 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Electronics : High amperage power supply
| Author | Message | ||||
| BenandAmber Guru  Joined: 16/02/2019 Location: United StatesPosts: 961 |
I am in need of a high amperage power supply It would be much easier to use than to try to hook 4 batteries up in series to test inverters It would be awesome to be able to control current of this power supply Power supply would at least need to be able to put out 40 amps And it would be nice if the power supply could give out different voltages so it would be more useful  This Transformer weighs almost 70 lb this is the Transformer I would like to use to make a power supply I will be rewinding the secondary lower voltage side so I can put in as many taps as necessary I would really appreciate help on this I know I'm not the only one that would like to have a high amperage Transformer based adjustable power supply be warned i am good parrot but Dumber than a box of rocks |
||||
| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Try and find an old transformer MIG welder. This is a picture from the internet, but you will see it has two switches that give 27 different primary voltage tappings on the transformer. Output voltages might as a guess be in the 16v to 55v dc range.  Cheers, Tony. |
||||
mackoffgrid Guru Joined: 13/03/2017 Location: AustraliaPosts: 460 |
Ben, I have a similar situation where I am, I can't do High power testing as my batteries aren't up to the job. Unless you are going to use a SMPS, you're going to need a big Choke. I know you have some big cores  If you do get some batteries (old car batteries) just to stabilise the voltage you may want to use some big blocking diodes to stop the power supply from over charging the batteries. It all depends on your eventual configuration. |
||||
LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
I have read that the newer cheaper welding setups that don't use transformers use high current DC convertors. If this is true, then this might be a possible solution? The question then is whether these could be modified to either regulate or limit the current - whichever is easier. |
||||
| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
It depends on the welding process the welder is designed for. Stick and TIG welders are pretty crude constant current sources, you dial up the amps, and that pretty much fixes the heat level in the arc. The full open circuit voltage can be pretty high. MIG welders are very different, its a constant dc voltage process, where you set the dc working voltage, then vary the wire feed in speed into the arc to adjust the amount of heat and current. These cheap Chinese wonder welders are often set up to be able to do both types of welding with the appropriate welding head and accessories. Ben was asking about high current transformer supplies, and an old resurrected transformer MIG might be a good basis to start from. An electronic welder might be o/k, but I have no experience with them. The output might be pretty noisy which may be a problem if you are testing an inverter or anything "sensitive" to noise on the dc supply. There might be some pretty vicious high voltage spikes on the output, its only a welder after all, not really designed to do anything else. Cheers, Tony. |
||||
| kentfielddude Regular Member  Joined: 09/05/2019 Location: United StatesPosts: 89 |
Buy a used server power supply off of ebay |
||||
| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
I'm pretty sure that this Transformer came out of an old stick welder I have some big switches to switch two different taps of the Transformer I was hoping I could build some kind of DC to DC to DC Buck converter to use on the output of this Transformer And maybe have three or four different tabs four different voltages that I could switch to make it closer to the voltage I would be needing and then Buck it on down to the exact voltage and current Or you something like a High amperage dimmer circuit on the input of the Transformer and then have a really good filter on the output If it is possible to do it that way I still wouldn't have any way to control the current If nothing else I would want to build a very smooth DC voltage output that would be good for all devices no matter how sensitive And then just put a bunch of TAPS for different voltages on the secondary I know some of you are probably pulling your hair out I'm trying to figure out the cheapest easiest best way with what I've already got laying around be warned i am good parrot but Dumber than a box of rocks |
||||
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
That is not so easy. For high amperage you will need very big capacitors to filter the ripple. Capacitors the size you saw in the picture of my warpinverter... Before you get carried away and end up spending much money, build a smaller power supply and see the the effect of the capacitor at the output. Of course, to *see* that you need an oscilloscope. And then you need to know how to use an oscilloscope  Best stop dreaming about building big things and learn first how they work and how to use the equipment required to test them. You'll get nowhere without that knowledge, no matter how many questions you ask here. Klaus |
||||
| dwyer Guru Joined: 19/09/2005 Location: AustraliaPosts: 574 |
|
||||
| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
I have had a few goes at different times building really big dc power supplies, and none of them ended up being really nice or easy to use. The simplest is probably just a big transformer, bridge rectifier, choke and electrolytics. Then adjust the voltage to the primary of the transformer either by phase control with a couple of SCRs, or better still a large variac. No voltage regulation and no current limit. When overloaded it just pops the circuit breaker on the main power board. I built it into an old computer case, zero to +/- 50v at about 20 amps continuous. Its ultra crude and very ugly, but can be useful sometimes for a bit of rough dc power.   Cheers, Tony. |
||||
| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
That is awesome warpspeed If that's the way you done it I'm sure it's the best that can be done with what I'm asking Would you trust this to power a inverter board for testing If so could a light bulb be put in the circuit to limit amperage in this setup If your battery Bank was very low would you trust it just for bulk charging I know that when someone doesn't know a lot about a subject they can ask a lot of hair pulling out questions I apologize for the aggravation I think Kent had a very good idea those server power supplies can be hook together for higher voltage but they are very expensive I already have this really big Transformer here and I would like to do something with it besides scrap it be warned i am good parrot but Dumber than a box of rocks |
||||
| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
Kent had a very good idea but those power supplies can be doubled up to increase voltage but they are expensive Mack idea is pretty good too I guess a person could go to Walmart and get those $20 lawn mower starting batteries four of those would still be 80 bucks And like he said four of them isolate from a power supply so they won't overcharge Some of the best Minds in the world is on this form Is there just no cheap way to go about this or what be warned i am good parrot but Dumber than a box of rocks |
||||
| kentfielddude Regular Member Joined: 09/05/2019 Location: United StatesPosts: 89 |
I spent 5 minutes searching eBay. I was thinking something like this |
||||
 Print this page |
