[tmalcolm]

Hey all,
I'm hooking up my electrical and am noticing in the sample schematics from Victron, they all put the Inverter (Phoenix 1200 in my case) on the input side of the smart battery protect device. Why wouldn't they put in on the output/load side of the smart battery protect device where the DC loads are?
When it's on the input side, the smart battery protect can't see the load it's handling.

Also, any opinions about this design aside from the Phoenix 1200 inverter location? The only difference between Design 1 and Design 2 is where the inverter is installed.
Assume appropriate use of grounding, fuses and manual switches.

Thanks,
Tom

 

[Sams stock van]

The unit description indicates it is a one way directional device that can't pass a charger voltage back thru the unit. So if it's an inverter/charger, then before the device to allow charging.

It seems to be a simple low voltage cutoff switch to prevent draining your batteries, with a Bluetooth feature.

 

[tmalcolm]

The unit description indicates it is a one way directional device that can't pass a charger voltage back thru the unit. So if it's an inverter/charger, then before the device to allow charging.

It seems to be a simple low voltage cutoff switch to prevent draining your batteries, with a Bluetooth feature.

Thanks Sam. Bit of clarification on the inverter. This inverter is only an AC supply powered by DC. So it looks like to me it could be considered just another DC load...so why not put it on the output of the smart battery protect so it can include the load of the inverter in it's "calculations" for when to shut off the load to save the batteries?

 

[Sams stock van]

Thanks Sam. Bit of clarification on the inverter. This inverter is only an AC supply powered by DC. So it looks like to me it could be considered just another DC load...so why not put it on the output of the smart battery protect so it can include the load of the inverter in it's "calculations" for when to shut off the load to save the batteries?

If the unit can handle passing the amps required by the inverter and dc panel together (or however you see them running), then it seems fine on either side. What amperage unit do you have? I see 65, 100, and 200 amp units on the victron web page. Note: I'm just looking at the victron web page info; I don't have one of these units.

 

[gregoryx]

Agreed: the Phoenix is just another DC load. Design 2. If it were a Multiplus, then design 1.

Of course, the Smart Battery Protect is unnecessary in this position since the house batteries can be protected by the Cerbo utilizing the Smart Shunt; but if you want to have one... sure. The other useful location for it would be before the Orions; but that is protected by CCP2, so unnecessary there as well. 🤷‍♀️

 

[tmalcolm]

If the unit can handle passing the amps required by the inverter and dc panel together (or however you see them running), then it seems fine on either side. What amperage unit do you have? I see 65, 100, and 200 amp units on the victron web page. Note: I'm just looking at the victron web page info; I don't have one of these units.

Sam, we have the Phoenix 1200, see datasheet attached. Correction, you're asking about the BP. We have the 100A

Agreed: the Phoenix is just another DC load. Design 2. If it were a Multiplus, then design 1.

Of course, the Smart Battery Protect is unnecessary in this position since the house batteries can be protected by the Cerbo utilizing the Smart Shunt; but if you want to have one... sure. The other useful location for it would be before the Orions; but that is protected by CCP2, so unnecessary there as well. 🤷‍♀️

ohhh dude, are you sh!ttin' me?? I didn't catch that...😕

With regards to CCP2 - With Engine off, it shuts down after ~30 minutes anyway, so if I needed AC after 30 minutes, that's a moot point?

 

[Sams stock van]

Sam, we have the Phoenix 1200, see datasheet attached

ohhh dude, are you sh!ttin' me?? I didn't catch that...😕

With regards to CCP2 - With Engine off, it shuts down after ~30 minutes anyway, so if I needed AC after 30 minutes, that's a moot point?

Yes, the inverter is rated at 2200 watts peak. That's over 150 amps give or take. Add your DC panel, 40 or 50 amps? So in the 200 amps max load range?

Which Victron Smart Battery Protect do you have? If it's the 65amp or 100 amp unit, then diagram 1. If it's the 220 amp unit, then diagram 2?

 

[tmalcolm]

Well, apologies for heading down the road without adequately reading the instructions (I hate instructions...) But I found in the SBP manual that inverters cannot be attached to the output of an SBP. Rather it must be controlled via the remote switch. See attachment.
Sam - I have the 100A model.
Gregory - Correct me if I'm wrong but the CCP2 will turn itself off after ~30 minutes to an hour? If so, I can't use CCp2 for AC after that time.

 

[gregoryx]

...

ohhh dude, are you sh!ttin' me?? I didn't catch that...😕

With regards to CCP2 - With Engine off, it shuts down after ~30 minutes anyway, so if I needed AC after 30 minutes, that's a moot point?

Not quite sure which part you're meaning with, "didn't catch that."


WRT BP, there have been some issues with the BP and I think the most common usage I've seen currently is more with protecting the starter battery. But since you're on CCP2, that's covered. The issues include frying the BP when used with an inverter because of the initial power-up of the inverter. See thread here.

Just looked up the BP specs, and there are three 12/24 versions - 65/100/220A versions. So you could certainly use it in design 2 based on spec. Except for the issue above - and the quote from the Victron person that says it will be fried. I'd send it back and do it differently. But that's me.


But the way you're describing the CCP2 question above... maybe there's a misunderstanding here. Your diagram shows CCP2 connected to two Orions. Then those feed the three house batteries. The house batteries feed the inverter and the DC loads. With the BP isolating the DC loads - with or without the Phoenix inverter (design 1 vs 2).

The advantage to using the BP in the model is to be able to kill house loads (DC and/or inverter) if the voltage drops. Which you could certainly do with just the BP on the DC loads - then use the Cerbo to disable the Phoenix if the SOC drops too low.

One of the key issues I have with the BP is it's voltage based and a hard draw on the inverter might lower voltage enough to trigger it. This is in addition to the above described issues. I'd lean more toward a single relay to just cut it all off from the Cerbo with the logic therein - potentially based on SOC, not just voltage. And because then it's the WHOLE load set and the relay won't have "smarts" the will get fried as the BP does (in theory).


All that said... I'm curious why you're not going with a Multiplus? Just keeping price down? If so, maybe consider a more powerful inverter made by someone other than Victron so that you're not limited by the Phoenix? Advantage to the Multiplus would be an option to charge from shore-power; but it's very expensive. Of course, you could do that with an additional device... but you're spending money on the Cerbo, so... ???

 

[njvagabond]

Dunno but maybe the Phoenix has an adjustable setting for low voltage shut down, so maybe the battery protection device is only necessary for the other DC loads?

 

[gregoryx]

Dunno but maybe the Phoenix has an adjustable setting for low voltage shut down, so maybe the battery protection device is only necessary for the other DC loads?

As that link says (from a Victron person), the BP can't handle the high power inrush and it fries it. That's literally what the Victron person says. "Fries it." Ugh. Just seems like a device to avoid to me. 🤔

Granted, I wouldn't run the Victron Phoenix; but if I'm running a Cerbo (or RPI VenusOS), I'd put in a beefy relay if I really wanted an automated cut-off. But I'd rather send the logic to the Multiplus to turn OFF then use smaller relays for various loads for other things to shut off in such a case. I'm looking at replacing our 8-port relay switch unit with something controllable from Home Assistant. But it could just as easily be a smaller relay controlled by one of the Cerbo (or Multiplus) relays. So many better ways to do it.

 

[njvagabond]

As that link says (from a Victron person), the BP can't handle the high power inrush and it fries it. That's literally what the Victron person says. "Fries it." Ugh. Just seems like a device to avoid to me.

I think I was not clear, well actually not thorough. I was saying that the Phoenix could be put in parallel with the battery protection device (hence no large inrush) since it may have an adjustable low voltage shutdown built in. That looks like what the drawing with the green check mark shows, which I did not look at before posting (RTFM ) . Unless I am missing something, I don't see why an external relay (controlled by other Victron whizbangery) would be needed to shut off the inverter.

Presumably the other DC loads would be small with little inrush (assuming no DC aircon) so hopefully within the capacity of the battery protection device.

 

[gregoryx]

I think I was not clear, well actually not thorough. I was saying that the Phoenix could be put in parallel with the battery protection device (hence no large inrush) since it may have an adjustable low voltage shutdown built in. That looks like what the drawing with the green check mark shows, which I did not look at before posting (RTFM ) . Unless I am missing something, I don't see why an external relay (controlled by other Victron whizbangery) would be needed to shut off the inverter.

Presumably the other DC loads would be small with little inrush (assuming no DC aircon) so hopefully within the capacity of the battery protection device.

We're on the same page.

My preference for a relay versus BP is that I don't think the BP is part of the "network" with the VenusOS stuff. Which could be viewed as a good or bad, I suppose. It operates on its own based on voltage. Fine and good. But if the objective is to have a safe fall-back, I'd lean toward a big relay (NO or NC is a design challenge) that the VenusOS shuts down OR the whole thing unplugs.

I'm not a fan of the BP for a system that's generally accessible (including from a Venus controller). If this is a boat or RV that's in storage (with the inverter in an OFF state), then it makes sense as the dumbest last-resort to save the batteries. But not otherwise. If something is draining the batteries that far, I expect to receive VenusOS notifications and maybe even do something about it remotely (relay / relays / etc).

 

[jkmann]

There is a community monitored by Victron employees and engineers that work with Victron equipment. If you want to do something different from what Victron shows in their install manual, it's worth asking on that community. They have a lot of experience breaking and troubleshooting Victron gear.

All Posts - Victron Community

community.victronenergy.com

My simple take would be that design 2 should be OK as long as you aren't presenting it with more than a 220A load. The SBP 220A is rated for 600A peak load for up to 30 seconds, so I don't think that inrush current would be the issue unless you have large motor loads.

 

[Sams stock van]

OP has the 100 amp smart battery protect.

 

[gregoryx]

There is a community monitored by Victron employees and engineers that work with Victron equipment. If you want to do something different from what Victron shows in their install manual, it's worth asking on that community. They have a lot of experience breaking and troubleshooting Victron gear.

All Posts - Victron Community

community.victronenergy.com

My simple take would be that design 2 should be OK as long as you aren't presenting it with more than a 220A load. The SBP 220A is rated for 600A peak load for up to 30 seconds, so I don't think that inrush current would be the issue unless you have large motor loads.

Unfortunately, the Victron staff and/or gurus who have chimed in on the SBP on the Victron community and on the link above have said that it can't handle the inrush. Good news is that the Phoenix has a low-voltage shut-down of its own, so... they'd operate in parallel at least.

As has been noted elsewhere, the support on the Victron community is more from peers than official Victron folks (with certain exceptions). And the company line is, "see your dealer / reseller for support," which makes sense since they've got all that training, I guess. But neither of those angles answers many of the questions effectively in many cases.

But the one-way nature of the SBP seems absolute. And the "don't put an inverter on the load side" also seems absolute.

So... officially, design 1. No matter what.

 

[tmalcolm]

I think I was not clear, well actually not thorough. I was saying that the Phoenix could be put in parallel with the battery protection device (hence no large inrush) since it may have an adjustable low voltage shutdown built in. That looks like what the drawing with the green check mark shows, which I did not look at before posting (RTFM ) . Unless I am missing something, I don't see why an external relay (controlled by other Victron whizbangery) would be needed to shut off the inverter.

Presumably the other DC loads would be small with little inrush (assuming no DC aircon) so hopefully within the capacity of the battery protection device.

Thanks for all the comments Sam, NJ and Gregory! Really appreciate the input. Here's what I found out after reading your comments, giving me food for thought.
After pouring over videos and manuals from other sources as well as Victron, here's what I found. (note to self - RTFM first)

Great info on the link from Gregory with Justin from Bay Marine Supply!

Gregory, my comment "didn't catch that" referred to the ability of the smart shunt to cut the circuit. However after looking into it more comprehensively, I find that it cannot cut the circuit. It is strictly a monitoring device. If you know otherwise, I would appreciate further input on that.

Our build model is that of minimalists, not just for cost savings, but because that's our style. We don't have solar panels, instead relying only on batteries, propane and vehicle power. We very rarely camp where there is shore power, so shore power circuitry is not needed. But do want things to be as robust as possible.

NJ, the Phoenix 1200 does have a low voltage cutout that is programmable, thus no need to be worried about where I hook it up. (as long as not on the load side of the BP) In addition, the notes as describe here earlier and by Justin, the inrush current from the caps charging in inverters will exceed the ratings on the BP and cook it.

So if the above is true, I do still need the BP for DC loads and I can use the Phoenix' low voltage cutoff for the AC loads and not risk BP damage from over-current from the Phoenix 1200. Alternatively, the Phoenix can utilize the remote port from the BP to shut it off at the same time as the BP shuts down the DC load.

 

[gregoryx]

The Smart Shunt can not cut the circuit; you are correct. But you show a Cerbo unit. A Cerbo unit can use the input from a Smart Shunt (or other devices) to determine battery voltage and/or state-of-charge. And a Cerbo can push a shut-down to any devices it controls. The Phoenix can be connected with VE.direct, so... not sure how much control is there, but I bet it can push a shut-down (it can on the Multiplus).

As I mentioned above, if the additional loads risk draining the battery and you won't be around to intervene (and/or don't want to do your own logic-controlled disconnect with the Cerbo), then you've got your solution. Design 1.

 

[njvagabond]

the dumbest last-resort to save the batteries.

I think many (most?) BMS's have a low voltage disconnect. Based on the specs for my SOK's it does seem that it is intended as a failsafe and not as a normal operation control "Recommend low voltage disconnect: 11.2V - BMS discharge cut-off voltage: Around 10.4V - Reconnect Voltage:>11.6V " Probably not good for the battery to go below 11.2V often. So I guess some sort of cut off for the 12V loads might be a good idea if that was becomes a frequent event. Of course one would need some sort of data logging to know how oten the batteries were in that 10.4>111.2 range.

Looking at the specs, it does not look like the BP , it is sort of disappointing that there is just a choice of fixed settings where disconnect and reconnect are paired. None of which seem to play very well with the spes for SOK's.

If I was t chose 11.25V cut off, then it won't reconnect until 13.8V whereas the BMS is good to go at 11.6V
There is a 11.5V setting that reconnects at 12.8V so give up a little capacity to reduce reconnect voltage.
Where charging is by alternator (or shore power) it would seem these settings are leaving the system off muche longer that necessary. Never thought about any of this stuff before. Always good to RTFM.

 

[tmalcolm]

The Smart Shunt can not cut the circuit; you are correct. But you show a Cerbo unit. A Cerbo unit can use the input from a Smart Shunt (or other devices) to determine battery voltage and/or state-of-charge. And a Cerbo can push a shut-down to any devices it controls. The Phoenix can be connected with VE.direct, so... not sure how much control is there, but I bet it can push a shut-down (it can on the Multiplus).

As I mentioned above, if the additional loads risk draining the battery and you won't be around to intervene (and/or don't want to do your own logic-controlled disconnect with the Cerbo), then you've got your solution. Design 1.

Agreed! I have a couple of options!