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Synapse 3.0V+/Axpert fan mod


jbroo

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So, as others on this forum and online have attested, some Axpert models tend to have noisy fans, with no speed control. They are either on or off, and when on, they are fairly loud. In my case, I don't have a garage or distant room for my installation, so my inverter is installed in close proximity to my bedroom, and the fan noise is somewhat annoying.

I've been studying the fan pattern and it is regular as clockwork - the fans come on at 41°C and stay on until the inverter heatsink temperature drops to 31°C. The fans then turn off, and the temperature slowly increases, until the fans come on again at 41°C. This pattern repeats every 10-15 minutes, ad nauseum, and is something of a design flaw in my opinion. It's a mystery why there is no variable speed on these...

As a proof of concept I rigged a 12V PC case fan to the side of my Synapse, over the top vent, sucking hot air out. I left this on for about 45 minutes.

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The results speak for themselves. The temperature on the unit dropped to 29-30°C and remained there. The inverter's own fans never came on during this period, and the PC case fan is virtually silent.

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It's possible that under heavy load/charging, the temperature might rise enough to trigger the built-in fans, but that would be an exception, not the norm.

I may open up the inverter case and see if I can fit the fan inside permanently (there appears to be space) or get a smaller fan. I think this would ultimately prolong the life of the inverter (running cooler) and the fans (less usage), as well as add to quality of life (less noise).

Has anyone else done something similar? Is there a 12v output on the PCB I could use to power the fan? Currently the plan is to use a 12v adapter connected to a nearby plug.

I will post an update here when I've made a more permanent modification.

Edited by jbroo
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  • jbroo changed the title to Synapse 3.0V+/Axpert fan mod
7 hours ago, jbroo said:

Is there a 12v output on the PCB I could use to power the fan?

5 kVA models have a small connector marked "FAN3", almost as if designed for this purpose. I don't know about other models. If present, it will probably be a 2-pin JST connector.

Be aware that you likely want to have the extra fan drawing air out from the case, i.e. upwards. The factory fans also blow outwards, but are at the bottom, so they pull the air downwards. So unless you invert the factory fans (this will give some benefit on its own as it doesn't go against natural convection), the fans will oppose each other.

This could be a great mod for people with VM models that have to be near living areas.

You could also consider replacing the factory fans with quieter ones, perhaps with silicone mounting kits as well.

 

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I installed the extra fan on the left side vent, albeit I decided to install it in reverse - drawing air into the inverter, so as not to oppose the factory fans when running, and to avoid having to reverse them (and void my warranty). Pleased to report that the results are very similar and the heatsink temperature now idles at about 30°C. The factory fans only activate when charging or when powering the load from battery. This is a great quality of life improvement for anyone who wants to do it, and costs a few bucks to do.

I ended up powering the fan with a 12v adapter from a nearby plug, and fitting it permanently to the side of the inverter. I could not find any additional fan ports inside the inverter, nor a 12v supply I could tap into.

Edited by jbroo
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I have done the same on another inverter (Easun iGrid SV4), but I've used two fans, one on each side. They are blowing air inwards as the original fans are not reversed, so the air is still circulating in the opposite way of natural convection :(. The inverter still runs pretty warm, morning temperature is around 33C yet I've never seen it go above 60C since. The ambient temperature is 22-27C. I would not necessarily call this mod a success (I have expected more) however it more of peace of mind in case the oem fans stop for some reason, there is still something on the forced cooling side operational. I've used two Arctic Cooling P8.

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