help to mod a car usb charger to dashboard and Android and Apple fast charge - Page 1
Forum section: electronics / beginners

author: mikael1985
author_rank: Contributor
timestamp: September 24, 2015, 05:21:56 pm
content: Hi and hello to everyone.I have some questions about a project that haven't been able to answer on my own, hope you will and can help me.I would like to add 2 rapid charging USB (>2.0A@5v) ports to my dashboard, and I had thought about buying this car charger it is apple compatiable so I assume it will have 2.5v on the datapins (apple rapid charge signal) - but I want android as well.http://www.ebay.com/itm/HOT-Belkin-2-Dual-Port-Car-Charger-Micro-USB-Cable-For-Samsung-Android-4-2-AMP-/151815123207?hash=item2358e2f107could i then open it up, and ad pustbtton to each USB port to the 2 middle pins, so I can push it and short the two data pins in one configuration(allows rapid charge for most android phones), or allow the 2.5V stay on (allows rapid charge for apple phones). I would then merge the +/- input of the USB charger wires to those powering my 12v dashboard power outlet, so it will not drain power when the car is turned off. I would then wire +/- output power and the pushbutton to a convenient place on the dashboard so it is just below the 12V outlet, but the actual charger is hidden behind the console (not my car - just an example Photo of what i wish for)http://topcoolcars.com/wp-content/uploads/2010/08/USB-Power-Outlet.jpg1 - is this a smart or a stupid way to do this?but I have for the love of god not been able to find some female USB ports that have the some kind of plate or something that lets it look pretty and flush with the surface, after I have cut a hole in the plastic, so a thing much like the small metal plate on the Picture - but I use ebay and china vendors as this is the only viable option for me and don't know what such a thing would be called so havent been able to find it.2 - can you help me track Down a female USB port which will hide the ugly hole in the plastic I will have to makebut apperently the cheapo usb charger to car from ebay apparently have a reputation of failing and/or shortening and even the normal/reputable USB modules are apparently not so good either as they introduce RF noise and what not into the electrical systems.. atleast according to maximhttp://automotive.electronicspecifier.com/connectivity/max16984-quickly-and-reliably-charge-any-portable-device-over-usb-in-a-car-with-a-single-ic(have not found a charger with that chip.. have been looking)3 - Is RF etc. really a concern for the car and the phone being charged, and can you recommend a brand of charger that already adress this?So is this a real worry and can you suggest a good alternative, I'm not afraid to do a Little tinkering and use a buck or linear regulator - if they are a better option - but don't know how they regulate charging of a phone - because it seems to me that lithium batteries requires alittle more for charging with over current protection etc. (offcourse this might allready be built into the phone?)4 - any other suggestions or commentThanks for any help/Mikael(sorry for the long post - but a rapid car charger for both Apple and Android is not something I have been able to find online - so I would add as much info to help anyone else would like to make or incorporate an apple/android rapid charger like me).

author: mikael1985
author_rank: Contributor
timestamp: September 26, 2015, 07:53:04 am
content: no response?thank you for reading the post anyway/Mikael

author: Monittosan
author_rank: Regular Contributor
timestamp: September 26, 2015, 08:14:58 am
content: http://www.siliconchip.com.au/have a design that is pretty much exactly what you are after. Check it out it was in the September issue.You can even buy the PCB directly off them!

author: RobertHolcombe
author_rank: Frequent Contributor
timestamp: September 26, 2015, 08:23:10 am
content: As for the USB connectors, search panel mount USB port or dash mount USB port

author: mikael1985
author_rank: Contributor
timestamp: September 26, 2015, 10:20:48 am
content: yes it seems to be the Circuit I need unfortunately I can read the full article on the preview,but I can atleast see the compoentn list and buy it offcourse - but it is a Little expensive when shipping etc is calculated but it have inspired me to what to look for, if making my own battery disconnect - this is preferable to leaching on the 12V outlet as I can give it is own fuse, and keep high drain on the 12V outlet unaffectedand thank you for the heads up on the USB parts proper names, found them now/bestMikael

author: rjeberhardt
author_rank: Regular Contributor
timestamp: September 27, 2015, 04:02:06 pm
content: If you're going to build your own charger you need to consider the high voltage transients that can occur on the car electrics. Load dump transients of over 70 V can occur also it is quite common for breakdown services to use a 24 V battery to jump start cars with a 12 V system.There are special regulator ICs for automotive applications with built in protection.Russell.

author: mikael1985
author_rank: Contributor
timestamp: September 28, 2015, 07:33:09 pm
content: I don't know if I would make one from scratch as I have little practical experience, the plan was to use a generic buck circuit preferable from a car usb charger and then mod it so it looked and behaved like I wanted it to with a little tinkering and external circuits.but unsure how to protect from transient voltage spikes - resetable fuse, capacitor, I really havent seen anything in the cae charger circuits I have looked atactually been thinking about incorporating a current sensing circuit which alternate between the "usb data pin charging modes" and find the configuration that draws the biggest current and in that way make it automatically charge Iphones/android at max speed - I thougt it was very clever myself.