What are LiFePO4 Lithium Batteries?
Learn how LiFePO4 batteries work in charging and remote power systems and how they have a surprising number of benefits over traditional lead acid AGM type batteries.
LiFePO4 batteries are gaining traction as a popular choice for power storage in for battery powered equipment and situations where remote power is required. LiFePO4 or Lithium Iron Phosphate batteries are a very stable chemistry which offers safety benefits over their Lithium-Ion counterparts often found in portable devices. Quite simply, they are the safest lithium chemistry available on the market today.
They are an incombustible design which can withstand harsh conditions that Australian remote power systems demand, with excellent resistance to heat, cold and high levels of vibration. They are ideal for portable battery installations such as those commonly found in recreational vehicles, 4WD's and caravans.
Whilst LiFePO4 batteries tend to come with a higher price tag than their lead acid equivalents, they do offer a number of benefits which are worth evaluating if you are considering making a purchase for your power needs.
Benefits
The biggest benefits to LiFePO4 batteries are listed below:
Weight - up to half the weight of equivalent SLA models
Low self discharge - longer shelf life when not in regular use.
Longer run times - holds higher voltage until capacity is almost exhausted, unlike lead acid batteries.
Longer service life up to 10 years.
Can't be damaged by over discharging
Built in battery management system BMS to protect the battery
Non-toxic chemistry - no rare earth metals making them more environmentally friendly.
Structure
A LiFePO4 battery is made by combining multiple cells in series and parallel to provide the required voltage and charge capability. For a standard 12V battery this requires 4 cells in series (often expressed as 4S) with a nominal voltage of 12.8V.
Within each battery housing exists a battery management system (BMS). This is used to oversee the well being of the overall battery pack and manages issues such as Over-voltage cut off, Low battery cut off and Over temperature shut down. It also balances the multiple single cells within the battery ensuring they are all correctly charged.
Due to the BMS design, not all LiFePO4 batteries can be wired in series, and if they can be, there are limitations as to how many can be wired in a series string. Maximum for our range is 4 pieces. Generally there are no problems wiring the batteries in parallel. In theory, you could use unlimited batteries in parallel.
Charging
It is important to note that prior to first use, all LiFePO4 batteries should be fully charged. Altronics LiFePO4 batteries are supplied 30% charged from the factory.
If a LiFePO4 batterys BMS "low battery cut off" activates, it will disconnect the battery from the battery terminals. This will present a very low voltage across the battery terminals (potentially 0V) which may look like the battery is dead, but simply indicates that it is protecting itself. Chargers designed for LiFePO4 batteries will recognise this and bring the battery out of protect mode via various methods. For example our M8536A charger will pulse charging voltage into the BMS until it has charged the battery enough for the BMS to reconnect the battery (this can take up to 20 minutes). Once the battery has been reconnected, charging will proceed as normal.
At a pinch a LiFePO4 can be charged with an SLA charger, however this will make poor use of the battery's capacity and we strongly recommend a LiFeP04 compatible charger such as M8538, M8534B or M8536B.
If a LiFePO4 battery management system experiences a problem condition, the battery can go into "safe sleep" mode. This cuts off voltage from the battery terminals and it will display zero volts on a multimeter. The video below explains how to wake up the battery from this mode:
LiFePO4 chemistry battery is a superior long term investment for any battery powered equipment or remote power system.