question

iand avatar image
iand asked

Multiplus II 48/10000 external fan control

Does anyone know under what conditions external fans (if connected via the relay and an assistant) are switched on?

The internal fans are variable-speed temperature controlled (noisily!) but any external ones are just on/off. Do they only turn on when the internal ones have reached maximum speed, or at some other point controlled by an internal temperature sensor?

I can imagine the case where with the external fans off the enclosure warms up, then the external fans switch on, which blows cold air in so the temperature drops, so the internal fans slow down and the external fans switch off, and then this repeats.

A (better?) alternative would presumably be to connect the (24V) external fans in parallel with the fans inside the unit so the speeds track -- the internal fans on the 48/10000 draw about 20W total and the external ones would be less than 5W so this shouldn't cause a problem with the driver circuit.

Filtering would be needed for the external fans (2 x Noctua NF-A14 IndustrialPPC-24V-2000) to stop them being as noisy as the internal ones. I'm surprised nobody has tried an LC filter instead of RC because this would avoid the resistor voltage drop -- any reason for this?

Multiplus-IIquattro 10kvafan
11 comments
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Rob Duthie avatar image Rob Duthie commented ·
See the blog about noisy fans this explains all about the issues and fixes.

Regards

Rob D

NZ

0 Likes 0 ·
iand avatar image iand Rob Duthie commented ·

Thanks Rob -- I'd already read that (and all the others...) but I couldn't find a clear description of exactly how/when external fans are turned on and off (e.g. when internal fan comes on, or only when it reaches maximum speed, or something else) -- I'll have another look.

(assuming you mean these threads...)

https://community.victronenergy.com/questions/46137/victron-multiplus-ii-485000-noisy-fan-replacement.html

https://community.victronenergy.com/questions/20665/external-cooling-multi-plus-123000-how-to-setup.html

https://community.victronenergy.com/questions/47486/temperature-at-which-multiplus-fan-cuts-in.html

I'm still surprised nobody has tried an LC filter to remove the noise due to the low-speed PWM but without lowering voltage and rpm due to resistor voltage drop...


0 Likes 0 ·
sharpener avatar image sharpener iand commented ·

Conceptually it's a nice idea but as an electronics engineer I have a big variety of Rs and Cs in the junk box but very few Ls so it's less easy to experiment. Also they tend to be comparatively expensive, and bulky enough to require proper mountings.

0 Likes 0 ·
iand avatar image iand sharpener commented ·
Inductors (especially for low current) are easily available off-the-shelf or simple to wind yourself on a ferrite or metal powder core -- loudspeaker crossovers use them all the time. But they do need fastening down to something...
0 Likes 0 ·
Rob Duthie avatar image Rob Duthie iand commented ·

The LC filter does not work that well and is bulky to fit, my fix is simple and very effective. The problem is Victron very course PWM control is to low a frequency.

Regards

Rob D

NZ

0 Likes 0 ·
iand avatar image iand Rob Duthie commented ·

I'm well aware what the PWM problem is :-)

What is your "simple and effective" fix for the 48/10000, because for this model it's been reported that just adding a capacitor doesn't work (or not very well), and adding a resistor reduces fan speed and therefore cooling effectiveness?

(and doing any of this for the internal fans will void the warranty which I can't risk, which is why I'm only asking about external fans)

Still no reply about exactly *when* the external fans are turned on by the assistant, though... :-(


0 Likes 0 ·
Rob Duthie avatar image Rob Duthie iand commented ·
I changed the fan to another brand and rubber mounted to stop the noisy vibrations.
0 Likes 0 ·
iand avatar image iand Rob Duthie commented ·

I saw that, but didn't you also add a resistor as well as the capacitor, and the new fan plus resistor has lower airflow? Also IIRC this was the 48/5000 model, and others have reported that the same fix doesn't work as well on the 48/10000?

And the guarantee problem remains -- I really wish Victron had thought about this, a quieter cooling solution with proper PWM control (and maybe 140mm fans instead of 120mm) would have cost them next to nothing if they'd designed it in from the start... :-(


0 Likes 0 ·
Rob Duthie avatar image Rob Duthie iand commented ·

Hi

No resistor used, only a small cap and fan change, with a very small airlow change not worth worrying about, this is what i do for my clients installs who complain about it. Have they istalled the rubber dampners?

It is a much quiter unit than before.

Is Victron listning?

Regards
Rob D

NZ

0 Likes 0 ·
iand avatar image iand Rob Duthie commented ·
But is this the 48/5000 or the 48/10000? Others have said this doesn't work with the higher-speed fan on the 48/10000...
0 Likes 0 ·
Rob Duthie avatar image Rob Duthie iand commented ·
I use this mod on the 48/500 models

Fitting rubber dampers will help a lot.

0 Likes 0 ·
1 Answer
raymiller avatar image
raymiller answered ·

I've also added some stick-on sound deading sheeting to the inside cover of my MulitiPlus 2 which also reduced the sound levels. I used this because it was very simple and quick to install and reduced the front panel vibration which is also part of the problem.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.