AT1 Generator AutoStart Issues

Product Discussion BLUETTI Apex & AC Series
1

I have asked support about this too, but wanted to see if any other community members were using their AT1/Apex300 in a similar way and had any insight on it.

I’m looking for some help with configuring Generator Auto-Start on the AT1.

The Apex300s seem to have the correct power flow for the working mode setting, but I’m seeing problems with the AT1 not sending the start or stop signal to the generator. I know the generator start/stop wiring is electrically correct because I can ‘manually’ start and stop the generator using the Generator Enable/Disable setting in the Bluetti app. Something is wrong in my generator start/stop settings or the logic of the AT1.

System Overview
My system is an AT1 with Hub A1 and 2x Apex 300+2x B500k
• AT1 Serial Number: AT12538118033148
• Apex 300 Serial Numbers: AP3002545210138313, AP3002545210405916

All components state that ‘You’re up to date’ when I check for Firmware Upgrades as of 24 March 2026.

The AT1 firmware versions are:
• IOT v30007.01.06
• ARM v9086.11

AP300 firmware versions:
• IOT v8026.13
• ARM v2204.13
• DSP v2174.16
• AC Hub v9081.09
• BMS v1073.07

Bluetti App on an Android Phone - Phone App Version v3.0.6 (up to date)

Goals
I am an off-grid user, so am using the AT1 for integrating a generator power source and the generator auto-start functionality of the AT1.

I want to configure the system so that the generator starts when the SOC drops below 30%, the ESS charges until the SOC has reached 70%, then the generator is stopped.

I have connected the Generator via a 40A breaker to the Generator connection on the AT1, and I have connected the 2-wire start signal (Common (C) and Normally Open (NO)) terminals on the AT1 control board.

Current Settings
Working Mode: Self Consumption, SOC Setting: 70%

Advanced->Generator: Enable
Generator Pro Mode: On
Generator SOC: 30% - 70%
Period: 00:01-23:59 On

Advanced->Max. Grid Input Current->Pro Mode ON: Max 40A (which I believe controls Gird and Generator Max input current)

Status
The generator can charge the ESS and charges up to 70% as per the self-consumption mode SOC%, but then the ESS stops charging and the generator keeps running and powering the loads.

In the app, I can see the power flow status after the SOC had got to 71% and the ESS had stopped charging. I was expecting the AT1 to give the generator stop signal, and to disconnect it, but it didn’t.

I can stop the generator manually by setting the Generator to “Disabled” in the Bluetti App, and then the ESS starts to supply the load.

Questions

  1. Why is the generator stop signal not given by the AT1 without completely disabling the Generator in the app? Are my settings wrong?

  2. How do the “Generator->Period” settings work? There are no details on this in v2.2 of the AT1 User Manual.
    a. Do they define a time period that the generator…
    i. should be enabled for autostart but only if needed according to the current SOC% and SOC settings, or
    ii. will start and run regardless of SOC%, or
    iii. something else?
    b. Does the Generator SOC Setting override time period and start the generator even if outside an ‘on’ time period?

  3. What does the “Generator->Pro Mode ON” setting enable? I can’t find any difference with that on or off.

I’ll post updates here with anything I learn as I go along and/or what support come back to me with.

Thanks,
Julian

2

I haven’t heard back from support despite chasing a couple of times and having been promised a phone call too after phoning after-sales support the second time.

However, I have good news…
There has been a phone App Update (Android) to v3.0.7, so I thought I’d re-do the tests and see where its at now. I seem to have it working OK now…

The Device firmware is still all the same as reported in my prior post. It did seem that the App (or its user… me) might be part of the issue because the App interface did some strange and unexpected things - maybe one of those was not correctly adjusting the AT1 settings?

With the following settings, and the grid disconnected, the system has been cycling the generator on and off as expected running the test load, closing the genstart relay and drawing power via the Generator breaker.
Working Mode: Self Consumption, SOC Setting: 85%
Advanced->Generator: Enable
Generator Pro Mode: On
Generator SOC: 80% - 85%
Period: 10:00-10:05 On

What I’ve figured out

  1. The Pro Mode ‘ON’ seems to enable auto-start mode and giving it the parameters. I don’t really know what Pro mode ‘OFF’ means, but I’m making a guess that auto-start wont be enabled. It may still take power from a manually started generator when needed, but I haven’t tested it.

  2. The time periods, if configured seem to turn the generator on (using the relay contacts), at the time specified. Kin don a forced-on override (regardless of SOC%). Note that the system won’t draw power from the generator unless needed as per the other parameters. If the generator is started with by of these time parameters, but the BattSOC% is above SOC% High (see below) then it won’t go on-load and charge. The Generator will feed the loads though (aka ‘bypass’)

  3. Generator starts and goes on-load according to the defined Generator SOC Low and SOC High.

  4. There is also an interaction with the system “Operating Mode” parameters too. For example in ‘Self Consumption’ mode which defines the max % the system will charge from the Grid, this applies to Generator too. If the BattSOC% is above the SelfConsumptionSOC threshold, then it won’t charge from the Grid or Generator.
    4a) Solar inputs will always charge that battery as much as they can.

  5. I think ‘Backup’ operation mode is the same as ‘Self Consumption’ with SelfConsumptionSOC threshold at 100%. I haven’t explored the other modes: ‘Time Of Use’ or ‘Custom’ but expect they would interact to control whether the system is charging from Generator or discharging (Battery supplies loads even if generator is running) - if the generator is enabled and running per the Generator settings.

So, for this off-grid use, or grid-connected-backup-with-generator use case, the settings I need are
Working Mode: Backup, or something like Self-Consumption 50% if there’s a bunch of solar input available.
Generator: Enabled
Generator Pro Mode: On
Generator SOC Low: 20-30% (or as low as you’re comfortable with the BattSOC getting)
Generator SOC High: 50% (set to match the Self-Consumption % if using that, or something higher up to about 95% if you want longer cycle times). Probably useful to get it to 100% periodically if solar or grid don’t get it there.

Defining generator time periods is not necessarily helpful unless you want a daily exercise for the generator, or you have a daily high-load period you want to run from the generator without going via a battery charge/discharge.

Finally, I’ll answer my own questions from above:

  1. Why is the generator stop signal not given by the AT1 without completely disabling the Generator in the app? To be honest I’m not sure on this. Maybe there was some kind of bug in the app, or the user (me)!

  2. How do the “Generator->Period” settings work? There are no details on this in v2.2 of the AT1 User Manual.
    a)Do they define a time period that the generator…
    Answer: These Period settings start/stop the generator regardless of SOC. Note that generator charging is still controlled by the other parameters for working mode and SOC thresholds.
    b) Does the Generator SOC Setting override time period and start the generator even if outside an ‘on’ time period?
    Answer: Yes

  3. What does the “Generator->Pro Mode ON” setting enable? I can’t find any difference with that on or off.
    Answer: The Pro mode settings are all for when to start/stop the generator via the relay contacts and I don’t think it will auto-start if this is not ON.

I hope this is helpful for someone else out there now or in the future… I’ll let you know how it goes after a while of real operations…

Julian

3

I have continued testing and am sharing my findings below in case they are helpful:

  1. The Generator Enable/Disable button allows the AT1 to detect generator input, synchronize to it, and close the relay to connect it to the bus.
    It does not control generator auto-start. It only allows generator power to be used when the generator is already running.

  2. Enabling Generator Pro Mode allows configuration of generator auto-start behavior:
    a) Time-based mode overrides all other logic. When a time window is enabled, the generator starts and stops strictly according to the configured times.
    b) SOC-based mode is expected to start the generator when battery SOC drops below the lower threshold, and stop it when SOC rises above the upper threshold, independent of time.

  3. The AT1 / Apex 300 will only charge the battery if the current working mode permits charging (for example, Self Consumption mode when SOC is below the set threshold).

Issue observed

SOC-based generator control in Generator Pro Mode (point 2b above) does not appear to operate reliably in practice.

  • The lower SOC start threshold is sometimes respected, but not always. When it is not respected, the generator does not start, the battery continues to discharge, and power would be lost without manual intervention.
  • The upper SOC stop threshold is often not respected. The generator frequently stops before the configured upper SOC percentage is reached.

As a temporary workaround, I can force charging by enabling a nearly full-day time window (for example 00:01–23:59).

Hopefully more to follow when I hear back from support…

Julian