Smart BMS + External Cell Balancer for 12S-18S LiPo / LiHV Packs (PCB + Firmware)
Budget / Salary₹75,000–100,000
TypeFreelance project
LocationRemote
Posted2 hours ago
PLEASE READ BEFORE YOU BID
- Read this post and both attached spec PDFs fully before you bid.
- We are looking for PCB designers. BMS experience is a big plus.
- In your bid, give a short basic understanding of this project in your own words.
- Bids with general text will not be selected.
The project
We need a BMS for our own 12S, 14S and 18S LiPo / LiHV battery packs (cells up to 30 Ah, pack 30-80 V). This is 1 project with 2 PCB works. A detailed spec PDF for each work is attached.
Work 1: BMS board + optional cut-off module (inside the pack)
- Monitors every cell (≤10 mV) and measures current through an off-board shunt (0.5-400 A, no overflow to 800 A for 3 s).
- Balances at about 100 mA per cell, counts charge, keeps a log, shows charge on 5 green LEDs.
- Talks over isolated CAN (DroneCAN), plus Bluetooth on one model.
- USB port (micro USB, USB-C or similar) to write firmware and copy logs / data to a PC.
- No pack current flows through the board. One PCB makes all models by fitting or leaving out parts.
- An optional cut-off module plugs into the board:
- 363 A continuous, 800 A for 3 s, 150 A charge
- pre-charge and a hardware short-circuit trip
- it never cuts flight power except on a short
Work 2: External cell balancer (at the charging place)
- 18 channels at about 1 A per cell, each switched on its own; heat stays outside the pack.
- USB port (micro USB, USB-C or similar) to write firmware and copy logs / data to a PC.
- Two modes, chosen by which input the pack is plugged into:
- BMS mode: our BMS controls it over CAN and an enable pin.
- Standalone mode: it serves other packs through a standard balance lead, with its own ≤10 mV readings, cell count check and stops.
The two works share the balance connector, the enable pin and the CAN message set, so one designer keeps them matched.
Deliverables for each work
- Schematic, PCB, BOM and Gerbers.
- Full firmware source with build steps.
- Protocol documents (Bluetooth / CAN; balancer messages).
- A PC tool for testing, firmware writing and log / data copy over USB.
- Test and calibration procedure, and a test report.
You choose all parts: branded, with steady supply and a datasheet.
In your bid, tell us
1. Your basic understanding of this project, in your own words.
2. Your PCB design experience, with 2-3 boards you designed (pictures or links).
3. Your plan and time for Work 1 and for Work 2.
4. Any question you have about the spec.
- Read this post and both attached spec PDFs fully before you bid.
- We are looking for PCB designers. BMS experience is a big plus.
- In your bid, give a short basic understanding of this project in your own words.
- Bids with general text will not be selected.
The project
We need a BMS for our own 12S, 14S and 18S LiPo / LiHV battery packs (cells up to 30 Ah, pack 30-80 V). This is 1 project with 2 PCB works. A detailed spec PDF for each work is attached.
Work 1: BMS board + optional cut-off module (inside the pack)
- Monitors every cell (≤10 mV) and measures current through an off-board shunt (0.5-400 A, no overflow to 800 A for 3 s).
- Balances at about 100 mA per cell, counts charge, keeps a log, shows charge on 5 green LEDs.
- Talks over isolated CAN (DroneCAN), plus Bluetooth on one model.
- USB port (micro USB, USB-C or similar) to write firmware and copy logs / data to a PC.
- No pack current flows through the board. One PCB makes all models by fitting or leaving out parts.
- An optional cut-off module plugs into the board:
- 363 A continuous, 800 A for 3 s, 150 A charge
- pre-charge and a hardware short-circuit trip
- it never cuts flight power except on a short
Work 2: External cell balancer (at the charging place)
- 18 channels at about 1 A per cell, each switched on its own; heat stays outside the pack.
- USB port (micro USB, USB-C or similar) to write firmware and copy logs / data to a PC.
- Two modes, chosen by which input the pack is plugged into:
- BMS mode: our BMS controls it over CAN and an enable pin.
- Standalone mode: it serves other packs through a standard balance lead, with its own ≤10 mV readings, cell count check and stops.
The two works share the balance connector, the enable pin and the CAN message set, so one designer keeps them matched.
Deliverables for each work
- Schematic, PCB, BOM and Gerbers.
- Full firmware source with build steps.
- Protocol documents (Bluetooth / CAN; balancer messages).
- A PC tool for testing, firmware writing and log / data copy over USB.
- Test and calibration procedure, and a test report.
You choose all parts: branded, with steady supply and a datasheet.
In your bid, tell us
1. Your basic understanding of this project, in your own words.
2. Your PCB design experience, with 2-3 boards you designed (pictures or links).
3. Your plan and time for Work 1 and for Work 2.
4. Any question you have about the spec.
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