Surlon Power's ESS 16S200A BMS is a 16S 200A LiFePO4 BMS: a 200 A class protection board for packs built from sixteen lithium iron phosphate cells in series. It sits between the cells and the rest of the system, reading cell voltages along the whole string, measuring current in both directions, and opening the main path when any reading leaves its window.
Sixteen cells in series put a LiFePO4 pack at 51.2 V nominal, which places this board in the 48V class rather than in 12 V or 24 V work. It is a bare board, not a finished battery. The pack builder supplies the cells, the enclosure, the wiring and the charger; the board supplies the judgement about when the pack may keep working and when it has to stop.
As a battery management system for 48V battery pack projects, its advantage is that every decision is taken per cell rather than at pack level. A single cell that drifts ahead of the others on charge, or sags early on discharge, trips protection before the rest of the string is dragged out of balance with it. The charge and discharge paths are limited separately, so a charger with a generous output cannot push more into the cells than they should take.
The main switching devices are electronic, so there is no contactor to weld shut and no fuse to replace after a trip. The board restores itself once the fault clears and the load or charger has been removed, which is what a remote cabinet or a working fleet actually needs: the pack comes back without a site visit.
Everything about the board is arranged for pack integration rather than bench experimentation. As a BMS protection board supplier, we lay out the terminals, wiring and sensor lead for someone assembling a finished pack around it, with the protection decisions already made.
| Protection point | Value |
| Over-charge detection voltage (per cell) | 3.75 ± 0.025 V |
| Over-charge detection delay time | 0.5–1.5 s |
| Over-charge release voltage (per cell) | 3.5 ± 0.05 V |
| Over-discharge detection voltage (per cell) | 2.5 ± 0.05 V |
| Over-discharge detection delay time | 500–1500 ms |
| Over-discharge release voltage (per cell) | 2.8 ± 0.1 V |
| Main circuit on-state resistance | ≤5 mΩ |
When a threshold is crossed, the board does not simply shut down and stay down. Over-voltage and under-voltage conditions clear once the cell has moved back into the band between the detection point and the release point. That gap is deliberate, so the board does not chatter on and off while a pack sits at the edge of its window. An over-discharged pack is brought back by the charger, passes the release voltage, and the discharge path closes again on its own.
A short circuit is handled on its own terms. The board treats an external short as a distinct fault, cuts the main path, and waits for the load to be removed before restoring the connection. The operator's job is physical: find the short, clear it, reconnect. Nothing is opened, and no part is replaced.
Over-current trips clear the same way. Once the heavy load comes off and current falls back within limits, the path closes again. In practice a fault shows up as a stop-and-restart in the equipment rather than as a dead pack. If the same trip keeps repeating on the same machine, treat it as information: the load profile is asking the pack for more than the board allows, and the delay window tells you how long a surge is tolerated before the board acts.
Thermal trips are the exception to instant recovery. A charge interrupted for temperature does not resume the moment the reading dips; the board waits for the pack to cool before letting charge back in. A pack left in the sun can refuse charge for a while and then accept it with no intervention.
Because the switching is electronic and the main circuit has a low on-state resistance, this battery management system for 48V battery pack use adds very little voltage drop or heat to the heavy-current path while the pack is working normally.
| Protection point | Value |
| Over-discharge current protection | 120 ± 10 A |
| Detection delay time 1 (discharge over-current) | 500–1500 ms |
| Detection delay time 2 (discharge over-current) | 500–1500 ms |
| Over-charge current protection | 80 ± 10 A |
| Detection delay time (charge over-current) | 500–1500 ms |
| Short-circuit protection current | ≈1000 A |
| Short-circuit detection delay time | 50–800 µs |
| Protection condition | Exterior short circuit |
| Release condition | Cut load Auto recovery |
| Maximal discharging current (time) | None |
Choosing a battery management system for 48V battery pack projects usually starts with the load rather than the board. Telecom and small energy storage cabinets are the most common home for a sixteen-cell string: the pack sits float-charged for long periods and only works hard during an outage, which is exactly the duty where cells drift apart slowly and per-cell voltage checks earn their place.
Traction is the second pattern. 48V packs in cleaning machines, utility carts and light electric vehicles pull high current for minutes at a time and then rest. The delay windows on the current protections are what stop a motor start from being read as a fault.
Marine, RV and off-grid 48V systems bring a third: shallow daily cycling with occasional heavy draws from an inverter, often inside an enclosure where temperature swings more than the designer would like.
Pack assembly shops working to a customer's drawing use the board as the protection layer inside someone else's enclosure, so cable length, sensor placement and terminal arrangement matter as much as the thresholds do.
In all four cases, pack builders ordering a 16S 200A LiFePO4 BMS tend to settle three things first: continuous load, peak load with its duration, and the charger's profile. Those three decide whether this board is the right one or whether a different current class in the range fits the pack better.
Technical questions reach the people who build the packs. Our engineering group in Shenzhen reviews your device's voltage window, load profile, enclosure space and charger before proposing a configuration; our sample group then builds units so you can validate fit and runtime before production. Cell selection, BMS design and pack assembly stay in-house, with quality checks in process and at final inspection, and a documentation team handling certificates, test reports and shipping papers. When a unit behaves unexpectedly in the field, our engineers help trace the fault and advise on installation and commissioning.
Yes. Sixteen cells in series is the configuration it is built for. Read at pack level, the per-cell detection points work out to roughly 60 V before the charge cut-off and about 40 V before the discharge cut-off, with release around 56 V and 44.8 V. The thresholds are set for lithium iron phosphate cells; a ternary string needs a different charge window and a different board.
Size against the trip points in the ratings, not the class in the model name. The name describes the board's current class; the protection thresholds are what it actually acts on, and they sit deliberately below that class so the board intervenes before the cells are stressed. If your continuous load runs close to the trip points, send us the load profile and we will tell you whether this board or another class in the range is the better fit.
The board cuts the main path and holds it open until the load is removed. Clear the short, reconnect, and the board restores the connection by itself, with no fuse to replace and nothing to reset by hand. On a bench, use a current-limited supply for the first power-up so a wiring mistake shows up as a trip rather than as damage.
Charging is blocked at the low-temperature limit, while discharging is allowed well below freezing. That split is deliberate: charging a lithium iron phosphate cell below zero damages it, so the board stops the charge regardless of what the charger is doing. A pack brought in from the cold needs to warm up before it will accept charge, which is normal behaviour rather than a fault.
No. The series count is fixed at sixteen cells, and because the detection points are set per cell, a string with a different cell count would sit outside the design window. The range covers the alternatives: the 16S 100 A board for lighter sixteen-cell packs, and the 4S 150 A and 4S 100 A boards for 12 V-class strings.
The published table carries no numeric set point for the MOS channel on this model, so the charge and discharge temperature limits are the figures to design around. Pack temperature reaches the board through the NTC input, which is why sensor placement matters: put it against the cells that heat first, not on the wall of the box.
