AC180 Noisy Fan Operation

I have tried to post the below message on the forum with no luck, just shows as pending for over a day.

Just taken delivery of AC180 in Australia primarily to use in UPS mode.
Battery is fully charged reading 100% constantly on display however with even a small load of around 30Watts constant in bypass mode the fan on the AC180 comes on and off.
Why is this occurring as the inverter circuitry should not be being used nor is the battery charging.
I have a second AC180 scheduled for delivery in the coming days but will be having to return both if this is how they function.
Unsure if I should be setting the charging mode to Silent rather than Standard to fix the problem but as the unit is supposedly at 100% and never changing, don’t see how this would fix the problem.
Firmware is ARM v2074.05, DSP v2078.04, BMS v1033.05 no updates available.
Hope to get an answer from Bluetti as I have many other units, very happy with them all and was not expecting the AC180 to behave this way.”

Further to trying to post this message I have tried the following whilst unit is operating in bypass UPS mode.

Worth noting is that prior to using the unit I have fully charged it then fully discharged it it twice.

I have disconnected all loads and have both DC & AC switched off.

Fan still comes on and off.

Much louder and faster than when the unit is actually charging.

I have also tried setting the charge mode to SILENT and still the Fan comes on and off, note please that the unit is always at 100% Battery capacity when fan is coming on & off.

I have cycled the unit on and off but it still has this problem.

This is unacceptable as this unit and the second one, still to arrive are being specifically for their UPS capability and having a noisy fan coming on and off is not expected.

Please pass this information onto your technical support for immediate response and if this is the expected behaviour,

I will be having to return both for a full refund as I had let the sales team here in Australia know that these would be being used this way.

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Bluetti Australia have advised that they will have a technician contact me shortly, fingers crossed a software push can fix this quickly.

Summarising the lengthy two posts that have been listed together the following is the main issue.

When the AC180 is operating in bypass mode, UPS and is fully charged, the fan comes on and off frequently at a very loud and unacceptable level, much louder than when it is actually charging.

Therefore making the unit useless for operating in an environment where noise is an issue.

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@DJR When plugged in for AC charging, the machine is working (even if it is fully charged, the machine is still on). During this period, the machine also has internal power consumption, and the temperature will still rise after a long time. When the internal temperature rises to a certain level , the fan will start. In response to this demand, it can be solved by modifying the software. The solution is to automatically shut down after a certain period of time when the AC charging is fully charged and not loaded, is this acceptable for you?

Thanks for your response.
Just confirming. I am operating unit in bypass mode, connected to mains power as a UPS with small load connected and fully changed.
You are proposing to send new software that when operating in the above conditions will stop the fan from coming on?
The fan will still come on when charging battery and when the battery is discharging powering the inverter correct?

@DJR I’m afraid that the firmware can’t meet the requirement as you said. Generally speaking, the fan is intelligently controlled and is affected by temperature and load power. The startup strategy of the fans cannot be changed through firmware upgrades.

So what you are saying is that somebody needing to use the unit in bypass mode as a UPS for medical reasons has to except a very noisy fan turning on and off for no reason as the unit is at 100% and inverter not being used.
So the AC180 doesn’t function as a true UPS?
I will be returning both AC180’s as I have been mislead by Bluetti.
Terrible customer service.
I wish I could return the many other Bluetti units I have.
Shameful business practice.

Can you please explain why with the AC & DC turned off so no load and battery at 100% why fans
cycle every 15 to 20 minutes?

Doesn’t make any sense.

Hello Bluetti are you there to respond to my last two posting?

@DJR We have paid attention to this problem, and the R&D department is currently looking for a solution. Please be patient and I will let you know if there are any updates.

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@DJR Could you please provide me with the SN of the AC180?

Appreciate you reaching out to me.

Steven from Bluetti has also been emailing me direct.

The S/N is AC1802316000479902

I have another AC180 waiting for me to pickup from the Post Office upon me returning from travelling for business.

I will send you that S/N later this week as well.

I hope for a solution here, have an early bird AC180 ordered. I am going to use the AC180 in a quiet living room, so this would also be a setback for me.
Could the fan be set to run more constantly on a very low, almost quiet speed, reducing the need to high speed every 20 min ?

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@DJR @Ponty In response to this problem, the software has been improved. Before the firmware upgrade, when the SOC reaches 100%, the fan will suddenly turn on when the internal ambient temperature reaches a certain value. At 50% speed, the fan will not be turned off until the temperature drops. The optimization made by the new firmware is that when the internal temperature reaches a certain value (a little lower than the original one), the fan will continue to work at 20% speed until the temperature drops to the shutdown condition.


@Ponty Please provide me with the SN of the AC180 and the technician can push the firmware for you to test.

Thank you, but still awaiting unit to be shipped. I will be back when it arrives.

@Ponty Thanks for your support.

I have successfully updated both AC180’s with the firmware pushed to me.
Early days, however it seems to have fixed the fan issues.
Will test both units for the next few days and post update here.
Appreciate the assistance form Bluetti especially Steven who has been emailing me.


@BLUETTI_CARE Will the update be made available to all AC180s? I’m experiencing the same issue when using it as a UPS.

@DLM This firmware is currently in the testing stage. If you encounter the same problem, please provide the SN, and we can push the firmware to you separately. If there is no problem with this firmware, it will be used for all AC180.

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Both AC180’s so far are still functioning correctly and I have had no sign of the fans coming on at the previous high speed when the units are showing 100%, just the revised low speed.

However, I am still concerned/confused on why when the AC180’s are running in bypass mode, connected to the AC input, with batteries starting at 100% they frequently drop to 99% which makes the fan come on when they are charging back up to 100%.

The confusion isn’t why the fans are coming, but why do these units drop so quickly and so often when supposedly the batteries are not being used?

All I can think of is that in the hysteresis parameters of the firmware something is not quite correct.

If the continuing depletion of stored battery capacity cannot be rectified, it may be beneficial to adjust when the unit begins charging form 99% depletion to say 95%, just so that the fan is not coming on and off as often?

Just a thought worth mentioning.

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