Frequently asked questions
Lithium Iron Phosphate, or LiFePO4 for short. These cells were developed in the Nineties for use in electric vehicles and they became affordable and available from around 2010 for this purpose. Freedom Won has been using these cells in our electric vehicles since 2011. They have proven themselves according to expectations and product specifications for longevity and reliability. Our immense expertise with these cells along with a slight reduction in cost has led to Freedom Won making this technology a resounding success in a vast array of stationary storage applications since the first installations were commissioned in 2014.
We do not expect substantial reductions in the price of LiFePO4 cells over the next few years. The demand for this technology is growing rapidly in certain countries including South Africa. Newly established producers might offer lower prices but Freedom Won will only purchase the cells that go into our Freedom Lite from reputed and high-quality manufacturers. The life cycle economics for Freedom Lite batteries is already extremely robust and surpasses any other battery technology we are aware of at the current prices. That being said we do anticipate an annual cost reduction of about 15% in the next 5 years (in USD terms). It is not economically sensible to postpone purchasing a lithium battery based on expected price reductions because the price reductions will be gradual if at all and in any event the lost potential savings in using a lithium battery will in most cases outweigh any benefit from waiting.
Our loose cells are imported from a long-standing manufacturer in China. The Freedom Lite module is manufactured and assembled in South Africa.
The Freedom Lite contains a number of large format prismatic LiFePO4 cells configured to 52V DC nominal output as well as a sophisticated Battery Management System (BMS) that looks after the cells and is able to shut down the battery if the operating parameters are exceeded. The Freedom Lite DC output is connected to an external inverter of the client’s choosing as to brand and size. This DC output is also connected to a Solar Charge Controller if one is used for the PV connection, or alternatively, a grid tie inverter can be connected to the output of the inverter to incorporate the PV. In some cases, a hybrid inverter may be used that incorporates the PV control and battery inverter systems all in one.
Most 48V inverters will work with the Freedom Lite, however, is it preferable that the inverter has a menu setting that can be selected for Lithium or for a custom battery setup so that the charge algorithm and voltage settings can be easily adjusted to suit the LiFEPO4 characteristics. It is further preferable that the chosen inverter has an interface that is compatible with Freedom Lite that will allow Freedom Lite to control the charger and inverter to maintain the voltage and current parameters within the desired ranges. This interface is by CAN Bus, analogue 0-5V outputs, or hardwired potential free contacts. The inverters that are approved in terms of this interface are present as follows: Victron Multiplus and Quattro, SMA Sunny Island, Ingeteam Sun Storage, Schneider XW+ and SW, Microcare, MLT Inverters, Goodwe and Studer (Variotrack and Xtender). Other inverters can be added to this list on request post successful interface testing. Other inverters that do not have the ideal interface have also been tested and confirmed to work satisfactorily including Outback, Axpert, Infinisolar and Growatt. Freedom Won will happily connect other inverters brought to us for compatibility testing onto the Freedom Won test bench on request.
Well, the list is extensive, but the main reason is that the life cycle cost of Freedom Lite is about 25-30% of the cost of a typical lead-acid battery. The best way to work this out is to divide the purchase cost by the kilowatt hours that the battery is realistically expected to deliver in its lifetime (not necessarily what the manufacturer’s say it can). Freedom Lite costs between R1,80 (USD0,13) and R2,20 (USD0,16) per kWh depending on the battery size. Lead acid batteries cost between R4,00 (USD0,29) per kWh for the best single cell examples to around R6,00 (USD0,43) for the lower quality types. There are also substantial savings provided by the high efficiency of Freedom Lite of 96% for a charge-discharge cycle versus 65% for lead-acid (or even less). The low efficiency equates to a waste of energy and translates into a 40% increase in the size of the PV array to achieve the same output.
Freedom Lite is guaranteed to deliver 3500 cycles with a 70% DoD average and an 85% DoD limit. The battery is expected to deliver more than 4800 cycles before it can no longer deliver 70% of the energy per cycle compared to when it was new. If the average DoD is 50% then the cycle life is designed to be 7000 cycles before the battery can no longer deliver 60% of its new capacity per cycle. A 10 year calendar time warranty also applies. The full warranty document is available from Freedom Won on request.
Freedom Lite can operate in temperatures between -15 Deg C and +45 Deg C without noticeable degradation of the battery life. Charging must be limited to temperatures above zero and continuous exposure above +40 Deg C is not advised (a few hours per day up to 45 Deg C is not a concern). If placed in a small room exposed to ambient heating it is advisable to provide ventilation. If inverters and charge controllers are present in the same small room then ventilation will be essential to remove the heat generated by these units.
Freedom Lite provides energy to the inverter when the grid is down or the PV power is insufficient. The inverter is integrated with the house electrical distribution by providing a circuit breaker in the main distribution board (DB) to feed to the inverter. The AC output of the inverter is then fed to a separate DB, which contains its own separate earth leakage and neutral bus as well as all the circuits that must have battery backup, typically all the light and plugs. Large power consumers like geysers, stoves and pool pumps are normally connected to the main grid supplied DB. If it is an off-grid system then the geysers and stoves usually use gas, or sun and gas, or heat pumps. If the grid is available and/or there is sufficient PV power available these sources will charge Freedom Lite through the inverter’s built-in charger or the solar charge regulator respectively.
The first number is the maximum amount of energy that is available from the unit on one cycle, which equates to 100% depth of discharge (DoD). Although it is common to use 100% DoD (or very near it) in electric vehicles from time to time, this is not recommended for daily cycling stationery storage applications. This is because the lifespan of the battery is significantly extended if an average of 70% DoD is used. This is designed into a system by making the battery slightly larger. The second number refers to the energy recommended per typical cycle, based on 70% DoD. This means that 70% of the maximum available energy has been used and this is the average DoD that should be targeted in an application design for optimal life. Typically lead acid batteries do not handle more than 50% DoD at all well, and many are designed to be limited to 30% DoD. This means that a lead acid battery often needs to be double the size of a Freedom Lite when comparing like for like capacity in Ah.
Excellent question – the rule of thumb is that the Ah nameplate capacity of a lithium battery like Freedom Lite need only be half of a typical lead-acid battery. This is largely because of the typical DoD that can be used in each case as explained above, but also because the lead-acid discharge efficiency of around 70% means that much of the energy is wasted instead of being available for the load. The discharge efficiency of Freedom Lite is 98% but for capacity comparisons we use 100% because the Freedom Lite cells actually deliver 10 % more than their nameplate capacity for a discharge time of more than 3 hours.
Very fast. The cells are designed for extremely arduous duties as in electric vehicles. They can be fully discharged in 20 minutes without damage. In Freedom Lite we take a more realistic view and design the module for a 2 hour discharge to contain costs in circuit breakers etc. A High Power option is however available on special request for short-term output UPS type installations that can deliver extremely high power. The cells can handle a full charge in less than an hour, but we know there will rarely be a charger connected with this kind of power so we assume a minimum charge time of 2 hours.
Very little, it is dead easy. The wall mounted units are hung on two Rawl Bolts. For the Freedom Lite 15/11, 20/14 and 31/21 the weight necessitates a high lift pallet jack for safely lifting them onto the rawl bolts. Alternatively, they can be hoisted into place using the eye bolt fixing point at the top of the unit. Then the positive and negative cables must be connected to the inverter along with the control cable. The control cable is supplied with the Freedom Lite. The Freedom Lite must be configured for the type of inverter being used, which can be done by Freedom Won prior to delivery or a qualified technician. To commission the unit, simply switch on the main switch and check that there are no errors indicated and confirm that the Freedom Lite enables the inverter and charger as required.
Yes, four units of the same model can be connected in parallel if required. It is, however, more economical to purchase one larger model to meet the needs of the application. If you decide later that you need more energy storage then adding additional units in parallel is perfectly okay provided that the age difference in the units is not more than around 3 years.
Yes, it is a first in the industry brought to you by Freedom Won! We are able to place a very accurate value on used Lite’s because of the extensive information collected by the BMS as to the service life consumed and remaining. This means you will obtain a very fair value on a trade in for a larger model and if you purchase a pre-owned Lite from Freedom Won you will receive the balance of warranty giving you assurance and peace of mind.