Questions tagged [automotive]
Questions about the design of electronics for use in an automotive environment. (Questions about the installation and use of automotive electronics are unlikely to be appropriate for this site.)
64
questions
95
votes
10answers
300k views
Why does a Tesla car use an AC motor instead of a DC one?
I was just watching a mega factory video and wondered why they use an AC motor which requires a power inverter instead of DC which may be powered directly from their DC battery? Introducing an ...
15
votes
4answers
5k views
Protection against automotive power supply hazards
I'm looking for a way to protect a small circuit which is to be used inside of a car or truck (12V or 24V power system). The circuit consumes about 12-15W. I use an isolated DC/DC converter module ...
9
votes
2answers
15k views
How do I protect against an automotive load dump?
A load dump occurs when the load to which a generator is delivering current is abruptly disconnected. In automotive electronics, this applies to disconnecting a battery while it is being charged by ...
7
votes
3answers
19k views
Detect car +12V using Arduino
I am looking to detect 12+V from a car wire using an Arduino.
I have found the following schematic:
I know how crazy automotive voltage can get so I just want to make sure the schematic I found ...
2
votes
3answers
2k views
Car bluetooth power delay- USB capacitor? [closed]
I just bought a bluetooth adapter for my car. It's input is 5V/0.3A and is powered via a 5V/1A USB power adaptor that is plugged into the 12V/10A/120W max. socket in the center console of my 2004 ...
3
votes
4answers
7k views
Combining RFID badges
I have multiple RFID cards that I use to get into parking garages at the office, client site, home, parents place, etc, etc, etc.....
I'd like to either
A) combine all of these into 1 card or ...
2
votes
3answers
7k views
How to calculate bus load of CAN bus?
I have a few questions regarding CAN bus load
Is there any derived equation/formula to calculate the bus load?
I need transmit below frames(Assume Standard frame format) at baud rate 500 kbps on the ...
40
votes
3answers
208k views
Why do we connect a battery to ground when jumping a car?
This may seem like a very simple question, but I've searched all over the place and haven't found an answer.
When jumping a car, we connect the + end of the charged battery to the + end of the dead ...
59
votes
8answers
17k views
Why are there so many relays used in a car, instead of transistors?
Recently I did some work on my car electric circuits. I see many relays are used in car circuits. These relays are used for simple switching, and I wonder why these circuits are based on relays and ...
6
votes
1answer
21k views
Why is there risk of overvoltage when jump-starting a vehicle?
Ford Focus C-Max manual describes jump-starting procedure as follows:
shut off everything, connect the jump cables, start the donor vehicle engine and let it run for a while, turn the ignition key on ...
26
votes
1answer
156k views
What is the polarity of a car cigarette lighter adapter?
There is a center pin, and two outside tabs. Which are positive and negative?
4
votes
2answers
4k views
Automotive electrical system. How does everything work?
I recently grew a big interest into the electronic world. I also love auto/mechanics, and I’m trying to understand where these two wonderful areas meet.
I’m trying to understand the fundamentals of ...
0
votes
1answer
1k views
current/voltage isolators in cars
When I attach something sensitive like a analog camera and LCD screen to a car battery along with a switched high amp load like a power door lock actuator, I get video problems when the load is ...
0
votes
2answers
2k views
Sense Automotive 12V Circuit from 3.3V microcontroller safely
I want to sense a circuit state in an Automotive circuit (12V nominal) from a 3.3V microcontroller (MSP430Gxxxx). The circuit is normally 12V (or VBat) until either the Wireless ECU or a Door Key ...
5
votes
2answers
8k views
Why do PTC fuses have different voltage ratings depending on package size / hold current?
I've been trying to figure out the PTC fuse I want to use in a little automotive power supply circuit and I'm a little disconcerted by the max Vdc ratings most of these things have.
For instance, ...
2
votes
2answers
2k views
Do fuse blow on ampere or effect?
I have a faulty car (bad central locking engines) and a fuse is blowing every time I open/lock the it. I'm looking to do a quick fix, and just replace it with an automatic fuse. The car runs on ~12V, ...
1
vote
2answers
347 views
What would happen if I choose a connector with current rating smaller than the actual current?
I need a butt splice connector that can handle up to 150A, which is really hard to find. What would happen if I connect it to a 12-10AWG butt splice connector?
Other type of connectors are not ...
0
votes
1answer
63 views
Which cell balancing method (active or passive) is best for low-voltage BMS (Battery Management System)?
As a beginner, I am going to design and develop a BMS (Battery Management System) for low-voltage applications (electric bike). So I would like to know which cell balancing method is perfect for low-...
81
votes
6answers
11k views
Will radar/lidar still work when every car is equipped with them?
Self driving cars rely on cameras, radar, and lidar to recognize the environment around them. Cameras of course don't interfere with each other, since they are passive sensors. Since a signal ...
19
votes
9answers
86k views
Why is the chassis used as ground in automotive electrical circuits
Automotive electronics generally use the metal chassis as the negative ground connector for the DC circuits. Obviously this saves something on wiring. Is there an electrical reason for this approach?
...
18
votes
5answers
13k views
Tesla Car “maximum torque at 0 RPM” - is this correct?
Tesla Model S Wiki
I've been watching youtube videos on this car, and everyone states that the crazy accelleration is due to maximum torque at 0 rpm. Doing further research, this car uses an AC ...
13
votes
3answers
30k views
Using LiFePO4 battery as car battery
I've had an idea of using LiFePO4 battery as replacement for car battery, since 4 of those in series make nominal 12.8V which is very close to standard 12V voltage. And depending on the cell we can ...
9
votes
2answers
3k views
Automotive power filtering, protection - feedback needed
I'm working on GPS tracker for automotive applications. Device should work in 9V-30V supply voltage range. In practice it will be fed from 12V car installation. This enforces the implementation of ...
11
votes
1answer
3k views
Simulating an automotive load dump with a bank of charged capacitors?
I've been working on a data logging device that will eventually go into my personal vehicle. I've scoured the interwebs and built what, in theory, should be a fairly stout power supply capable to ...
3
votes
2answers
7k views
Relay for Intermittent Wiper Function
I want to add an intermittent function to the wipers on my 40-year-old car without any additional switches. The details of the wipers can be found here [http://www.globalsoftware-inc.com/coolerman/...
14
votes
3answers
8k views
Arduino in car: capacitor for extra 3 sec of power
I want to install an Arduino Uno in a car, powered by a consumer 12V->5V car voltage regulator plugged into the lighter socket. The socket is switched, i.e, there's no power when the motor's off. When ...
7
votes
3answers
21k views
Splitting wires for newbies
I'm in the process of getting ready to build a car PC running Linux. One of the features I'd really like to incorporate is the ability to record car statistics from the sensors live using ODB2.
Due ...
6
votes
3answers
55k views
Is it okay to keep a USB charger plugged into the cigar lighter?
I have a USB micro charging adapter for my smartphone for my car. It is basically a cigar lighter plug that turns into a USB micro plug. When I don’t have my phone connected, and as such don’t want ...
5
votes
1answer
2k views
Converting a tachometer signal into something a microprocessor can understand
I am attempting to build a digital dashboard for my car (a 1998 honda civic), I have run into a bit of trouble, wherein the tachometer signal is quite hairy. I was wondering if someone would lend me a ...
8
votes
1answer
2k views
How can I simulate and handle an automotive load dump?
Long story short, I'm designing a little device to monitor a sensor or two in my car. I'm not an EE, but I'm a stickler for knowing things will work right and that I won't have wasted my time and ...
4
votes
5answers
16k views
CAN Bus Physical Layer Twisted pair or not
CAN bus is very common in automotive or vehicular applications. In our case, we are using aerial platforms with have CAN bus links between operator remote and ground control box.
As is very typical ...
3
votes
1answer
835 views
How can CAN transceivers ouput CANH=3.5V and CANL=1.5V?
When sending a dominant bit (0bit) on the CAN bus, I understand that CAN transceivers output CANH=3.5V and CANL=1.5V.
But when looking at the schematics of a CAN transceiver, I do not understand how ...
3
votes
7answers
3k views
Opinions on what I've come up with for a 12 V-to-5 V automotive circuit?
Is this a solid solution for an automotive 12 V-to-5 V circuit to power an ATtiny? I've been trying to come up with a solution for my needs that can handle the automotive environment that is so scary ...
2
votes
1answer
6k views
Jump start car from lithium ion laptop battery
Building the actual circuits is beyond me at this point, but I'm wondering if it's technically possible to jump start a car from the power contained in a large lithium-ion laptop battery.
For example,...
1
vote
2answers
144 views
First Time Using Integrated Circuits
I am building a circuit for a custom application. I have an old Toyota truck, and I keep leaving the headlights on, because there is no warning buzzer!
I have designed a circuit that takes 3 inputs:
*...
1
vote
2answers
168 views
Need a circuit to detect if something has gone from off-on or on-off
I'm new to circuit design but I'm trying to design a circuit for a power antenna that will send a 5 second pulse whenever it detects a a wire has gone from off-on or on-off.
So far I have designed ...
1
vote
1answer
1k views
Why is the CAN bus always busy (microcontroller)?
I'm trying without success to perform CAN bus communication between an microcontroller and the host (my computer). My question does not depend on the microcontroller, but on the CAN Bus (classic CAN).
...
1
vote
2answers
4k views
How to switch between two DC power sources powering a motor on an electric vehicle?
Background: For a university final project, my student group is investigating the possiblility of powering a motorcycle with two seperate batteries, each of a different chemistry (Lead-acid and ...
0
votes
3answers
3k views
Alternator current when charging flat battery
I've found some voltage-current-rpm graphs for car alternators and did not quite understand one thing.
Basically, my alternator is rated at 75A (small car), which it should output above 2000 RPM or so....
5
votes
4answers
426 views
Industrial electronics layout and design
Why do industrial panels for oil and natural gas compressors or other industrial equipment use terminal blocks for wire management? I have been doing some repairs for companies and was wondering why ...
5
votes
4answers
713 views
Does anybody recognize this automotive connector?
I'm trying to repair a wiring harness, and I'd rather pin and install a connector than splice into a junkyard pigtail. Does anyone recognize this and know where to find them? There's some serious ...
3
votes
2answers
5k views
OBD port power source [closed]
I've read on forums that OBD port can provide max 5A current at 12V. What is the source of the power? Is it coming from battery directly or is it regulated power supply from somewhere else, maybe ECU? ...
3
votes
1answer
951 views
Switch from electolytic to ceramic capacitors in car ECU?
I'm looking into replacing the capacitors in the vehicles ECU. I know the ratings and voltages for the three. My question though is which would be better to go with, electrolytic or ceramic. I'm not ...
3
votes
2answers
533 views
Possible to reliably run USB over a non-standard USB cable?
I'm planning on building a device for my car that sits somewhere in the rain tray or behind the dashboard. It will use automotive connectors so that things are sealed, easily connected and ...
2
votes
2answers
229 views
What to look in a desktop/small DC Power Supply?
I'm looking for the most adequate power supply that can go between ~0-30v and ~0-5A. These are going to be used for software development for automotive infotainment systems and the operation specs for ...
2
votes
1answer
222 views
Powering Atmega, DAC and Bluetooth in Car
I'm looking for a proper power supply schematic which would fit my needs and would have all required protections (overcurrent, overvoltage, reverse current, etc) for use in car. I want to power Atmega ...
2
votes
6answers
4k views
Electronic flasher with low load detection
The circuit above is an existing flasher without low load detection. I am trying to develop electronic 2-wheeler flasher with low load detection. While Googling, I got a circuit with relay in it, one ...
1
vote
2answers
415 views
Using a PIC to perform switch on and timed shutdowns in automotive environment
I would like to build a circuit to perform a timed shutdown, based on logic inputs from headlamp wires and ignition wires.
I have decided on PIC10F200 (datasheet) to perform the logic.
I also have ...
1
vote
3answers
2k views
How to measure the current drawn by the radio and the headlights from car battery easily?
I wonder how much current is drawn from car battery when the headlights and the radio are fully open. Is there a way to measure the resistance of the radio or the headlights without unscrewing or ...
1
vote
1answer
178 views
Powering a Behringer MicroMIX MX400 - Car Audio Application [closed]
I am installing a car audio system that will have TWO aux inputs; one in the dash and one in the rear passanger seat are.
I decided to purchase the Behringer MicroMIX MX400 mixer. The power spec for ...
