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dawsoncity asked

MPPT 150/45 and battery temperature sensing

Hello, I'm a new member. I'm in the process of setting up a small solar power system in the Yukon. I've purchased a Multiplus 24V/2000, an MPPT 150/45 and lithium batteries. Here's the issue.

The fellow who will do the final installation had a bad experience with a Victron charge controller. He says that it failed to read the temperature correctly, and as a result it fried a set of new batteries. He blames the problem on this, that information about battery temperature is communicated to the contoller via Bluetooth rather than via a cable. Because of this bad experience, he has stopped using Victron and is advising me to do the same, at least as concerns the controller.

My questions are these:

1. Is this a real issue? On this site I have found cases where an MPPT controller has misread battery temperature, but in these cases the reading was too low and the consequence was that charging stopped.

2. Is it possible to set up the MPPT controller so that temperature info is communicated via a cable and not through Bluetooth. (This is what the installer wants.)

Thank you in advance. (Ik ben engelstalig maar NL is geen probleem.)

MPPT ControllersTemperature Sensor
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jetlag answered ·

I had once this issue, that there was a bad reading in the MPPT and the charger stopped charging because the temperature was assumed to be too low to still charge the battery.

After a reset and a firmware update this problem did not occur any more within almost 2 years.

The temperature delivered via bluethooth is trasmitted from a separate device, from the smart battery sense. This you should use if you are using "not smart" batteries, that are otherwise not able to transmit any values.

If you are going to use some smart batteries, where a Victron compatible BMS is able to transmit voltage, current and temperature to the system, then it can be done via cable connection between the BMS and the Victron system. Therefor you need to have also a GX device, like a CerboGX, CerboGX-S (cheapter) or a RaspberryPI with Venus OS running (DIY solution).

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dawsoncity avatar image dawsoncity commented ·
Hello Jetlag,


Thank you for this. The problem you mention (that the temp. reading was too low) is the one I described in my Question 1 above. But the problem the installer mentioned is that a misreading of the temperature resulted in the batteries being boiled--and ultimately destroyed.

The lithium batteries I've purchased do have a BMS system. What they lack is Bluetooth. Thus, at the very least I will need to buy the Smart Battery Sense, as you mention. This will convey temp. info via Bluetooth, but I'd like to do this via a cable.

From what you say, a cable connection is possible, although I would have to add a GX device. Well, this is possible. I'll look into it.

The thing is, I'm not sure that the issue the installer describes is a real problem. This is my main reason to the post above: I'd like to see whether anyone has encountered this issue. Thus far I've found no evidence of situations where Victron MPPT controllers fry batteries as a result of a temperature misreading. The installer said this happened to him once, but once is once. I'm reluctant to spend money on a problem that may not even exist.

Anyway, that's the situation. Thanks again, for your feedback. Greetings from the Yukon.

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jetlag answered ·

In my opinion it is not a real problem. At least I did not hear/read regularly about such "boiled" batteries. Especially if you have a "smart" BMS that should be able to disconnect charging when the battery temperature is too high. This is one of the major tasks for a BMS.

The smart battery sense can be a nice additional option, to also have the temperature visualized in the victron app, but it is not neccessary.

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dawsoncity avatar image dawsoncity commented ·
Jetlag, thank you very much. Thus far I haven't found evidence that this is a real problem. Perhaps the person I mentioned just had some bad luck. Thanks again.
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