> ## Documentation Index
> Fetch the complete documentation index at: https://learning.kent.co.in/llms.txt
> Use this file to discover all available pages before exploring further.

# Backup Not Working: Loads Go Dark During Grid Outage

> Grid fails and essential loads go dark or trip within seconds — overload, battery state, motor start, phase imbalance, and wiring fault triage.

Your goal is to find why the Backup port isn't sustaining the essential loads and fix the root cause before the next outage. The leading cause is a load that exceeds the platform's backup rating.

**Symptom:** the grid fails and the essential loads go dark — or the backup trips within seconds of every outage.

<Warning>
  **For trained and authorized installers only.** Simulated-outage testing opens live breakers with the customer's loads connected — brief the customer before you start.
</Warning>

## Check first

1. **What was on the backup at the moment of failure?** Compile the peak load history with the customer. One appliance too many is the leading cause.
2. **Battery state at the time** — an empty bank or one parked by a reserve threshold has nothing to give. If the battery is the issue, go to [Battery Not Discharging](/troubleshooting/battery-not-discharging) first.
3. **Which device tripped** — the inverter's own alarm, the backup MCB, or an RCD? An RCD trip points to [Nuisance Tripping](/troubleshooting/nuisance-tripping).

## Causes

| Cause                                 | How to confirm                                                                                                                                        | Fix                                                                                                                                                                                        |
| ------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Backup overloaded                     | Kent M1: **E202** (off-grid overload) / **E405** (battery output overload) · Kent G3: **Over-Load / OV-ILLC**; clamp-meter during load steps confirms | Move heavy loads to the grid side; resize the essential panel per [Essential Loads](/handover/essential-loads)                                                                             |
| Motor start exceeds backup capability | Trips only when a compressor or pump starts — not under steady load                                                                                   | **Kent M1:** size to rated power only — no motor-start surge headroom is promised · **Kent G3:** overload capability is 2× rated for 10 s — verify the real inrush fits within this window |
| Battery empty or parked by threshold  | SOC was at cut-off when the outage hit                                                                                                                | Review the reserve strategy on the platform settings page; enable grid-charge deliberately on outage-priority homes                                                                        |
| One phase overloaded (Kent G3 only)   | Trip correlates with a single heavy phase; other phases are lightly loaded                                                                            | Rebalance loads across all three phases; per-phase limit applies — do not promise more than 100% of per-phase rating on any single phase                                                   |
| Loads drop on transfer then return    | Sensitive loads reset at every outage                                                                                                                 | The pass criterion is "loads ride through" — verify with the black-start test; do not quote a millisecond figure for Kent M1                                                               |
| Grid supply landed on the Backup port | Wiring trace; history of "worked once then died" after a grid outage                                                                                  | Installation fault with hardware consequences — isolate immediately and escalate; never re-energise as-is                                                                                  |
| Backup voltage fault                  | Kent M1: **E200** (output V high) / **E201** (output V low)                                                                                           | E201 usually means the source is exhausted (PV + battery low); check energy state and settings per the alarm guidance                                                                      |

## Prove the fix

Re-run the **black-start test** with the real essential loads: open the grid breaker, confirm loads ride through the transfer, verify a clean reconnect when grid returns, and confirm no RCD trips. Photograph the display during backup operation and log the measured backup load. 📷

## Escalate when

* Overload trips repeat with a measured load that is inside the platform's rated backup current.
* You have any suspicion the grid supply ever reached the Backup port.
* Transfer behaviour remains erratic after all of the causes above are cleared.

<Note>
  **Escalate to Kent New Energy service only** — through your registered Kent partner channel or the Kent service desk details on your work order. Do not contact any third-party or component-manufacturer support line for a Kent-branded system: tickets outside the Kent channel are not tracked, not covered, and can void warranty handling.
</Note>

## Related pages

* [Backup Can & Can't](/handover/backup-can-and-cant)
* [Essential Loads](/handover/essential-loads)
* [Battery Not Discharging](/troubleshooting/battery-not-discharging)
* [Nuisance Tripping](/troubleshooting/nuisance-tripping)
* [When to Escalate](/troubleshooting/when-to-escalate)