Replacing current inverter and charger with Victron Multiplus

[Tasemu]

Hi all, i have created a couple of flow charts below which encompass 3 setups i'm playing around with in my head. The current setup is how i have it now. It has a separate inverter and charger, i manually set the selector switch and the charger switch when i want to swap from inverting to charging. I have a victron multiplus I want to install and in the short term to avoid a large rewiring situation in my engine bay I was considering the Temp Setup for minimal wire chaging. It should just be a matter of swapping the sterling charger for the victron and swapping the inverter cable to the AC out on the multiplus. It would appear to me from this setup that i would still need to manually swap between inverting and charging to avoid the multiplus charging off itself. I have two main questions I was hoping to get advice one for this.

1: Is there a better approach to the temp setup that would not require rewiring my generator output?

2: Does the New Setup actually make sense as an appropriate way to configure this?

 

Thanks in advance for any and all advice!

[Tony Brooks]

2 minutes ago, Tasemu said:

It would appear to me from this setup that i would still need to manually swap between inverting and charging to avoid the multiplus charging off itself.

 

Are you sure? I thought they had a setting that did just that, but it may have a name that does not make what it does obvious. However, using that might disable the inverter augmenting the shore line input or high currents.

[IanD]

If you're looking to install new Victron gear and you want to be able to use both shoreline and generator AC, is there a reason (cost? size?) you didn't consider a Quattro rather than a Multiplus?

[Tasemu]

1 minute ago, Tony Brooks said:

 

Are you sure? I thought they had a setting that did just that, but it may have a name that does not make what it does obvious. However, using that might disable the inverter augmenting the shore line input or high currents.

 

I was under the impression that it can swap between charging and inverting automatically, however because the ac output loops back into the selector switch and then back into the AC input of the victron, i had thought it would detect it as a charging current.

[IanD]

2 minutes ago, Tony Brooks said:

 

Are you sure? I thought they had a setting that did just that, but it may have a name that does not make what it does obvious. However, using that might disable the inverter augmenting the shore line input or high currents.

You can set the Multiplus to be charger only, but then -- as you say -- you lose power boost.

 

A Quattro (or Quattro-II) is probably a better solution if one the right size exists, but is more expensive.

Edited January 8 by IanD

[Tasemu]

Just now, IanD said:

If you're looking to install new Victron gear and you want to be able to use both shoreline and generator AC, is there a reason (cost? size?) you didn't consider a Quattro rather than a Multiplus?

 

I got the multiplus for a decent price and its been sitting there for a year while I worked out how to get a clean 230v from my diesel genny.

Just now, IanD said:

You can set the Multiplus to be charger only.

 

I would like to be able to use the inverter too though

[IanD]

4 minutes ago, Tasemu said:

 

I was under the impression that it can swap between charging and inverting automatically, however because the ac output loops back into the selector switch and then back into the AC input of the victron, i had thought it would detect it as a charging current.

 

It's absolutely verboten to connect ACout to ACin, the Multiplus will throw a complete wobbler -- hopefully with no damage but this is not guaranteed...

 

4 minutes ago, Tasemu said:

 

I got the multiplus for a decent price and its been sitting there for a year while I worked out how to get a clean 230v from my diesel genny.

 

I would like to be able to use the inverter too though

You need to be *really* careful in your "temp setup" then, see above...

Edited January 8 by IanD

[nicknorman]

14 minutes ago, Tasemu said:

Hi all, i have created a couple of flow charts below which encompass 3 setups i'm playing around with in my head. The current setup is how i have it now. It has a separate inverter and charger, i manually set the selector switch and the charger switch when i want to swap from inverting to charging. I have a victron multiplus I want to install and in the short term to avoid a large rewiring situation in my engine bay I was considering the Temp Setup for minimal wire chaging. It should just be a matter of swapping the sterling charger for the victron and swapping the inverter cable to the AC out on the multiplus. It would appear to me from this setup that i would still need to manually swap between inverting and charging to avoid the multiplus charging off itself. I have two main questions I was hoping to get advice one for this.

1: Is there a better approach to the temp setup that would not require rewiring my generator output?

2: Does the New Setup actually make sense as an appropriate way to configure this?

 

Thanks in advance for any and all advice!

No! Both of them are very bad ideas! Connect the shore power and the generator to the inputs of the selector switch. Connect the output of the selector switch to the Victron mains input. Connect the output of the Victron to the RCD and ring main. That is all!

[Tasemu]

2 minutes ago, IanD said:

 

It's absolutely verboten to connect ACout to ACin, the Multiplus will throw a complete wobbler -- hopefully with no damage but this is not guaranteed...

 

You need to be *really* careful in your "temp setup" then, see above...

 

Yeah absolutely, i'm so used to this setup of manually switching that I'm honestly not worried about forgetting. Basically just can't get down into the bilge to rewire my generator until the weekend and i've uninstalled my old inverter already haha.

6 minutes ago, nicknorman said:

No! Both of them are very bad ideas! Connect the shore power and the generator to the inputs of the selector switch. Connect the output of the selector switch to the Victron mains input. Connect the output of the Victron to the RCD and ring main. That is all!

 

Like so?
 

 

[nicknorman]

7 minutes ago, Tasemu said:

 

 

Like so?
 

 

Yes!

Edited January 8 by nicknorman

[Tasemu]

8 minutes ago, nicknorman said:

Yes!

 

As i've had trouble getting this victron working with my diesel generator in the past, i believe it should work now but i really want to test that it can actually charge from the generator with the new AVR installed. If the utmost care was taken as a test run before implementing your solution, would you allow a test run using the temp setup (with selector switch set to generator) for charging only, to ensure it can charge before i tear apart my rcd and selector switch for the permanent install?

[IanD]

21 minutes ago, Tasemu said:

 

As i've had trouble getting this victron working with my diesel generator in the past, i believe it should work now but i really want to test that it can actually charge from the generator with the new AVR installed. If the utmost care was taken as a test run before implementing your solution, would you allow a test run using the temp setup (with selector switch set to generator) for charging only, to ensure it can charge before i tear apart my rcd and selector switch for the permanent install?

I thought the reason you had problems was generator overvoltage due to failed AVR, which is now fixed?

[Tasemu]

4 minutes ago, IanD said:

I thought the reason you had problems was generator overvoltage due to failed AVR, which is now fixed?

 

Yup, i covered all the details in my SX-460 thread in this section, but basically i was able to remove all the old gubbins like the choke and rectifier and old broken AVR, and successfully run the generator at 50hz 230v cleanly using an SX-460 and passing the exciter voltage through the brushes.

 

EDIT: I would definitely like to test that the victron works though, as i haven't been able to yet. Once confirming that then i'm happy to rip the engine bay apart to install properly. Just been bitten once already and was very gutted when i had to put it all back the way it was haha

Edited January 8 by Tasemu

[cuthound]

3 hours ago, Tasemu said:

 

Yeah absolutely, i'm so used to this setup of manually switching that I'm honestly not worried about forgetting. Basically just can't get down into the bilge to rewire my generator until the weekend and i've uninstalled my old inverter already haha.

 

Like so?
 

 

 

That Is how mine is wired, even though the generator (Travelpower) was never installed.

[GUMPY]

The way Nick suggested is the only way to do it properly.

Any other temporary way is dancing with disaster.

JFDI 

[Tasemu]

I did a charging test with the temp setup and had no luck charging, but after going into the victron connect app and changing a few settings I have it up and running. I was careful with the setup and no issues occured, now i'm going to rewire everything to fit Nicks description. I am curious just for the theory of it though, what would go wrong with the victron charging off its own output? I would have just assumed it would lose power over time due to all the innefficiency. Curious as to what would happen and why.

[IanD]

9 minutes ago, Tasemu said:

I did a charging test with the temp setup and had no luck charging, but after going into the victron connect app and changing a few settings I have it up and running. I was careful with the setup and no issues occured, now i'm going to rewire everything to fit Nicks description. I am curious just for the theory of it though, what would go wrong with the victron charging off its own output? I would have just assumed it would lose power over time due to all the innefficiency. Curious as to what would happen and why.

 

Because inside the Multiplus is an inverter which tries to synchronise the voltage and phase of the sinewave it is generating with what is applied at the AC input terminals, both to allow seamless switchover and to allow power boosting (added inverter power to shoreline/generator power). There's only one bidirectional DC<==>AC power bridge inside which is used for all functions -- inverting, charging, power boosting, grid backfeed.

 

If you connect the output to the input then it'll chase its own tail by trying to adjust the output to follow the input, which then moves the input, which then moves the output -- and this is likely to lead to an overvoltage or undervoltage as well as possible large currents and failure to synchronise, and perhaps permanent damage -- depending on how robust the protection circuits are...

Edited January 8 by IanD

[nicknorman]

51 minutes ago, IanD said:

 

Because inside the Multiplus is an inverter which tries to synchronise the voltage and phase of the sinewave it is generating with what is applied at the AC input terminals, both to allow seamless switchover and to allow power boosting (added inverter power to shoreline/generator power). There's only one bidirectional DC<==>AC power bridge inside which is used for all functions -- inverting, charging, power boosting, grid backfeed.

 

If you connect the output to the input then it'll chase its own tail by trying to adjust the output to follow the input, which then moves the input, which then moves the output -- and this is likely to lead to an overvoltage or undervoltage as well as possible large currents and failure to synchronise, and perhaps permanent damage -- depending on how robust the protection circuits are...

It is noticeable that when external power (shore or generator) is connected to the input of a Combi, the Combi continues inverting for a couple of seconds before switching to pass-through mode. As IanD says, this is to allow the inverter to match frequency and phase to the incoming power before switching over. Instantly switching to a new supply at a significantly different instantaneous phase could cause nasty things to happen!
On the other hand, when the external power is removed, the inverter instantly takes over because it has been tracking the frequency and phase in the background even though it was not producing any power, so it can seamlessly match the phase and frequency.

Edited January 8 by nicknorman

[Tasemu]

Cheers, that makes much more sense now. I'll start prepping for the rewire job. Very chuffed i finally have a working charger after a year of generator prep and research. Feels damn good.

[Tasemu]

Just rewired the engine bay to follow @nicknorman's instructions. All works well and have the added bonus of it automatically switching over to charge when i turn the genny on. Very chuffed

[Tasemu]

I was under the impression that the charger would charge my lifepo4 battery to full and then passthrough the generator power to my loads until I turn the generator off. I'm seeing a weird thing happen where when the battery reaches full, it seems to revert back to inverting, then after a few seconds when the voltage has dropped it cycles back into charging again, this cycle seems to continue. Could this be because of my victron settings? I have a gut feeling it might be.

[Tasemu]

 

I've just changed my HVD on my bms to 14.4v and the absorb/float values on my multiplus to 14.1/13.5v. Hopefully if it was a case of the BMS doing a HVD then this might solve it...?

[nicknorman]

2 hours ago, Tasemu said:

I was under the impression that the charger would charge my lifepo4 battery to full and then passthrough the generator power to my loads until I turn the generator off. I'm seeing a weird thing happen where when the battery reaches full, it seems to revert back to inverting, then after a few seconds when the voltage has dropped it cycles back into charging again, this cycle seems to continue. Could this be because of my victron settings? I have a gut feeling it might be.

If the Combi is switching to inverter mode, it is likely to be because the Combi doesn’t like the incoming mains. Possibly when the generator is unloaded by the charge finishing, the regulation is a bit lax and the voltage gets too high, or the waveform is a bit nasty. Pretty sure there is a setting or two to make the Victron more tolerant of ugly waveforms and to widen the acceptable voltage range.

 

“Weak AC” is the setting to try, and it looks like you can increase the maximum input voltage.

Edited January 22 by nicknorman

[Tasemu]

1 hour ago, nicknorman said:

If the Combi is switching to inverter mode, it is likely to be because the Combi doesn’t like the incoming mains. Possibly when the generator is unloaded by the charge finishing, the regulation is a bit lax and the voltage gets too high, or the waveform is a bit nasty. Pretty sure there is a setting or two to make the Victron more tolerant of ugly waveforms and to widen the acceptable voltage range.

 

“Weak AC” is the setting to try, and it looks like you can increase the maximum input voltage.

 

Weak AC is currently enabled, it could be the waveform... Do you think it unlikely that its the BMS causing an issue?

[nicknorman]

1 hour ago, Tasemu said:

 

Weak AC is currently enabled, it could be the waveform... Do you think it unlikely that its the BMS causing an issue?

I suppose it could be. Do you have an LA in parallel? If not then a HVD is obviously going to remove any sort of battery connection to the Combi. I don’t have a Victron, but I know my Mastervolt is a bit funny if I remove the DC power with shore power connected, sometimes it carries on working, sometimes not.

 

Anyway it will certainly be a good idea to have the HVD set higher than the Combi charge voltage.