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Wired
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Distributed
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Description
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N+1 tap wires are connected to N cells.
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A cell board is mounted on each cell.
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General
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- Simple to understand: one box, wires.
- Few electronic assemblies
- Lots of wires
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- Safer: no high voltage wires in battery
- Few cables
- Lots of electronics
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Costs
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- Total initial BMS cost is similar
- Cheaper electronics: fewer assemblies
- More expensive wiring: lots of wires
- Cost of thermistors, beyond just a couple, escalates rapidly
- If there's a connector on the tap voltage wires, labor cost is high
- Total repair cost is similar
- Parts cost is higher: entire BMS is replaced
- Labor cost is lower: BMS is easy to access
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- Total initial BMS cost is similar
- More expensive electronics: more assemblies
- Cheaper wiring: few cables
- No additional cost for temperature measurement
- If there's a connector on the cables, labor cost is low
- Total repair cost is similar
- Parts cost is lower: single cell board or module is replaced
- Labor cost is higher: access to cell boards is harder
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Measurement accuracy
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- Inherently more immune to AC noise: filters in slave
- DC errors: current in tap wires, resistance of bus bars
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- Inherently more immune to DC errors: voltage is measured directly, at both cell terminals
- Careful design required for AC noise immunity
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Temperature measurement
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- Limited temperature information: few thermistors
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- Complete temperature information: one thermistor per cell
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Volume, weight
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- Larger master
- Space required for lots of wires
- Practically no space required for voltage tap terminals
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- Smaller master
- Little space required for few cables
- Little space required for cell boards
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Reliability
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- Reverse or peak cell voltage beyond a certain duration will damage entire slave
- Open connection within a bank will damage entire slave (no damage if open is between banks)
- Inherently ESD proof
- If there's a connector on the tap voltage wires, lots of terminations may result in more failures
- Cell voltage tap wires may be exposed to some mechanical stress during installation; vibration during use not an issue
- Sealed slave is environmentally water-proof; connectors are not
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- Reverse or peak cell voltage, even of short duration, will damage only one cell board
- Open connection within a bank will damage only one cell board (no damage if open is between banks)
- Some ESD sensitivity
- If there's a connector on the cables, few terminations may result in fewer failures
- Cell boards may be exposed to some mechanical stress during installation, vibration during use
- Sealed cell boards and slaves are environmentally water-proof; connectors are not
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