Engine starter / HU capacitor mod

In some cars, such as mine, when I start the engine, ACC power is cut to the HU. So, if I am sitting in the car with the HU on and engine off, when I then start the engine, power is briefly interrupted to the HU. Sometimes this can cause issues with Android. It can also restart the boot sequence if the HU hadn't fully booted. So I have been considering this mod...

Quote:

Originally Posted by dsa8310 (Post 61872889) Since the ignition wire gives a very weak signal to the HU, using a diode and a capacitor at the ignition entry of the HU should prevent the reset without any Xposed based module. It works for my mirror with compass. (the diode has one end connected to the ignition wire; the capacitor has one end connected to ground; the other two ends are connected to the ignition entry of the HU - the red wire(?)) Just use a so called solid/polymer capacitor (not with liquid electrolyte!) which works below freezing temperatures - or otherwise rated up to -40 degrees Celsius. Code:                   HU IGN IGN o-------i>|-------X------i]-------o GND

Quote:

Originally Posted by dsa8310 (Post 63023207) Any (Sillicium) diode would do, finding the appropriate capacitor value, only by testing. If it's too big, then the normal powering off is delayed objectionably, while if too small, it won't delay enough (to cover for those few seconds while the engine starter is working). You would also need a capacitor that still works at below freezing temperatures (solid, tantalum). Just connect the diode between your ACC/IGN car (or CAN bus adapter) wire and the HU IGN entry, and the capacitor between the same HU entry and ground.

Quote:

Originally Posted by clearchris (Post 63026847) I reccommend against tantalum caps unless you really know what you are doing as tantalum caps failure mode is flames. :fingers-crossed: Solid polymer organic caps, though harder to find, or low temp rated electrolytics (they exist) are what i would go with.

Quote:

Originally Posted by dsa8310 (Post 63315573) Read my lips: :) Connect a diode (Si) between the car's ACC wire and the HU's ACC entry. If the HU does not start then reverse the diode. Connect a capacitor between the HU's ACC entry and ground. Choose a capacitor able to function below freezing temperatures. If capacitance is too big, the HU will remain on too long after stopping the car engine. Conversely, if it's too small, the starter will reset the HU as before. Start with a 100uF capacitor and find the optimal value for your car. If unhappy with this hardware solution, delve into the Xposed framework based software solutions (mtc... xposed... something).

680uF & 1,000uF capacitors have been suggested.

But then I saw mention of some prebuilt timer PCBs and there were some links to listings on eBay USA. Has anyone got any links to tried and tested devices sold through UK based sellers that are relatively simple for a non-electronics expert to configure?

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