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Q about Victron SmartSolar MPPT "remote on-off" capability

Centex

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This in the context of a 12V nominal travel trailer system I am building, the key components are
  • 4x Grape Solar GS-STAR-200W parallel PV array
  • Victron SmartSolar MPPT 150|60-Tr controller
  • BestGo BWP-FE12400-ATI-PF LiFePO4 battery (~400Ah nominal)
  • Victron BMV-712 Smart Battery Monitor w/ included shunt
Two excerpts from the Installation Manual for the Victron MPPT SmartSolar charge controllers:

3.5 Remote on-off
The left terminal is connected to the internal 3,3V supply, with a resistor in series for short circuit protection.
The right terminal (marked as + or marked as H) will switch the controller on if >3V is applied, and will switch the controller off if <2V is applied or if the terminal is left free floating.
The recommended use of the remote on-off is:
a. A switch wired between the left and right terminal
b. A switch wired between battery plus and the right terminal.
c. A switch between the right terminal and the charge disconnect terminal of a VE.Bus BMS

5. Specifications, 150V models
Self consumption: Less than 35mA @ 12V / 20mA @ 48V
__________________________________

Questions ....
  1. Has anyone here rigged a switch per 3.5 a. or b. above to serve as an "on-off" switch for their SmartSolar controller?
  2. If yes, when the controller is turned "off" using that switch, does the controller continue to draw the small "self consumption" current or does the controller draw NO (zero) current from the battery?
  3. Is it correct that this switching capability can be safely used to turn "off" charging from the PV array without first disconnecting the PV array from the controller inputs?
I'm trying to understand if this simple low-current "remote on-off" switching capability serves to totally eliminate solar controller loads and output to the battery, or if a high-current switch/breaker on the controller output to the battery (with prior PV input disconnect) is still required to effectively totally remove the controller's output and load from the battery?

Thanks In advance, with apology if this has already been answered and my search failed to find that.
 
  1. 3.5a is the means of control via the Electrodacus BMS. If the BMS senses over-voltage on a cell, it opens the circuit.
  2. Unknown. I doubt it, but even if it does, hopefully 1Ah/24 hours isn't a deal breaker, and see #3.
  3. Yes. This warning is a red herring in the vast majority of cases. The primary reason to connect battery first is to ensure the SCC knows the battery voltage. The Victron documentation describes the ability of MPPT to continue being powered by PV input if the battery is disconnected.
If the circuit is open, no current will be sent to the battery.
 
I haven't setup such a remote switch so I'm curious about the answers.

But do keep in mind that even if the answers to question 2 is "there is no self consumption" and the answer to 3 is "you don't need to first turn off the PV input", you still need a 75A breaker between the SCC and the battery. And that breaker can act as a disconnect. But of course you do also need the PV disconnect. So the answers to your questions only affect the steps you need to take to truly turn off the SCC so there is no "self consumption".
 
  1. 3.5a is the means of control via the Electrodacus BMS. If the BMS senses over-voltage on a cell, it opens the circuit.
  2. Unknown. I doubt it, but even if it does, hopefully 1Ah/24 hours isn't a deal breaker, and see #3.
  3. Yes. This warning is a red herring in the vast majority of cases. The primary reason to connect battery first is to ensure the SCC knows the battery voltage. The Victron documentation describes the ability of MPPT to continue being powered by PV input if the battery is disconnected.
If the circuit is open, no current will be sent to the battery.
With regard to "2." the effect can be meaningful when to trailer is stored for a long-term absent solar exposure, no?
 
With regard to "2." the effect can be meaningful when to trailer is stored for a long-term absent solar exposure, no?

No more so than the battery's own BMS. It will drain the battery during long term storage. That's why most indicate that they need to be recharged every X months.

With long term storage, you need to make provisions to address charge loss in all cases.

A DIY battery can be dealt with simply by unplugging the BMS sense leads, and it will lose only a very small amount of charge in a year.
 
I haven't setup such a remote switch so I'm curious about the answers.

But do keep in mind that even if the answers to question 2 is "there is no self consumption" and the answer to 3 is "you don't need to first turn off the PV input", you still need a 75A breaker between the SCC and the battery. And that breaker can act as a disconnect. But of course you do also need the PV disconnect. So the answers to your questions only affect the steps you need to take to truly turn off the SCC so there is no "self consumption".
The protective purpose of that 75A breaker can be satisfied with a simpler, more compact, and more cost effective fuse, no?

Lacking a need for regular access to actuate as a switching device, a fuse lends to much shorter relatively high-current cable runs and more convenient installation in my specific case (attractive attributes if the relatively high-current switching isn't necessary).
 
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No more so than the battery's own BMS. It will drain the battery during long term storage. That's why most indicate that they need to be recharged every X months.
Respectfully, the effect is more than the battery's own BMS because it is additive to that drain. By eliminating all loads other than the battery's own BMS one extends the time interval "X" (or the amount of battery depletion over a period less than "X").

The DIY battery scenario is understood, but again respectfully that's not the subject of this thread.
 
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Respectfully, the effect is more than the battery's own BMS because it is additive to that drain. By eliminating all loads other than the battery's own BMS one extends the time interval "X" (or the amount of battery depletion over a period less than "X").

Respectfully, that's a distraction. If you're trying to cut the charge controller drain, you need to disconnect it from the battery. Period. The purpose of this circuit is to receive a signal from another device to indicate that charging should stop. If you're just trying to use it as an on/off switch, you should use an actual on/off switch or disconnect unless you can confirm if the open circuit also cuts the 35mA drain. That information may already be available at http://community.victron.com. If it's not, that's the better place for a definitive answer.

If you're putting the trailer in long-term storage, you need to make provisions to prevent the battery from discharging even if nothing is connected.
 
..... unless you can confirm if the open circuit also cuts the 35mA drain.
That's one [<edit] purpose of the post, perhaps another person here already knows the answer. Thanks for your replies!
 
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The protective purpose of that 75A breaker can be satisfied with a simpler, more compact, and more cost effective fuse, no?

Lacking a need for regular access to actuate as a switching device, a fuse lends to much shorter relatively high-current cable runs and more convenient installation in my specific case (attractive attributes if the relatively high-current switching isn't necessary).

While I don't turn my main Victron MPPT 100/50 off very often, it does happen a couple times a year during maintenance. Using the circuit breaker is a very convenient way to do that. My second Victron MPPT 100/50 is used for my ground deployed panels and it DOES get turned off frequently, so the circuit breaker is the way to go for me.
 
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