FM80 always silent? Power lower limit?

Discussion about the FM100, FM80, and FM60 Charge Controllers

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Jpro556
Forum Member
Posts: 18
Joined: Thu Mar 22, 2018 7:19 pm
My RE system: Two systems:
- Dual Radian 8048's, two FM100's, 10.3kw pv, 12 Simpliphi 3.5's, 1 Kohler 14Resa, 1 Honda EU7000IS
- SystemEdge FP1 3648, FM80, 1 Simpliphi 3.4

FM80 always silent? Power lower limit?

Post by Jpro556 » Thu Dec 20, 2018 1:15 pm

Hi,
I recently replaced a 24v Xantrex system with a new 48v FP1 with FM80 and new 48v batteries.
The array, for the moment is still a couple of old 24v nominal panels. They output 41vdc and 5.5adc several hours per day per my meter. ItÔÇÖs a tiny 220w or so until I get the new panels in.

The FM 80 reads a Voc of 10.1v when the Volts In are 41. It doesnÔÇÖt read any amps in at all.

Is there a lower limit to the amount of power an FM80 can see coming in? I thought an MPPT controller could take any volt/amp combo in and turn it into what is needed to charge the batteries? Is that incorrect?
I see in the documentation something about Volts In needing to be at least .3v above battery voltage to exit sleep mode. Is that the issue?

I could rewire the panels in series but they are in a very difficult location and snow is a problem right now. And IÔÇÖll be replacing them in the spring anyway. Just hoping I can use that 200w I get 5-6 hours per day to offset some of the static load I need to keep running in the cabin.

Am I out of luck?
Thanks

jbakker
Forum Guru
Posts: 217
Joined: Fri Feb 23, 2018 5:47 am
My RE system: 2 VFX3648 Inverters 2 FM60 150VDC Charge Controllers Mate3 3.4 KW of panels 15kw JC Onan NG Generator made in 1975 I love that generator almost as much as my wife.
7 banks of 14 cells each from a 2017 Chevy Volt. Parallel for the AMP Hour. 7 Chinese made BMS systems.
Location: Goderich Ontario Canada

Re: FM80 always silent? Power lower limit?

Post by jbakker » Fri Dec 21, 2018 4:23 am

You need at least above 50 volts comming in to the FM80 for it to charge the 48 volt battery that you have.
You are going to have to install mlore panels.
May also have to find a way to charge battery using the inverter and a Generator as thats the only way your going to keep that battery charged up.

The smarter people here will comment as well.

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