Disable overheat protection for automotive application?

[Michael Steinbach]

I have a Nexus 7 2013 mounted in my dash (2009 Mazda 6). It's hard wired, meaning I have removed the battery cell and replaced with a power converter connected to the vehicle battery.
This past few weeks have been quite hot and the tablet will often restart due to the heat and keep booting over and over until the temperature drops. Since the battery is gone, I don't really have to worry anymore about a critically hot Li-Ion burning up the car and would like to either disable the function or if that's not possible, replace the thermister with a resistor so it thinks it's always x degrees.

 

[Rukbat]

Since the battery is gone, I don't really have to worry anymore about a critically hot Li-Ion burning up the car

No, all you have to wory about is the CPU overheating (that or the GPU are usually why the device shuts off) and taking the motherboard out. Then you've turned a minor pain into a major repair. (And you'll still have the same problem.)

BTW, the battery has a couple of functions. One is supplying power. Another is as a noise filter. Another is smoothing out power fluctuations in the supply.

The power converter has only 1 function - supply enough voltage to keep the battery charged. Noise and power fluctuations are okay, since the battery handles them. Removing the battery gives you an unstable (and very noisy) power source.

 

[Michael Steinbach]

I didn't just remove the battery and plug in a USB supply. I replaced the battery cells with a 4.2V regulator from the car battery. I left the battery circuitry in between the regulator and the tablet so that it wouldn't report low battery all the time but there is still that temp. sensor for the battery that is causing the problem.

I do still have the USB 5volt connected and it's off when the car is off, telling the tablet to sleep. (I'm running Timurs Kernel)

 

[pjoseph]

Mine is installed in my dash as well did not remove the battery I have it charging via USB. I'm In southern CA and it gets hot plus I park in the street never had any issues with restarting due to heat