question

Hi Schnitzel, welcome to the community; and sorry that this answer took a while.

1. Datasheet for the temp sensor: no we don’t have one available; sorry. Putting it in the freezer would perhaps be the most practical solution :-).

At some point we’ll add a feature in the inverter/charger itself so that you can configure it to stop charging at a certain temperature; just like our solar chargers already have.

For any other readers thinking about their lithiums:

- Victron VE.Bus BMS connected-, or BMS 12/200 connected-, Smart lithium batteries will stop charging; there the logic and temperature measurement is in the battery; and controls the connected equipment like the Multi. See recent Smart Lithium firmware update for details.

- same thing for CanbusBMS connected batteries like BYD or Freedomwon: the battery itself measures temperature and decides what to do by logic implemented by the battery manufacturer.

2. What does the Multi do with the temperature: it uses it to compensate the charge voltage. Only for lead batteries: lithium doesn’t need charge voltage compensation.

1-small: voltage reading on aux inputs: no; not available. Nice advanced feature though!

2-small: indeed. Last settings. Yes; its the issue with the Assistants:: gives you lots of power! :-)

I would like to do a similar variation of this, to restrict max charge current to 10% of the battery capacity if the temperature is at or below freezing.

Can I achieve that on the Multiplus using the Multiplus Temperature Sensor (for ambient temperature sensing) and an assistant? In other words, not an on-off relay function, but rather a dynamic config change?

Hi @Schnitzel long time since you posted, but I hope you are still around and the following is useful to you.

I just found this on the BMV manual PDF (p.29 in the file and p.27 in the paper manual):

45. Low temperature alarm -702 and -712 only

When the temperature falls below this value for more than 10 seconds, the alarm will be activated. This is a visual and audible alarm. It does not energise the relay.

Sorry if you are already aware of that, and/or if I'm missing something.

Hello everyone,

I was pleased to find such a great source of information for people who decided to purchase Multiplus unit but don't have "smart" BMS batteries that can communicate low temp info to the multi for the purpose of disabling charging at these conditions. I am in the process of finishing my van build where I used Multiplus 24/3000 and was wondering if any progress was made in software development? Located in Slovakia, EU so the winter just ended here, but it would be nice to have this feature in upcoming software releases before winter.

@mvader (Victron Energy) do you have any updates on this issue?

This is a bit roundabout and not a software fix, but using a thermocouple and a temperature controlled switch to switch a relay, you can redirect PV current to a heater to warm batteries up to chosen temperature, then switch back to charging once they are warm. Put the thermocouple between the batteries, set the controller to switch, and also to reset, at 5 or 6 degrees centigrade. Use a pet heat mat, or similar resistive load. Use appropriate voltage regulators, fuses, and safety techniques...

@Schnitzel , is it possible for you to please detail the process for: "My current setup is to connect the BMV-702 Temperature Control Sensor to the Battery and then connected the BMV-702 Relay to the MultiPlus AUX1 which controls the Charger via the Charge Assistant. This works nicely"

Much appreciated

Just a heads up for anyone arriving at this question from Google:

I've just updated the firmware on my Multiplus, and since v489 (or v494 for multi-phase systems), with the latest version of VEConfigure, this feature is now present on the chargers tab.

The information about this feature implies you need to connect the temperature sensor directly to the Multiplus, but I've got my temperature sensor connected to a CerboGX, and shared over DVCC, and this also appears to work.