cycle!
Yet another common twist for the unwary is they offer a 10-year warranty but with a limited throughput. This means that over the 10 years you can only store and discharge so much energy, say 3 megawatt-hours which sounds like a lot. However, if you do the sums, it effectively means you have about a 6-year life on the battery if you charge it most days and discharge it during the night.
Review: Zenaji LTOs under the microscope
The worst of all in this writer’s opinion are warranties that are so called “declining warranties”. These have been used by major brand names and what they do is give an unlimited warranty for the first few years of the battery life then only warrant the battery in part against you purchasing a replacement from them. After about 6 years you are effectively paying them for a new battery so they WANT you to claim against the warranty. They make money from it!
Other factors which may be built into the warranties are limiting the temperatures in which the battery is operating, limiting charge and discharge to once per day, and of course limiting the rate of charge/discharge to very low levels which may not be in the warranties but the battery itself limits this below what you believe is reasonable. Note here all batteries have a limit to their charge and discharge rate.
Above: Safety should be the first question every customer asks about battery chemistry.
Brand names are no guarantee here either. No matter how good you think the company behind the warranty is, remember it’s the chemistry of the cells which dictates the life of the battery. Its true the battery manufacturer can do things to help maximise this life but predominantly it’s the chemistry and not the brand name behind it or the clever lawyer who wrote the warranty.
Watch: Former university professor’s reasons for choosing Zenaji
On a positive note, there is a chemistry in the market which usually carries a warranty for 20 years and is for 22000 full cycles. It is given by companies supplying LTO chemistry cells, including Zenaji, and the warranty has none of the “tricks” mentioned in this article. The underlying reason they can give such a warranty is the chemistry is very different and although it will deteriorate over time also its nothing like LFP or NMC cells. These cells are safer, will operate in an incredibly wide temperature range {+60 to -40 degrees C} and can be charged and discharged multiple time per day without damaging the cell.
So read the fine print and ask you supplier/installer anything you don’t understand. Go online as most reputable suppliers put their warranty online for you and read it. It should give you real comfort and if it doesn’t then think again about what battery you are buying.
By Dawson Johns
Recent Comments