BMV 702/712 temp sensor and sensor lug size - fitting

DIY
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1

I have the Victron Smartshunt IP65 and optional BMV 702/712 temperature sensor. This sensor comes with an M10 size lug/sensor, and it seems you can’t get an M8 size lug. I have done the conversion of fitting the temperature sensor to the Smartshunt IP65.

My battery poles are M8, and I have an MRBF fuse fitted. With this setup in mind, I’d really appreciate thoughts on the following:

I assume that cutting off and replacing the M10 sensor lug with an M8 size lug is not an option since the lug incorporates the sensor. That said, what is the most effective/safest way of fitting the M10 sensor lug to the M8 MRBF setup?

I’m thinking I should place the temperature sensor lug directly after the MRBF bar (before the actual MRBF main battery fuse) and bolt it down (via the battery post bolt), or should I place it on the MRBF M8 post after the main battery cable? Either way I would need to ensure movement is kept to a minimum (this is not a mobile setup, which I guess will result in less possible movement).

Any thoughts/solutions appreciated. Cheers all.

2

It’s generally OK to put an M8 bolt through an M10 lug. If necessary, use a larger washer. There should be a spring washer and plain washer under the bolt head anyway.

The sensor SHOULD be isolated from the Lug - I had one that was not, so it may be an Idea to test the isolation before installing the sensor.
Then install the sensor where you need to measure the temperature. Traditionally this was the battery terminal, but if you have lithium batteries, these have a zero temperature coefficient, so the only requirement is low temperature measuring to disable charging at low temperatures.

3

Thanks MikeD,

Don’t know why I thought about placing the temp sensor lug AFTER the MRBF holder as I’d probably just measure any fuse heat! - should go directly on the battery terminal with the MRBF holder on top of it.