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Outback upgrade versus total rebuild to all Victron, or other

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kcbuild

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Joined
Feb 11, 2024
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Location
NW Washington
I have a off-grid island cabin running on an Outback system centered on a 24V FX3524 inverter installed in 2007. This is part of an old-school prebuilt system that includes the inverter, AC and DC breaker boxes and the charge controller together on a single mounting plate. Over the years I swapped out to an FM-80 charge controller and a Mate3s so that I could take advantage of Outback’s internet monitoring and control system (Optics RE).

Flash forward to 2024, and the FX3524 continues to chug along, but for a variety of reasons, it is time to upgrade to 48V and lithium. The dilemma I face is that the simplest move would be to buy the modern versions of the Outback FX inverter (VFX3548) and charge controller (FM-100). These could be dropped into place on the existing mounting plate, and with a few breaker swaps, the upgrade would be finished. Another point favoring Outback is that my local solar installer primarily installs Outback systems.

I am wary of Outback though. Over the intervening decades, Outback has been bought and sold several times, and they were just purchased by Big Battery. This has not been widely announced, but the new president of Outback acknowledged the purchase and engaged with the Outback User Forum community recently regarding a nearly-week-long outage of the Optics RE online communication system. Even before this latest sale, I felt like Outback was adrift, especially with respect to the off-grid market. I suspect Outback hardware purchased now would be nearly as robust as their older hardware, but I am particularly concerned about the long-term prospects for Optics RE since remote monitoring and control are critical for my use case.

So, do I go with the simple (and thus less expensive) choice, stick with Outback and roll the dice that the new owners of Outback will support the hardware and monitoring software long term? Or do I look elsewhere? Given my situation, I would like to go with a well-established manufacturer with good remote monitoring and controls. I am already partially in the Victron world on the battery side so it would be a reasonable choice. A Midnite system is also a consideration, but the equivalent Rosie/Classic combo would be pricey, and I’m not sure I can wait until Midnite’s new AIO is available.

I know there is no single right answer here, but any thoughts and suggestions would be appreciated.
 
I like outback, and I'd heard the rumors, but yeah.. Victron. No question. It's actively developed. The owner's son is the CEO and he manages the development of the Venus OS. They have firmware updates on the regular. THe majority of their employees are developers and engineers.

There's been an issue with VRM from time to time, but the good part is that multiple Victron folks are on their community forum (including the CEO) giving updates and an ETA on the fix.

I recently became aware that during the pandemic, Victron experienced explosive growth on the order of 60%, and they recently had a significant price reduction across their offerings.

Yes. I'm a fricken' smurf, but I wouldn't consider any other option EXCEPT maximizing the existing system and avoiding the upgrade altogether. While the FX3524 may not support LFP explicitly, it might be able to be configured to work acceptably with it.
 
Thanks sunshine-eggo. In a way I already have the FX3524 supporting LFP. In order to keep things running over the winter I needed a quick battery fix but was not able to tackle the system as a whole at the time so I opted for Victron 24v 200amp hr batteries x4 paired with the lynx system (and Cerbo), including the lynx smart BMS. I know the LFP Victron batteries are not the cheapest, or necessarily favored even by smurfs, but the fact that they can be put into a series configuration to go to 48V let me hedge my bets. So for now I am running at 24v and have programmed the Outback side of things to charge the Victron batteries, but with the Victron smart BMS standing sentinel ready to shut things down in the event of an over temp or overcurrent scenario (low temp is a bit unclear and something I am trying to clarify). Not to mention the whole issue of fusing at 48 V (the T-class fuse vs. Megafuse debate, again).

I could carry on at 24v for a while, but I also want to upgrade my solar panels. I am in dense trees except one narrow window so I can’t change the square footage, but 2024 panels can nearly double the output in the same footprint compared to 2006 panels so the time seems right. This will necessitate, at minimum, a charge controller upgrade to handle the new PV voltage and amperage ceiling which would be simpler with a 48V upgrade . Also due to State solar incentives, and the typical technology upgrade cascade, I think I have locked myself into a 48V upgrade. If Victron had better fixed-installation, US-friendly, charge controller options, that would help make the decision to go to an all-Victron system easier (nudge..nudge Victron you know you should to do it). Otherwise I may be looking at some odd hybrid of Outback Inverter, Victron battery/BMS and a Victron vs. third party (?midnite) charge controller running at 24V. This seems like a remote-monitoring nightmare in the making.
 
sunshine_eggo said:
dang... you went off the deep end! :ROFLMAO:

Well, since they lowered their prices, they're at least cheaper than Battleborn now.

I'm not following you on the seeming lack of US-friendly charge controller options. What do you mean?
Click to expand...
Yep. Definitely off the deep end. But I can switch from 24 to 48V with just a few cable and fuse changes. It helps that I have a local Victron dealer that I can actually walk in and talk to and get parts and supplies, usually the same day.

I've been watching Victron installation videos on You-Tube and combing the forums as I try to get my mind around an all Victron installation in my setting. What I see is that most of Victron charge controllers seem focused on the mobile market and all lack provisions for conduit which makes for some awkward installations for those trying to meet at least the spirit of North American code in their installations. I was looking at both the Victron VE-panel and the Midnite e-panel available at Current Connected and neither offer a method for mounting a Victron charge controller directly to the box I think because of the design limitations of the charge controllers. As noted on some of the forums, a range of conduit-capable, fan-cooled charge controllers would help address this.
 
kcbuild said:
Yep. Definitely off the deep end. But I can switch from 24 to 48V with just a few cable and fuse changes. It helps that I have a local Victron dealer that I can actually walk in and talk to and get parts and supplies, usually the same day.

I've been watching Victron installation videos on You-Tube and combing the forums as I try to get my mind around an all Victron installation in my setting. What I see is that most of Victron charge controllers seem focused on the mobile market and all lack provisions for conduit which makes for some awkward installations for those trying to meet at least the spirit of North American code in their installations. I was looking at both the Victron VE-panel and the Midnite e-panel available at Current Connected and neither offer a method for mounting a Victron charge controller directly to the box I think because of the design limitations of the charge controllers. As noted on some of the forums, a range of conduit-capable, fan-cooled charge controllers would help address this.
Click to expand...

With native 240v split phase in a single unit also. And get a UL Listing on the LYNX POWER IN busbars already.
 
kcbuild said:
Yep. Definitely off the deep end. But I can switch from 24 to 48V with just a few cable and fuse changes. It helps that I have a local Victron dealer that I can actually walk in and talk to and get parts and supplies, usually the same day.

I've been watching Victron installation videos on You-Tube and combing the forums as I try to get my mind around an all Victron installation in my setting. What I see is that most of Victron charge controllers seem focused on the mobile market and all lack provisions for conduit which makes for some awkward installations for those trying to meet at least the spirit of North American code in their installations. I was looking at both the Victron VE-panel and the Midnite e-panel available at Current Connected and neither offer a method for mounting a Victron charge controller directly to the box I think because of the design limitations of the charge controllers. As noted on some of the forums, a range of conduit-capable, fan-cooled charge controllers would help address this.
Click to expand...

If I go with Victron for another system, I’ll just use my stock pile of Sunny Boy 7.7s and AC couple and not worry about SCCs. If I didn’t have those, I’d look at Fronius line inverters.

Maybe not the most efficient system overall, but shines in the sunshine.
 
kcbuild said:
Yep. Definitely off the deep end. But I can switch from 24 to 48V with just a few cable and fuse changes. It helps that I have a local Victron dealer that I can actually walk in and talk to and get parts and supplies, usually the same day.

I've been watching Victron installation videos on You-Tube and combing the forums as I try to get my mind around an all Victron installation in my setting. What I see is that most of Victron charge controllers seem focused on the mobile market and all lack provisions for conduit which makes for some awkward installations for those trying to meet at least the spirit of North American code in their installations. I was looking at both the Victron VE-panel and the Midnite e-panel available at Current Connected and neither offer a method for mounting a Victron charge controller directly to the box I think because of the design limitations of the charge controllers. As noted on some of the forums, a range of conduit-capable, fan-cooled charge controllers would help address this.
Click to expand...

Ah... Well, they're spendy as shit, but the RS450/100 or /200 address your concerns.
 
Ampster said:
I still don't see any indication that Enersys sold off Outback. I assume Neipert left Big Battery to become CEO of Outback.
Click to expand...
I used the wayback machine to confirm that Enersys did remove Outback from their "family of products" on their website sometime around March or April this year.

What I'm more confused about is the relationship between Signature and Big Battery.
 
I was running a Radian with Flexmax controllers and an FLA battery bank. I am now running a Sol Ark and lithium.

Here is what I learned: If you stick with an Outback inverter like a Radian 48 volt, the onboard charger does not directly communicate with lithium batteries. But it will charge them just fine IF:

Batteries such as Pytes offer directions for configuring the Outback Power onboard chargers for Outback inverters and Flexmax charge controllers. After those settings are made on the Outback side, the BMS of the Pytes secures proper charging.

So a simple upgrade would be to a 48 volt Radian and lithium stack keeping your Flexmax chargers and combiner boxes intact.

Otherwise, in my case, I wanted to upgrade to a high voltage MPPT charge controller and a closed loop lithium battery system for ease of use by other persons if I am unable to maintain system. I chose Sol-Ark for this task. BUT, at my combiners, I hade to remove the lower voltage parallel PV strings and replace with a single serial high voltage string. This meant new breaker in the combiner box, new fuses in the combiner box and a new DC disconnect switch. All needed the proper amperage as well as 600 VDC ratings, not 250VDC ratings. So that was extra work. Also my Midnite surge protectors were all upgraded to 600 VDC at the combiners.

But once done, the new closed looP system works great.
 
Last edited:
kcbuild said:
Yep. Definitely off the deep end. But I can switch from 24 to 48V with just a few cable and fuse changes. It helps that I have a local Victron dealer that I can actually walk in and talk to and get parts and supplies, usually the same day.

I've been watching Victron installation videos on You-Tube and combing the forums as I try to get my mind around an all Victron installation in my setting. What I see is that most of Victron charge controllers seem focused on the mobile market and all lack provisions for conduit which makes for some awkward installations for those trying to meet at least the spirit of North American code in their installations. I was looking at both the Victron VE-panel and the Midnite e-panel available at Current Connected and neither offer a method for mounting a Victron charge controller directly to the box I think because of the design limitations of the charge controllers. As noted on some of the forums, a range of conduit-capable, fan-cooled charge controllers would help address this.
Click to expand...
You may want to consider the rs450/100 and 200 SCCs, should work fine with conduit. Fan cooled, PV is isolated from the battery, two or four trackers, few other niceties.

20240524_084317.jpg
 
glandpuck said:
....the onboard charger does not directly communicate with lithium batteries. But it will charge them just fine....
Click to expand...
That was my beef with Outback, because of their affiliation with Enersys they did not open their communication protocol to other batteries or BMSs. Clearly any configurable charger will charge just fine. To me there is value in closed communications between inverter and battery.
 
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Remember the parallel and serial ports on personal computers? Then some persons came up with USB plug and play communications and the old ports went by the wayside. Remember Sony Betamax? They wanted to keep it closed to themselves. So VHS was invented and used by all the competitors and eventually Sony had to switch to VHS too.

Closed loop for lithium battery banks is wonderful, a great time saver and requires little to no hardware knowledge.
 
I am reviving this post to ask a specific question about what is turning into a slow upgrade to an all Victron system, specifically about replacing an Outback FM80 CC with a Victron Smart Solar MPPT 250/100. Background details are below for those interested but the bottom line is I am trying to figure out if I can wire in the Victron MPPT into the Outback DC panel in the same manner that the Outback FM80 is wired in. The FM 80 PV neg and battery neg are bonded internally as per the image below so there is only a single negative in (at battery neg) on the charge controller and in the wiring box the PV- and battery neg share a single bus bar as per attached schematic. There is not even a PV- bus bar as part of the prewired DC panel. The shunt for the PV side of system is also integrated with the shared negative bus.

From what I can tell the Victron MPPT 250/100 likely also has nonisolated PV/battery neg (unlike the RS series). If this is the case it seems like I could just wire in the Victron MPPT 250/100 to match the wiring of the Outback FM80. Am I correct in this thinking and if so is there any downside to doing this?

Background details:
As noted in my original post, I have a off-grid island cabin running on an Outback system centered on a 24V FX3524 inverter installed in 2007. This is part of an old-school Outback prebuilt system that includes the inverter, AC and DC breaker boxes and the charge controller together on a single mounting plate. I have am on a slow upgrade path with a recent switch to Victron Smart Lithium batteries and new solar panels. I have been holding on the inverter/CC side of things, waiting to see if Outback was going to be be successfully reconstituted under new ownership (not looking great, mostly radio silence. See the Outback user forum for some pretty bleak posts). Was also interested in the where Midnite was heading with their new AIO and batteries. Looks intriguing, but the Midnite AIO is a beast, bigger and more featured than I need, and I am already down the Victron Smart Lithium rabbit hole so Midnite is not a great option for me. So this is likely a slow conversion to an all Victron system but I am going to do it a bit piecemeal as I have time a figure out what the best configuration would be.

I think my next move will be replacing the Outback FM80 charge controller with a Victron Smart Solar MPPT 250/100 in large part to leverage the communication with the Victron Smart BMS for low temp "no charge protection" which I can not directly set up on the Outback FM80. The Victron will also take care of the significant "clipping" I have with FM80 and strong solar days. I could probably get away with an MPPT 150/100 but if we match the historical local low temp some year the Max VOC could just barely exceed 150V.

Current set up:
Off grid remote Cabin
Currently running at 24V nominal but will likely move to 48V in future
Silfab 410HCx6 (3S2P)=2460W, VOC 137V, Max VOC at record low temp ~153V. MPPT output at 24V=102.5 amps
Victron 24v 200amp hr batteries x4->
Lynx Distributor in->Lynx Smart BMS->Lynx Distributor out (M8 versions)->
Outback 3524VFX and Outback FM80 Charge Controllers
 

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kcbuild said:
I am reviving this post to ask a specific question about what is turning into a slow upgrade to an all Victron system, specifically about replacing an Outback FM80 CC with a Victron Smart Solar MPPT 250/100. Background details are below for those interested but the bottom line is I am trying to figure out if I can wire in the Victron MPPT into the Outback DC panel in the same manner that the Outback FM80 is wired in.
Click to expand...

Yes. Connect it exactly as the FM80 is, and the 250/100 has a chassis grounding screw that should be bonded to your AC ground.

There is no need to ground the DC (-) to the structure's AC ground/earth system. Code only requires DC grounding above 60V system voltage.

I will admit that I do not have even a tenuous grasp on the variety of BMS options for Victron batteries. Their cost and complexity of options has pushed me in the DIY direction. If your goal is to get low temp charging protection, I'm confident there's a means to do so with their BMS options, but I can't advise.

One thing I KNOW for certain is the use of a Smart Battery Sense, BMV-712 (with temp sensor), or smartshunt (with temp sensor) can supply the MPPT with valid battery temperature data in a VE.Smart network (bluetooth) that can be used to engage the MPPT's low temp charge protection feature.

kcbuild said:
I think my next move will be replacing the Outback FM80 charge controller with a Victron Smart Solar MPPT 250/100 in large part to leverage the communication with the Victron Smart BMS for low temp "no charge protection" which I can not directly set up on the Outback FM80. The Victron will also take care of the significant "clipping" I have with FM80 and strong solar days. I could probably get away with an MPPT 150/100 but if we match the historical local low temp some year the Max VOC could just barely exceed 150V.

Current set up:
Off grid remote Cabin
Currently running at 24V nominal but will likely move to 48V in future
Silfab 410HCx6 (3S2P)=2460W, VOC 137V, Max VOC at record low temp ~153V. MPPT output at 24V=102.5 amps
Victron 24v 200amp hr batteries x4->
Lynx Distributor in->Lynx Smart BMS->Lynx Distributor out (M8 versions)->
Outback 3524VFX and Outback FM80 Charge Controllers
Click to expand...

Yeah. 137Voc is too high. I upgraded from a 150/100 to a 250/100 when I realized 135Voc was too high for our -6°F. The extra 20A should allow you to fully utilize your array with some headroom. It's also very tolerant of over-paneling. Just keep your Voc under 250A and your array Isc under 70A. Guessing your Isc around 11.5A, you could put a 4S6P array of those panels on your MPPT and be within limits. You'd clip the crap out of it, but it can handle it.
 
sunshine_eggo said:
Yes. Connect it exactly as the FM80 is, and the 250/100 has a chassis grounding screw that should be bonded to your AC ground.

There is no need to ground the DC (-) to the structure's AC ground/earth system. Code only requires DC grounding above 60V system voltage.

I will admit that I do not have even a tenuous grasp on the variety of BMS options for Victron batteries. Their cost and complexity of options has pushed me in the DIY direction. If your goal is to get low temp charging protection, I'm confident there's a means to do so with their BMS options, but I can't advise.

One thing I KNOW for certain is the use of a Smart Battery Sense, BMV-712 (with temp sensor), or smartshunt (with temp sensor) can supply the MPPT with valid battery temperature data in a VE.Smart network (bluetooth) that can be used to engage the MPPT's low temp charge protection feature.



Yeah. 137Voc is too high. I upgraded from a 150/100 to a 250/100 when I realized 135Voc was too high for our -6°F. The extra 20A should allow you to fully utilize your array with some headroom. It's also very tolerant of over-paneling. Just keep your Voc under 250A and your array Isc under 70A. Guessing your Isc around 11.5A, you could put a 4S6P array of those panels on your MPPT and be within limits. You'd clip the crap out of it, but it can handle it.
Click to expand...
Thanks Sunshine_eggo. That is very helpful.

There is already a DC negative ground in place. I thought I would keep that for now unless it seems like I should do otherwise. I guess in that case one question is where to land the Victron MPPT chassis grounding screw, DC or AC grounding side?

The Outback AC and DC wiring boxes are pretty beefy and well-equipped with bus bars and circuit breakers/slots and I might keep them in play even when I get around to completing the upgrade with a Victron inverter (some Victron blue paint may be required to address the early-21st century Outback forest green). Either way I will eventually need to deal with the question of grounding and the multiple ground rods scattered across the install as per common practice at the time of initial installation, especially since the inverter/battery shed, solar panels and cabin/main AC panel are all about 100-150ft apart and there might(?) be a role for more than one set of ground rods in that scenario. That will be some questions for another time.

A more pressing question is breaker and wiring for the Victron MPPT. For the short runs of cable from the MPPT to the DC wiring box landing sites I thought I might as well upgrade to 2AWG thin stranded wires as per Victron specs (wires are currently 6AWG multistanded but not fine stranded), although I suspect 4AWG would be fine. The current 80amp breaker on the PV in side should be fine, but I think the PV out side needs to be upgraded. As long as I stay in 24v mode, I thought I would need to upgrade to an Outback 125 amp DC breaker to match the MPPT output. Sound correct?

On the BMS/ low temp charging front, I think now that I will be all Victron on the DC side, that will be well coordinated via the Cerbo. My understanding is that the Lynx smart BMS monitors the individual cell temperatures and will shut down the MPPT charging as needed based on low temperature. For non-Victron charge controllers the smart BMS has a "do-not-charge" dry contact out; it's just that the Outback FM80 has no input to accept the "do-not-charge" command so I was going to have to rely solely on keeping the batteries warm, with no failsafe in place. I am currently planning out a battery warming solution, but I did not want that to be the only line of defense for a remote, part-time cabin so I will be glad when I get the Victron MPPT in place.

Thanks again for the help!
 
kcbuild said:
Thanks Sunshine_eggo. That is very helpful.

There is already a DC negative ground in place. I thought I would keep that for now unless it seems like I should do otherwise. I guess in that case one question is where to land the Victron MPPT chassis grounding screw, DC or AC grounding side?
Click to expand...

If DC negative is already grounded, that means your AC and DC grounds are the same, so it technically shouldn't matter.

The preference is to run a ground wire from the chassis screw to the AC ground that is connected to an earth rod.

kcbuild said:
The Outback AC and DC wiring boxes are pretty beefy and well-equipped with bus bars and circuit breakers/slots and I might keep them in play even when I get around to completing the upgrade with a Victron inverter (some Victron blue paint may be required to address the early-21st century Outback forest green). Either way I will eventually need to deal with the question of grounding and the multiple ground rods scattered across the install as per common practice at the time of initial installation, especially since the inverter/battery shed, solar panels and cabin/main AC panel are all about 100-150ft apart and there might(?) be a role for more than one set of ground rods in that scenario. That will be some questions for another time.
Click to expand...

Everything above the ground (dirt) bonded.
Everything below the ground (dirt) bonded.
ONE connection from above ground to below.

Worth watching link #7 in my signature from the timestamp linked.

No ground rods at array. Run a ground conductor from the panel frame along with the PV wires back to the system ground.

kcbuild said:
A more pressing question is breaker and wiring for the Victron MPPT. For the short runs of cable from the MPPT to the DC wiring box landing sites I thought I might as well upgrade to 2AWG thin stranded wires as per Victron specs (wires are currently 6AWG multistanded but not fine stranded), although I suspect 4AWG would be fine. The current 80amp breaker on the PV in side should be fine, but I think the PV out side needs to be upgraded. As long as I stay in 24v mode, I thought I would need to upgrade to an Outback 125 amp DC breaker to match the MPPT output. Sound correct?
Click to expand...

With a 2P array, you don't need any fusing or breakers to protect the wire. PV wire should be sized for 1.25X array Isc and fused for 1.25X that value if your array is 3P or more. In a single string or 2P, the panels themselves will act as fuses before the panel wires will burn up. In 3P or greater arrays, a short circuit of two strings through a 3rd string (or more) could exceed the panel wire rating and cause the panel wire to catch fire.

I relax the fine strand requirement on the PV input of the MPPT because it's lower current than the output, but it is very important to properly secure the wire in the terminals.

100A fine strand wire from MPPT to battery with 125A fuse/breaker.

kcbuild said:
On the BMS/ low temp charging front, I think now that I will be all Victron on the DC side, that will be well coordinated via the Cerbo. My understanding is that the Lynx smart BMS monitors the individual cell temperatures
Click to expand...

Probably not all cells within the battery, but probably the battery temperature in 2 locations.

kcbuild said:
and will shut down the MPPT charging as needed based on low temperature. For non-Victron charge controllers the smart BMS has a "do-not-charge" dry contact out; it's just that the Outback FM80 has no input to accept the "do-not-charge" command so I was going to have to rely solely on keeping the batteries warm, with no failsafe in place. I am currently planning out a battery warming solution, but I did not want that to be the only line of defense for a remote, part-time cabin so I will be glad when I get the Victron MPPT in place.
Click to expand...

From the Lynx Smart BMS manual:

Low temperature or high cell voltage cut off

If a cell voltage becomes too high and has reached the high cell voltage threshold (3.75V hard coded in battery), or if the low temperature threshold (adjustable in battery) has been reached, the ATC contact opens and will turn off all chargers. If the Lynx Smart BMS is connected to a GX device, DVCC compatible chargers that are connected to the same GX device will be turned off as well.


It should be pretty straightforward provided you configure it properly and have both the Lynx and the MPPT connected to the Cerbo with DVCC enabled.
 
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