Reddit reviews DROK 200101 DC-DC Buck Converter 3A Regulator Power Supply Module Step Down Reducer 12V/24V/36V to 5V Transformer with Dual USB+Ear for Cell Phone MP3 MP4 Car GPS

The way kevdav described it, the tablet will still go to sleep when you cut ignition and use very low power so the draw on your car battery should be very low.

I removed the battery from the tablet Friday. The car is powering the tablet as expected, but my tablet will not go to sleep when I cut ignition. The only way for me to trigger sleep mode is to physically unplug the OTG cable from the tablet.

This may be caused by the cheap power converter I'm using to power the OTG port. Some other reading I've done here suggests it may be caused by too much voltage coming from one of the power converters.

I'm using this converter for powering the tablet: https://www.amazon.com/gp/product/B016XI9BJS

I'm using this one to power the OTG port: https://www.amazon.com/gp/product/B00C3DQRY0

Thanks.

I have two cars and three 'projects'.

One underhood project:

1. Electronically-switched oil accumulator (accusump). Just ignition-hot.
   
2. Subtle under-hood lighting (no rice - subtle - will be playing around with it. Might decide it looks like shit, and not do it.) Might also install a switchable work light in case something needs to be done at night.
   
3. My own version of a lojack that I haven't gotten around to building. Also, if possible, have it control a secondary fuel pump relay to make the fuel pump die; basically an interlock that makes the car seem broken instead of locked.
   
   Two under-dash projects that are identical, one for each car:
   
   
4. Hard-wired radar detector
   
5. Hard-wired dash cam
   
6. Hard-wired USB outputs - one or two dual-12v-to-USB converters
   
7. Potentially the lojack-equivalent's battery charger (since it would have a separate small battery)
   
   The hard part is figuring out where to get a non-fused 12V supply under the dash. An add-a-fuse circuit is very appealing and I should find places where an extra 5-10A won't pop anything, so I may end up doing one 5-10A-add-a-fuse on an ignition-hot line, instead of a 12v-master-fuse + ignition-hot-relay, as the single master fuse for all these.
   
   Then it would just be a 15A strip terminal instead of a big fat 100A ground bar at the ground side, and a small fuse box at the positive side (with 1A or 2A fuses for each circuit, depending on their needs).
   
   ---
   
   I really appreciate your feedback. The only reason I haven't already built all this is because of worries of fucking up and coming back to a smoldering ash heap.
   
   ---
   
   I'm also figuring out how to mount all this securely under the hood... I figure these little wire clamps for the wires, and something like this velcro alternative to mount things like the fuse box, except it's hard to tell what temperature they're rated for (and it seems that the 3M stuff I linked will fall off due to heat.) Any ideas there? I want something that is 1) secure as fuck, but 2) that I could potentially remove without damage in the future, maybe using a heat gun or something. I would be mounting it mostly to plastic, but I don't want to drill any holes if possible.

I was hoping something like this to split into two usb connections and then simple as running usb cables to the camera. https://www.amazon.com/dp/B016XI9BJS/ref=twister_B01875XMKE?_encoding=UTF8&th=1

Oh and for power I just have a 12v to 5v USB adapter and hook it up to the ignition/accessory power in the dash. I'm not worried about corrupting the SD with that kind of shut down, if you are you could get a little more creative. https://www.amazon.com/dp/B016XI9BJS?ref=yo_pop_ma_swf

I haven't sorted out charging the phone yet though...