[Huawei R4850G2] Automatic Fan Control

[gitisgreat2023]

With the newest 2025.06.11 release I got curious on the fan control "full" and "automatic".
Something peculiar I discovered. On my R4850G2 the automatic fan control is not changing its fan speed as function of temperature!

I did a test, at 3kW permanently with fan control "auto" the temperature reached about 90°C. With "full" it went to 55°C, also at 3kW. Standing next to the setup with "auto" I didn't hear the fan rotating faster going from say 30°C to 90°C. At "full" it really roared.
To quantify that: "auto" about 28dB, at "full" about 45dB.

@schlimmchen you have a lot of experience with your Huawei right now. Does its fan increase its rpm's up (fully) towards 3kW and corresponding high temperatures?

I'm very positively surprised about the low 55°C at 3kW, because the high temperature at 3kW charging was always a concern for me. I opened a bug report, because that's probably more the appropriate location to catch people's attention.

Of course I researched a bit, I found this. Here also an Akkudoktor thread.

The Akkudoktor thread gives an indication that the fan might be broken, I just ordered a new one. Nevertheless it's weird that "full" works but "auto" not. Therefore I start here a discussion to find out whether other people have the same issue.

I remember quite some people have high temps at 3kW, with the 55°C at "full" speed it might be others also find out their fan isn't really ramping up when going from low charging speeds to 3kW....

[Manos1966]

@gitisgreat2023

EDIT: Ich habe gerade gesehen, du hast breits die notwendige Zeit-Intervalle vorgegeben am anderen Post 👍

Ich habe OpenDTU Version Firmwareversion / git Hash | 434ff8a laufen.

Online / Offline Lüftermodus ist Automatisch
Soll ich die Eingang- oder Ausgangstemperatur betrachten?
Wie lange dauert bis die Temperatur sich erhoeht?
Ich habe leider eine extra 10A Sicherung am 230V Kaltstecker, das bedeutet ich kann nicht ueber 2300W gehen.

[gitisgreat2023]

Ausgangstemperatur. Es geht relativ schnell hoch. 2.3kW müsste es auch sichtbar sein. Nach einigen Minuten sieht man wo es hingeht, dann dauert es noch 15 Minuten wo's nochmal 5 Grad hochgeht.
Schalte mal 2.3kW und schalte dann mal Auto auf full um für den Lüfter. Angenommen Umgebung ist etwa 30 Grad ist er mit Auto fast 60 nach langer Zeit. Und hör man ob der Lüfter schneller läuft als bei 100W. Füll müsste deutlich drunter sein...

Wie schnell löst die 10 amp aus? 4 Minuten auf 3kW zeigt sich ob er 90 nähert und ob der Fan hochfährt...

2.3kW ist vermutlich nicht eindeutig wenn's nicht über 75 Grad geht. Da müsste er thermal throttling machen und logisch wäre es wenn der Fan dan maximal läuft vorher schon...

[schlimmchen]

you have a lot of experience with your Huawei right now.

Only on my desk, sorry.

Does its fan increase its rpm's up (fully) towards 3kW and corresponding high temperatures?

I can say for sure that "auto" causes the fan to slow down an ramp up depending on the load. I can't say that the temperature readings have much to do with its speed.

To be honest, I don't think your fan is broken. If it runs fine at full speed and if that sounds like high RPM and if the sound is bearable, then it should be fine. If it does not sound like high RPM, then it might be stuck. If the sound is crazy loud, there is a physical issue (I had one of those fans in an older PSU, which I had to replace).

[gitisgreat2023]

Well turn it around: when its at 90 degrees why isn't the fan at full speed?

It's like something is missing in auto mode.
No I don't think the fan is broken but I want to have a replacement when I'll run it more often at full speed. And maybe the new one is less noisy...

@schlimmchen
Would it be possible to implement a set and get the fan mode via MQTT? I can put in a feature request for that if necessary, because it's solving it but another request.
Steering it via MQTT would solve it for me as well. I can implement the logic in node red, temperature&load based fan mode.

Happy to share it then with others having the same issue. But most don't seem to charge with 3kW. But all the YouTube videos also report much higher temps at 3kW. Only with some extreme cooling setups temps were lower, but not barely 50°C.

[schlimmchen]

Would it be possible to implement a set and get the fan mode via MQTT?

Already implemented. However, not yet documented. Use an MQTT browser and you will find the respective "stat" topic. Replace the "stat" in the topic with "cmd" and publish "full" or "auto" -- I guess... Also possible that 1 or 0 needs to be published in the respective topic... Don't know by heart.

[schlimmchen]

It's ".../fan_online_full_speed" and the respective "offline" version. The value shall be 0 to set "auto" and a value greater zero to set "full".

[Manos1966]

by the way, as per R4850G2 user manual(s), it seems as if 55 degrees C is the optimal temperature.

V2.2 (EDIT: as identified by spcqike, the numbers in the graph are not percentages % , but Temperature:
55,100% = 55,1 C
75,70% = 75,7 C
80,0% = 80 C
)

R4850G2 Rectifier User Manual V2.2.pdf

V1.4

Huawei_R4850G2_Rectifier_User_Manual_V1.4.pdf

[spcqike]

thats a good and valid point.

I believe the number 55,100% is wrong

i believe 55,100% and 55,3000W are the same, arent they? the diagramms show the same info, one in percentage, one in absolut watts.

temp	percentage	absolut
55	100	3000
75	70	2100
80	0	0

🤷‍♂️

[Charly-2]

55,100% .... 55degree and 100%
75,70%. .... 75degree and 70%
80,0%.....80degree and 0%
It Just gives the Points in the Diagram.
This Diagram Shows how the psu reduces its max. Power when IT geht's hot
(Sorry für the German autocorrection...)

[gitisgreat2023]

Because the fan can be controlled via MQTT I just implemented the Node Red logic to switch from auto to full mode once either the temperature with the fan on auto exceeds 50°C or with full fan the temperature exceeds 35°C. Once full mode is activated a 5 minute counter counts down before it switched back to auto mode.

const output_temp = global.get('state.huawei.output_temp'), input_power = global.get('state.huawei.input_power'), mqttValue = global.get('mqtt.Huawei_online_fan_mode');
let currentTime = new Date().getTime();
let lastActivationTime = context.flow.activationTime || 0;


if (((mqttValue == 0) && output_temp < 50) || ((mqttValue == 1) && output_temp < 35)) { // input_power < 1750  
    if (currentTime - lastActivationTime > 5 * 60 * 1000) { // 300000 milliseconds = 5 minutes
        msg.payload = 0; // auto fan mode
        return msg;
    } else {
        // Still within the x-minute delay, don't deactivate yet
        msg.payload = 1; // full fan mode
        return msg;
    }
} else {
    msg.payload = 1; // full fan mode
    context.flow.activationTime = currentTime;
    return msg;
}

The input is a timestamp of 1 minute, output goes to a function which checks whether the state changed:

var incomingPayload = msg.payload;
const mqttValue = global.get('mqtt.Huawei_online_fan_mode');

if (incomingPayload !== mqttValue) {
    return msg;
}

I'll report back in a few weeks to conclude whether this thermal control works and whether some modifications were necessary.
Edit: first experience after hot, sunny days: it works very well! The 5 minute timer prevents frequent fan on/off cycles and for this hot summer (T_in is 25°C) 50°C with fan auto and 35°C with fan full as thresholds work very well.

Here's the JSON code

[
    {
        "id": "97d8744db83c82ec",
        "type": "function",
        "z": "1dbe8fbb90194999",
        "name": "fan mode control",
        "func": "const output_temp = global.get('state.huawei.output_temp'), input_power = global.get('state.huawei.input_power'), mqttValue = global.get('mqtt.Huawei_online_fan_mode');\nlet currentTime = new Date().getTime();\nlet lastActivationTime = context.flow.activationTime || 0;\n\n\nif (((mqttValue == 0) && output_temp < 50) || ((mqttValue == 1) && output_temp < 35)) { // input_power < 1750  \n    if (currentTime - lastActivationTime > 5 * 60 * 1000) { // 300000 milliseconds = 5 minutes\n        msg.payload = 0; // auto fan mode\n        return msg;\n    } else {\n        // Still within the x-minute delay, don't deactivate yet\n        msg.payload = 1; // full fan mode\n        return msg;\n    }\n} else {\n    msg.payload = 1; // full fan mode\n    context.flow.activationTime = currentTime;\n    return msg;\n}",
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