Lithium batteries otherwise known typically as LiFePO4 (Lithium Ferrous Phosphate) actually have many variations of chemical compounds which in many cases confuses the matter greatly. The other big consideration is the total size (in AH) of these cells and how small differs from large.
A few examples of battery types and how they are used include:
Watches (you know the things we used to wear on our wrist pre smart phones) have had Lithium batteries in them for 40 years. These are Lithium Manganese cells which only discharge once. These are therefore referred to as Primary Cells (batteries that are built in a factory fully charged and can’t be recharged). Secondary cells however can be recharged by the end user in various methods.
Cordless phones - we all use these in our homes these days and in the beginning they were Nickel Cadnium (NiCd) cells then commonly upgraded to Nickel-metal Hydride (NiMH) because of their larger capacity in the same physical sized cell. The larger capacity required some smarter management of the battery voltages and typically a small battery charging monitor was included inside the small prepacked housings like in a Camcorder battery pack. These are commonly seen today in wireless Xbox or PlayStation controllers. In high-end cordless phones and Cordless drills we are now seeing Lithium Ferrous Phosphate cells being used with a small inline charging management system (which is loosely described as a battery management system).
Lastly Lithium Polymer or (LiPo) as commonly referred to by most and used in your Cellphone with a computerised management system ensuring over temp, over discharge, over voltage conditions and reporting these issues to the operating system of the phone and then the operating system is shutting it down. This is an integrated system where the device is controlled by the triggers and is disabled rather than damage the device.
The same batteries are used in Radio Controlled Toys but no battery management system is connected or built into the toy so if it all goes wrong the battery is normally destroyed by over voltage discharge or over current open circuit. When these cells are recharged however they are connected to a special charger which charges each cell within the battery so each cell receives the correct charge voltage and current. They are no larger than say 5 Ampere Hours and typically 6.6 Volts but are available up to 12 volt (4 cells in series / 4S)
So having told you about different cells, what they are used in and how they are used and how they are charged you should have some understanding that why we could change out one battery type for another there are situations where the purpose or intended use of the battery, battery suitability, or ability to control charge or the device is required. These all constitute what is very loosely referred to as a management system. It’s sometimes using creative marketing referred to as a battery monitoring system but rarely is the monitoring system able to control the device. These are actually Passive Monitoring Systems, or when we change out passive for Battery we get a BMS Battery Monitoring System but not a Battery Management System. And in the case of Toys the management is done on the charging only by the charger and not a management system at all. This is where the Operating System of the smart phone or an Active Management System differs and is an expensive piece of hardware or development commonly overlooked in the modern day when considering a chemistry change from say Lead Acid batteries (Wet, AGM, Gel, Calcium or Maintenance Free) to something like a Lithium Based Secondary cells.
When considering a change of chemistry in a Motor vehicle, Generator, Motorcycle you must ask if the alternator could control the voltage correctly to safely charge a Lithium battery. The answer is no. But seeing the depth of discharge is so light (only 3% of the batteries energy is needed to start a vehicle) a relatively stable low voltage will not overcharge a battery and it will recharge in time to be used again the next day.
When considering a change of chemistry in an application that discharges a lot of the batteries energy each time it’s used the issues multiply exponentially where increased voltages are required to recharge in reasonable time frames. Increased current is needed to replace depleted energy. Voltage imbalances between cells and even temperature needs controlling of the environment and the battery cells themselves.
A common example would be use in a Motor home or Marine House/secondary Battery Bank scenario; These are some of the questions commonly asked.
Are these secondary cells available globally? Yes.
Are they available in capacities above 5 Ampere hour like used in Cordless Drills? Yes
Are these larger cells suitable for use in bigger applications like reserve power? Yes and they are made like larger Lead Acid equivalents where rather than parallel connecting lots of small cells they are made with bigger plates holding more capacity so you can get up to 3000 Ampere Hour cells but they require an appropriately sized Active Battery Management Systems. Lead acid batteries have had 2 volt 2700 Ampere Hour cells available for 30 years plus also but they are used and installed by professionals in controlled environments in specific applications for power companies or cruise liners. But Lead Acid batteries charge very differently to Lithium. Lead Acid in comparison is considered very safe and reliable with battery banks lasting 15-20 years on average all over the world.
Can they replace and perform like Lead Acid equivalents? Yes. But discharge or recharge rates need considering for suitability of application. Cycle life needs consideration, size and dimensions differ and the batteries have exposed terminal connections unlike Lead Acid so other considerations to safety and installation are required. An Active Battery Management System is a must which isn’t commonly available off the shelf and those that are have little or no local support other than email.
Keeping in mind a 5 Ampere Hour Battery Management System and batteries fits in the palm of your hand and that the charger is typically on 5 Amps (to achieve a 1 hour recharge time) and costs approx $250 Retail. How big would a 400 Ampere Hour battery bank and Active Battery Management System have to be with a 100 Amp charger attached to it via the alternator of your vehicle or 30 Amps from solar panels. And what would the cost of a system capable of isolating charging or discharging devices without side effects to your vehicle not running or all your equipment being shut down instantly?