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Forum Index : Electronics : 48V to 12V converter suggestions?
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Guys I need a 48V to 12V down converter for my RE set up. The 12v output would need to supply a couple of amps. Been checking out ebay and I see 2 types listed by several sellers. The first on is a 10 amp output, for about $25 to $35. eg http://www.ebay.com.au/itm/Industry-Grade-DC-48V-DC-12V-10A- Step-Down-Converter-AU-/220957202035?pt=AU_Solar&hash=item33 72135673 The other one is a smaller 3 amp unit, for about $5. eg http://www.ebay.com.au/itm/DC-DC-HRD-Converter-DC-24v-36v-48 v-step-down-12v-3A-/260861322252?pt=LH_DefaultDomain_0&hash= item3cbc8be40c My concern with these it there is very little documentation, and no indication of max input voltage. In my situation, my battery bank may reach 60v on the odd occasion, and I dont want the 48v-12v converter to spit the dummy. Does anyone have any experience with these ebay items, or maybe could suggest another that will safely work at 60v? Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| brucedownunder2 Guru  Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
Hi Glenn ,, I know you said 12v ,, but.. I purchased a used 48v- 24v 20 amps from OATLEY ELECTRONICS .Nice looking unit , They still have a couple left at around $35 plus postage .. Probably dosen't help ,,but ??? Bruce Bushboy |
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Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1345 |
Hi Glenn, This sounds like an easy project to make onesself, just need to wind a toriod with a 4:1 stepdown ratio and use the required transistors for the current then use a 5 amp rated 7812 reg on the output. I do know in the siliconchip circuit notebook several simple designs have been published over the years. So following along those circuits as a guideline it wouldn't be too hard to make one yourself. Regards Bryan |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Bryan Yeah I've seen a few circuits I could put together, but I figure for the price of the cheaper unit, $5, I could buy a couple of them so I have a spare, and save myself the time of making one. I also have a 24v to 12v 10 amp buck converter, and checking out the circuit, it should be straight foward to convert to 50v input with a few component changes. But again, its the time factor. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
This might interest your Bryan, a 2 transistor buck converter. http://www.romanblack.com/smps/smps.htm Finding a transistor and high speed damper diode for 50v might be a challenge, they would need to be rated at over 100V. Old TV's and monitors would have the parts, in the EHT section. Nice little circuit, might have a play around with it when I get some time. I did some reasearch on the ebay listed converters. The cheaper unit is only rated at 40v, even though they are advertised at 50v. So they may run at 50v, but 60v would be asking for trouble. The larger unit is rated at 60v, so it would be the one to go for I think. Glenn Edit. Actually, I'm wrong. That circuit uses a PNP transistor in the drive, just about every TV or monitor I worked on used a NPN. The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
gizmo if you find something that will work reliably and efficiently I would love to know. The best I have come up with is a step down from 48-60 volt to 27.6 or 24 volt to drive a fridge etc. Then re-step from there to 13.8 and 12 volt. It's not a great solution. I have found a lot of 24 volt rated gear is not capable of handling a 24 volt battery bank on charge, the danfoss compressor control board on fridges will handle 31.5 volts, but over 28 volts is pushing it with other stuff. I see inverters chewing power idling over with 12v and 24v plug packs bristling out of power-boards and think there has to be a better way. yahoo I'm confused, no wait... maybe I'm not... |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Yahoo this is the one I bought. It's rated at 60v. Comes from China, so quality may vary, or could be a fake, wont know till I test it out. http://www.ebay.com.au/itm/250869419023 One day I would like to play around with a PC power supply. They will run down to 90V in many cases, so I imagine we could fiddle with the electronics to bring that down to 40V, suitable for a 48v battery bank in deep discharge. The concern is the transformer getting warm, as the PWM would need to be higher to supply the same output voltage with a lower than designed input voltage. PC power supplies are cheap, and most of us would have a few spare in the cupboard. Will experiment one day. I did find a apple iPod charger that ran at 50V, supplied 12V at 2 amps. Start up was unreliable though. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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FrancisGreaves Newbie  Joined: 07/04/2012 Location: IrelandPosts: 4 |
Hi Glen I am looking for a 48v to 12v converter to drop my turbine down to 12v so I can run all the controlling electronics from a 12v battery and use the turbine to charge it. How did you get on with the Chinese item from Ebay? I did get a GPS board from China via Ebay, excellent service, excellent board, so I am optimistic. Thanks in advance Francis Perfect in every way, Modest and Misunderstood! |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Francis Yeah its been working for a few months now, no problems so far. So I can recommend this module. The only drama I had, which was my silly fault, is I connected it back to front once, fed 48 volts into the 12v output. its not a isolated converter, and fed the full 48 volts out the "input" and gave my 12v circuit a bit of a frazzle. Popped a couple of caps in a little LCD screen, but apart from that, no permanent damage. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| FrancisGreaves Newbie Joined: 07/04/2012 Location: IrelandPosts: 4 |
Thanks for the swift reply, I will go ahead and get one order up. I will try not to do what you did! Cheers Francis Perfect in every way, Modest and Misunderstood! |
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| phase Newbie Joined: 16/09/2012 Location: AustraliaPosts: 7 |
hey glenn ..if you have trouble doing this then ask some of the locals..as it stands from where i sit it .seem,s easy but there you go it really is not that hard to drop that much current..don't worry about the voltage.... |
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