Need help choosing a device for this project - Page 1
Forum section: electronics / projects

author: Aldietur
author_rank: Contributor
timestamp: May 27, 2016, 03:32:34 pm
content: HI, I'm currently looking for a circuit that can be used alongside a car battery (to read the output voltages) to transmit wirelessly to another device (phone, app, etc). I've been looking at arduino volt meters but haven't quite found exactly what I'm looking for.Parameters for this would have to be: Able to withstand high temps, can read 12V DC, ability to set up a wireless component for data collection. I don't have much of a background in electronics but can understand some of the basics/read basic circuits.

author: Aldietur
author_rank: Contributor
timestamp: May 27, 2016, 03:46:12 pm
content: Thanks for the fast reply, do you happen to know of anything a bit more simple than this device though? I'm currently doing an internship for a university professor who tasked me with this. I don't have a huge background in electronics (just a couple basic introductory courses) and he doesn't want anything with a complicated circuit.From what I can tell by looking at the 101 specs listed athttps://www.arduino.cc/en/uploads/Main/Arduino101-REV4Schematic.pdfit's a very complicated circuit for what he wants accomplished, I also can't find an operating temp range, do you happen to have a data sheet link by any chance? The 101 also apparently has a limit of 5V input, but if we're measuring a car battery (12V) this would be too much for the arduino circuit.

author: ajb
author_rank: Super Contributor
timestamp: May 27, 2016, 04:35:08 pm
content: You're not going to find anything much simpler that can "transmit wirelessly to another device (phone, app, etc)". That requirement means bluetooth or wifi, neither one of which can really be done without a fairly complex module or IC. The good news is that devices like the Arduino 101 have all the hard work done for you, and all you have to do is plug it in and program it. The complexity of the schematic becomes completely irrelevant to you.The 101's barrel jack will accept up to 17V, so that's fine for powering it from 12V*, then in order to read voltages up to 12V you'll need aresistor voltage dividerto scale the 12V signal down to 0-5V so that the ADC can handle it.* If you're using this in an actual car, it would be prudent to add some additional protection to your power input and signal inputs, but for a standalone device that just happens to use a car battery for power this may not matter.

author: Aldietur
author_rank: Contributor
timestamp: May 27, 2016, 04:44:50 pm
content: Yes, the plan is for this to directly go into a car. If the circuit doesn't matter, great, but one of the things he's asked me to do was to test a circuit on a 12V DC power source before we implement it into a car (proof of concept). However if it works as you're saying (circuit already done for me, easy to plug in and go) then that should be fine with the voltage divider. Hopefully I can convince him of a voltage divider and this system. Price can be an issue with this device.What he wants is something wireless, or an AUX like jack-in system where plugging the phone in "connects" it to the app and then displays the output voltage over a period of time on your phone.

author: Aldietur
author_rank: Contributor
timestamp: June 01, 2016, 05:32:41 pm
content: Well I guess an update, this one is too much for what he wants it to do, changed his mind and just wanted something that can go to an LED display, or something you physically plug into your phone to receive the data. ~$10 price tag, realistically speaking.

author: ebclr
author_rank: Super Contributor
timestamp: June 01, 2016, 05:50:13 pm
content: ESP8266http://www.aliexpress.com/item/New-Wireless-module-CH340-NodeMcu-V3-Lua-WIFI-Internet-of-Things-development-board-based-ESP8266-We/32565317233.html?spm=2114.30010308.3.19.apHTAV&ws_ab_test=searchweb201556_8,searchweb201602_4_10037_10033_507_10032_10020_10017_10021_10022_401_10009_10008_10018_10019_101,searchweb201603_3&btsid=ac79a36f-12d9-46c6-97e2-f7537e9c34e4

author: Aldietur
author_rank: Contributor
timestamp: June 27, 2016, 05:19:45 pm
content: I don't normally like bumping threads but I'm at a point where I really do not know what he wants to do with the parameters he has given me.He wants to take a volt meter and attach it directly to a car battery (while you're driving) where it is then sent to a display or sent to an app on a phone. I have already shown him the arduino but he turned it down. I'm not sure why. He wants me to compile a table of various volt meters with things like "is it programmable" which is something only an arduino can do, right? I'm seriously not sure what to look up.Regular volt meters are just testing volts, there are volt meters that plug directly into your cig lighter that read volts. What he wants is to specifically connect something to the leads of the battery so that it reads in "real time" to provide updates on whether or not your battery is running optimally, or if it's close to dying/needs a charge. From the replies here, arduino seems like my best bet. On my table I have 5 options, 4 are random cig-lighter displays and then 1 is the arduino again, but he's trying to teach me something and I just can't wrap my head around what it is I'm supposed to be learning.

author: Wirehead
author_rank: Regular Contributor
timestamp: June 27, 2016, 05:38:06 pm
content: Why does the professor wants to reinvent the wheel? How about transients on the supply blowing your meter up? A car's electrical system is a ridiculously noisy and harsh environment. And what about insurance? Will they like the fact that you've added wiring all over the place? (Risk of fire?)There's a standard to read this out. Canbus. Read that out. Along with tons of other information.

author: Aldietur
author_rank: Contributor
timestamp: June 27, 2016, 05:43:30 pm
content: He keeps telling me it's simple but my 1 year of very basic electronics taught me about noise and interference (just some really rudimentary stuff, which is why I'm here) . So if he wants something that's programmable, you will need protection on it, also the ability to withstand lots of heat (engine + summer heat) as well as ridiculous cold climates (living in Canada). I've tried to explain to him but he cuts me off or snaps at me for not finding exactly what he wants.When we had our last meeting he told me to do X which I rebutted with interference because of noise, but he cut me off so... I'll read that Canbus thing, thanks.Also probably why I'm close to being fired, because instead of just finding X, I'm trying to find something that won't cause the problems with added wiring to a car system.

author: Kilrah
author_rank: Unknown
timestamp: June 27, 2016, 05:46:22 pm
content: Quote from: Aldietur on June 27, 2016, 05:19:45 pmIt sounds like he himself has no idea either of what he even wants to do, or does but is grossly unaware of the technical complexity... which would mean he'll turn down any valid solution.

author: Aldietur
author_rank: Contributor
timestamp: June 27, 2016, 05:49:36 pm
content: Quote from: Kilrah on June 27, 2016, 05:46:22 pmHe turned down the arduino earlier this month, and has since gotten angry because I haven't updated him in a month. This isn't even my current project. The one I'm working on now has the same flip-flop attitude around it, but I'm much better at electronics than mems devices. He hasn't listened to me on either subject though.I just want him off my back or at the very least something I can say to show him that what he wants to do isn't feasible or that looking at 20 different volt meters doesn't change the fact the arduino is the only one that has the capabilities of what he's looking for (minus the whole attaching wires to a car battery)

author: cowana
author_rank: Frequent Contributor
timestamp: June 27, 2016, 07:06:40 pm
content: http://www.ebay.co.uk/itm/ELM327-Super-OBD-II-Bluetooth-Auto-Car-Scanner-for-Android-Torque-elm327-OBD2-/252084732958?hash=item3ab16bc41e:g:yK4AAOSwnDxUfrlASorted. Plug it into most modern cars, and you'll have a real-time record of battery voltage (and a bunch of other parameters) streaming over bluetooth, where it can be displayed on a phone or other display.

author: Aldietur
author_rank: Contributor
timestamp: June 27, 2016, 07:21:42 pm
content: Quote from: cowana on June 27, 2016, 07:06:40 pmSorry I think I was unclear. He wants a circuit/voltmeter that goes from the battery to a display near the radio (cig lighter, or even an option to cycle to it on a panel on newer cars). This is cool, but he wants to create his own so this wouldn't work. All you'd do for this is plug it in to scan battery voltage and transmit it over bluetooth, but I can already tell you he's going to turn this down. He is very adamant about using a volt meter that goes on the leads of the battery, not a plug in like this one is.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 27, 2016, 07:27:02 pm
content: https://moosh.im/Probably too expensive for your use case, but it's a bargain for a wireless dual channel multimeter.

author: PartialDischarge
author_rank: Super Contributor
timestamp: June 27, 2016, 08:20:44 pm
content: Just tell the sucker to get a Fluke 233 and its donehttp://en-us.fluke.com/products/digital-multimeters/fluke-233-digital-multimeter.html

author: Pack34
author_rank: Frequent Contributor
timestamp: June 27, 2016, 08:21:36 pm
content: Why don't you just pick up a cheap cigarette lighter USB charger and use that to power whatever microcontroller you're using, wire in a Bluetooth module, and put it in a small IP68 enclosure. Just be sure that everything is fused.If you want him off your back and you're unsure of the proper circuit protection portion then just start cranking out a simple Bluetooth ADC firmware and app. There's a lot of canned stuff that should be able to be thrown together fairly quickly.Since you seem to be a fresh engineer, you could just get an Arduino prototype going, get that to talk with a phone and then replace the Arduino with something custom. That way you'll have something easy to validate with so you aren't wondering which side (embedded vs app) isn't working. Then when you have this working you can focus on making sure it doesn't blow up when you turn your car on.Is the end result of this supposed to be a sellable mass produced product or is it a handful to be used by your company?

author: Wirehead
author_rank: Regular Contributor
timestamp: June 28, 2016, 04:49:24 am
content: Quote from: Aldietur on June 27, 2016, 07:21:42 pmFind a rather large USB charger to put in a 12V socket; put in a small esp8266 board which you power from the usb charger. Use a resistive divider on an analog input to measure the 12V. Slap on a display somewhere.That guy sounds like a total douche. First rule when starting a project: get a good spec. Even a "professor" should know that.

author: physiii
author_rank: Newbie
timestamp: June 28, 2016, 01:54:21 pm
content: I pull data from OBDII --- bluetooth --->phone-->server...battery level is somewhere the massive data I get from this. I just bought a cheap $10 bluetooth adapter but you can find a few DIY schematics out there.

author: Aldietur
author_rank: Contributor
timestamp: June 29, 2016, 08:32:41 pm
content: Quote from: Pack34 on June 27, 2016, 08:21:36 pmI'm not an engineer, I'm a nanotechnology student. My first year had 2 electronic courses which is where everything I know/don't know comes from, it's to set us up for making mems devices (and nano devices when I get to industry). I've tried really hard to push the Arduino product for him, yet that's not what he wants. As far as I know, this is supposed to be a sellable product in the future. He has a cheap USB voltmeter and wants something that can go to that or to another device and I'm just really unsure of what it is he exactly wants (as evident here where I can barely even explain it).

author: Aldietur
author_rank: Contributor
timestamp: June 29, 2016, 08:39:31 pm
content: I can find a lot of voltmeters that read the voltage from a car batter, either through the cig lighter or as a custom panel. When I show him these things he tells me it's not what he wants, and then explains to me again that he wants Battery > Wired to voltmeter > Display/wireless transmission of readings. I can go home and hook up my voltmeter to my battery to test it (without having the car on), easy as pie, but then what he wants is some sort of cheap voltmeter that would read a car battery as it's running, sending the data to an app or display that would set off an alarm when the battery is showing signs of failure/low charge.So for me, Arduino or another customizable volt meter are the only options I can think of, but then he wants a table of volt meters for me to show him with the specs of each on it, but then I'm at a point where I can put on some random volt meter like the one I have at home, or the more expensive ones like an Arduino that would actually work for this project.There are already so many designs out there that you just plug it into your cigarette lighter and it displays your voltage, some even have USB chargers. He really does want to reinvent the wheel on this project it seems.

author: Aldietur
author_rank: Contributor
timestamp: June 29, 2016, 08:46:48 pm
content: http://www.anbond.com/product/smart-3-4a-dual-powerful-usb-car-charger-with-led-power-dc-voltmeter-digital-and-current-temperature-inside-the-car-2/This is literally what he wants except that it doesn't read straight from the battery and doesn't go to an app, which means it's likely a no-go because it's not the type of "voltmeter" he's looking for.It seems like he wants to forgo some of the electronics side of this (fuses and plugs) and wants to develop something that is literally hooked up directly to the battery.

author: David Hess
author_rank: Super Contributor
timestamp: June 29, 2016, 09:17:50 pm
content: For a one off project I might consider an older technique but I think a wireless DMM is the way to go if you just want to buy something that already works.Use a voltage to frequency converter to generate a biased output, say 300 to 1900 Hz for 0 to 16 volts and send *that* using an existing audio solution like Bluetooth. On the receiver end just an application for measuring frequency and subtracting 300 is needed.

author: Aldietur
author_rank: Contributor
timestamp: July 04, 2016, 04:55:34 pm
content: Wireless DMM is way too expensive. Max price he's looking at is something like 50 bucks. Most wireless DMM's are way more than that. He has english as a second language, so maybe he's looking for the item I linked above but has trouble communicating that.

author: David Hess
author_rank: Super Contributor
timestamp: July 05, 2016, 03:50:45 am
content: I wonder if a wireless temperature meter could be modified to read voltage then. They are very inexpensive.Designing a wireless voltmeter which would cost less than $50 is certainly possible but not real practical.

author: Aldietur
author_rank: Contributor
timestamp: July 08, 2016, 03:30:18 pm
content: Quote from: David Hess on July 05, 2016, 03:50:45 amWell we aren't supposed to be designing a new voltmeter, or as he put it "reinvent the wheel". He just wants a voltmeter that can go inside a car, but I'm 100% sure it would just melt, so I look for alternatives and send him links but then he gets mad because he doesn't know what capabilities the product has.

author: edavid
author_rank: Super Contributor
timestamp: July 08, 2016, 04:06:50 pm
content: I think you are worrying a little too much about the automotive environment. It's harsh, but not that harsh.However, you are not worrying enough about transmitting radio from the engine compartment to the cabin. The battery is surrounded by grounded metal = Faraday cage. Why bother fighting that, when the voltage is right there at the lighter plug? Your professor sounds like an idiot.

author: Aldietur
author_rank: Contributor
timestamp: July 08, 2016, 04:22:38 pm
content: Quote from: edavid on July 08, 2016, 04:06:50 pmIn upper Canada it can be very harsh with very cold winters, and this summer has been one of the worst on record. Faraday cage isn't even something I know to account for. Maybe he just wants to recreate a device that already exists, or at the very least add a way to transmit it with a wireless signal to a phone, but that would mean adding something directly to the battery.

author: Pack34
author_rank: Frequent Contributor
timestamp: July 08, 2016, 06:24:18 pm
content: If you just use the ODBII connector, a lot of the temperature issues should be mitigated since it'll be in the climate controlled portion of the car and not in the engine compartment. Then just use an ADC to measure the voltage.Get the prototype working first before worrying about making it robust.

author: rrinker
author_rank: Super Contributor
timestamp: July 08, 2016, 07:19:04 pm
content: He keeps saying he doesn't want to reinvent the wheel, but when you can buy a $10 adapter that gives you the voltage via BT (and a whole lot of ADDITIONAL operating parameters) then that is EXACTLY hat he's trying to do. How cheaper can it possibly get to make a voltmeter that transmits via BT and mounts under the hood? A device that is fully inside the cabin wouldn't have to worry much about operating outside human compatible conditions - non op conditions may be extreme (closed car, hot sunny summer day, or car parked outside overnight on a cold winter night) but the typical cabin environment would be far more stable than under the hood.Maybe I misread part of this, but I see no point in locating the measurement device under the hood like that, and especially not when any relatively modern car already provides this info, even if it is not natively displayed on the instrument panel. ANd mine would have to go in the trunk - that's where my battery is. Unless it's not battery voltage that is really being measured but some other parameter.

author: David Hess
author_rank: Super Contributor
timestamp: July 09, 2016, 03:39:34 am
content: For amateur radio equipment, I install fusible links at the battery and bring a separate set of 10 gauge wires through the firewall to the radio directly from the battery and any other equipment. This also works fine for monitoring the battery voltage precisely and a cheap digital voltage meter is all that is needed.

author: Blastcap
author_rank: Regular Contributor
timestamp: July 11, 2016, 04:12:18 pm
content: Ive seen a finished gadget that does exactly that. (I have to dig around)Some sort of overpriced gadget with a smart app, telling you live the battery voltage, and when to replace your battery.But i find it silly to spend 50$ on a gadget to monitor your battery, when you can put those toward a better battery and not having to monitor at all.If hes worried about the car not starting in the cold weather, then he could invest in a starter module.http://www.aepint.nl/hybrid-power/products/engine-start-modules/powerstart-100/