Disabling temperature compensation on a NetSure plant
This is one of the two settings that most often makes a lithium retrofit misbehave. It is also one of the quickest to fix — if the firmware lets you.
Key figures at a glance
| Parameter | Value | Where it comes from |
|---|---|---|
| Temperature compensation sensor | Set to None — not merely unplugged | Plant maker's lithium application guidance |
| Automatic equalize | Per application — lithium is not equalized | Plant maker's lithium application guidance |
| Battery thermal runaway management (BTRM) | Off — thermal protection belongs to the BMS | Plant maker's lithium application guidance |
| String capacity entered as | Ah × number of modules | Plant maker's lithium application guidance |
| Charge current limit above 0.25C | Requires a minimum NCU firmware version | Controller firmware condition |
| Module default voltage and walk-in | Require a later firmware version again | Controller firmware condition |
| Plant low-voltage disconnect | ≥ battery LVD + 0.5 V | Plant maker's lithium application guidance |
Why it has to go
Temperature compensation exists because lead-acid batteries need a different charge voltage hot than cold, so the plant raises and lowers the bus with the battery temperature sensor. A LiFePO4 pack has a BMS that manages its own cells and does not want the bus moving underneath it. Leaving compensation enabled on a lithium retrofit means the plant is applying a correction curve for a chemistry that is no longer installed.
The setting itself
On a NetSure plant the controller is normally an NCU, and the parameter is the temperature compensation sensor selection — it has to be set to None rather than merely unplugging the probe. Alongside it, automatic equalize should be set according to the application rather than left on a lead-acid cycle, because lithium is not equalized at all.
The setting nobody remembers: thermal runaway management
NetSure plants also carry a battery thermal runaway management function (BTRM). On a lithium installation it should be off: thermal protection belongs to the BMS, which measures cells directly, not to a plant controller inferring from a string-level sensor. Two controllers fighting over the same protection is worse than either one alone.
The firmware condition
Firmware version is a condition of entry, not a footnote. On NCU controllers, setting a charge current limit above 0.25C requires a minimum firmware version, and adjusting the module default voltage and walk-in requires a later one again. If the plant is below the threshold, the correct response is not 'we'll try' — it is to quote the controller upgrade as part of the work, or to decline the site.
If it is not a NetSure
On an Eltek Smartpack or Smartpack2 the equivalent parameters exist but carry different names, and the mapping has to be done before the quotation rather than during a commissioning window with the site already down. That mapping — plant by plant, controller by controller, firmware by firmware — is exactly what our compatibility audit produces and hands over signed.
Equipment this guide covers
- Vertiv NetSure & Emerson R48 Rectifier Modules
- DC Plant Controllers & Monitoring Units
- 48V LiFePO4 Telecom Lithium Batteries
Common questions about this family
Can I just unplug the temperature probe instead?
No. Unplugging a sensor usually raises an alarm and can drive the controller into a default behaviour you did not choose. Set the compensation sensor selection to None so the plant is configured for what is actually installed.
What else changes at the same time?
Float and equalize go to the same value, automatic equalize is disabled, thermal runaway management goes off, the string capacity is entered as Ah × number of modules, the charge current limit is enabled and set, and the low-voltage disconnect is placed at least 0.5 V above the battery's own disconnect. They are one change, not six independent ones.
Limitations
Parameter names follow the NCU menu at the time of writing and can change between firmware releases. This guide does not confirm that a given firmware version exposes the settings; that is read on the controller.
Sources
- Vertiv — DC power systems (NetSure platform), product documentation
- User manual of the installed controller, for the firmware version actually running (no public URL — cite by title)
- Datasheet of the specific rectifier module and of the specific battery model quoted (no public URL — cite by title)
Editorial and technical methodology →
Other guides
- Is the Emerson R48-2900U the same as the Vertiv R48-2900U?
- Can I mix R4850G2 and R4875G1 modules in the same shelf?
- What float voltage do I set for lithium on a Flatpack2?
- Can I put a 51.2 V rack battery in my −48 V telecom plant?
- Is the Eltek Flatpack2 discontinued?
- Where do I set the low-voltage disconnect on a lithium retrofit?
- What paperwork does a telecom lithium battery need to ship?
- How do I identify my 48 V DC plant?
- Does my controller need a firmware update before a lithium retrofit?
- How does a lithium BMS talk to a telecom DC plant?
- How do I size a lithium bank to replace my VRLA string?
- Does the grounding scheme change when I retrofit a −48V plant to lithium?
- Can I reuse the old breaker when I swap VRLA for lithium?
- Can a VRLA string and a lithium string run in parallel during a migration?