My 12V DC motor is not turning. - Page 1
Forum section: electronics / beginners

author: IIINicky
author_rank: Newbie
timestamp: December 26, 2021, 12:14:11 am
content: Hello, I am new to electronics and I have a 12V motor that I bought from Amazon and I cannot get it to turn. Originally I bought abattery packthat I could put 8 1.5V AA batteries that would make up 12V. At the time I thought my 12V battery pack would turn my 12V motor. I was very wrong and I found out about amps. I then bought aSealed Lead Acid 12V 1.2Ah Batterywhich from my research looked like it would be able to power the motor. It did not turn but it made quite a large spark and the terminals of the motor got very warm even though it was only connected for maybe a second or two.I am confused as to why it isnt turning and why I saw a spark? Am I missing something?here is the motor:https://www.amazon.co.uk/gp/product/B08CXL9BPL/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1here is my battery:https://www.toolstation.com/sealed-lead-acid-battery/p29879?store=O9&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&mkwid=_dc&pcrid=565612566369&pkw=&pmt=&gclid=CjwKCAiAn5uOBhADEiwA_pZwcEbfMAu3FUodPVMYZWIk-56RlHoSyMmiplv4a4Kqexs-LexldvU3vRoC_3EQAvD_BwE&gclsrc=aw.dsThank you very much

author: BrokenYugo
author_rank: Super Contributor
timestamp: December 26, 2021, 12:33:29 am
content: Sounds like a bad motor. It should make a spark (this is called inrush current) and instantly jump to life, even with AAs.

author: Gregg
author_rank: Super Contributor
timestamp: December 26, 2021, 01:31:25 am
content: Does the motor turn fairly easily by hand? It may seem a little ragged when turned by hand but there should not be any segments of a revolution that are harder to turn than others, It seems to be a pretty standard brushed series wound DC motor; meaning that the armature windings are in series with the static (outer) windings and the brushes conducting all of the current.Don't leave the lead acid battery in a discharged state; these like to be in a state of float; i.e. approximately 13.2 to 13.3 volts for longevity.

author: IanB
author_rank: Super Contributor
timestamp: December 26, 2021, 01:37:55 am
content: It'sprobablyreversible, but have you tried connecting it both ways round, just in case?It seems like it may be faulty, but I'm wondering if one of the brushes is somehow sticking on the commutator? Thismighthappen if you try to make it go the wrong way.But a motor like that should easily turn when powered by 8 AA cells in series. It won't give maximum power output by any means, but it should at least spin.

author: sleemanj
author_rank: Super Contributor
timestamp: December 26, 2021, 04:13:14 am
content: It should have run off your AA batteries just fine (assuming that the batteries were in series). I'd say you got a bad motor most likely. The Amazon ad you posted has errors in the description, they say it is a gear motor, when it assuredly is not, so probably not the best seller.Get on your local facebook, craigs list, goodwill, scrap yard or whatever and find yourself some old battery drills being discarded for a buck or free or whatever, dismantle and extract the tasty motor from them.

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 26, 2021, 12:21:13 pm
content: Sounds like a bad motor. As others suggest the shaft should turn easily by hand. The specs doesn't make sense. A 12V 0.32A motor can't be 60W. A 60W, 12V motor would have to draw 5A. But without any load connected to the motor it should turn fine with 8 AA batteries.

author: Siwastaja
author_rank: Super Contributor
timestamp: December 26, 2021, 04:47:56 pm
content: Broken motor. Ask for money back quickly, before the time runs out.This is why Ebay/Ali parts suck. For the experienced, it's just waste of time. For beginner, you can't know if the problem is somewhere you are doing, or in the parts.This being said, When I Was Young, the local brick & mortar stores (especially the legendary chain in my country) sold similar or even worse crap. It was colossal waste of time for a young hobbyist. But sometimes, you got something that works, by luck. But I bet many were disheartened enough to gave up the hobby.

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 26, 2021, 05:31:02 pm
content: I've bought several mabuchi motors at AliExpress to fix car locking mechanisms, zero issues...

author: Benta
author_rank: Super Contributor
timestamp: December 26, 2021, 10:14:50 pm
content: Yep, defective motor. It should run with just a single AA cell.Looks like a Johnson Electric. They're normally OK, but not high end.

author: IIINicky
author_rank: Newbie
timestamp: December 27, 2021, 02:08:12 am
content: Hello again, thank you for all the responses. I tried connecting the postivie and negative wires both ways and still no turning. I couldn't spin the motor by hand so I used pliers to turn the shaft a few times. It was super held in place and really stuck down. I twisted the thing a few times to to loosen it up. I didn't open the motor but it is still extremely hard to turn, you cannot do it by hand. It just made the big spark again and got warm. The battery is still sitting at 12.6V (read from my multimeter).It sounds like its broken from the responses. I bought the motor over a month ago so I'm not sure about my chances on getting a refund but I've sent the Amazon seller a message anyway with my new information and I'm hoping to get a replacement since it was sent to me in a non working order. If not I'll have to look for a new one to match my12V 1.2Ah Sealed Lead Acid Battery. Any suggestions?Thanks again,Nicky

author: BrokenYugo
author_rank: Super Contributor
timestamp: December 27, 2021, 02:38:01 am
content: Hard to tell you what motor to buy if you don't tell us what it needs to do.

author: mikerj
author_rank: Super Contributor
timestamp: December 27, 2021, 09:18:01 am
content: If you are unable to return it you have nothing to lose by attempting a repair. The end of the motor (where the electrical connections are) is "staked" in place, small sections of the metal are bent over to retain the end plate. Some careful work with a hammer and a suitable punch (even a sturdy screwdriver) to bend these back out will allow you to take the motor apart. Don't use extreme violence, and don't crush the motor housing in a vice, you could easily break the magnets inside.The armature will need a bit of force to remove, the magnets will be quite powerful and will exert quite a pull on the armature, and the spindle at the end may be a tight fit in the bearing. Try to remove the end plate and the armature as a complete assembly rather than just pulling the end plate off separately, which risks damaging the brushes. Most likely there is some issue with the front or rear bearing which is not turning freely.

author: Siwastaja
author_rank: Super Contributor
timestamp: December 27, 2021, 01:42:24 pm
content: Trying to repair it could be a valuable learning experience. At least you'll see first hand how such motor looks inside. "Don't turn it on, take it apart".

author: Zero999
author_rank: Super Contributor
timestamp: December 27, 2021, 02:22:01 pm
content: Quote from: IIINicky on December 27, 2021, 02:08:12 amIt sounds like bad bearing, or brushes.

author: wizard69
author_rank: Super Contributor
timestamp: December 27, 2021, 06:40:03 pm
content: A couple of things that might help with future motor implementations.With a all motors, new or used, make sure you can turn the rotor. Different types of motors have different "feel" so it might take awhile to develop that feel. In any event the 360 degrees of rotation should feel the same. Some motors will exhibit cogging others will not, so you need to know how that feels.If you have problems it pays to check for shorts to ground with a DMM before doing a lot more. You do not want to apply a direct short to a battery.Speaking of shorts, once you have a power supply capable of supplying lots of current (lead acid battery) you should seriously consider protecting that battery with a fuse or other from of overload protectionThat size of a motor should at least turn with no load on AA batteries. By the way don't disrespect Alkaline batteries as they can supply significant power in series / parallel configurations.Surplus / used motors are a gamble. I once helped a guy with a tread mill motor issue. Most of these used motors are decent for what they are, however his sucked. Come to find out the motor had about half its field magnet missing. So sometimes stuff that has a "good" reputation in the used world really was the cause for the tread mill to be scrapped.There are a lot more things to consider but it is just good practice to make sure you don't have shorts and that the rotor turns with every motor new to you.

author: IanB
author_rank: Super Contributor
timestamp: December 27, 2021, 06:53:09 pm
content: One thing to watch out for with turning the rotor, is thatifthe motor has a gearbox attached, then turning the output shaft of the gearbox might be difficult or impossible.It will usually be pretty obvious if there is a gearbox, since it will be quite visible, but just mentioning it for completeness.

author: Gregg
author_rank: Super Contributor
timestamp: December 28, 2021, 10:55:00 pm
content: If you can’t return the motor, by all means take it apart and consider the cost as educational. First make a mark in the back plate and housing so that you will easily align it if you can repair it; this can save a lot of frustration. Be careful of the brushes springing out of their holders when removing the back plate.I have seen these small cheap permanent magnet motors that have the magnet segments glued to the inside housing where the glue either wasn’t applied well or didn’t stick causing the magnet segment to wedge against the armature.Also the static magnets are usually fragile ceramic subject to breaking with a slight drop of the motor to a hard surface or other rough handling leaving shards of magnetic debris locking up the rotor.

author: m3vuv
author_rank: Super Contributor
timestamp: December 29, 2021, 12:57:50 pm
content: why no follow up to this,this seems to be a common ocurance on a lot of forums,leave everyone hangging why dont you!! FFS!!!!

author: IIINicky
author_rank: Newbie
timestamp: January 05, 2022, 12:02:24 am
content: Hello again, hope you've had a good new year!I've read all responses/advice and have taken it all on board. ThanksRegarding the motor I bought from Amazon, after messaging the seller back and forth I got my full refund and bought two new working geared DC motors (from a different seller). I knew there were different types of motor, but the names and what they were for is completely new to me. After looking around on Google and YouTube, geared motors sounded best for my project.I decided on making a "lift assisted" trash can. It's basically a bin that winches up the trash bag. I drew a few of my designs down beforehand and just started cutting pieces of cardboard and glueing things together with hot glue. I made a prototype version out of cardboard and after a lot of messing around with how it's all put together I now have something that actually works. I thought it would be best to work out most of the issues with cardboard, then purchase the materials needed.After I got it all working, I forgot / missed the part of getting the winch to go back up. It would winch down fine, but there was nothing to get it back up. So I bought a six terminal switch that basically allows me to flip the positive and negative terminals. Works well and got the job done. The only thing is if I accidentally didn't flip the switch off while it was winching the trash, the wire that connects the winch part to the base would rip through the housing that holds the motors. I'm surprised how strong this £10.00 motor is. I have been programming for a while, so I can use an Arduino to write a program to control it. The motor is 12V and an Arduino can only output 5V so after looking around online again, I have to use something called a relay which seems pretty simple. I feel like I'm on the way to getting this done. If there was a simpler way I'd choose not to use the Arduino, but this is what I found so I'll go with it.Thanks again for all the help, without it I probably would have spent more money on buying a different battery. Also, I have a job and other responsibilties to attend to so that's why I responded slow. I haven't left anyone hanging lol

author: Ian.M
author_rank: Super Contributor
timestamp: January 05, 2022, 12:56:54 am
content: You need to master the idea of limit switches.One of the simplest methods is to put two NC microswitches in series with the motor, rated for the motor current, that open when it reaches its travel limit, shutting off power to it, each with a beefy diode across the switch (in opposite directions) so the motor can reverse out of the limit.In your case, one switch would detect if the cable was nearly fully winched in, and the other if its nearly fully out. Detecting fully in is easy - clamp a stopper to the cable and let that trip the switch lever. Detecting fully out may be difficult with a high current mechanical switch - we'd have to see your build to think of a good place to put the switch.You shouldn't need an Arduino - simply wire the reversing switch + the motor, limit switches, etc. direct to the 12V supply and every time you reverse the reversing switch, the motor will run till it trips the corresponding limit switch.

author: Capernicus
author_rank: Frequent Contributor
timestamp: January 05, 2022, 03:34:56 am
content: make sure u dont use a resistor, but motors turn at any voltage just about. lower than an led.

author: IIINicky
author_rank: Newbie
timestamp: January 05, 2022, 09:56:21 am
content: This sounds like it could work. I've never heard of a limit switch, so I went on YouTube and found this tutorial.It's a bit different to my setup but easily transferable. Instead of attaching a stopper to the wire, I was thinking of attaching the limit switch above and below the platform that moves the disposable bag up and down. This makes it a lot easier on the mounting side of things. I'm still a bit confused on how it will be wired up, but I'll figure it out. Thanks, you're a genius!!

author: mcz
author_rank: Contributor
timestamp: January 05, 2022, 10:13:15 am
content: You could do it with two relais and an up and a down pushbutton. Pushing the down button once makes it goes down to the bottom and pushing the up button once makes it go up all the way.But there are easier options, it all depends on your requirements.

author: Ian.M
author_rank: Super Contributor
timestamp: January 05, 2022, 12:51:56 pm
content: There's a decent diagram here:http://www.trainelectronics.com/limit_switch/You want the second one, with the diodes. Note that the correct direction for the diodes is very important. Set up the first circuit with no diodes, and run it to one limit. Check the polarity of the voltage across the now-open switch and mark the positive terminal. Reverse the control switch, and briefly short the limit switch its stuck at to get the mechanism out of the limit and let it run to the other limit. Now measure and mark the other switch. Power off and add the diodes across the switches, cathodes (diode body end with ring mark round it) to the terminals you marked as positive. N.B. the diodes have to carry the full motor starting current, decreasing as it speeds up till the motor is up to speed or drives out of the limit. The starting current is equal to the (locked rotor) stall current, which is equal to the supply voltage divided by the motor's DC resistance. Although silicon rectifier diodes can survive surge currents of many times their continuous current rating, its advisable to choose a diode with a continuous rating of at least several times the motor's fully loaded running current.If you are a cheap-skate, you'll find a *very* beefy dual diode in a single package in just about any dead PC PSU. It will be a 3 pin device in a TO-220 or more likely TO-247 package, mounted to a heatsink on the secondary side, with a common cathode which is its center leg. The anodes are the outer legs. You want the one that feeds the +12V rail. Trace from its center leg through tracks and thick wire inductors till you get to a yellow output wire. If you get to any other color wire, try a different diode on the heatsink, or if you can, trace back from the pad with the yellow wires. Once you've extracted it, check both halves are good using the diode check mode of your DMM, or a bulb and a battery, then wire it into circuit with each limit switch between one of its end legs and the center leg. Note that to use a common cathode dual diode you need the connection between the switches to be the positive terminal of the switch from the test procedure in the previous paragraph. If it turns out to be the negative side, swap the order of the switches in the series circuit and re-test to confirm its now positive. The salvaged dual diode wont need heatsinking because it only passes current briefly when driving out of the limit.Any time you use a gear-motor, or any other type of motor with external high reduction gearing or mechanical advantage, limit switches that physically cut the power to it before it can break your mechanism by forcing it past its limits, are advisable, even if you have limit sensors further in from the mechanical limits, as inputs into your controller for the normal operational limits.