Design power supply for 12V 1.5 Horse Powered Winch - Page 1
Forum section: electronics / projects

author: Upandcomingrookie
author_rank: Newbie
timestamp: September 06, 2012, 05:26:39 pm
content: Hello my Electronic peers,I am a senior at Devry University and am about to graduate in Fed 2013.I am currently an Engineering Tech at my company.I've been charged with designing a power supply for a 12V 1.5 horsepower winch. This will be the first time I've ever built a power supply besides on a lab scale. Theoretically I'm confindent, but I think we all know there is a huge difference between knowing the science behind it and actually doing it. I have an EE I will utilize but I would like to approach him with a decent design to start with.This winch needs a minimum of 12AH but under max load can draw as much as 110A.My boss suggested I do this using a 12V battery and recharger for stability (He's not an EE he's a PHD). I'm pretty sure this is not the best way to accomplish this. Can anyone give me some guidance on the best way to approach this. Thanks in advance.

author: SeanB
author_rank: Super Contributor
timestamp: September 06, 2012, 09:27:18 pm
content: Given that a winch motor is rated for a very intermittent load ( basically max 30 seconds then at least 10 minutes to cool off otherwise it goes all smokey on you) the use of a car battery and a permanently connected charger is a very good idea. You will need a car battery with a CCA rating higher than 110A, and this is easily exceeded by most batteries over 36AH rating. The charger should be able to charge at around 10A, to be able to get the highest duty cycle out of the winch, basically you need to be able to put back roughly what the winch drew in 30 seconds in around 10 minutes or so. If you use a smaller charger then it will take longer to fully charge the battery, but if it can be left on for a longer period it will work.Do remember that both the winch and the battery will not have a long life if used frequently in this application, you might be able to get an hour total out of the winch at full load, but the battery may suffer damage in doing so if you run too often. If the load is low then you will be able to do more operations per hour, but the battery will have to be bigger ( or you need 2 in parallel to increase capacity, you just have to buy 2 of the same model at the same time to do so) or it will be discharged fast, but you will need to have the charge over a 24 hour period into the battery exceed the discharge by more than the efficiency of the battery. That is you need to put in roughly 1.6 times the AH that you take out ( given typical lead acid cell efficiencies).

author: Shale
author_rank: Contributor
timestamp: September 06, 2012, 10:35:52 pm
content: Depending on how much operation time this will see, you may consider a larger battery. I know that semi truck batteries should be able to work for quite some time. If you are going the automotive battery route it may be something to consider.http://www.dcbattery.com/lifeline_GPL-8DL.htmlNominal Voltage: 12VAmp Hour Capacity @ 20 hr rate: 255 a/hReserve Capacity @ 25 amp discharge rate: 475 minsBCI Group Size: 8DMarine Cranking Amps @ 32* F: 1675 ampsCold Cranking Amps @ 0* F: 1350 ampsWeight: 162 lbs.Length: 20.76 in.Width: 10.89 in.Height: 8.60 in.

author: firewalker
author_rank: Super Contributor
timestamp: September 07, 2012, 08:38:01 am
content: I was working for a couple of years in small boats industry. The anchor uses 0.7~2 Hp 12 volt dc motors. Those motors is the best way to kill a battery. Even Calcium-Calcium batteries ("special" one for boats). The vast majority of those circuits uses a thermal resettable fuse that trips after a minute or so. Every boat with a anchor winch uses at least two batteries.Maybe you should use two large batteries and use them alternately. I don't know if an array of super capacitors could help protecting the batteries.Alexander.

author: Simon
author_rank: Unknown
timestamp: September 07, 2012, 09:30:06 am
content: Batteries sound like the easiest option. No need to over complicate life. 110 amps is quite hefty for a power supply particularly given its low usage regime.A couple of car batteries should do it easy to buy, cheap and made for such loads

author: G7PSK
author_rank: Super Contributor
timestamp: September 07, 2012, 09:22:27 pm
content: use a battery and a charger?booster starter. Some thing like this one, it will give 300 amps at 12 volts in order to start a vehicle with a dead battery.http://www.machinemart.co.uk/shop/product/details/bc335-batteryor this one at 400 ampshttp://www.sipuk.co.uk/tools/info_SIP05294.html

author: MikeO
author_rank: Contributor
timestamp: September 08, 2012, 02:58:56 am
content: Step one: is this a winch or a hoist? If it is a hoist, and you fail to use a worm drive to create failsafe load braking, you might kill someone. Never forget the ethics of your trade: setting aside the folks working in defense, don't design things that hurt people.I'd encourage you to choose a AGM battery if you are looking for long life, or the new generation of lithium ion batteries for power tools if you need to keep volume and weight down. I'm out of date but, some years back, A123 was out front with this technology. Ignore the cycle life rating on lithium ion, it's going to last no more than 3 years from the date of manufacture, less if the product is rarely used: they like exercise.The very low internal impedance of the AGM battery will allow much faster recharge, and, will suffer much less voltage depression under load, significantly increasing the performance of your winch.If you are using a lead acid, size the battery to live between 50% and 80% charged. You'll be doing damage below 50% on a starting battery. A deep cycle will tolerate going down to 20%, but not as well as the manufacturer claims. If using AGM, size for 20% to 80%. Batteries have a life, and they lose capacity over that life. Beware the temptation to size the battery so it only achieves the duty cycle when brand new. Add in at least 20% reserve capacity for lead acid and AGM, more for lithium based technologies (like 40%).The AGM will cost about three times as much as a good quality lead acid. Shale referred you to Lifeline. They are high quality.Don't be tempted to switch power with standard relays, they aren't rated for inductive loads, despite the misleading horsepower ratings. Use a motor starter. These are very cheap and dependable:http://www.mouser.com/ProductDetail/Magnecraft-Schneider-Electric/W199X-12/?qs=LQJGOuQCHKRYGVjEKfXYftw09xfiyRXjThey are available in different configurations and coil voltages.If you are using any solid state drivers, include a protection diode.The battery manufacturer will provide charging algorithms. Ignore them at your peril.Learn the language of batteries: research and understand "C rate."Disconnecting the charger when the motor is running is wise.If you can squeeze it in, including a low voltage shutdown to prevent overdischarging the battery will significantly improve the dependability of the device. Including over current and over temperature protection to the motor will prevent rare, but smoky, catastrophes.Or, if this is not a portable device, you can use a DC drive... Honestly, I think it is a better approach (In the interest of full disclosure, and to allow you the ability to judge the credibility of source, I'm ten years in manufacturing equipment and automation, ten years in battery and charging systems, first ten years as an electromechanical systems technician, working my way through school for a BSEE, second ten years started as a design engineer and worked my way to engineering manager--now I'm a corporate refugee, but that's another story).N.B. I'd be advising you poorly to ignore the direction your mentor has given you. At the very least, give him control and your confidence. If you want to pursue an alternate direction than he has given you, involve him right away in the selection of direction you take. I've got a lot of reasons for encouraging you to consider this approach. I'm not going to tell you any of them. If you must know, then take this post to your mentor, and let him answer himself.Good luck, and good for you for seeking multiple opinions. Now get started on some block diagrams.Regards,Mike O'

author: MikeO
author_rank: Contributor
timestamp: September 08, 2012, 03:28:25 am
content: Oh ho ho! I forgot the most important thing!!!A big battery is practically a theoretical current source. Starting a motor is practically a dead short. It is very, very rare, but batteries can, and do, explode. Don't have it near your face while doing your development. If a robust enclosure is not convenient, put the battery under a metal chair, a desk, behind your co-worker, anything, so that there is some barrier between you and it.It's rare, but not so rare that I haven't seen it happen more than once.Regards,Mike O'

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 08, 2012, 05:59:17 am
content: Use a 60Hz UPS transformer or rewound microwave oven transformer along with a pair of heavy duty rectifiers.

author: Upandcomingrookie
author_rank: Newbie
timestamp: September 08, 2012, 05:33:54 pm
content: Thank you all for your great advice!I will definitly use the 2 battery approach and research more efficient batteries.I will include a charger as well.Now that is decided. I have to get a transfomer to step down the power from 120vac to 12vdc. for charger.He also wants me to provide power for small measurement sensors from this power supply, this should be a small amount of power needed.It's basicly a DAQ that needs the power.As far as current, what size circuit breaker if any should I put in between charger and transformer. (I'll spec out the charger and see what is required).I guess my question is if I limit the current before the battery will that effect that amount of current that can be drawn from the battery itself?I have to put an estop and and auto/manual switch on there as well.I've attached the manual product number 68144 with specs as well as a diagram i found with a car battery hook up to generate any other great ideas and guidance.Next I'll post a diagram of the layout for your review!!Thanks again!Winchhttp://www.harborfreight.com/5000-lb-electric-atvutv-winch-with-automatic-load-holding-brake-68144.html

author: MikeO
author_rank: Contributor
timestamp: September 11, 2012, 07:46:02 pm
content: Do a block diagram of your design. Some of your questions will begin answering themselves.A 12 volt supply will not charge a 12 volt battery, you'll need a difference.You need to think more on what "limiting current" means, and the effects of different mechanisms for doing so.Regards,Mike O'

author: ptricks
author_rank: Frequent Contributor
timestamp: September 12, 2012, 01:13:06 pm
content: Be sure to design back EMF protection into the circuit or your design will not last very long. Charger designs are mostly used with non connected batteries, the exception being things like charging systems in cars. The motor on the winch will be changing its load on the battery constantly as the weight of the object and length of the cable changes and that will increase the back EMF produced.