Customer’s 52V Efoil bike Lithium ion Battery Requirements
Introduction
This Australia customer is developing a second-generation efoil bike with 52V Efoil bike Lithium ion Battery. This product will also be for a foiling water bike.
The Product Development team have started on the design concept for the product, however the specifications for the battery have not yet been finalised. This means that the following product specifications can be challenged by the supplier if they believe an alternative specification may improve the reliability, cost or performance of the battery.
Battery Product Requirements
. Simple, low cost solution
. 2 different battery models, 500Wh and 1000Wh, to use same housing
. Continuous power delivery to motor without overheating – 1500W
. Short burst boost power delivery – 3000W for 30seconds at a time . Voltage: 52V nominal (14S)
. Regulatory Compliance
o Required to be design with good EMC design practise, and to rework battery design if necessary, to pass EMC testing requirements for complete assembled new hydrofoiler product
o Required to meet UN38.3 standard
. Certification to enable shipping from any port in the world, unless otherwise agreed with Our Efoil bike
o Required to meet IEC62133 standard
o Required to satisfy performance as specified in e-bike battery standards for EU and USA . High quality, reliable lithium-ion cells from known manufacturer
. IP67 housing, made from materials suitable for marine environment
Battery Technical Specification
Our Efoil bike is still developing. The below specifications may be modified after further study, but to initiate a business relationship discussion the following specifications help to
describe the project scope.
. Cell spec: 18650 30Q (or equivalent, by agreement with Our Efoil bike) . Voltage: 52V nominal (14S)
. Continuous power rating: minimum 1500W . Boost power: minimum 3000W for <= 30s
. Battery does not overheat (i.e., any single cell above 75deg Celsius) at continuous power load (1500W) when discharging full battery to empty when starting cell pack temperature is 40°C
o Note – battery is housed inside waterproof chamber
o Minimum 2 thermistors incorporated into design to continuously measure cell temperature . Communication
o Able to communicate with battery via CAN to read out all battery parameters
o Required outputs
. State of Charge
. State of Health
. Pack voltage
. Cell voltages
. Cell Temperature
. Number of charge cycles
. Current
. When switched off, battery to last as long as possible (ideally 6 – 12 months) without recharge
required, for storage
. Operating ambient temperatures
o -10 to 40deg Celsius
. Packaging of Battery pack (size of Housing)
o Maximum size envelope (including battery housing, excluding connector) . The following maximum total dimensions;
| Preferred dimension | Maximum allowed dimension | |
| Length | Less than 400mm | 420mm |
| Depth | Less than 135mm | 145mm |
| Width | Less than 80mm | 85mm |
. Battery Housing
o Waterproof rating: IP67
o Material
. Material must be resistant to UV. Plastic materials must have UV resistant additives
. Any ferrous material (eg, screws) must not corrode in marine environment
. No dissimilar metals to be assembled together that can cause galvanic corrosion
. Handling
o Housing must provide solution for battery pack to be picked up by only accessing the top of the battery pack (the battery will not have access to side of battery when inside the
hydrofoil product)
Battery Requirements January 2021 – Page 2
. Connector
o Connector must be rated waterproof to IP67
o Connector must be located at the top on the battery pack (not on the ends, unless agreed with Our Efoil bike)
Permanent low current power supply output 7.5V 150mA
. BMS power on/off input – positive voltage on this pin switches on battery high-current output. Compatible with both 3.3V and 5V.
. Power switch on Battery for end user
o Not required
. Power charge level indication
o Not required . CANBus Protocol
o Baud rate of 500kbit/s . Tamper proof construction
o Housing must not be able to be easily opened with common tools by end user
o If any assembly parts that a User can unfasten, a “void” sticker or similar must be used so Our Efoil bike can know if battery has been tampered with
. Conformal coating
o Conformal coating for BMS PCB
. Charging
o Allow charging up to 10A
o BMS prevents charging if below 5deg Celcius
o Minimum 60% of original capacity after 250 discharge cycles . Packaging for shipping
o UN certified packaging to be provided
o Recyclable packaging material used
Flion Power‘ Custom 52V Efoil Lithium ion Battery Pack Solutions
General Battery info
• Use samsung 25R 2500mAh cell,8C Max 20A continuous discharge
• Large Battery: 13S8P 48V 20Ah 960Wh
• Small Battery: 13S4P 48V 10Ah 480Wh
• Large Battery and small battery share same customized battery cell frame,customized BMS
General BMS info
• 80A BMS
• UART communication,read battery information
• customized wireless structure (as below picture shows),welding connection instead of wiring connection
Battery Temperature issue
• Even though the Samsung 25R cell with very good discharge performance,but when it made to battery pack ,we have tested it and found that it should control the battery discharge C rate around 2C(less than 2.5C).
• For 48V 20Ah battery,it should work well and capacity can be full discharged @1500W and start @40 ℃,this is estimation and practise testing is needed.
• For 48V 10Ah battery,it should work ok @≤1000W from estimation, if you still need to use it @1500W,you should make a sample and do practise testing.
Battery Housing Idea
• IP67 rating, sealed with rubber ring,screws,and gel
• With power button and led indicating lights
• Will complete the case&structure design if our solution got your approval
Battery Cost & Lead time
Testing cost
• IEC62133 is not applicable when battery >500Wh
| Battery | Testing items | Cost | Time |
| 48V 20Ah | EMC certificate +UN38.3 | USDXXXX+5pcs battery sample | 4-6weeks |
| 48V 10Ah | IEC62133 Testing report +UN38.3 | USDXXXX+5pcs battery sample | 4-6weeks |
Battery cost
• Below cost not include IP67 housing cost
• Battery prices with IP67 case will be figure out after housing design fully completed and confirmed.
| Battery | Cell | Inside Battery pack prices without IP67 housing | Time |
| 48V 20Ah | Samsung 25R 2500mAh cell | USDXXX based on 200pcs,USDXXX based on 500pcs | 4-5weeks |
| 48V 10Ah | USDXXX based on 200pcs,USDXXX based on 500pcs | 4-5weeks |
Molds cost and R&D cost
• The costs of customized cell frame,nickel sheets and IP67 housing will be figure out after housing design fully completed and confirmed.
• Currently we don’t have standard IP67 connector to fit this battery project,it may need to make customized IP67 connector and charge extra R&D cost.Please kindly recommend to me If you have trusted connector suppliers.
•Before open molds, 3D prototypes of Cell frame and IP67 housing is available.
| Item | Cost | Remark |
| Customized BMS | USDXXX | R&D time 5-6 weeks, |
| Customized Cell frame | Around USDXXX | A rough estimated cost,R&D time 4-5weeks |
| Customized Nickel sheets | Around USDXXX | A rough estimated cost,R&D time 2-3 weeks |
| Customized IP67 housing | Around USDXXX to USDXXX | A rough estimated cost,R&D time 5-6weeks |
| IP67 Connector | Pending |
