Flexmax 80 getting hot - fan LOUD - 2 weeks old

Discussion about the FM100, FM80, and FM60 Charge Controllers

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Clem Jonze
Forum Member
Posts: 20
Joined: Sun Apr 05, 2015 12:32 pm
My RE system: 12 - 300 Watt ReneSola Panels. 48 Volts - Connected 4 strings of 3 @ 120 Volts each string. Midnight Solar Combiner box, 15 amp breakers - 1 each per string. FlexPower 1 3048. (FlexMax 80, Mate 3, HUB 4, Flexnet DC. Firmware version, (as of 05/28/2015 003.009.000. 8 - (wired in series) Deka L16 375 AH Batteries. The whole RE system lives in a "solar shed" located in the back yard, panels facing South - South West. 4 to 5 hours of full sun per day. Sub panel with 50A breaker that runs to House Main Panel. (ground bond removed from Flex Power 1 - Ground Bond @ Home Main Panel) No 240 V requirements - all 110 Volt.
Location: Hilo, Hawaii

Flexmax 80 getting hot - fan LOUD - 2 weeks old

Post by Clem Jonze » Sat Apr 25, 2015 6:37 pm

Aloha from Puna on the Big Island!

We're a couple weeks off grid now with our FlexPower 1 system. The build was much easier than anticipated, (I work on commercial and residential electrical systems), but the FM 80 charge controller seems to be running hot. The cooling fan is very LOUD and literally runs at full power all day.

Setup:
12 Renesola 300 W panels. 4 strings of 3 panels, (producing 120 DC volts) running thru individual 15A breakers in a 6 space Midnight Solar combiner box. Using the "string sizing tool" I seem to be well within optimal operational voltages.

FlexPower 1 (2015 build, prewired with the Mate3 - latest firmware)

48 Volt system, using 8 L16 Deka Solar Batteries.

In the morning, the battery level is generally around 75 percent, with "float" achieved around 3 in the afternoon. On the weekends, (when the wife runs a washer/dryer/vacuum/etc, I will run our Honda inverter generator for a couple hours if it is cloudy.

All in all, the system is highly functional - except for a perceived issue with the Flexmax80 charge controller. The thing runs hot. The cooling fan comes on pretty much soon as the panels begin moving electrons, and does not shut off until a half hour into the "sleep" cycle.

My spider sense tells me something is wrong...but all physical indicators are green.

Thanks in advance for any thoughts, ideas or assistance!

Aloha,

Chuck

Vic
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Re: Flexmax 80 getting hot - fan LOUD - 2 weeks old

Post by Vic » Sat Apr 25, 2015 6:53 pm

Hi Clem, Welcome to the Forum.

Your string voltage is pushing the limits of the input voltage to the FM Charge Controller (CC).

A relatively high Vin reduces the efficiency of the CC a bit. This results in more heat that the CC needs to get rid of. The fan helps the CC do this.

If the ambient temperatures around the CC are a bit high, this magnifies the issue.

You could have gotten away with running only two PVs in series for a string voltage of about 73 volts, instead one of about 108 volts.

I, too run three real 24 volt PVs in series, for a string Vmp of about 106 volts. When in Float, the string voltage rises to about 122 V, or so, with light loads. But, have chose to run A/C in the power room to reduce the average ambient temps.

This fairly constant fan run situation is not abnormal, given your relatively high Vin to the CC, and probable fairly ambient temps around the CC.

Just my experience, FWIW, Vic
4/20/08: 18 Shell SQ 175-106 Vmpp, Stacked 5548 SW+, 1350 AH Surrette 4KS25's, MX-60, Kubota SQ-3250 25 KVA Polyphase Diesel genset. Thanks OutBack for this Forum + the great Support and Service.

Clem Jonze
Forum Member
Posts: 20
Joined: Sun Apr 05, 2015 12:32 pm
My RE system: 12 - 300 Watt ReneSola Panels. 48 Volts - Connected 4 strings of 3 @ 120 Volts each string. Midnight Solar Combiner box, 15 amp breakers - 1 each per string. FlexPower 1 3048. (FlexMax 80, Mate 3, HUB 4, Flexnet DC. Firmware version, (as of 05/28/2015 003.009.000. 8 - (wired in series) Deka L16 375 AH Batteries. The whole RE system lives in a "solar shed" located in the back yard, panels facing South - South West. 4 to 5 hours of full sun per day. Sub panel with 50A breaker that runs to House Main Panel. (ground bond removed from Flex Power 1 - Ground Bond @ Home Main Panel) No 240 V requirements - all 110 Volt.
Location: Hilo, Hawaii

Re: Flexmax 80 getting hot - fan LOUD - 2 weeks old

Post by Clem Jonze » Sun Apr 26, 2015 12:26 pm

Hey Vic and thanks for the reply!

Going thru the mate settings for the hundredth time, I found the Charger Current Limit setting on the FM 80 = 0.1

Is it possible the heat I am experiencing may be the CC choking down heavily on a limiter?

Seems this setting should be significantly higher.

Chuck

Vic
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Re: Flexmax 80 getting hot - fan LOUD - 2 weeks old

Post by Vic » Sun Apr 26, 2015 4:46 pm

Hi Chuck,

Have never needed/used any Mate (do not use OB Inverters), so I do not know how to interpret that 0.1 value. But it seems to me that if that is the Current Limit of the CC in amps (ie, 0.1 A), that you would know it, as the batteries will not get any effective charge at all. Have not seen a CC that allows 0.1 A resolution of Current Limit on CCs.

OK, in full sun, with the CC in Bulk. What is the current displayed on the FM's main status screen? What is the Vin to the CC?
Does the fan run when the CC is in Bulk (?) ... guess that it must.
What is the approximate ambient temperature of the area where the FM CC is located?

More later, Thanks, Vic
4/20/08: 18 Shell SQ 175-106 Vmpp, Stacked 5548 SW+, 1350 AH Surrette 4KS25's, MX-60, Kubota SQ-3250 25 KVA Polyphase Diesel genset. Thanks OutBack for this Forum + the great Support and Service.

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Kurt Lundquist
Alpha Energy Engineering
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Joined: Tue May 31, 2011 7:23 am
My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank
Location: Arlington, WA

Re: Flexmax 80 getting hot - fan LOUD - 2 weeks old

Post by Kurt Lundquist » Mon Apr 27, 2015 1:27 pm

4 x 72 cell modules in series is way too much voltage for the FM80. The module Voc X modules in series should be <145VDC. Regardless that shouldn't cause your fan to run non stop and be really loud. I suggest you take the little plastic cap off the top of the FM80 and look to see if part of the shroud is touching the fan blades. I assume you have heard the fan sound from a different FM80, or FM/MX60 in the past as a point of comparison for what is loud. In standard operation the fan is more than happy to tell you that it is working, even if you are in another room (or two) away from it. The FM fan is a higher pitch but about the same volume as the external inverter fan. If you want to hear the external inverter fan go to the Inverter Auxillary menu and press ON to turn the AUX port on. Make sure to press Auto when you are done so the inverter can turn the fan on/off when it needs to.

-Kurt
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/

Clem Jonze
Forum Member
Posts: 20
Joined: Sun Apr 05, 2015 12:32 pm
My RE system: 12 - 300 Watt ReneSola Panels. 48 Volts - Connected 4 strings of 3 @ 120 Volts each string. Midnight Solar Combiner box, 15 amp breakers - 1 each per string. FlexPower 1 3048. (FlexMax 80, Mate 3, HUB 4, Flexnet DC. Firmware version, (as of 05/28/2015 003.009.000. 8 - (wired in series) Deka L16 375 AH Batteries. The whole RE system lives in a "solar shed" located in the back yard, panels facing South - South West. 4 to 5 hours of full sun per day. Sub panel with 50A breaker that runs to House Main Panel. (ground bond removed from Flex Power 1 - Ground Bond @ Home Main Panel) No 240 V requirements - all 110 Volt.
Location: Hilo, Hawaii

Re: Flexmax 80 getting hot - fan LOUD - 2 weeks old

Post by Clem Jonze » Mon Apr 27, 2015 4:05 pm

Hey Kurt!

Thanks for your thoughts. To clarify, I have four strings of three panels. (12 panels total)
Open voltage is around 120v. Connected, my voltage runs around 114 - 117 depending on sun. Outback says this setup is within spec.

If it is more better to have six strings of two panels, I don't mind buying a couple breakers and cable! Will be kind of a PITA to reach some of the connectors though.

Been cloudy here in the jungle for the last few days. I'll post the actual stats later today, if the full sun comes out.

It just seems the CC is working really hard and charging takes way longer than calculated.

Honestly, the whole setup was too easy....there must be something wrong! (Ha!)

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