The weather right now is so bad and hot! A friend of mine runs a mobile stream and his phone refuses to charge when it is hot. His stream crashes because he can't charge his phone or it overheats. Not even shade helps! So I'm thinking about making something for him that would clip onto his phone while he is streaming. A fan might help. But I think a peltier module would work better?

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   This streamer has access to 12V 6A outputs from a buck boost convertor. He uses multiple 20k mah 5V ~3A battery packs during his cast that power the buck boost. I don't know much about these ... so I thought I'd ask. I think a heat sink is needed. But is a fan absolutely necessary? I'm not trying to freeze the phone. Just cool a spot on the back to a reasonable operating temp. Any other information or warnings you have would be great!

  • \$\begingroup\$ Posting my results. Running the 12v peltier at 5v, it worked perfectly for this application. 12v generates too much heat for a 40mm heatsink. But 5v, the heatsink only gets warm to the touch. The cooling sid of the peltier feels a little bit warmer then a pop out of the fridge. (I don't have a way to measure temps.) \$\endgroup\$ – datguy.dev Jul 17 at 23:07

There are a few problems with that setup both thermally and electrically. Electrically there is the problem of connecting multiple 5V regulated battery packs in parallel to get the required amperage. They were not designed for this and there is a likelihood that one will output slightly higher voltage and prevent the other from load sensing and staying turned on. The peltier will be under powered. There are at least 3 unnecessary regulators wasting battery power and generating additional heat in the area around the phone. Just supplying a proper 12V battery without regulator goes a long way toward making this more viable and cleans up the wiring. The peltier does not magically create cold from electricity. It uses electricity to pump heat from one side to the other. It generates 60W of waste heat in the process. Where does all that heat go to? Only a few mm away from where it was collected, on the other side of the peltier. That puts all the heat right back into the air immediately surrounding the phone. A fan and heatsink might help move heat a bit further away, but that is more power draw.

The phone really needs to be inside an insulated container to keep it away from the heat. And if you are going that route, why not just take a frozen ice pack with you, or drop in a cold can of soda from a store. There could be moisture problems from condensation. In a pinch, velcro the phone to a cold aluminum pop can.

If the phone can handle moisture, I might try to fashion a case or stand and sunshade from terra cotta. Soak it in water and allow the heat of the day to evaporate the water cooling the terra cotta and anything within.

  • \$\begingroup\$ Thank you for your input! What kind of amperage is required for mere operation? I wasn't planning on running a battery packs in series nor parallel... I wouldn't even bother with that personally. I would simply power the peltier with what a battery pack has to offer and hope it's enough to allow "some" cooling. Maybe 3A max. I mean, would a peltier be useless at 12V and 3A max? Something about the way this whole thing works, cannot change because they're already in place like the 5V to buck booster to 12v. I'm getting the gist a peltier just isn't practical for this sort of use? \$\endgroup\$ – datguy.dev Jul 6 at 3:04

Peltiers will work fine from lower currents, in fact they work much more efficiently, as the waste heat depends on I^2, whereas the heat pumped depends on I.

Do an experiment with driving it from a single 5v battery pack. Locate which is the hot side, and put a heatsink on it. While you don't necessarily need a fan, a fan helps a lot with getting a small heatsink to be effective. Every degree rise in the hot side means a degree rise on the cool side, so you need all the hotside cooling you can reasonably get. Use a CPU cooler heatsink, a small heatsink with lots of thin fins and an integrated fan (preferrably 5v fan), designed to fit on exactly that size and shape of hot surface. A CPU cooler can be had new for not a lot, or for free from a dumped PC, clean the dust from between the fins before you use it.

In fact, using a CPU cooler heatsink on the hot part of the phone might be all that's needed, without the Peltier.

Experiment with the simple stuff before getting too complicated.

  • \$\begingroup\$ Thank you for the advice. I'll have to try it then. But I was hoping someone else already had done so. Nonetheless, I will not be able to use anything near the size of a CPU cooler. The phone wold be in a phone holder, ontop a tripod. If the contraption was big, it would not really work out for this particular scenario. Thanks again! \$\endgroup\$ – datguy.dev Jul 6 at 17:59
  • \$\begingroup\$ @datguy.dev how about a waterblock and pump then? That can be much smaller at the hot end. \$\endgroup\$ – Neil_UK Jul 6 at 19:15
  • \$\begingroup\$ i think water cooling would be the most effective option. But it is out of scope for this project. It would be out of budget, my friend doesn't want a water block attached to their phone, and it would be clunky for mobile use. \$\endgroup\$ – datguy.dev Jul 6 at 19:44
  • \$\begingroup\$ @datguy.dev If you haven't got room for a small waterblock, you certainly haven't got room for a Peltier and a heatsink! \$\endgroup\$ – Neil_UK Jul 6 at 20:22
  • \$\begingroup\$ It is not the size of the water block. It's simply the application of adhering the block to the phone. A pump with tubes and a water reservoir are also factors. We just don't want to go that route. \$\endgroup\$ – datguy.dev Jul 7 at 4:50

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