Magnum Inverter Fans

[jenkinswt]

After recently upgrading our solar panels we discovered a new problem. We are running more power through the inverter than before and the transformer is getting hot. I finally decided that there probably wasn't any warranty left on the inverter anyway so I cut the seal and took the cover off and discovered it has 2 small fans side by side and one wasn't working. I can spin it by hand and it will take off but eventually quits again.

For now we've closely monitored it and I have a small table fan I put out there that cools it down.  I'm considering maybe putting in higher flow fans but don't know enough about brands, etc. to know what is decent. Right now they are some chinese brand with a part number ym1209pts1 but even that part number I found they make slightly different fans with the same number. Its 92 x 25 mm 52 cfm (I think) and has a 3 pin connector but the fan only has two wires.

I found a Delta Fan that has ball bearings and 102 cfm. Maybe I'm over thinking all of this but I'm assuming this has actually been bad for awhile and didn't catch it because we weren't using it as hard. If that is the case then the factory fans probably weren't too good to begin with.

Here's the link to the delta fans:
https://www.ebay.com/itm/Delta-92mm-x-25mm-3pin-Extreme-Hi-speed-102-59cfm-12V-fan-EFB0912SH/181269793974

[MagnetJuice]

If you would live close to me, you could find what you need in my basement. I have 3 big boxes full of fans, some used, some new. I am a noise freak, noise drives me crazy, so I'm always replacing the cooling fans on my computers and padding them with resistors to quiet them down. Right now I have 7 working PC's and I've been working on computers for over 23 years. That's why so many fans.

To replace the fan all you need to match is size and voltage. And the amps will determine your RPM and therefore your CFM. If noise is not a problem for you, you can go with a higher AMP/CFM. That will keep things cool and happy.

For the connection, you can cut the connector from the old fan and put it on the new one. You only need to connect 2 wires. One is positive, usually red, and the other negative, usually black. Any extra wires you can cover with tape and leave not connected, they are sensing wires that your inverter doesn't need.

As for brand or quality, I have found that Delta and Sunon are usually better quality. But any fan will last you many years.

If I were you I would replace both fans. The one that is still working could follow his twin brother to the fan graveyard soon.

Ed

[DanG]

Deltas website used to have detailed specs on their product line - static pressure is an important number, push up against that boundary and the fan overspeeds as it is not doing much of any work and becomes a noise generator (halving the RPM speed reduces the noise by about 15 dB)

Anyhow, pressure to volume graphs are available, matching the two fans to a medium impedance profile (mm of H2O) might give the best reward for doing the surgery, hopefully the OEM fan is not a custom unlabeled unit so can lead you to a better match.

[jenkinswt]

I was planning on replacing both as a set because I don't know how good the other one is anyways. As far as putting too big of a fan in there and it speeding up and making noise, is there any issue other than noise? The inverter is in the shed 100' away so....noise isn't an issue, although I wouldn't want it to sound ridiculous! The Delta fans I am looking at are .75 amp and the old one is .4 so about double. Down the road I plan on running more of my diversion heating on the dc side and take a fair load off the inverter. For right now its handy as the water heater is 125' away and I have a scr hooked to a 2000 watt heating element. Were making a ton of hot water when its sunny.

Thank you both for a quick response!

[MagnetJuice]

I did a search and found a fan for Magnum inverters. I don't know which model you have but it matches the number that you gave before.

The part number is 44-0004. Full model number could be MAG-44-0004. It sells for about $10 in many places, especially in marine websites.

Could be a good idea to stay with the original fan because it seems that the fan RPM is controlled by the temperature of the inverter.

Ed

[jenkinswt]

Ya I had found a few places with that same fan as well but had also read a few places online that said magnum fans were junk but not sure. If the general consensus is that I should stay oem or the same size for I will probably do that. I was hoping to put a little bit better flow in there to gain some more life out of the transformer by keeping it cooler but maybe its fine. Oh the inverter is a ms4448pae.

[MagnetJuice]

I don't see a problem with installing a fan with higher amps to get better air flow.
This is what the user manual for that inverter says:

MS4448PAE Inverter Fan Operation

The inverter contains two internal cooling fans that are automatically controlled. The speed of these fans is determined either by internal temperature of the inverter or by the load on the inverter.

The inverter's fans will come on under the conditions listed below:

Fans run full speed if the internal transistors (FETS) or the power transformer reaches 176°F degrees Celsius (80°C), or the inverter is running at 100% of its rated load.

Fans run medium speed if the internal transistors (FETS) or the power transformer reaches 140°F (60°C), or the inverter is running at 50% of its rated load.

Fans run low speed when the inverter is running at 25% of its rated load.

The fans shut down when none of the above conditions are met, or if the battery voltage is below 19.0V (24-volt systems)/38.0V (48-volt systems).


I'm going to run some tests on some of the fans that I have to collect some data.
I'll post the results later.

Ed

[jenkinswt]

That's very useful information! I suppose I could have looked in my manual if I had thought of it. Sounds about right as I can remember a few times in the past putting a heavy load on it and hearing the fans rev up. I also found out today that there is a replacement fan with the part number YW09225012LH made by Y.S. Tech. I'm guessing either the original fans weren't very good or this was just another supplier they found. The new fan is .32 amp and the old one was .40 so basically the same. I'll probably order something this weekend. I look forward to your test data.

[MagnetJuice]

It appears that this inverter controls the RPM of the fan by lowering the voltage supplied to the fan. That seems to be the case because there are only 2 wires on the fan. If this is not the case, there are electronic wizards in this forum that can correct me on this.

Here is an Image of the data that I collected. All the fans for this test were 12 Volts. I'm not sure how useful the data is. I was mostly interested to find out how running the fan with lower voltages affected the fan RPM.


In all cases, if the fan was running very fast and had a good air flow at 12 volts, it also ran fast with a good flow at lower voltages.

Therefore, Jenkins, my conclusion is that it is OK to install a fan with a higher CFM on your inverter.

Since the fan is blowing more air to the transformer and the rest of the electronic components, it will keep the temperature below the triggering point of 176°F degrees. That will keep the fan running at a lower voltage, using less power even though it is a more powerful fan than the original. It will also run quiet since the fan will be running at a reduced voltage most of the time. And it will also keep the electronic components cooler extending their life.

The Sunon fans that I tested seem well constructed and were quiet. Try to get one of those or a Delta. As for amperage try to get something between .6 and .9 amps.

I hope this was useful to you.

ED

[joestue]

add heatsinks to the transformer

[DamonHD]

Rather than lowering the voltage, the fan supply may be PWMed (Pulse-Width Modulated) which is generally nicer for the driver and the fan and avoids wasting so much energy as heat.

Rgds

Damon

[MagnetJuice]

All the fans that I've seen that are controlled with PWM have 4 wires, the third wire for RPM sensing and the forth wire for speed control. Is it possible to control a fan that only has 2 wires with PWM? Could be, I don't know.

Anyways, I found a fan that could be a good candidate for replacing the stock fans of these inverters. It is made by CUI and has the same bearing suspension as the Sunon fans. CUI calls it omniCOOL and Sunon calls it MAGLEV. It is a form of magnetic suspension that keeps the rotor (blades) suspended and centered by the flux of the magnet. They claim that this helps extend the life of the bearing and also runs quieter.
 
The fan number is CFM-9225-13-10. It is sold by digikey for US$9.64. It has a current rating of .4 amps, the same as the original fan. But it has an air flow of 96 CFM compared to 52 CFM for the original. It also has only 2 wires, making it an easy ‘plug ‘n play'.

Ed

[jenkinswt]

I don't think there's room to add any heatsink to the transformer, the back of the inverter is basically a big block of aluminum I believe, and even looks like there might be heatsink compound between the transformer. I think the transformer stays cool enough on its own with no fan if I'm using 1000 watts or so but haven't kept a real close eye on it. Right now all of my electronics are mounted on the wall in a shop which isn't quite finished. Eventually I want to wall off the electronics area and possibly cool it. The charge controller & inverter do throw off a fair amount of heat when its sunny.

Thanks for all the testing you did on the fans and everyone elses help. If I get a chance maybe I will test to see if its controlled by voltage for fan speed. I've ordered the delta fans I linked earlier, when I get them here and installed I will post an update.

[MagnetJuice]

Great! Keep us posted so we all can learn. Hopefully from your success.

Ed

[jenkinswt]

I received the fans today and got them put on right away. They plugged right in without modifying the wiring. I didn't do any testing around, just cleaned dust out and put it all together. They don't make getting the fans out very accessible, kind of a 3 handed 1 person job 

Thanks for all of the replies on the fans. As far as noise, they are much louder than the old ones when at full speed but can't even really hear them when their running slower. I was using the table saw, miter saw, etc. quite a bit in the shed and the hottest I observed was 143 at the transformer. I should have taken pictures, and tested voltages of the fan at different loads but I was busy so I apologize for that. Maybe down the road I will.

[MagnetJuice]

Thanks for the update.

It seems like it is a good idea to replace the stock fans with high CFM one's. An investment of less than $50 can keep a $2000 inverter running cooler and extend its life.

Ed

[jenkinswt]

We had a lot of wind power and sun today and it got pushed pretty hard and I kept checking the temperature. It looks like these fans are rarely needed to run on high but when they do they can bring the temperature down. I think the highest I observed was 172 and that was when it was putting out 4000 watts or more for awhile. I still plan to take some of my loads off the inverter down the road but for now I'm hoping I caught the fan problem before it actually caused any damage to the transformer. I watched a video where they had 3 of these magnum inverters and they were replacing all the fans at once as preventative maintenance after 3 years of use. Seems like a good idea considering the cost of the inverter like you said.