Using Victron Battery Protect as solar shutoff relay

[jordanbigel]

Originally Posted by goboatingnow

I’m puzzled that Cerbo can’t issue ve.direct stop commands though

Yes. The crazy thing is that if (when) I have internet access, I can use the VRM feature of Victron Connect, and THAT will allow me to access the MPPT config and shut down/turn on. But, not via local network. So clearly the VE.Direct via the Cerbo CAN access the MPPT. Seems like a software problem to me. Also, Catnewbee claims the CerboGX can be customized to enable this capability, and I am investigating that angle before proceeding.

[alctel]

So if I understand this thread correctly, a Victron Battery Protect device could be used as a standalone HVC contactor? (assuming you have a divided load bus and charge bus)

Because that is mighty tempting as a backup feature.

[CatNewBee]

Originally Posted by jordanbigel

Yes. The crazy thing is that if (when) I have internet access, I can use the VRM feature of Victron Connect, and THAT will allow me to access the MPPT config and shut down/turn on. But, not via local network. So clearly the VE.Direct via the Cerbo CAN access the MPPT. Seems like a software problem to me. Also, Catnewbee claims the CerboGX can be customized to enable this capability, and I am investigating that angle before proceeding.

1.) If you can access it via VRM, you can access it via LAN / WLAN too.

2.) DVCC stands for Distributed Voltage and Current Control and means an external battery management system can signal CV / CC charge, reduce current or stop charging at all.

The Cerbo will then instruct the chargers to do so based on the signals it gets from the BMS or is pre-set (maximum charge current etc.) across all connected manageable devices.

[goboatingnow]

Originally Posted by alctel

So if I understand this thread correctly, a Victron Battery Protect device could be used as a standalone HVC contactor? (assuming you have a divided load bus and charge bus)

Because that is mighty tempting as a backup feature.

Yes it can be so used but the over voltage is fixed at 16V and this is arguably too high for lithium HVC usage


It does support remote shutdown etc. But as a backup HVC it’s missing the ability to set the over voltage

[jordanbigel]

Originally Posted by CatNewBee

1.) If you can access it via VRM, you can access it via LAN / WLAN too.

2.) DVCC stands for Distributed Voltage and Current Control and means an external battery management system can signal CV / CC charge, reduce current or stop charging at all.

The Cerbo will then instruct the chargers to do so based on the signals it gets from the BMS or is pre-set (maximum charge current etc.) across all connected manageable devices.

> If you can access it via VRM, you can access it via LAN / WLAN too.

This has not been my experience. When I disconnect my shore internet connection, and open VictronConnect, I can select my Cerbo or my MultiPlus under the Local tab. If I select the Cerbo, the ONLY option presented is the VRM button.

If internet is connected, and I open Victron Connect and select the VRM tab, I can select the CerboGX, and then I see in the top right icons for the BMV-700, and the 2 MPPT solar controllers. I can pick one of them and click the gear icon to access settings.

But, without Internet, using the Local tab, selecting the CerboGX does NOT reveal any options to select or modify the MPPT settings. Please, if I have done something wrong here I would love to know what it is.

[jordanbigel]

Looking at options for using a relay to cut off panel leads into (instead of battery leads out from) the MPPT, I am wondering if a simple automotive relay like this would be appropriate. Looks good to me. Each panel is only 15a and this appears to be rated for 30a.

https://www.amazon.com/ONLINE-LED-ST.../dp/B01N66W2XF

My only question about using one of these is should I rig is as NO or NC - (these relays can be wired either way)? Is there a "right" way? Logic tells me that rigging at as NC makes sense, then, when the switch is on, powering the relay, the connection is made, and when you turn off the switch, killing power to the relay trigger, disconnects the panels from the controller.

If I rig it as NO then the relay is not energized (no trigger signal) until I want to disconnect the panels, in which case the switch then applies power to the trigger, and disconnects the circuit, but then I have to leave the switch ON, powering the relay, to keep the solar charger is off, which is the part that makes no sense, because for storage, that means the only way to keep the solar panels off is to feed power to the relay, which kills the batteries. So I think I answered my own question, it should be wired NC.

Is this right?

[alctel]

Originally Posted by goboatingnow

Yes it can be so used but the over voltage is fixed at 16V and this is arguably too high for lithium HVC usage


It does support remote shutdown etc. But as a backup HVC it’s missing the ability to set the over voltage

Yeah that is way too high, but I've read somewhere that that's actually adjustable - you just have to put the 'reconnect' voltage below the 'disconnect' voltage, which you set to 14.2 or whatever.

The person talking about this had only done it in demo mode, so I'm interested if other people have done this.

Failing that, I would probably try to use a Sterling Prolatch R for the same thing but it looks hellishly fiddly to setup.

[noelex 77]

Originally Posted by jordanbigel

Looking at options for using a relay to cut off panel leads into (instead of battery leads out from) the MPPT, I am wondering if a simple automotive relay like this would be appropriate. Looks good to me. Each panel is only 15a and this appears to be rated for 30a.

https://www.amazon.com/ONLINE-LED-ST.../dp/B01N66W2XF

The relay is not suitable.

The maximum voltage rating is too low.

This may be just the rating for the coil voltage, but even if this is the case 14v is too low. Also keep in mind this kind relay will consume a considerable amount of power. A latching relay would be much better

[CatNewBee]

Originally Posted by jordanbigel

> If you can access it via VRM, you can access it via LAN / WLAN too.



This has not been my experience. When I disconnect my shore internet connection, and open VictronConnect, I can select my Cerbo or my MultiPlus under the Local tab. If I select the Cerbo, the ONLY option presented is the VRM button.



If internet is connected, and I open Victron Connect and select the VRM tab, I can select the CerboGX, and then I see in the top right icons for the BMV-700, and the 2 MPPT solar controllers. I can pick one of them and click the gear icon to access settings.



But, without Internet, using the Local tab, selecting the CerboGX does NOT reveal any options to select or modify the MPPT settings. Please, if I have done something wrong here I would love to know what it is.

Just open a browser and enter the local ip address of your cerbo. Don't use the BT App, the App needs the internet connection, not you, nor your Cerbo.

You can lookup your Cerbo IP adress in the WLAN settings or LAN settings - whatever you use in your network.
Attachment 257355

[goboatingnow]

Originally Posted by alctel

Yeah that is way too high, but I've read somewhere that that's actually adjustable - you just have to put the 'reconnect' voltage below the 'disconnect' voltage, which you set to 14.2 or whatever.

The person talking about this had only done it in demo mode, so I'm interested if other people have done this.

Failing that, I would probably try to use a Sterling Prolatch R for the same thing but it looks hellishly fiddly to setup.

I read through the manual it makes no reference to this.

[jordanbigel]

Originally Posted by CatNewBee

Just open a browser and enter the local ip address of your cerbo. Don't use the BT App, the App needs the internet connection, not you, nor your Cerbo.

You can lookup your Cerbo IP adress in the WLAN settings or LAN settings - whatever you use in your network.
Attachment 257355

Yup, I am familiar with the web interface. I have a bookmark in my web browser for it.

But, the web interface only presents a copy of the CerboGX interface, and there is NO WAY in the CerboGX UI to modify the configuration, or turn the MPPT device on or off.

If you select the MPPT controller in the Cerbo UI, you can see data like the voltage, current, other stats like total yield, history, etc. - if you tap DEVICE, you can see more info about the MPPT, but, there are NO options to configure or control the device!, the only thing editable is the device name.

[alctel]

Originally Posted by goboatingnow

I read through the manual it makes no reference to this.

Yup it's not in the manual, but in one of the discussions linked above on the Victron forums a Victron rep says it's possible, and in another one someone says it works in demo mode.

Wondering if anyone has tried it.

[jordanbigel]

Originally Posted by noelex 77

The relay is not suitable.

The maximum voltage rating is too low.

This may be just the rating for the coil voltage, but even if this is the case 14v is too low. Also keep in mind this kind relay will consume a considerable amount of power. A latching relay would be much better

Ach, I didnt notice that 14v limitation, I just assumed if it normal 12v range, from 10 - 14.6 basically. Okay.

As for using a lot of power, that's bad obviously. I will look for a suitable latching relay (I assume the latching part means that once it is in one position or the other, it stays there without using any power - is that close?). Thanks again.

[noelex 77]

Originally Posted by jordanbigel

I assume the latching part means that once it is in one position or the other, it stays there without using any power - is that close?.

It is better than close, it is spot on

The only current consumed is when changing states (from off to on, or vice versa) and this is only a brief pulse.

A conventional relay consumes power when either off or on (depending on which contacts are chosen). A magnetic coil has to hold the relay switching mechanism in one of the positions.

When choosing a relay it is worth looking up the manufacturer’s actual specifications. The better manufacturers provide copious details including the maximum switching voltages and current, as well as the maximum and minimum voltages for the coil and also the coil resistance. This later value enables the consumption of the relay to be calculated.

[jordanbigel]

Originally Posted by noelex 77

It is better than close, it is spot on

The only current consumed is when changing states (from off to on, or vice versa) and this is only a brief pulse.

A conventional relay consumes power when either off or on (depending on which contacts are chosen). A magnetic coil has to hold the relay switching mechanism in one of the positions.

When choosing a relay it is worth looking up the manufacturer’s actual specifications. The better manufacturers provide copious details including the maximum switching voltages and current, as well as the maximum and minimum voltages for the coil and also the coil resistance. This later value enables the consumption of the relay to be calculated.

The latching relay sounds far superior.

I've spent an hour so far looking at various devices which come up in google. Most seem designed to slot into specific sized breaker panels, or they are circuit boards designed to go inside another component maybe.

If you have any specific suggestions or a link to an appropriate device for this application, I would be eternally grateful.

Also, I'm trying to understand how to wire such a device - if it only uses power to make the change in position, does it use some kind of momentary switch, some kind of a pushbutton or what? Maybe a lighted pushbutton to show state (on or off)?

Thanks again!