Temperature sensor for multi-layer pack

[smeagol222]

I'm wanting to put temperature sensors inside the pack I'm building here: https://endless-sphere.com/forums/viewtopic.php?f=14&t=99374

It has 3 layers, and I have a dual LED temp sensor


The probes are quite thick and are metal on the outside. Can I heatshrink around these probes? will that give me inaccurate readings?


my 2 ideas were

1. attach prob to outside of pack (one on each side of a single cell)
2. sandwich probe between layers of battery. Need to heatshrink and make space with foam and plastic sheet
(this way the probes would be more to the center of the pack.

 

[krlenjuska]

I guess its better to put sensor somewhere between cells.

 

[flippy]

pull the top holder off, put the sensor between the center cells and hot glue in place, run the wire to the side between the cells and replace holder.
if hot glue is not desired then use kapton tape to tape it -good- against the center cell. preferably 2 layers of tape.

 

[john61ct]

And of course only measures its specific location.

If you had an active cooling system, even just airflow, then even small rises in the overall temp at the exit point would give an indication overall.

 

[krlenjuska]

even small rises in the overall temp at the exit point would give an indication overall.

https://www.youtube.com/watch?v=PuL6ddSOOt8

 

[smeagol222]

pull the top holder off, put the sensor between the center cells and hot glue in place, run the wire to the side between the cells and replace holder.
if hot glue is not desired then use kapton tape to tape it -good- against the center cell. preferably 2 layers of tape.

Flippy do you mean pull off the metal thing, so the sensor inside should be smaller? I don't want to break the sensor

When the metal thing is on the end of the sensor it wont fit in between cells. My only option is to sandwich between layers of 7s

so with the plastic sheet between them I would have to cut a small hole to allow for the thickness of the sensor, maybe use some padding too

And of course only measures its specific location.

If you had an active cooling system, even just airflow, then even small rises in the overall temp at the exit point would give an indication overall.

I would love to have some kind of cooling system, put a small 12v dc converter and some fans (one intake one extract) but then the whole pack isn't water resistant anymore. My ebike isn't the most waterproof. I think I would be worried about water getting in

 

[flippy]

Use different sensors. You can get flat ones that is basically just no thicker then a piece of tape.
The bead ones are easyer to get and fit between the cells better.

 

[smeagol222]

Hmm. I wonder if in general temp sensors are the same. I want to keep the LED displays

I have 2 sensors with one dual led

And 1 other sensor with on led

So I would have enough to put 1 sensor in each 7s pack. I guess this is overkill? I could just put 1 sensor inside middle pack perhaps

The temp sensor metal ends look like they are glued in. I could heat them up and try to remove- would there be a thinner sensor inside maybe? But the glue Heatproof epoxy? But wouldn’t that affect readings?

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[flippy]

measure the resistance and then get NTC's like this:

https://www.ebay.com/itm/10pcs-NTC-Thin-Film-Thermistor-100K-precision-1-MF5B-SMD-for-3D-Printer/201415005626

but mind the resistance rating. otherwise the value will be way off. or just order a bunch and take the ones that are right.

 

[smeagol222]

I think I got something here. I chose to take the metal end off the led temp sensor to make it easier to work with

I discovered that some of the cell spacers have a gap. I can make a small hole and push the sensor into the center pack. I will cut a channel in the plastic sheet to allow for the cable when they are sandwiched together

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