Looking for victron support to chime in on this please.
I’m getting ready to install my multiplus 2 2x120 in my rv and I want to know if I can run my multiplus with no batteries.
In the winter when not in use I pull batteries and keep in garage due to negative degree weather.
However I will enter the rv at times and open the slides turn lights on and do some work from time to time so would need to use lights plugs etc.
Can I run the multiplus 2 without batteries.
I’ve read posts on here that no I can’t I’ll damage it, I have to use a bypass switch but I’ve also read that yes you can run with no batteries
once wired the Multiplus II can be connected to shore power without the batteries connected as was my previous understanding before doing research for this specific case. In this state the inverter will only of course be able to work within the limits of the shore power connection and the build in DC converter/charger.
So with all the conflicting reports I’m looking for victron support to please step in and let me know. for sure on this topic.
To be clear, this is the Victron Community which is not an official support channel (note the introductory paragraph of the Community Guidelines). Most of the people here are other system owners, enthusiasts, and some volunteer experts - this can be a very useful resource, but you can get wildly conflicting answers and opinions here too.
Your official support channel is the authorized Victron distributor/dealer from whom you purchased the unit.
That said, the above answer is correct - the MultiPlus is a DC device, do not run it without batteries connected.
Thats the problem. I emailed victron and got this response.
Justin,
Thank you for sending this over. I spoke to a Victron Representative about this over the weekend although consulting an electrician for wiring is still strongly recommended once wired the Multiplus II can be connected to shore power without the batteries connected as was my previous understanding before doing research for this specific case. In this state the inverter will only of course be able to work within the limits of the shore power connection and the build in DC converter/charger. It looks like the inverter was purchased through Inverters R US. They will be the best place to get support for further inquiries on this specific serial number.
So I then contacted inverters r us and got this response
Yes, you can briefly operate the Multiplus without batteries, but that answer comes with the caveat that there is a risk of damaging the unit and errors.
The internal capacitors need to charge and sometimes this inrush of current can damage the unit.
It may work fine for a few cycles but will likely eventually cause damage.
You can also deep-dive into making programming changes to the unit or go the route to install a manual bypass transfer switch to circumvent the Multiplus completely.
Fortunately your distributor, Inverters R Us, has it correct. Brief connection with extreme caution is possible, but it should not be done unless it is brief and with a very specific purpose, due to the risk of damage to the unit that would not be typically covered by warranty.
On my test bench it has been sometimes necessary to do this, for a very specific purpose, but it should certainly not be done in an installed environment as a design function. A bypass switch, as others have suggested, is the correct way to accomplish what you’re trying to do.
Emailing Victron just sends to a general mailbox that could be answered by a number of people, some more familiar with the equipment than others, so not sure who answered you but fortunately they at least directed you to the proper resource (your distributor) who provided the correct answer.
Honestly I have no idea, I’m not an installer. I’d suggest discussing with a reputable, experienced installer who’s familiar with the requirements of that installation environment, as I’m sure there are solutions out there - I know that bypass switches are very common in the RV world, I just don’t know what people are using for them.
Can you please explain this? Which (extreme) caution measures?
Why brief?
If an inverter doesn’t have the battery at its input, it will not function. Did you saw a power source malfunction because it has no input voltage?
And when charging, if there is no battery (load), there will be no current. Did you saw a power source malfunctioning because it has no load?
There are situations that during high load, a breaker was triggering leaving the inverter without battery.
There are even cases when the BMS itself disconnects the battery from the inverter.
Did you believe that a good manufacturer leave this situation without contingency?
In extremis, you are saying that if you have a battery disconnect, you can loose warranty… Odd.
And all these because Victron says so…
No offense, let’s look at the internal schematic and firmware and draw an educated conclusion.
By the way, about the above…
Did you know that Chinese guys, in all their inverters, have a special DC bus soft start circuit?
It’s a small switching mode power supply unit responsible, as soon as the unit is connected to AC-IN, of only charging as quickly as possible the DC capacitors and to avoid that big inrush current…
All components for this are no more than 5 USD, but the benefit is much more than that…
Then, with respect, please, could you share and explain to us why such well built products like Victron’s risk damage when running without batteries?
Because, like I’ve said, the BMS could decide at some point to disconnect the battery and then… puff… here goes the warranty.
It’s a DC device. Running a DC device without DC can cause many issues, not sure why this would require a lot of explanation. I’m not going into which issues here, because I have neither the time nor really the inclination. I am uncertain why a concept like “if you would like manufacturer warranty coverage, please use the device in the manufacturer-proscribed manner” is such an offensive idea, but I am not here to argue about it.
At the end of the day, anyone can use any device in any manner they see fit, so long as they accept full responsibility for all effects thereof. You and I have had this discussion before, so I don’t think anything more needs to be said.
Yes, you can run the MultiPlus without batteries and AC pass-through will work. However, since you want to use the Multi as a large 12V power supply, I wouldn’t recommend running it w/o batteries to operate the slides or other large DC loads. Will it work? Probably. Maybe even a few times. But I don’t recommend it because large voltage spikes could occur without a battery to buffer them when operating large loads.
I have owned two RVs - the first with lead-acid batteries and the second with lithium batteries. I removed the lead-acid batteries once and stopped after that. It’s not necessary. Unless you live in Fargo ND and store it outside in strong winds, I wouldn’t bother taking them in and out. It would have to get really cold to freeze the electrolyte and that’s easily solved with a simple battery heater. If you have lithium batteries, same thing. Just keep them above freezing and in place. And if you keep them in the RV then the topic is moot. Just my two shekels.
That certainly falls into the brief, purpose-driven use-case, yes. My point above, and Inverters R Us’s point, is that it is not to be used as a design function for the end-user.
Well, you do you do. But, I’ll paste some info below just to round out this conversation for anyone searching the archives in the future. You can choose to spend a little energy keeping the batteries charged and/or warm or blow up your MultiPlus.
P.S., I spoke to my Victron rep a bit ago about a few things and I mentioned this topic. He said I was exactly right. Hopefully that helps answer your initial question.
And if the dc fuse blow, you blow the victron mp/rs most likely?
I think I remove all dc fuses… thanks Victron.
No.
If a fuse blows, you’ll immediately get a “low battery” alarm, and you’ll shut the system down, work out why the fuse blew in the first place, correct the installation, replace the fuse, and start the system back up.
Hopefully you’re joking about the suggestion to remove your fuses.
Just my two shekels.
