# Cheap, high amp dc power supply?

T

#### twags6

Jan 1, 1970
0
Is there any way to make a dc power supply capable of 50+ amps at
12-13.8 vdc? Basically, I'm looking for something to simulate the
power from a car without the whole battery and charger setup. Parts
express sells a nice rackmount one, but I'd rather not part with $190. TIA Trevor T #### Tom Biasi Jan 1, 1970 0 twags6 said: Is there any way to make a dc power supply capable of 50+ amps at 12-13.8 vdc? Basically, I'm looking for something to simulate the power from a car without the whole battery and charger setup. Parts express sells a nice rackmount one, but I'd rather not part with$190.

TIA

Trevor

Hi Trevor,
What is the application for this supply?
If you need nice clean regulated power you can spend more than the $190.00 that you quoted. When I worked on high current mobile transceivers I would use the battery and charger set up, best power for the money. Regards, Tom E #### exxos Jan 1, 1970 0 twags6 said: It would mainly be for testing various equipment such as dc motors, car amps, etc. I was looking for something with decent regulation that i could possibly build. I've seen a few designs, but i'm not sure what the best would be. heres a few i found: http://www.mitedu.freeserve.co.uk/Circuits/Power/1230psu.htm http://ourworld.compuserve.com/homepages/Bill_Bowden/page12.htm#5reg.gif the regulator is easy, any switchmode chip powering a external fet will do the job, the hardest part is finding a transformer which will kick out 50amps..... Chris J #### JeB Jan 1, 1970 0 Is there any way to make a dc power supply capable of 50+ amps at 12-13.8 vdc? Basically, I'm looking for something to simulate the power from a car without the whole battery and charger setup. Parts express sells a nice rackmount one, but I'd rather not part with$190.
u might find something on eBay for about half that.

B

#### Byron A Jeff

Jan 1, 1970
0
Neither of these. Linear regulators will burn up a whole lot of power.
The 1230psu circuit above will have to dissapate 360W of power. Much less
than 50% efficiency.
the regulator is easy, any switchmode chip powering a external fet will do
the job, the hardest part is finding a transformer which will kick out
50amps.....

Why not an isolation transformer like this one:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4665&item=7509045051&rd=1&ssPageName=WDVW

The 1KVA is 66 percent more than the 600 VA the original poster requested.
And it'll be isolated.

Essentially you want to switchmode power from a 170 VDC filtered source.

But even at 90% efficiency you'll still have to get rid of 150 W of heat.

BAJ

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