Outback Inverter - disable transfer switch?

lotw33
lotw33 Registered Users Posts: 4
in Advanced Solar Electric Technical Forum #1
I am considering replacing a Samlex inverter and IOTA battery charger with an Outback off-grid inverter at a remote cabin. Currently the IOTA charger is used to charge the batteries from a small 3000 watt generator occasionally when the sun isn't shining. From what I gather, if I connect the generator to the Outback's AC input it will switch the load to the generator when it's running. Is there any way in the Outback to disable the transfer switch so that the load always runs off inverted power while the built in charger charges the battery bank? I don't really want the loads switching back and forth between inverter and generator, and don't like the dirty generator power running my loads anyway. I thought about using the IOTA for charging instead of the Outback, but I would be changing the battery bank from 24V to 48V with this inverter upgrade, so I won't be able to use the current IOTA. I would be getting the Mate3 as well, but didn't find any settings which describes my scenario in the manual.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,626 admin
    #2
    Re: Outback Inverter - disable transfer switch?

    Make sure you get the "correct" inverter... There are those intended to run from AC utility power, and others that will work on a generator (more variable frequency/voltage).

    The latest AC Inverter-Charger option is generator support. The inverter does not really "switch" between inverter and generator. Instead, the AC inverter's charger sync's up with the AC input and starts drawing current from the generator to recharge the battery bank.

    As your AC loads increase, the AC inverter-charger cuts back on current going to charging the battery bank.

    And if your AC loads surpass the AC rating of the genset, the inverter-charger starts to support the AC loads instead (discharging the battery bank). You can have a smaller genest+AC inverter and support large/surging loads pretty nicely.

    So--In the above case, you cannot select AC generator or AC inverter power--It is a blended result to the loads. Of course, if the AC generator/mains "go away", the inverter takes over and supplies battery powered AC to your loads.

    Is your generator power that "unstable" that you do not want to subject your AC loads to generator power "ever" (in normal operation)?

    In general, if you need to isolate your AC loads from the genset, you will need a separate AC battery charger (like the Iota). As far as I know, most (all?) AC Inverter-Chargers use much of the same hardware for both AC inverter and Charging--So they cannot really "isolate" Generator to AC load and recharge at the same time.

    -Bill "not an expert" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    #3
    Re: Outback Inverter - disable transfer switch?
    lotw33 wrote: »
    Is there any way in the Outback to disable the transfer switch so that the load always runs off inverted power while the built in charger charges the battery bank? I don't really want the loads switching back and forth between inverter and generator, and don't like the dirty generator power running my loads anyway.

    There's no real switching back and forth between charging and inverter. There's a relay that closes when the grid/generator is available, but the inverter/charger is always on. In inverters like the Outback the charger and the inverter use exactly the same circuitry, so you can't have one without the other.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Outback Inverter - disable transfer switch?
    lotw33 wrote: »
    I am considering replacing a Samlex inverter and IOTA battery charger with an Outback off-grid inverter at a remote cabin. Currently the IOTA charger is used to charge the batteries from a small 3000 watt generator occasionally when the sun isn't shining. From what I gather, if I connect the generator to the Outback's AC input it will switch the load to the generator when it's running. Is there any way in the Outback to disable the transfer switch so that the load always runs off inverted power while the built in charger charges the battery bank? I don't really want the loads switching back and forth between inverter and generator, and don't like the dirty generator power running my loads anyway. I thought about using the IOTA for charging instead of the Outback, but I would be changing the battery bank from 24V to 48V with this inverter upgrade, so I won't be able to use the current IOTA. I would be getting the Mate3 as well, but didn't find any settings which describes my scenario in the manual.

    No this is not possible. An inverter-charger operates either as an inverter or as a charger; it cannot do both at once. NO inverter can.

    Nor would you want to because even if you did the power going to the battery for charging would be coming back out again through the inverter to power loads. This is how it happens with a stand-alone charger and inverter and you actually use more power that way.

    You will not notice the switching with an Outback; it is totally undetectable. If your generator power is that far off, get a different generator.
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  • lotw33
    lotw33 Registered Users Posts: 4
    #5
    Re: Outback Inverter - disable transfer switch?

    Thank you very much for the info guys. I don't think I would be able to find that anywhere in the manuals for the inverters.

    I assume when you say "correct inverter" that you mean one meant for off-grid use such as the FX3048T or VFX3648? Out of these two I think I'd be leaning towards the FX, because I'm assuming that the FX should be quieter (less fan noise). Less noise is a bigger consideration than an extra 600 watts of power. Am I making a correct assumption that the FX is quieter?

    It sounds like there wouldn't even be any noticeable switching from the standpoint of the loads. In the past I find it annoying when the transfer switch kicks in and any electronics like computers, satellite or stereo either glitch out, freeze or reboot. It doesn't sound like that would be an issue with the Outback. I guess I can see how my loads react to being supplied by the generator and generator/inverter, hopefully the generator power isn't as dirty as I think. The worst case would be disconnecting the AC input on the Outback and picking up a 48 volt IOTA charger.

    Is there a setting to limit how much the inverter tries to pull from the generator? I could see my loads and battery charging drawing more than my generator can supply.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,626 admin
    #6
    Re: Outback Inverter - disable transfer switch?

    Sounds like the correct inverter.

    You need a Mate to program the outback inverter.

    The inverters are "ok" ups devices. But I find that a fail over ups will glitch/reboot a PC about 1 out of 10 real power failures. I recommend a laptop both to save power and because they have their own battery backup.

    If you have a critical load, install a small UPS or a dedicated small ac inverter for that load.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • upa123
    upa123 Registered Users Posts: 17 ✭
    #7
    Re: Outback Inverter - disable transfer switch?
    lotw33 wrote: »
    Is there a setting to limit how much the inverter tries to pull from the generator? I could see my loads and battery charging drawing more than my generator can supply.

    Yes through the Mate controller/display you can establish max generator A/C in amperage and the max amperage dedicated to just charging. This particularly helpful if you use a small generator.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
    Re: Outback Inverter - disable transfer switch?

    That's not all you do with the MATE. Let's just say Outback's default values leave something to be desired.

    The fan in a VFX only comes on when needed, i.e. when the unit is hot. This would be when current flow, either in or out, is at its highest. Most of the time my VFX is silent because I don't run it near capacity. The only time it vents is when it's being used as a charger and the cabin is warm (roaring fire in cold, wet weather so the gen has to be used).

    As I said you'll never notice the switch. The only trouble that ever arises is if you apply a load the gen can't handle when charging and fault the gen. Then there will be a blip as it switches to inverter again.

    You could always get an inverter-generator; wave form is as clean as can be. :D
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  • lotw33
    lotw33 Registered Users Posts: 4
    #9
    Re: Outback Inverter - disable transfer switch?

    Once again, thanks a lot for the replies! I appreciate all the good info!
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  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    #10
    Re: Outback Inverter - disable transfer switch?

    What transfer switch are you using now?

    I have basically your same type of setup, an Iota charger and I use a (modified) Iota transfer switch which is nothing more than a couple of mechanical dpdt relays. When mine switches from inverter to generator it is done in an instant and my computers, etc never even notice the difference.

    Now, if the generator runs out of gas, or I simply hit the kill switch on the generator, then those devices will drop out because the generator drops out the voltage little by little as the engine winds down and by the time the transfer switch realizes it and switrches back to inverter it is too late.

    I solved this by simply flipping the breaker (or pulling the plug) on the generator AC line BEFORE shutting off the generator and never have reboot/freeze issues this way because the transfer switch instantly switches back to the inverter.

    And on your other point about running loads from the crappy generator, I kinda agree, and in the case of when I run my small non-inverter generator (1400w), I simply have it run my 15amp Iota charger and then run my AC from the inverter. It basically ends up being a wash at then end of a 10 hour period. Yes, it is not super efficient to convert ac to dc and then back to ac again, but for a $189 generator that only uses 1.4 gallons every 10ish hours to run my ac unit, it is worth it for me to have the "clean" power going to it so I don't hear the fan ramping up and down in small variations due to the poor generator output.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
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  • lotw33
    lotw33 Registered Users Posts: 4
    #11
    Re: Outback Inverter - disable transfer switch?
    jcheil wrote: »
    What transfer switch are you using now?

    I don't currently use a transfer switch. When the generator is running the IOTA charges the battery bank and I run large loads from the generator. It's a fairly manual setup, but usually it would be large power tools that would be used with the generator so it's not a big deal to plug them in directly.
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  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    #12
    Re: Outback Inverter - disable transfer switch?
    lotw33 wrote: »
    It sounds like there wouldn't even be any noticeable switching from the standpoint of the loads. In the past I find it annoying when the transfer switch kicks in and any electronics like computers, satellite or stereo either glitch out, freeze or reboot. It doesn't sound like that would be an issue with the Outback.

    No, and part of the reason that the term "transfer switch" is misleading. Most transfer switches are DPDT (double pole double throw) switches that disconnect one source, swing over to the other source, then reconnect. You see glitches for two reasons. One is that the switch isn't connected to EITHER source while it's in the middle of the switching process, and the other is that you are often switching between two different phase sources (i.e. one might be 80 degrees out of phase with the other.)

    Neither is true when the Outback switches. It first synchronizes its inverter to the source, and then just closes a single switch to accept the AC input. The inverter stays on at all times; the transfer switch just connects a new source to the existing source so there's no discontinuity and no phase mismatch. Then if the inverter needs to support the generator it adds more power, and if the battery needs charging it takes some of that power from the (now-connected) source to do so.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #13
    Re: Outback Inverter - disable transfer switch?
    bill von novak wrote: »
    Neither is true when the Outback switches. It first synchronizes its inverter to the source, and then just closes a single switch to accept the AC input. The inverter stays on at all times; the transfer switch just connects a new source to the existing source so there's no discontinuity and no phase mismatch. Then if the inverter needs to support the generator it adds more power, and if the battery needs charging it takes some of that power from the (now-connected) source to do so.

    That would be the GFX series, not the standard FX; they do not have generator support function.
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  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    #14
    Re: Outback Inverter - disable transfer switch?
    Cariboocoot wrote: »
    That would be the GFX series, not the standard FX; they do not have generator support function.

    You're right; I forgot he specified an off-grid inverter.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #15
    Re: Outback Inverter - disable transfer switch?
    bill von novak wrote: »
    You're right; I forgot he specified an off-grid inverter.

    Not so fast... the GFX inverters are preferred by a few off-grid folks who want to do generator support. Requires a very well regulated generator or an inverter generator.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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