Victron dual inverters split phase but on 120 dogbone

[justinm001]

Running Victron inverters in split phase but using this dogbone adapter going from 240v 50a to 120v 15a and it appears that it powers both legs. I know many including myself on here said we need to modify these dogbones but apparently not.

https://a.co/d/imQcNmm

Victrons showing both legs getting power (117v/119v) but only using one. Seems it's smart enough to know both legs are on same phase so only uses 1 of them. Unfortunately I don't seem to have my voltmeter to make sure both legs are hot but my surge is showing both legs active.

Not sure if this is a new feature or always was smart like this.

 

[Cmiller]

Do you normally use 120/240 to charge? And how are the inputs to your inverters configured? On my personal system, I have 4 Victrons on 120/240 split phase. I normally use a splite phase gen, but have used a 120V small gen for backup. But I always reconfigured the inverters to have one inverter's input configured as a separate source, then I could charge with a single unit. I'm a but curious now on all of this. In a minute I'll go start my gen (Remotely via the interface on my phone! Gotta love Victron!), then I'll turn off the charge breakers feeding the 2 inverters on L2, and see what happens....

 

[justinm001]

Do you normally use 120/240 to charge? And how are the inputs to your inverters configured? On my personal system, I have 4 Victrons on 120/240 split phase. I normally use a splite phase gen, but have used a 120V small gen for backup. But I always reconfigured the inverters to have one inverter's input configured as a separate source, then I could charge with a single unit. I'm a but curious now on all of this. In a minute I'll go start my gen (Remotely via the interface on my phone! Gotta love Victron!), then I'll turn off the charge breakers feeding the 2 inverters on L2, and see what happens....

At my house I use 240v/50a to 240v/30a gen cord back to 240v/50a and set the limit to 27a.

If your inverters are setup as split phase there's an option to switch as group, if you disable that you can use 120v and it'll invert on the other inverter to pump out 240v. I've done this before multiple times and have a special 30a dogbone that only gives 120v to 1 leg.

Most 50a to 30 or 15a dogbones split the 120v into both hots. This is became most RVs just use 120v so the dogbone will continue to let all outlets run. Many have said if both inverters get the 120v power that's on the same leg it'll reject it.... But apparently not. Victrons smart enough to know it's same phase and just use 1 inverter.

Meaning any dogbone will work fine

I've never reconfigured from 240v to 120v. If you do I'm betting that switch as group is on. I have Quattros so have switch as group disabled on shore but enabled on genset since it'll always be 240 and hardwired.

I have a dogbone that goes 2 15a to 240v 50a and hoping I can use it to get 240v using 2 15a outlets on separate legs. Just haven't tried it yet.

 

[Cmiller]

Got it. That all makes sense. I have the multiplus-ii 3000/48 inverters. So only have single input. I have had to use that option to disable switch as a group a few times now. I used a Honda 2000 to charge, and that's real slow when you have a 30kw battery bank! I'm down to 20kw now, but had 30 kw at the time. Just had 2 borrowed batteries from the shop. Lol.

I just now tested out my setup with my usual configuration. (Switch as a group is enabled.) And made a strange discovery. While the inverters will not connect up if only one leg is available, regardless of L1 or L2, I was able to switch off gen power to any combination of 2 inverters, as long as each leg was still represented. So as long as 1 inverter from L1 and 1 inverter from L2 got gen power, they stayed connected and charging. However...... depending on the combination the charging would go up to ~9kw, instead of the ~7kw that I have it set for. (35A) And then also some combinations gave me only ~3.8kw of charging. None of this was particularly helpful, but interesting none the less. It's bedtime, or I would have checked voltage on the grid in terminals to see of the relays stayed closed even when the breaker was flipped off...

Anyway, it is interesting to know that if I would keep switch as a group disabled, I could still charge with 120/240V. But for me it wouldn't work, as I'm AC coupled for my solar and the assistant for the frequency shift is not available when switch as a group is disabled.

 

[justinm001]

Got it. That all makes sense. I have the multiplus-ii 3000/48 inverters. So only have single input. I have had to use that option to disable switch as a group a few times now. I used a Honda 2000 to charge, and that's real slow when you have a 30kw battery bank! I'm down to 20kw now, but had 30 kw at the time. Just had 2 borrowed batteries from the shop. Lol.

I just now tested out my setup with my usual configuration. (Switch as a group is enabled.) And made a strange discovery. While the inverters will not connect up if only one leg is available, regardless of L1 or L2, I was able to switch off gen power to any combination of 2 inverters, as long as each leg was still represented. So as long as 1 inverter from L1 and 1 inverter from L2 got gen power, they stayed connected and charging. However...... depending on the combination the charging would go up to ~9kw, instead of the ~7kw that I have it set for. (35A) And then also some combinations gave me only ~3.8kw of charging. None of this was particularly helpful, but interesting none the less. It's bedtime, or I would have checked voltage on the grid in terminals to see of the relays stayed closed even when the breaker was flipped off...

Anyway, it is interesting to know that if I would keep switch as a group disabled, I could still charge with 120/240V. But for me it wouldn't work, as I'm AC coupled for my solar and the assistant for the frequency shift is not available when switch as a group is disabled.

Interesting. Haven't dug into frequency shift or anything yet but good to know