Outback fm 80 charge controller set up

Discussion about the FM100, FM80, and FM60 Charge Controllers

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YardApe03@msn.com
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My RE system: Flex max outback 80

Re: Outback fm 80 charge controller set up

Post by YardApe03@msn.com »

Yes I have it set that way at the moment
2h
But still only seeing 40-50 amps in the system at the most
Think I will have to tie two more panels in parallel to bring it to 8 X425 = 3400 watts 100voc per array to try and get close to 80 amps as possible
raysun
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Posts: 6531
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Outback fm 80 charge controller set up

Post by raysun »

YardApe03@msn.com wrote: Tue Nov 09, 2021 9:08 am Yes I have it set that way at the moment
2h
But still only seeing 40-50 amps in the system at the most
Think I will have to tie two more panels in parallel to bring it to 8 X425 = 3400 watts 100voc per array to try and get close to 80 amps as possible
Hopefully there's an 80A circuit breaker between the charge controller and the battery.

You can probably "get away" with over-paneling the array this time of year, due to your high latitude (and the attendant lower sun angle). However, that is substantially over the 2000W limit @ 24V and could easily destroy the controller in certain conditions. In fact 6 panels @ 2550W is well into the "danger zone".

Long term: a 2nd charge controller is needed.

In the interim, do you have any other MPPT charge controller laying around?
raysun
Forum Emperor
Posts: 6531
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Outback fm 80 charge controller set up

Post by raysun »

In practice, all the solar panel / charge controller gymnastics are due to supporting a 24V inverter. If it was replaced with a 48V inverter, the FM80 should handle 8 425W panels easily.

The battery would charge more effectively as well.
YardApe03@msn.com
Forum Member
Posts: 21
Joined: Tue Nov 02, 2021 3:33 pm
My RE system: Flex max outback 80

Re: Outback fm 80 charge controller set up

Post by YardApe03@msn.com »

Yes I have 80 amp from pv array to controller and an 80 amp breaker between controller and batteries, always well protected that way old electrician
I do have an old 60 amp mppt that you can’t adjust any settings on, that’s who upgraded to the outback 80 fm, could adjust absorption from the 2 hr min
YardApe03@msn.com
Forum Member
Posts: 21
Joined: Tue Nov 02, 2021 3:33 pm
My RE system: Flex max outback 80

Re: Outback fm 80 charge controller set up

Post by YardApe03@msn.com »

Almost better to upgrade the charge controller or add a second one, looked at current in and out seems to be very weak. I hooked up the shunt and voltage seems to be good after coming out of float running 26.6 volts most times or 93% charge, full charge would be 27.2 correct? I’m only getting 30-40 amps outputting to the batteries at best on 1700 watts of panels
I was looking at the outback 100 flexmax which would allow me to tie 2 strings of panels in series I could even bump the panels to 4 each on each string (8 total) which should bump my amps, but if I bought a flex 60 I’d have to parallel 2 so almost better to increase charge controller , I also was looking at the midnite 250v but only out puts 63 amps max
So so many options
I think series 2 strings would give me the max charge for my batteries though, so even with another controller I’d be stuck with only 2 in series, seems I’d have to buy another controller with more voc would be the better option options?
raysun
Forum Emperor
Posts: 6531
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Outback fm 80 charge controller set up

Post by raysun »

The 30-40A output isn't likely caused by the charge controller, rather by the physics of the PV array. 1700W rating @ STC is predicated on ideal lab conditions, rarely duplicated in the real world. The amount of solar energy on the panels, shading of cells, loose connections, and improper wire guage can all limit output.

I'm in Hawaii at 19°N latitude, so the sun is high in the sky year 'round. Even with that, output from the two 3.5kW PV arrays is never consistent. Passing clouds have a big impact. The chargers can be putting 20A into the battery, and literally the next minute, 100A. The STC maximum of 135A is never seen. (At least when I'm watching.) When the sun is intense enough, panel heating reduces output.

My battery is rated at 225A max charge current, but I'm happy with 60A, which seems to be a fairly natural charging point. The two FM80s are set to allow the maximum charge current, and that amount is dictated by the arrays.

In your case, the two parallel strings of gel cells are capable of absorbing max. 150A charge current. Personally, I'd never charge gel cells that "hot". If charging forms gas bubbles on the lead plates, they will push the gel electrolyte away from contact, causing permanent capacity loss. I'd shoot for 85-100A total charge current (50A per string or less) to keep heat and gassing to a minimum.

A 2nd FM80 with another 1700W array would be serviceable for charging. Though, TBH, the 24V limit is really hobbling the ability to operate this system efficiently. Its not mentioned what inverter is being used, but unless its a diamond-encrusted memorial edition signed by Albert Einstein's granddaughter, I'd replace it with a 48V unit and make life a whole lot easier.

A single string of battery blocks is more effectively kept in balance than parallel strings.

The 80A charge controller can handle a 4000W PV array @ 48V.

The 48V battery delivers power more efficiently than a 24V battery delivering the same amount of power.

I'd do the inverter swap WAY before I'd invest $1k in an FM100.
YardApe03@msn.com
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Posts: 21
Joined: Tue Nov 02, 2021 3:33 pm
My RE system: Flex max outback 80

Re: Outback fm 80 charge controller set up

Post by YardApe03@msn.com »

Yes since you put it that way it seems the best way to run things but I have two questions with that
1. I’d have to have several parallel strings that way most likely 4 parallel strings of two which is fine, but wouldn’t 2 strings of 4 series be more efficient, the fm 80 only allows 4 strings of two
2. I would lose amp hours , would reduce from 840 down to 420, how would this effect performance hrs wise then, would 48 v require less juice to run things, less amps is what I’m thinking?? Is that correct?
Thanks again
YardApe03@msn.com
Forum Member
Posts: 21
Joined: Tue Nov 02, 2021 3:33 pm
My RE system: Flex max outback 80

Re: Outback fm 80 charge controller set up

Post by YardApe03@msn.com »

I have a 3000 watt fox power charger /inverter
It’s not a great inverter but pretty decent
What would be a good upgrade for 48v?
raysun
Forum Emperor
Posts: 6531
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Outback fm 80 charge controller set up

Post by raysun »

1. I’d have to have several parallel strings that way most likely 4 parallel strings of two which is fine, but wouldn’t 2 strings of 4 series be more efficient, the fm 80 only allows 4 strings of two
I have two FM80s each with an array of eight 440W panels, in four strings of two panels each for a total of 3500W per array.

Prior, I had twelve 330W panels in each array - six strings of two panels each.

The panel strings were wired to a combiner box and fed to the FM80. At 48V the total array power can add up to 4000W.

The 1700W array could be increased to a 3400W array using the same 2S-4P pattern.

The V(oc) of the individual panels must be taken into account when designing an array. The total series voltage cannot exceed 145V under any circumstance (a cold, clear early morning for example). With 400W+ panels, two in series is generally safest. Three in series *might* work. Four in series is likely trouble.

More parallel strings may have a slight voltage loss over longer series strings, but will be more tolerant overall for shading, delivering higher net charging power. Use 10AWG cable, and keep the runs to the combiner box reasonable (40' or less) and everything will be fine with two in series.
2. I would lose amp hours , would reduce from 840 down to 420, how would this effect performance hrs wise then, would 48 v require less juice to run things, less amps is what I’m thinking?? Is that correct?
The AH is reduced in half, but the voltage is doubled. The battery capacity in kWH remains the same. However, on discharge the 48V battery is more efficient than the equivalent 24V configuration due to the lower current flow. (At higher current, losses due to internal resistance in the battery increase, effectively reducing capacity. See Peukert's Law).
raysun
Forum Emperor
Posts: 6531
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Outback fm 80 charge controller set up

Post by raysun »

YardApe03@msn.com wrote: Tue Nov 16, 2021 6:04 pm I have a 3000 watt fox power charger /inverter
It’s not a great inverter but pretty decent
What would be a good upgrade for 48v?
I'm not familiar with the brand. Most of the Chinese designs are pretty similar, and tend to give middle-of-the-road performance.

Of course, I'll recommend an Outback without reservation if you're willing to spend $2k.

If that's too much, there's a bunch of Chinese units out there.
YardApe03@msn.com
Forum Member
Posts: 21
Joined: Tue Nov 02, 2021 3:33 pm
My RE system: Flex max outback 80

Re: Outback fm 80 charge controller set up

Post by YardApe03@msn.com »

The pv box to the charge controller would have to drop to 6 gauge wire 60amp rated
Also what would be a good recommendation for A 48v inverter?
raysun
Forum Emperor
Posts: 6531
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Outback fm 80 charge controller set up

Post by raysun »

Outback FXR3048A, or VFXR3648A would be my primary recommendations, (and coincidentally, what I use.)

The FXR is a 3kW sealed unit, the VFXR is a 3.6kW vented unit. I use the sealed units (no fan filter to maintain.)

Both are rugged, reliable, have excellent power handling, a great deal of flexibility for off-grid and grid-hybrid use, and very good battery charging from backup generator or grid. Both are compatible with any battery type, including Lithium.
raysun
Forum Emperor
Posts: 6531
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Outback fm 80 charge controller set up

Post by raysun »

YardApe03@msn.com wrote: Tue Nov 16, 2021 6:21 pm The pv box to the charge controller would have to drop to 6 gauge wire 60amp rated
Also what would be a good recommendation for A 48v inverter?
Yes 10ga from array to combiner, and 6ga from combiner to charge controller.
YardApe03@msn.com
Forum Member
Posts: 21
Joined: Tue Nov 02, 2021 3:33 pm
My RE system: Flex max outback 80

Re: Outback fm 80 charge controller set up

Post by YardApe03@msn.com »

This is off topic , but a friend of mine is looking for the idle amps on his inverter
It’s a giandel 2200 watt inverter, I checked the website but there is no information on idle amps, is there a spec sheet somewhere for inverters ?
I’m waiting on my outback 48volt inverter so I’m trying to help others
Thanks
raysun
Forum Emperor
Posts: 6531
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Outback fm 80 charge controller set up

Post by raysun »

YardApe03@msn.com wrote: Thu Nov 25, 2021 2:35 pm This is off topic , but a friend of mine is looking for the idle amps on his inverter
It’s a giandel 2200 watt inverter, I checked the website but there is no information on idle amps, is there a spec sheet somewhere for inverters ?
I’m waiting on my outback 48volt inverter so I’m trying to help others
Thanks
There isn't a comprehensive list, that I'm aware, of specs for the oceans of inverters on the market.

If your friend already has the inverter, perhaps idle current is listed in the owner's manual.

If not, DC battery current could be measured relatively easily with an ammeter.
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