What the 4901 alarm means

Encoder backup battery voltage is below the warning threshold; absolute position will be lost at power-off if the battery dies. Codes 4900-4999 are warnings — the robot keeps running, but act now. We have built up many handled cases of this EFORT EC2-S controller + TSINO drives alarm, and usually the first on-site inspection tells us what is wrong.

Most common causes

  • Battery past its service life
  • Poor battery contact
  • Long storage without power
  • Wrong battery type
Field note: Confirm or rule out the first cause first — it is the situation we encounter most.

Step-by-step field fix

  1. Replace batteries on all axes together
  2. Confirm type and polarity
  3. Verify absolute position data after replacement
  4. Log the date on the PM label
  5. Add battery replacement to the annual PM plan
Safety first: For EFORT 4901, service work needs lock-out/tag-out: an e-stop alone is not isolation - servos stay live and an accidental enable will move the axis. On site you may look at after confirming power-off the first step yourself: Replace batteries on all axes together. Beyond that it is mechanical areas and rotating parts work - leave it to a professional.

What we recommend for maintenance reminders

EFORT 4901 belongs to the maintenance due family. On EFORT 4901 the failing stage is matched servo drives assigned per axis in the cabinet on the EFORT robot controller - not a fault but a due-date signal: runtime or cycle counters reached a service interval and the controller asks for maintenance. We start reading EFORT 4901 at the pendant alarm list (four-digit codes, 1xxx / 3xxx / 4xxx segments).

The chain involved in EFORT 4901 runs: runtime / cycle counters -> service item due -> reminder alarm -> stop window planned -> consumables changed and re-checked.

For EFORT 4901 confirm which service item is due first: Maintenance is not swapping parts by feel; it is working an interval table item by item. Intervals differ widely - grease, batteries, fans and filters each run their own clock, and reducer re-greasing intervals depend on load duty: a high-takt continuous cell re-greases sooner. We put the official interval table for the model next to the customer's actual duty, compute due dates per item and hand over a schedule, so nothing due gets missed and nothing not due gets spent on.

Field notes on this page cover EFORT 4901 (Encoder Battery Low Warning (EC2-S)); written by the Henghuan repair team, updated 2026-10-01.

Blocked by this alarm? We can help you analyze it over the phone

Tell us the alarm code, the model and what the machine was doing when the alarm appeared. EFORT 4901 is an everyday diagnosis for our engineers, and remote diagnosis (phone or video) costs nothing.

Get a Free Remote Diagnosis See Repair Services

Hotline: +86-20-39029800 · WhatsApp: +86-188-1886-2860

Related Maintenance alarms

1030 — Drive Overtemperature (TSINO) 4905 — Maintenance Interval Due (EC2-S)
Same family: this code belongs to the Maintenance due alarms family - the page collects all Maintenance due-family codes we have handled, with the common inspection order and spares.
Other brands: we also keep field-fix libraries for JAKA · AUBO · ROKAE and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the EFORT 4901 alarm mean?

Encoder backup battery voltage is below the warning threshold; absolute position will be lost at power-off if the battery dies. Codes 4900-4999 are warnings — the robot keeps running, but act now. We have built up many handled cases of this EFORT EC2-S controller + TSINO drives alarm, and usually the first on-site inspection tells us what is wrong. EFORT 4901 sits in the maintenance due family; on our work orders the highest-frequency trigger for this code is "Battery past its service life".

QCan I clear a EFORT 4901 alarm myself?

Whether EFORT 4901 clears on its own depends on the outcome of "Replace batteries on all axes together". Finish the flow with "Add battery replacement to the annual PM plan" to confirm EFORT 4901 - do not skip it. If that step is clean, the second most frequent cause on EFORT 4901 is "Poor battery contact". After clearing EFORT 4901, watch it for one shift. A second trip means stop and let an engineer arrive with the right test gear for mechanical areas and rotating parts.

QEFORT 4901 is only a maintenance reminder - do I need an engineer on site?

The commonest causes we see on EFORT 4901 are "Battery past its service life, Poor battery contact, Long storage without power", so we stock the van against those. For EFORT 4901 specifically, we stock consumables against the interval table: grease, batteries, filter mats, belts - changed in one visit to avoid a second stop. For EFORT 4901, a maintenance reminder can be planned rather than rushed, but fit it into the nearest stop window. Before we roll, tell us what EFORT 4901 shows on the pendant alarm list (four-digit codes, 1xxx / 3xxx / 4xxx segments) and what the machine was doing - phone or video triage is free.

This page on EFORT 4901 is based on the field experience of the Henghuan Robotics repair team. Alarm explanations are our own summary for troubleshooting reference and may differ across controller and software versions — if unsure, verify against EFORT documentation or reach out to us. Henghuan is an independent service provider with no affiliation or endorsement by EFORT.