Any way to set a minimum Absorb Time on a FM80

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Surfpath
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My RE system: Outback Flexpower-1-6 system (VFX3048e, FM80, 48v, 50hz, 240v), 2,750w of PV (4 series of 3 panels/ea, 100v max-combiner to controller), 370amp/hr L16REB battery bank. Honda 2k briefcase generator. 100% offgrid.

Re: Any way to set a minimum Absorb Time on a FM80

Post by Surfpath » Mon Apr 01, 2013 3:29 pm

I should have explained that the goal is to get my batteries up to actual 100% SG (1.270/1.275), and then unplug the CAT5 cable from the FNDC to reset it.

I realize that I could have done this simply by performing an EQ. However I wanted to tinker and monitor for myself how the FNDC works. By setting a low RETURN AMP value (2A) I was able to get longer (than the usual 30 minute) absorb times. One day I got 3 hours, the other 4 hours :razz: . I brought up SG's to 1.260.

When I get home tonight I plan to generator charge my battery bank to 1.275 then unplug the FNDC (so that it resets to this new actual 100% SOC).

With my system now realizing this actual 100% SOC I believe I have to then enter in a new end amps value (& not keep the 2A value that 'forced' my system to charge). I will start with 7amps (like I had before), and see how that goes.

gww
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Re: Any way to set a minimum Absorb Time on a FM80

Post by gww » Mon Apr 01, 2013 5:27 pm

Thanks for the update. It sounds like you are learning how it is working and getting close to full charge. I don't have advice but will try to learn from you.
Good luck
gww

Surfpath
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My RE system: Outback Flexpower-1-6 system (VFX3048e, FM80, 48v, 50hz, 240v), 2,750w of PV (4 series of 3 panels/ea, 100v max-combiner to controller), 370amp/hr L16REB battery bank. Honda 2k briefcase generator. 100% offgrid.

Re: Any way to set a minimum Absorb Time on a FM80

Post by Surfpath » Mon Apr 22, 2013 1:30 pm

A wee update:

I've managed to raise Absorb times from an average of 30 minutes a day to around 2 hrs a day. As a result my end of day SG's have improved from an average of 1.245 (and dropping), to consistently about 1.260 /1.265. I still have to perform a lite EQ to get up to 100% SOC (1.275), but only every other week. Consequently I am cycling between 90% and 70% (SG's), rather than the comtinuously dropping 80% -> 60%.

What I did was lower both end amps and return amps to 2A. Simple. But I still have to make a few more tweaks*. The reason why EA and RA are so low now is because (like others have said), my FNDC is not fully aware of 100% chemical SOC. Ie in order to perform a more appropriate absorb charge I had to artifically dial down end amps.

*I believe what I now need to do now is:
a) after one of my lite EQ's when I achieve actual 100% SOC (1.275): unplug the green CAT5 cable from my FNDC for ? 1 minute. When I plug it back in I have been told the FNDC "resets" the SOC to 100%. Is this right? Then
b) reset my end and return amps higher (now that I will have a more accurate SOC). Say raise it to 4 AMPS and see how long absorb runs (and SG's raise)

Am I on the right track?

ps. one other strange finding. In an earlier post I said:
3. On the FNDC Return Amps there is no zero or "00" value, like there is on the CC END AMPS screen (in fact below "1" it annoyingly goes to 999, and you cannot go "up" to return to 1. Yes, I had to hold down the "down" button for something like 10 minutes to return to single digits again. Thus it seems that one cannot turn off the "END AMPS" feature (like I was advised in another forum) by simply entering '00' in the END AMP field, because a FNDC "Return Amp" value will still exist & take precedence over a "00" END AMP value set in the FM80

This weekend I experienced something different when 'playing around' with the same return amps buttons (in ADVANCED--DC). This time, (for whatever reason) I could not go lower than 0.5 RETURN AMPS.

Either way, it still appears that you cannot turn off END AMPS if you have a FNDC connected to your system. The only way to disable end amps (if you need to) is to unplug/disable the FNDC.

I came close to disabling my FNDC :???: Though the verdect is not yet out.

blackswan555
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Re: Any way to set a minimum Absorb Time on a FM80

Post by blackswan555 » Mon Apr 22, 2013 3:55 pm

a) after one of my lite EQ's when I achieve actual 100% SOC (1.275): unplug the green CAT5 cable from my FNDC for ? 1 minute. When I plug it back in I have been told the FNDC "resets" the SOC to 100%. Is this right? Then
Un-plug power cable to it to re-set
I came close to disabling my FNDC :???: Though the verdect is not yet out.
FNDC is good for Generator charging to save fuel but I disable it for solar charging, As long as you manage your water usage and temps correctly there is no such thing as too long an absorb charge in a "normal" off grid environment (Not seasonal) Reasonable periods of "good gassing" will reduce the need for EQ and combat sulphation & stratification, As long as your voltage is not to high, Plate shedding vs reduced maintenance & better bat health/long term capacity, You come out on the plus side :smile:

Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.

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tallgirl
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Re: Any way to set a minimum Absorb Time on a FM80

Post by tallgirl » Mon Apr 22, 2013 8:34 pm

Surf,

The "ending current" value on the FNDC is satisfied whenever the current is =below= the desired value. You need to figure out your "ending current" and set the value accordingly so you'll get the correct "days since full" value. Fiddling around with the numbers will confuse the FNDC and make it not work correctly.
Julie in Texas

I ride bicycles. A lot.

Surfpath
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Posts: 59
Joined: Wed Apr 18, 2012 8:46 am
My RE system: Outback Flexpower-1-6 system (VFX3048e, FM80, 48v, 50hz, 240v), 2,750w of PV (4 series of 3 panels/ea, 100v max-combiner to controller), 370amp/hr L16REB battery bank. Honda 2k briefcase generator. 100% offgrid.

Re: Any way to set a minimum Absorb Time on a FM80

Post by Surfpath » Tue Apr 23, 2013 2:17 pm

blackswan555 wrote:
Un-plug power cable to it to re-set
HI Tim,
On reseting the FNDC:
Is the CAT 5 cable the power cable for the FNDC? From memory the only other cables going to it is a set of thin 'curly' cables going to one common 'din' looking plug.

On disabling the FNDC:
I think one can do this using the Mate screens, right? (or is leaving it unpluged the only way to go)

Hmmm. I've thought several times about going to a "time-based" absorb, rather than a FNDC controlled absorb, but I've always worried about a time based absorb overcharging my bank (say if the weather one day is super bright and cloudless when I am stuck in the office and unable to be at home to turn absorb off).

We have no winter (sunrise and sunset is around 6:30 - varies little), and we typically get 4-6 hours of good sunlight/day. The only seasonal variation is for half the year when we get more clouds/rain (we are entering that period now). Let's say we get 4 hours of decent sun now.

I guess I can just adjust absorb time slightly for these seasonal differences.

My bank seems happiest with a 2-4 hour absorb. Perhaps I should just stop fiddling with the FNDC, turn it off and set a max bulk/absorb time for 6 hours?
-SP

blackswan555
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Re: Any way to set a minimum Absorb Time on a FM80

Post by blackswan555 » Tue Apr 23, 2013 4:16 pm

Is the CAT 5 cable the power cable for the FNDC? From memory the only other cables going to it is a set of thin 'curly' cables going to one common 'din' looking plug.
The "thin" curly looking cables with the green plug on the end ( wires go to bat + - & shunts)

My bank seems happiest with a 2-4 hour absorb. Perhaps I should just stop fiddling with the FNDC, turn it off and set a max bulk/absorb time for 6 hours?
-SP
:grin: Set your absorb for 6+ hours, Keep a very close eye on water usage, When you are happy that 6 hrs is too much, Dial it back by 1/2 hour every few weeks till you get to your "happy place" (Or leave it at 6+ :grin: Warning to anyone who does this, You MUST check water regularly until you know your usage, Letting water go below plate`s is THE WORST thing you can do to your batteries, undercharging them is the second worst lol)

Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.

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