LITHIUM-POLYMER BATTERIES
ELECTRAVIA is using Superior Lithium-Polymer Batteries. Supplier is KOKAM in Korea.
KOKAM produces Li-Po for military and industrial use since more than 10 years, and have a very good experience feedback.
See details on : www.kokam.com and www.kokamamerica.com
The Superior Lithium Polymer Battery ( SLPB) technology was derived through the culmination of traditional Lithium-Ion (Li-Ion) technology with an advanced form of Lithium Polymer that uses thin film lamination in the manufacture of the plates.
Weight per stored energy (Wh/kg) : 130 Wh/kg
Weight per power (W/kg) : 2900 W/kg
Battery Life : between 800 and 900 cycles
Max discharge continuous current : 200 A for 40 Ah cells
KOKAM LiPo cells
A complete industrial Li-Po batteries system has to contain the four following elements: a BMS, a PCM, an equalizer and a dedicated LiPo charger :
PCM
The PCM (Protection Circuit Module) is an electronic module connected to every cell which checks permanently its voltage. In case of overshoot of thresholds (high 4,2V or low 2,9V), the PCM sends a signal to the BMS. ELECTRAVIA has developed it own PCM system.
PCM
BMS
The BMS (Battery Management System) manages load and discharge of the battery. Indeed, you should never load a Li-Po element in more of 4,2V and to unload it unless 2,9V. This BMS is major on a battery Li-Po and its quality is essential in the life cycle of the battery. ELECTRAVIA has developed it own BMS system.
BMS
EQUALIZER
When there is an unbalance of tension between elements of the same battery, it's the element of the lowest tension that starts the stop of the discharge, while the other elements still contain some energy. The more this unbalance becomes more marked, the more the available energy decreases. The remedy consists in returning all the elements to the same tension. It is the role of the equalizer that unloads the fullest elements to settle comfortably on the tension of the weakest element. Once these well-balanced voltage, we can proceed chargeable to the whole battery. ELECTRAVIA supplies a good equalizer system.
Equilizing is performed every 50 to 100 charge/discharge cycles depending of unbalance.
LiPo Equalizer
LIPO CHARGER
The charger must be specially dedicated to batteries Li-Po. The charge is made at constant intensity until obtaining a tension of 4,2V by element, then it continues at constant tension until the intensity of charge passes below c / 20.
In order to keep as reliable as possible the inboard electronics, only PCM and the part of BMS dedicated to discharge is located in battery container. The other electronic functions are located on ground equipment to be plug connected when charging or equalizing.
LiPo charger
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ELECTRAVIA'S ENERGY STORAGE SYSTEM
ELECTRAVIA has develop a complete energy storage system using KOKAM cells : BMS, PCM, equalizer and charger.
TECHNICAL DATA :
Example of one pack of batteries ->
- Stored energy : 3 kWh
- Nominal voltage : 74 V (20 Li-Po cells in serie)
- Capacity : 40 Ah
- Mass of one pack of 20 cells of 40 Ah : 23,5 kg
3 kWh battery box dimensions are ->
- Heigth : 300 mm + 50 mm for electrical wiring
- Length : 250 mm
- Thickness : 220 mm
Battery cells can be packaged in smaller boxes: it depends on space available.
This battery configuration implemented on ElectroTrike (previously powered by a Corsair M25Y engine) allows between 45 and 60 mn flights at 60-70 km/h.
Of course several packs can be added, in order to have more stored energy.
In order to keep life of battery as long as possible (800 to 900 cycles), only 80% of the stored energy is available. The last 20% can only be used in emergency configuration.
ELECTRAVIA's battery using KOKAM cells |
ELECTRAVIA's battery on ElectroTrike |
ELECTRAVIA can supply all components, assembled or separately.
Please ask for information : infos@electravia.fr