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PROFICIO avatar image

VE Bus Smart Dongle Batttery Connection

The cable that is shipped with the dongle, B+ (red) and B-(Black) is assumedly to provide power to the unit? If I have a battery bank of 8, 2 x 4 = 48V, do I connect the unit to one specific battery (12v) or over the 48V bank?

battery system voltage
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3 Answers
mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi, indeed power it from 48V. Both you you -never- (read rest in @Boekel his answer), but also because it does work as a Voltage sense.


From the manual:

When used with Multi- inverter/chargers the dongle provides on-battery temperature and voltage sensing capabilities - allowing compensation for possible cable losses which can occur during charging and discharging. Temperature sensing allows accurate temperature-compensation during battery charge cycles. On MultiPlus-II models the dongle is, at present, the only way to add an “on-battery” sensing capability.

What I meant with that is that it provides voltage and temp sense to all Multis ans Quattros.

And for where most of those inverter/chargers also have analog sense inputs; the MP-II does not. Hence this dongle is the only way to have V and T sense.


If anyone can rewrite that paragraph, by all means. Its not easy to explain that dongle since it does quite many different things.

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Thanks - It all makes sense. I have connect the B+ and B- directly onto the Quattro's battery connection so that it is spread over both my battery banks. I assume not sticking the dongle onto a battery does not mean that I will not receive the temperature readings directly from the Quattro's T-Sense cables?

If you just use the dongle for connecting to the Multi that's fine.

If you connect the dongle directly to the battery terminals, you also use the voltage sense function so the Quattro can compensate for cable losses (and also go in error a connection somewhere goes high resistance)

I don't know if the Quattro will still use it's own temperature sensor if the Smart Dongle is present, so I'd connect the sensor for the Smart Dongle to be sure.

Boekel avatar image
Boekel answered ·

Hi Proficio, the smart-dongle provides measurements to the VE.bus network, so it has to sense the battery voltage otherwise it's sending the wrong information.

See the manual:
https://www.victronenergy.com/live/vebus_smart_dongle_manual

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I have it the other way around. The Quattro inverter sends all the information to the smart dongle which communicates that information to my android phone via Bluetooth. The battery voltage, loads, etc are all done by the inverter and the dongle is only a conveyer of information?

Thus my question - If the dongle simply needs power (12v or ????) to communicate the inverter's info to me via the ethernet cable (VE Bus on Board the Quattro Inverter), then why should I attach it to my batteries in the first place? Only for power to the dongle?

The same applies if I connect my Laptop to the VE bus of the inverter via the USB/ethernet adapter. Nothing is attached to the batteries then as my laptop has its own power and the inverter conveys the information to my Laptop. I see no difference.

My concern is that the dongle can "Blow-up" if the voltage is too high or am I still missing something?

O wow when I read the manual again it does indeed say that it only provides voltage / temp readings to M II devices and non-VE.bus devices. that's a shame as it would be a nice way to do this.

as the dongle is also used to sense battery voltage, you can connect to a 48 V battery.

Thanks - much appreciated!

Paul B avatar image
Paul B answered ·

if the bank is in series and 48 volt then over the 48 volt bank

if they are in parrallel the the pos on the first battery and the neg on the last battery in the parallel string.

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Thanks Paul, just to make sense why over the bank and not on a single battery only? Is the dongle capable of handling any voltage? The cable (b+ and b-) according to my assumption is merely to supply power to the unit and not for any measurements? All readings are provided by the Quattro inverter via the ethernet cable? Am I missing something?

You -never- connect anything to a single battery in a string (except for BMS-like equipment) this leads to imbalance in the string and an early death to your batteries.

If you have another single 12v battery somewhere else, this might work (I don't know if the VE.bus and power supply are isolated in the dongle), but not a single 12v battery from a higher voltage string.