Duratrax Ice Temperature Sensor
 

I just bought a new Duratrax Ice charger with the temperature sensor.

Question: for those of you that have this charger, have you noticed that the temp sensor is extremely inaccurate as compared to a Duratrax temp gun or something similar?

When the temp sensor read 110 F, my temp gun read 145 F and I couldn't even touch my batts! Is there something I'm doing wrong, or is my temp sensor just a bad one?

Thanks,

Brian

(I hope this was an okay place to post this.)

Hi Kulangflow,

in principle, a contact thermo element is always more accurate than an IR sensor. The thermo element (bi-metal thermo-couple, for example) is not susceptible to chanes in surface and such, whereas a reading on a IR temp gauge varies with different surface.
Therefor you could expect much better results from the contact sensor.

I have never seen this Duratrax ICE sensor. Do you know what kind of sensor it is??

Some things that you could look for: Is the sensor really snug on the batts?
Maybe there's a protective film or something.

Maybe you can check with some handwarm materials. Double check with your IR gun, to see if the difference in readings is constant.

http://www.duratrax.com/caraccys/dtxp4171-2.jpg

Ice link

Thanks for your quick response.

I'm pretty confident that the IR gun is accurate, cause I've tried two with very similar results. Also, if the pack is too hot to touch, yet the sensor only reads 110F, that's definitely not right.

The sensor is snug, but it is having to fight through shoe-goo for its heat reading. It's not wide enough to go over a cell, so it has to fit between two cells in a pack. I'll rip the shoe-goo off between two of my cells and see if that helps. Of course, even if that helps it's highly less than practical.

I'll let you know what I find out.

Thanks again.

I don't use the sensor my self. I find the charger does pretty good with out it. Let me know what you come up with. I thought about getting me one of these sensors. Make me think twice now.

My best guess for this would be that the sensor is giving inaccurate readings because it is exposed to the ambient air temperature. So, the sensor is getting different temperature readings, and will display something between actual and ambient temperatures.

Yep, that was it! I peeled up enough shoe-goo between two cells for the sensor to have direct contact with the cells, and now it is reading almost exactly the same as the IR. (w/in 2 F)

I am very glad to have this temp sensor on there. It works on the discharge part of the cycle as well, pausing when necessary to allow the pack to cool a bit.

I wish it could just read through the goo, but if I just pull the goo up half a cell length on the battery bar side, then I'll still have 75% of the goo holding things together. It's a small price to pay I think.

Thanks for everyones' help!

Brian

kulangflow,

I noticed the same thing with my ICE temperature sensor, so I adjusted and just programmed the ICE to stop at different readings. For instance, when I want my nimh packs to stop at 120F, I set the charger to stop at 106F. For my lipo packs, I set to 110F. I took the approximate difference and adjusted the charger.

Batfish, you set the temperature sensor for Lipo packs? Lipo packs should only heat up a few degrees maximum during charging.

Yessir, I do. Nearly all of the incidents I have read about involving lipo fires are due to problems charging, which cause the pack to overheat, swell, and catch fire. Why take the chance when you have one more safeguard? :)
If the cells are supposed to stay below 140F, I'm going to make sure my charger is watching the temps if it can.
In practice, my 3s 3200 packs have never even gone up 1 degree while charging, but since I have the sensor there and I don't have to set the temp every time, why not? :)

Well, if the battery is able to heat up to show that is damaged, then it is. The possibility of a balanced pack to puff up or go up in flames is pretty small, unless it has been distressed during discharge. You might want to set the temp. to a low setting, a few degrees above ambient if you are going to use it. By the time the battery gets past 100 degrees, it will probably be too late.