FM80 fan failure

Discussion about the FM100, FM80, and FM60 Charge Controllers

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LorenAmelang
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FM80 fan failure

Post by LorenAmelang » Mon Sep 09, 2013 6:52 pm

My water pump runs to fill large tanks whenever the battery voltage is decent, and I've been getting behind on pumping water the last few days. Today I discovered my FM80 cooling fan frozen, heatsink at 124F, and output limited to ~400 W. Any single bank of panels produced ~300W, but adding more banks did not proportionally increase output. Adding an external fan beyond the top air vent (duct tape is wonderful stuff) increased output to ~800W. By the time I figured out the internal fan was solidly frozen and fighting my new airflow, the sun was going away. Outback is supposedly sending me a new fan.

Turns out the UTEC CFM7254 AT6025L-12FH2B-PD7 860mA 12VDC fan has a molded boss ~5/16" diameter around the moving rotor end of the metal shaft, which fits closely inside a mating cylinder projecting from its bearing and coil assembly. Mine fit much too closely, eventually creating enough friction to stall the rotor and burn out the motor coils. I had thought ever since the unit was new that the fan sounded like it was grinding grit instead of rolling smoothly on ball bearings. Turns out that was exactly right.

My FM80 is from 2009, or maybe earlier (it was a factory replacement for the one I bought in 2009). I have no idea how long that particular fan was used. It looks like a nice ball bearing fan, probably one of the "new high quality ball bearing fans" people were talking about back then. Except for the tight-fitting plastic...

If your FM80 fan sounds like it is working too hard, and stops too quickly when the power goes off instead of coasting smoothly to an eventual stop, you might want to check the rotor friction. Might save yourself running low on power on the hottest day yet this summer.

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MyEnergyWarehouse
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Re: FM80 fan failure

Post by MyEnergyWarehouse » Tue Sep 10, 2013 10:25 am

Thank you for the tip. I'm sorry to hear of your fan failure

offgridmainac
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My RE system: FLEX MAX 80 , 4 KW OF PV POWER, 450 AH, 2500 WATT INVERTER.

Re: FM80 fan failure

Post by offgridmainac » Thu Aug 28, 2014 4:52 pm

A goof practice is always to have an spare fan Like I do, The weak link on all Charge controller are the little 12 vdc fans, If your charge controller is overheating often turning the fans to run to much will end up running for so long that eventually, the fan will die failing to do the job of cooling. Once in a while make sure the fan works if not replace it or have and additional external fan that you can control manually of also by using a thermal switch. That will cool of the Charge controller and will keep the inner fan working as less as possible.

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