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Batteries
Rechargeable Lithium Batteries

The nominal voltage of lithium-ion is 3.60V/cell, phosphate-based lithium-ion has a nominal cell voltage of 3.20V/cell or 3.30V/cell and lithium-titanate has 2.40V/cell.

We supply state of the art energy storage systems (Kokam, Yuntong, Saehan, Winston) for all types of applications including automotive, rail, construction, solar systems, industrial DC energy storage systems, marine, electric scooters, e-bikes etc.

Currently, the LiFePO4/Graphite electrochemical couple offers the most promise, as it provides beneficial power, safety and cycle life over the most mature cobalt-based systems.

Li-Polymer batteries may also power the next generation of battery electric vehicles. The cost of an electric car of this type is prohibitive, but proponents argue that with increased production, the cost of Li-poly batteries will go down.

Cells sold as Li-Polymer batteries have a different design from the older lithium-ion cells. Unlike lithium-ion cylindrical, or prismatic cells, which have a rigid case, polymer cells have a flexible, foil-type (polymer laminate) case, but they still contain organic solvent. The main difference between commercial polymer and lithium-ion cells is that in the latter the rigid case presses the electrodes and the separator onto each other, whereas in polymer cells this external pressure is not required because the electrode sheets and the separator sheets are laminated onto each other.
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Frequently Asked Questions (FAQ’s)

How do you charge the batteries correctly?
The standard charging profile is a 2 stage regime i.e. constant current followed by constant voltage. Note that lead acid chargers may not be used with LiFePO4 Batteries.

Balancing during charge - Why is it important?
Due to the way the batteries are constructed, from many internal cells, it is very important that during charging these cell are allowed to balance (i.e. reach the same charge level), otherwise the total battery capacity may be slightly degraded. This balancing is performed by Cell Controllers, which continuously monitor cell voltages and ensures that the complete battery pack is balanced.

Do I need to cover the battery to protect against moisture ingress?
We recommend that the batteries are installed in a location where direct application of water is avoided and certainly there should be no pooling of water on any surface of the battery. It is recommended that the batteries as with other electronic components contained in the appliance are contained in a suitable enclosure rated for the environment it will be operating under.

Is cooling required on battery packs?
This really depends on the environment and the typical energy usage profile. A small capacity pack which is being “stressed” will generate more heat than larger capacity pack. In charge the batteries should be operated between 0 & +45 degrees Celsius and in discharge the batteries should be operated between -20 & +60 degrees Celsius.

Can the batteries be deep discharged? How can they be recovered if this happens?
The Lithium Iron Phosphate (LiFePO4) & Li-Polymer chemistry do not exhibit any ‘memory’ effect in the way other types of batteries do, so remain usable across 100% of capacity. However the batteries must remain above minimum voltage (>2.0V per cell) to protect the cells from possible reverse currents, once the battery reaches this minimum level it should not be left at this level and must be recovered up to its normal operational voltage as soon as possible. It is recommended that the module/battery is cycled if stored for longer than 4 months even if it is fully charged at the beginning of the storage or non operational period.

How do I select the right battery for my application?
The important factors are to match;

* The battery pack voltage and system minimum and maximum voltages.
* The battery capacity in Amp hours needs to be matched with nominal current consumption and run-time.
* The system peak discharge current must be carefully matched to battery specification and if necessary a larger capacity pack chosen to prevent overheating.
* The total weight and dimensions also need to balance with these overall factors.

Do batteries self-discharge when not in use?
Yes there is a small self discharge with all battery chemistries, however LiFePO4 & Li-Po cells can be stored for up to 1 year without needing to be re-charged. To ensure maximum performance, it is recommended that the module is recharged after 4 months of storage. Caution: the self discharge is accelerated with higher storage temperature (>45degrees C).
Note: In all situations it is advisable to check the condition and state of charge every month to ensure that batteries are not over discharged.

How does temperature affect the performance of my batteries?
At higher temperature the capacity will be reduced and constant exposure will cause increasing capacity fade. At lower temperature the impedance will be higher reducing efficiency of charging and discharging. The temperature Monitoring Unit will protect the system from short term over temperature operations, but the installation must keep the batteries within the recommended temperature for operation -20 to +60 degrees C at all times. Room temperature is the optimum for both long life and performance. Please contact us for more information.

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