Same VE.Smart Network and/or Cerbo GX for a two-battery setup?

DIY
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1

I have a two-battery setup with a starter lead-acid battery and a LiFePO4 house battery. Both batteries are monitored via a BMV-712, each battery is charged from on-shore power via a Phoenix Smart Charger. The house battery is also charged via MPPTs from solar and the starter battery from the alternator when the engine is running. Moreover there is a Orion DC-DC from the starter to the house battery.

To allow coordinates charging between the different chargers for each battery I want to connect the chargers either via VE.Smart Networking or a Cerbo GX. (I am not sure what I am going to use. Probably I go for the more cost efficient solution with a VE.Smart Network).

My question is: Do I need to setup to different VE.Smart Networks (or two Cerb GX for that matter) to coordinately control two sets of chargers or can I use the same VE.Smart Network for everything?

The crucial point is that the Phoenix for the starter battery must be controlled via the BMV-712 connected to the starter battery and the Phoenix for the house battery plus the other chargers (MPPT, Orion) must be controlled via the BMV-712 connected to the house battery. Also only the chargers for the house battery must coordinate charging of the house battery among each other while the Phoenix for the starter battery is out-of-scope.

I am not sure if a single VE.Smart Network can do that. However, a single VE.Smart Network has the nice benefit that the user sees everything at once. Same for the GX: A single GX has the nice benefit that I see everything at once in a single dashboard, but I haven’t found any information whether a single GX can use two battery monitors where each controls a distinct sets of chargers.

Here is a summary of the setup in bullet points:

  • Starter battery (lead-acid)
    • 1st BMV-712
    • Phoenix Smart Charger IP43 120-240V
    • Alternator
  • House battery (LiFePO4)
    • 2nd BMV-712
    • Phoenix Smart Charger IP43 120-240V
    • SmartSolar MPPT 75/15
    • SmartSolar MPPT 75/15
  • Orion-Tr Smart DC|DC 12V (from Starter to House)
Wohnmobil IP22 und Ladebooster
2

You need to set up a separate VE.Smart network for both the starter and auxiliary batteries.

The BMV supplies the voltage and current values.

This means that the networks must be separate.

For the lithium battery, you also need a temperature sensor to prevent charging at low temperatures.

3

OK, thank you. I expected so.

I thought that had read somewhere that it is possible to have more than one source of voltage/current values and then configure each charger which one it should use as input. But probably I remember that wrong, because I do not find that information anymore.

Thank you, I knew that. For me a BMV-712, a Smart Shunt and a temperature sensor (connected to that Smart Shunt) are an inseparable unit, so I didn’t mention explicitly the temperature sensor. (Yes, I know, one can use the Smart Shunt without a temperature sensor, but I never do so.)

Some additional questions which popped into my mind when I followed your link. Why does a VE.Smart Network with a BMV-712 (incl. a Smart Shunt and a temperature sensor) with several charger not control the total charging current? That’s suprising. The manual for VE.Smart Network, chapter 3 states

Connect multiple […] charge controllers together in a VE.Smart network to make them charge […] as if they were one large charger. The chargers will synchronise the charge algorithm between themselves. […]

Each unit will (and should) regulate its own output current. […] As such, it is not possible to configure a ‘network-wide’ maximum charge current. In case such feature is needed […] consider using a GX Device and its DVCC features.

[…]

Synchronising the chargers works in a master-slave manner. […]

As mentioned before, battery charge current is not controlled by the master, but by each of the chargers individually.

[…]

In the absence of battery current sensor, such as the BMV, the chargers on the network will have their output current combined to estimate a better battery charge current.

(Highlighting by me.) This completely confuses me. The last sentence says that all chargers use there combined output currents to estimate the battery current in case there is no BMV. OK, that makes sense as the chargers have no better option. However, the sentence also suggests that if a BMV is available the chargers actually use the BMV to read the real battery current. (I mean it would be stupid not to do so.) But in the light of that, how do I have to interpret the previous sentences? Those sentence suggests that the chargers do not take the centrally measured battery current into calculation, but only make a local control decision. That sounds wrong. Let’s assume that the combined chargers can deliver more charging current than the battery can handle and the BMV reports a current too high. I would assume that each charger starts to throttle its output. Maybe each charger does so locally and individually, but the result should be the same compared to what a GX does. What am I missing?

4

Quick answer it’s Sunday…

Orion-Tr Smart DC|DC 12V (from starter to house)

How is the charge booster activated?

With automatic motor detection, the charge booster will start when the charger is charging the starter battery.

The VE.Smart Network is only for simple installations and cannot regulate the total charging current.
I have already suggested this. Only a GX device with a Multiplus or so can do this.

Charging the starter battery via the solar system of the house battery is a frequent topic here.
I charge the starter battery via a PTC diode combination. You can use the translate button under the text.

5

Hi,
your answer confuses me, but I assume you answered to two different aspects.

That’s unfortunate. But I assume as long as my combined chargers two MPPT 75/10 and one Phoenix Smart 30A are not able to deliver a combined charging current higher than my battery allows (Eco Worthy 100Ah, 50A max charging current), I will be fine.

This question is a different aspect and unrelated to the question about VE.Smart Network, right? Yes, I am aware of the problem, that the Orion-Tr will kick in if the starter battery is charged via the Phoenix as the Orion-Tr will falsely assume that the engine would be running.

Currently, I am considering various workarounds:

  1. Option 1: The alternator has a dedicated “charging control output”. Usually, this signal drives a small light bulb to indicate whether the alternator provides energy and this signal is independent of the main output of the alternator, i.e. the signal is not affected by the Phoenix. So maybe, I connect this signal to the H signal of the Orion-Tr and disable engine detection. However, I am not sure how well this works as the output signal of the alternator is not a clean DC signal but some wild half-sine wave like voltage curve. The engine is from the 60s and the “charging indicator lamp” was a simple filament bulb which was also happily working with a distorted half-sine wave forms. However, I don’t know how happy the H input of the Orion-Tr will be.
  2. Option 2: I install a relay which is triggered by 230V on-shore power and drives the L/H input of the Orion-Tr. I only need to figure out whether I need a NC or NO relay and whether I need to connect L or H. Also see my other post about the L/H input signals of the Orion-Tr.
  3. Option 3: I install a NC relay which is triggered by 230V on-shore power and cuts the connection between the starter battery and Orion-Tr when on-shore power is available. So the Orion-Tr is cut-off from power.