Where do u put ur temp sensor?

[hummieee]

I could put it with its tip against the copper plate but think just taped along a cell is likely the intention. Depending on airflow I imagine it could post very different temps

[marketthrowaway]

In the ones with two sensors, one above the main chip on the BMS where it sinks into the metal plate, one on the cell/p-group battery positive main lead is coming off of.

With one sensor, I would probably default to the cell/p-group battery positive is coming off of.

I’ve also seen people tape it to the XT60/90/else power connector to the ESC

[hummieee]

@marketthrowaway

In the ones with two sensors, one above the main chip on the BMS where it sinks into the metal plate,((((so on the bms? Weird. ))) one on the cell/p-group battery positive main lead is coming off of.(((so intending to get a temp from the main circuit? So try to get the hottest temp you can?)))

With one sensor, I would probably default to the cell/p-group battery positive is coming off of.
((( What temp is acceptable?)))

I’ve also seen people tape it to the XT60/90/else power connector to the ESC
(((assuming the plug is shrouded/shrinked the sensor will just be touching plastic n not meal and won’t be revealing much.)))

I’ll try w the tip touching the copper plate

[me_ashman]

You might want to add insulation between those cells and the copper strips.

[hummieee]

These a123 are made backwards and the “can” is the positive… so if the copper rubs through it will contact the same polarity.

I’ve got paper on the end of the negative and between groups.

[Battery_Mooch]

@hummieee

I could put it with its tip against the copper plate but think just taped along a cell is likely the intention.

Yup.
You want the temp sensor as tightly coupled (thermally) as possible to the cells you think will get the hottest. Typically they are in the center of the pack but cells close to hot electronics should be considered too.

Against the metal can itself is best but through the cell’s plastic wrap is okay. Just don’t try to sense temp through fishpaper or lots of tape.

For that pack I would press the sensor down into the valley between two cells and hold it in place firmly against the cells while your hot glue (or whatever) hardens. Don’t use tape as it can loosen a bit over time, ruining the good thermal coupling you had. Though I guess you could tape it down with a small piece and then hot glue or epoxy it all permanently into place.

I feel the copper isn’t a good place to use as it will be significantly cooler than the can of any hot cells. And monitoring connectors should never be needed and you don’t know their temps anyway. The cells are the real safety issue, temperature-wise, and so you want to monitor those. Unless you have a crapload of sensor channels.

If you wanted to monitor one of the electronics instead then do it on the hottest component, typically that’s the FETs.

The main BMS chips typically run pretty cool and even if they are handling balancing internally they all have their own internal temp sensors so the FETs would be better. But most BMS’ already have their own temp sensors (in addition to the main chip’s internal sensor) so best to monitor the cells IMO.

Same for the ESC…the FETs can get hot but the ESC should be monitoring that already.

Be sure to check the overtemp and undertemp thresholds for the sensors. Use 60°C max and -20°C min. If you’re not riding in cold weather then use 0°C min so you never charge when the cells are too cold.