question

Hi

Their fans are noisy in those units even from day 1, yes there are 120mmx38 and are 24v.

It's to do with the blade design etc to have a low noise fan, this fan might be middle of the road type? As i side note this is the company that has made capacitors for years, not fans.

They are ball bearing type. Brand Jamicon data sheet attached.JF1238-14.pdf

Regards

Rob D

NZ

I will try and find some replacement with lower noise (db) and attempt to change it...
The noise of the factory fan is just too annoying and loud

Ok, so I found a possible replacement(s)...I understand that it is less thick, but that is not that important as diameter and flow rate...
Noise however is significantly less.

Only thing I'm not sure is which exactly fan is inside of the Multi II ?

The replacements (Noctua Industrial 120mm)

Also, the connector PWM has four contacts but it can be modified to two only so that won't be an issue

I have an EasySolar 48V 5000VA and it is extremely noisy

With an uncalibrated phone based noise meter, my Easysolar measurements are:

1 - Silence - 20dB

2 - My workspace - 50dB (EasySolar fans at full speed)
5 meters from
the Easysolar

3 - 1m from blue encl. - 60dB (fans at full speed)
of the EasySolar

4 - Outside the encl. - 80dB (fans at full speed)
at hot air outlet

The current fan JF1238B2HR-R, gives a spec of 43.5dB, which means the position of fans in the blue enclosure is the noise generator. I have not opened the enclosure to understand the noise sources.

I need some advice - do I replace these fans, and will it affect the warranty?

The alternative is to have the Enclosure moved, and the associated costs and additional wiring.

Not specific to Victron, but in general the perceived fan noise of equipment is mostly contributed by vibrations threw the chassis rather than the fan itself. I'll put some good money on those fans being a lot quieter if taken out of the inverters and measured in free space. Often you can get rubber mounting systems for fans which helps a lot, pads, washers, screws etc. A good fan manufacturer like Noctua should sell some of these accessories. Best I think will be to buy a bunch of accessories with a good replacement fan then open up the inverter and see what you can do in mounting the replacement fan with some rubber accessories. Often something simple like rubber mounting screws in place of metal or plastic can make a big difference, or just ensuring that the mounting screw doesn't touch any other part like the chassis or cover.

I'm resurrecting this old thread for other readers to share my experience.

I have a Multiplus-II GX and I too find that fan noise absolutely excessive. I have applied stenis' advice and had taped bitumen mat on the inside of the housing cover, to find out that it had only improved the problem marginally -- i.e. when you're in front on the device. The situation is not improved when, as in my case, the enclosure is hung on the wall (a *concrete* wall) that separates the house from the parking garage : it can be heard from everywhere in the house !

I too have searched for fans with similar characteristics and found none that would be allegedly quieter, at least on their datasheet.

The vibrations induced by the fan activity are just absurd ; even its neighbour the Fronius inverter saturated with solar power generates less than half of that noise.

Moreover, the problem has gotten significantly worse since I upgraded my MPII firmware from v470 to v490; with the old firmware, the fan would only kick in when the device was sending to or drawing power from the battery and stay quiet in passthrough mode - now it spins even in AC passthrough mode, when all the power on the output comes from the grid input ! This is ridiculous and infuriating.

In my opinion the last thing that would work, apart from moving the enclosure far away from the house which is unacceptable, would be to create a forced air duct, well fitted to the enclosure's air intakes, long enough to breathe air from the outside, and deport the fan all the way there.

I see no other solution, apart from enabling that "silence fan" configuration assistant which has the big drawback of reducing the inverter power.

This annoyance is, IMO, by far the #1 negative point of these devices, and if I had known they would be so noisy I probably wouldn't have bought one. Buyers beware.

@Bobby I had a chance to compare different fans with same voltage, amperage, and size. The Jamicon model - thank you Rob for sharing - that is in MP2 was the one of the most powerful form air flow perspective. From noise perspective you can hear mainly the air flow from the Jamicon fan when it is supplied with DC or high freq PWM from 20 to 24V.

Unfortunately MP2 need a hi flow fan to cool down especially the transformer and also the MOSFET's and choke due to "redesign".

I visit a showroom to discuss the fan noise issue. @Deon similar measurement results. There one unit MP2 was with fan on and it was also loud. I convince a technician to remove the front panel and he did it. We were surprised about the difference. With the front cover off the noise was way less but when he put the cover back, the noise comes back at high level again.

If you change the fan i think that you will loose the warranty but if you still want to do it, in my opinion you have to address to:

- noise source - fan itself - change with a better one with same flow rate;

- fan speed control hardware - low frequency PWM - add a basic RC filter;

- mounting bracket - transmit vibration to the housing - add a damping material under it and between the screws and housing @Nickus de Vos Victron should consider your remarks.

- housing - being half empty it resonate like an acoustic guitar - here you have to be careful because also the housing has an important contribution to heat transfer. @stenis good ideea.

Having some experience in NVH from one of my previous job I can say that this kind of issues are not so easy to solve and has to be considered in the design phase which, unfortunately was not the case.

Good luck!

Hi,

up to know I thougth the fan is just voltage controlled, has it has only to wires (+ and ground).

Are there new multiplus II with a pwm controlled fan?

I still don't understand why Victron do such a lousy job of fan speed control -- every single PC on the planet has proper HF PWM control to give quiet variable-speed fans and the circuits to do this cost next to nothing, so why on earth don't Victron do the same? And mount the fans on little silicone feet like Noctua do, the cost is pennies but it makes a big difference to noise from the case...

Well, it seems clear to me that vibration dampening and keeping sound levels acceptable were
*never* considered at all as possible issues by the designers of these products. It's to a point that many design choices that have been made were in fact the worst ones in this regard.

Now to recover from here... Apart from the forced air duct, or redesigning the enclosure completely and retrofitting the boards into a carefully hand-crafted one, I don't even think there's a proper solution.

I'm still watching this thread in the hope of a miraculous idea, but I'm slowly pushed into thinking it's a waste of time. Currently I live with it.

Hi Bobby

I have modified a my own Mulitiplus2 unit with a Sunon fan 25mmx120mm model # EEC0252B1-0000-A99 with rubber mounts and with 47uf 63v cap across the fan terminals. And results are, the bad droning noise or PWM noise due the low PWM frequency you normaly heard has gone.

Much quieter unit now, no droning like before. just air flow noise though the unit now which is much more pleasant to listern to.

The air flow is the same as the orignal Jaicon fan, the 25mm thick fan allows for the rubber mounts to used on the original mounting bracket.

If Victron could just change the PWM to a higher frequency rate the problem would go away , and they would have a much quieter inverter on the market.

Regards
Rob D

NZ

Hi

Didnt not have a dB meter, just it is much quieter than before no droning noise.

I can also confirm that the recommended SUNON EEC0252B1-A99 (EEC0252B1-000U-A99) fan is much more quieter than the original fans of the Multiplus-II.
The fan is available on the SOSElectronic website in EU and is cheap.

I used a 220 uF capacitor because at 47 and 100 uF I could stil hear some "vibrations" from the PWM at low speeds.

Hi folks, first time posting here. I also belong to the surprised, noisy Multiplus II owners club, mine is the biggest 10kW version. I almost fell off my chair when I heard the fans starting the first time. That was under a light load of about tad over 2kW which one would think to be easy for a 10kW unit (well, maybe 8kW instead of 10kW name tag) but anyway, only a fraction of max. The unit is brand new, and naturally Victron will not consider faulty, so no warranty claims to be done. As such, I am considering the same modification as you have done - but one thing caught my eye in the SUNON EEC0252B1-A99 (EEC0252B1-000U-A99) fan mentioned in this thread. The fan spec says the following, and I would like to hear how do you read and understand it.

On page 11 of the spec, they tell not to use PWM control with it:

Ie, the way I read it is that the fan has only two pins, power and ground, and neither of those should be used with PWM signal. Wonder if it means the fan will die prematurely without warning, or smth else? Should we find another fan which is ok for PWM control?

Thoughts?

Perhaps it would be good to add a series resistor anyway as @popnic suggests, so that the source of the PWM waveform (whatever it is) doesn't drive directly into a capacitive load. Depending on the source impedance, that could result in very high peak currents which would not be good for either the driving circuitry or indeed the capacitor. Like @RayMiller I too was surprised by the very "agricultural" fan noise from my new MP II, for its size it is certainly the noisiest fan I have encountered in a long career in electronics.

Hi Rob, all, and thanks for sharing your implementation, I'll be doing the same mods once back at my remote facility. I will also take my oscilloscope with me to see the signal waveforms and mean voltages before and after changes and can post my findings here.

BTW, does anyone know if the noise originates from just one fan or both in the Multiplus II 10kW model? (would expect Victron to run both fans with the same low freq pwm, though...). Do the smaller models have two fans like the 10kW one, or just one?

Looking at the fan specs, it shows 24V, 207mA, which works out to be the 5W. Thinking of the serial resistor and the impact of it on the power the fan receives, I did a rough math below. This is lacking the effect of the capacitor boosting the speed, and the current value is an estimation, so not exactly accurate but should provide some clues on how the serial resistor size impacts on fan output.

Ie, it would seem that already a 33 ohm resistor would cause the fan to receive only ~18V instead of 24V, and reduced current, resulting in about 60% of the fan power compared to what the factory setup with 100% duty cycle 24V feed would provide. While the fan spec doesn't tell how much less airflow that would mean, I'd guess it is going to be significantly less, probably in direct correlation with fan power and that would discourage using resistor values that high.

As such, it would seem that the implementation by Rob with no resistor is the safe one from maintaining the same (in fact, better) airflow, although a small resistor (say up to 10 ohms) should not cause too dramatic power drop, especially considering the boost from the capacitor which might compensate enough to keep the fan power and thus airflow close to factory spec.

Also, if using only 10 ohms resistor, a 1W model would be fine, as the power dissipation on the resistor would never exceed 0.4W. The 1W rating would actually be ok all the way to 30+ ohms. Then, is there a value of using such a small resistor even to protect the driver circuitry from the change in load impedance...?

Thoughts?

The new SUNON EEC0252B1-000U-A99 fans arrived, but no rubber mounts included, so need to find or create ones. Tested at home without PWM, just straight 24V corresponding to 100% pwm signal, with and without 10 ohm/3W serial resistor.

Without serial resistor and free airflow I get 24V and 192mA = 4.61W power consumption (100%). With airflow obstructed (fan against the table), current increases to 215mA and power to 5.2W

With serial resistor current drops to 170mA, power draw to 4.08W (89%); voltage over the fan to 22.1V, thus 3.76W for fan (82%), and 0.32W (7%) for resistor, which warms a bit but hardly noticeable with finger. With multimeter temperature probe I get a reading of 40C, correlating with finger reading. Based on above numbers, the actual resistor value is 11.2 ohms.

With obstructed airflow current increases to 190mA, power draw to 4.56W (99%) of which fan gets 4.16W (90%) and resistor 0.40W (9%). Resistor temp now 43C. The resistor was in standstill air, not in fan airflow. In MP2 the resistor would inevitably get some airflow, yet it is a warmer environment than +23C now. Tested also with the second fan, got the same readings - so these fans seem to be identical twins. (I ordered two fans as MP2 has two and I don't know if it is one or the other or both making noise - assuming worst case).

Based on quick testing I figure I could use a small serial resistor, lifetime should not be an issue due to minimal temperature rise. Will see if the resistor makes any difference in results, will decide once I get to try the alternatives. Surely without a serial resistor the circuit is most reliable as only one component to fail and no chance of cutting the circuit like failed resistor can cause; yet both have the same chance for shorted capacitor which can also happen.

An update, things seem different with the 10kW model of MP2 - and so far I have not succeeded in making the device quieter. First, the fans are different, and there are two of them. Second, the capacitor makes no difference on the noise the MP2 generates, I tried 47, 100, 220 and 330uF capacitors parallel to both fans with only marginal impact on noise.

Ths lower power fan is JF1238B2HR-R, 24V 0.32A = 7.7W fan, and the higher powered one is JF1238B2TR-R, 24V 0.60A = 14.4W fan, both JAMICON as in other models. However, the 5W fans I bought based on the information from smaller systems would not most likely not be adequate replacements, and would not be able to generate the same airflow and cooling.

On the signal waveforms, I didn't capture them at all power levels, but here some samples when the inverter was under a modest, bit over 2kW load. The first one is without any capacitors connected, standard Victron factory setup and showing just one of the fans voltage. To be noted that both fans were driven with exactly same kind of voltage and frequency PWM signal

The second oscilloscope screenshot shows the voltage of both, each with 47uF capacitor connected...

...and the last one with 330uF capacitor on fan power feed:

As you would expect with the largest capacitor, the peaks smoothen and the lowest voltage is no longer zero but a slope towards zero volts, until the next peak comes in. BTW, the scales in the oscilloscope were 5V vertical (in single graph displays, 10V in two channel displays) and 20ms horizontal division. As you can see, we get about 5 full phases in 8 intervals on the screen - ie. 8x20ms = 160ms for 5 pulses, which makes about 32 ms pulse interval, or about 31Hz frequency. I don't know yet if the PWM frequency changes along with the load, but at least in this case it seems to be slightly different than the 25Hz mentioned earlier, but maybe the same control circuitry with "approximately" 25Hz...

Just for the sake of it, here few more samples of the same signal with slightly different load - as you can see, there are varying number of peaks on top of the pulse, not clear if intended or just a by-product of the fan control circuit. Whatever the case, those seem to be 4 peaks in approx 13..14ms, or ~3.5ms per phase, or about 300Hz frequency. That's another nasty frequency to listen.

The next thing I'll try is to disconnect the Victron fan control completely, and drive the fans with plain DC power from a lab power supply to see if a plain DC voltage on the fan (mounted in the frame as is) would generate noise, and if so, which level. That should establish the reference which can be achieved with Victron standard fans. If still noisy, should see if a quieter fans could be found. If clearly less noise, then I'm thinking that it should be possible to convert this PWM to plain DC (0-100%) analog voltage. There are converters which change PWM to 0-100% voltage level, but the ones I've seen so far are all either 0-5V or 0-10V output, have not found any with 0-24V output. Yet it should be possible to convert to that range with a simple circuit.

Thoughts from your experiments and findings, and what do you think about changing PWM to just DC level 0-100%?

Googling for the specs of those fans, this is what I found:

Which says the bigger fan alone produces almost 53dB at full speed, while the other is about 10dB quieter.

Hello dear Victroniens and Victronniennes,

Concerning the subject of fan noise, I suggest you make an online petition on this forum in order to accumulate the greatest number of VICTRON customers.

So we could ask VICTRON R&D to include at least in the future version of the Multi-II Firmware the fact that the fans are only triggered according to the internal temperature of the device and more on a mix.

If you agree, here is the link to this petition:

https://community.victronenergy.com/questions/157987/petition-bruit-ventilo-multi-ii-noise-fan-on-multi.html

Victronement your

It seems this is a serious problem for many domestic users (myself included, I have had to soundproof the door of my kitchen because of it). So it is regrettable that Thierry Cortassa (Victron Energy Staff) has closed the Petition topic rather than taking the request for action seriously.

As noted above by many contributors to the discussion, there are various technical solutions which could easily be adopted to solve or at least improve the noise problem if Victron had a mind to do it.

Thanks to all the efforts by contributors above and in other threads on the Victron Community platform and elsewhere, we now know that the fans start based on :

a) ambient temperature of ca 30-35C

b) power drawn (actual current)

However, there seems to be one aspect missing in above discussions.

According to Victron specs the MultiPlus will work in ambient temperatures of -40C to +65C, with derating at higher temperatures, of course. Very impressive !

I´d say that at 65C in a residential environment you won´t be bothered by the noise of the MP II, because you have very serious other problems. Still, it is very impressive because at 65C the air blown through the MPII has very little cooling capacity. That means a lot of air has to be blown through the MPII, requiring a very powerful fan.

Common sense therefore says that if you are sure that the temperature where you will be installing the MPII will never be higher than e.g. 25C, you do not need such a powerful fan .....

No surprise therefore when I came across this link https://www.photovoltaikforum.com/thread/158718-lautst%C3%A4rke-multiplus-ii-48-5000-70-l%C3%BCfter-brummen/?pageNo=1 (in German) where German reseller Panda-Solar states that they have been installing the 2000 rpm version of the Noctua fan for clients, who have them running without any problems for more than 2 years. Difference being that the 2000 rpm Noctua has a noise level of 29.7 dB, whereas the 3000 rpm produces 43.5 dB .........

The difference between a whisper and an older model dish washer.

I love the sound of silence.-

to add upon the others.

MPII 48/5000

when not charging/inverting : loud humming noise

when above 2kw : fan kicks in and noise is annoying : goes through all the walls, neighbour complaints, discussion with wife, sleepless nights etc

modified the MPII with resistor/capacitor as stated above. Makes it a lot better, but still ...

to comment on the airflow : by adding the resistor, the maximum airflow is less. I use the inverter for hours at max power. I see that with ambient temperature of 20 degrees, it gradually decreaes its output power to around 4400W instead of 5000W, this happens after 10 minutes or so. probably because it's running to hot. so for many situations, adding a more silent fan, that switches 100% on from the moment a PWM signal is seen, should be good, unless you need the full 5000 W for prolonged periods.

personally cannot believe that someone can have this unit in a boat/RV.

to the experts here, anyone knows is the noise situation is the same with the Quattro's? will I have twice the noise in parallel configuration? thx u

Bobby the fan noise as you state is excessive, the fundamental problem seems to be the fan model being used. The centre cover ( which is large for a fan) of the fan electronics resonates easily which is causing an unusually extra sound emanating from the fan bearings, made worse by any PWM speed control.

I've successfully replaced my fan (as per Rob in NZ) with one, half the thickness and used fan mount isolation rubber mounts as suggested. The PWM of the replacement fan does not seem to make any extra noise.

I did at the same time add a dense stick-on noise-reducing material to the inside of the front panel which also helped reduce the MulitPlus case resonances. The final result is white noise from the inverter when under load, no more noise than what one would expect from normal fans and similar to Fronius inverters, and much less annoying.

Unfortunately to replace the fan requires removing the inverter fully to access the rear screws holding the fan mount bracket, although Rob seems to think it can be accessed from the rear on-site, I found it still much easier to have the unit on the workbench.

It's a simple mod but one which would not be necessary if a different model fan was used.

I found this thread because, for the first time in two years, the fan in my Multiplus (original) 24/3000/70 came on today. (A few days ago I upgraded my battery bank to 3p2s 24V/100 Ahr, increased the charging current to 21 Amps and increased the AC input limit to 8 A (120 VAC). Due to rain all day, the charging circuit turned on today, and the fan turned on shortly after.)

Even tho this thread is about fan noise in the MP II, the fan noise in my MP got my attention. I thought the fan blades must have been in contact with some wiring because that's what it sounded like with the rattling/vibration. But when the fan is off, the blades turn freely. So there's no mechanical interference.

The reason that I post here is because I noticed something else that I haven't seen stated in this thread. The fan assembly seems somewhat inefficient, in that I can feel air blowing backward at the fan intake!

As someone who build an airplane (a real one), I know that air doesn't often flow as we expect it to. Looks like I will have to take a Dremel tool to the shroud and smooth things out. Or add some baffles.

Ahoj,

Velmi užitečné vlákno. díky

můj velký problém s hlukem jsem vyřešil takto :-)

https://forum.mypower.cz/viewtopic.php?f=7&t=8299#p167566

Bitumelová výplň.. Nyní jde slyšet jen fučení vzduchu z ventilátoru.

Slunci zdar

Hey,

Very useful thread. thanks.

I solved my big noise problem like this :-)

https://forum.mypower.cz/viewtopic.php?f=7&t=8299#p167566

Bitumel filling... Now you can only hear the air blowing from the fan.

Sunshine.

............

Translated with DeepL

Hi all noisy MP II owners, here the latest from my side. As Victron came up with the fix (PWM frequency change PCB) for the 5kW models in February, it didn't apply to the 10kW model, so I asked Vicrton about the 10kW models, and in May they came out with an updated doc which now also covers the 10kW MP II, and includes two PCBs to install, one for each fan driver circuit (SPR00090 and SPR00091). Reached out to my dealer asking about the 10kW kit, and got it in about 2 weeks - and as soon as I was back on site (early July), I installed the mods.

Before doing so, I measured the noise with multiple different phone dB meter apps, using couple of load levels (2.5kW and 4.6kW). Didn't bother trying with higher power levels as according to Victron the max cooling noise doesn't change with the mod.

After the mods had been installed, I repeated the same measurements using the same load levels and measuring from the same spot/distance from the unit. I am not posting the dB readings here as I don't think any of the apps I used provided accurate results - however, despite of the actual value maybe being way off the real number, at least the same app should tell the difference in noise level before and after.

To my disappointment, there was very little difference in dB's the sound measurement apps indicated, hard to say if even 1dB overall - however, the kind of noise it makes changed to far more pleasant, just fans humming as others reported, the nasty droning sound is gone!

I then looked at one of the apps which has a spectrum analyzer also, and while these are not exact numbers (pulled estimates from graphs), there is a clear difference downwards, up to 10dB at some frequencies. Here's the difference calculated from two spectrum analyzer graphs (I should have done multiple measurements and use averages to get rid of single sample anomalies, but I didn't, too late now). Take the below with grain of salt...

As said, not very exact science but clearly something changed for better :o). Now the noise is much more tolerable, and closing the door gets rid of the hum, which wasn't the case before the fix.

In summary, I don't say it is perfect, but compared to previous the change is definitely a big improvement and I can live with it now! Still I keep wondering how my 13kW inverter back home doesn't need any fans, just convection cooling and zero noise.

Hi all, is anyone happy with the fan modifcation (noctua)? You can read that the original fan gets replaced by noctua 2000/3000, but I am not sure if this is the major solution.

Hi

Install the free fan upgrade kit from Victron works very well and much quiter now.

Regards
Rob D

NZ

I just got MP II 8000. I def. plan to print a mount to fit a 140mm 2000rpm noctua for the left fan. and I try to do the same for the right fan for the power electronics.
Has anyone tried to mount bitumen mates on the blue Cover - additional.
And does anyone know what the left fan is for? I doubt that the NA relais need them? Just to blow a bit air around?
Thank you for your hints.