Bench Power Supplies for automotive testing? Anyone use these?

[Seeker7]

Hi everyone, third post, and I'm already asking questions!

I'm an electronics n00b, but came across this site after being interested in cars and tools.  I went to the car forums first, and then the garage journal, which then led me here.  I am looking to re-shell a car project I have, and might (okay, will!) be making some slight modifications.  I also intend to be testing electrics, and looking at various components.  While I'm at it, since I like lego, I might find myself playing with the occasional electronics kit.   

Anyhow, after looking through the Autospeed site, one thing that came up on the wish list is a Bench Power supply: 
http://www.autospeed.com/cms/A_110892/article.html and http://www.autospeed.com/cms/A_109197/article.html

I have done some reading about BPS' here, and other forums.  There isn't much in the market here in NZ either - Sick Smith's gone all consumer selling ipods and TV's, and jaycar seems to sell just generic stuff, so I've no idea about their quality. 

On the checklist are:
* built-in (digital?) meters to show the current being drawn and the voltage being supplied;
* fine and coarse supply voltage adjustments
* variable current output facility
* extra outputs available (eg fixed 12 and 5 volt outputs)
* Power supply should also be completely protected against overload, high temperature and short circuits.

What range of voltage/current would I need? I'm figuring up to 15V, and while most components would be less than 10A, there are a few that far exceed this, but how far should I have to go?

So, does anyone here do work on cars and use these supplies, and if so, what would you consider important, not needed, etc.? Any particular brands I should be looking for? Any difference between used and new, and price, what about price?

One unit I have found is a Motorola S1348D - 0-20V DC, and 0-5A, two outputs, and three programmable voltage settings.  Is the amperage on this sufficient for my needs, and does anyone have any experience with this unit in general? I'm in no hurry to buy one, this is just one that's come up, is all.   

Of course, it may be that I'm in over my head, and running before I can walk by buying stuff I'm not knowledgeable enough to use just yet.  If it comes down to it, I can wait. 

Thanks for reading and for any advice given to this n00n, it's much appreciated!

[TheDirty]

A bench supply is more of a 'nice to have' than a 'must have', especially if you're doing basic car electronics, not talking about CAN network controllers, custom ECU's, or control modules...  You can get away with a PC power supply which gives you both 12V and 5V, which is generally all you will see in an automotive environment and a multimeter for current measurement.  The only thing I can think of that would take more than a few amps would be motors for window and such, in that case, just hook it up to the battery.

I would say wait until you get into it and find out how useful it will be to you before you jump into it.  A supply with all the functionality you listed will be fairly expensive.

[saturation]

As I know, a gasoline powered car's basic bus is just 12V, and regulation is fairly poor by electronics standards.  Individual devices usually have their own built in regulators to further improve that as needed.  Hybrid vehicle electronics and electricals, are not included and have special needs, its a whole new ball game.

That said, I think all you need is a basic linear lab grade variable supply less than 3A, 0-15 or 20V.  Such PSUs are typically overload, and short circuit protected.   Typical car electronics are not power hogs, and most linear variable PSU are fairly low cost and provide good regulation.

As thedirty says, if you need to test mechanico-electrical devices like starters, power locks, windows or others, it depends on how often you do such work ... even professional mechanics will run that out of a 12 battery which can deliver 75AH easily and cheaply, as they don't need the type of heavy regulation electronics requires.

[Kiriakos-GR]

On the checklist are:
* built-in (digital?) meters to show the current being drawn and the voltage being supplied;
* fine and coarse supply voltage adjustments
* variable current output facility
* extra outputs available (eg fixed 12 and 5 volt outputs)
* Power supply should also be completely protected against overload, high temperature and short circuits.

Those called as scientific type demands, and such gear are expensive,
starting from 1000$  for 10A output.

I do own one old Ken-wood   0-35V 0-10A.
The 24V its good to have too, so to deal with electrical systems found in big trucks. 

I was crazy enough to build my own 3-30V  30A nominal PSU, and I can even test starters,
the starter on my motorcycle uses 25A with out load. 
But it is damn heavy !!   with eight Japanese transistors and two rails of heat-sinks with active cooling,
they can handle 57A !!       and the t/f is just 30V 30A .     

Edit:  check this link 

[Seeker7]

Thanks guys, I was wondering if I was running before I could walk!

I saw the motorola unit here for about $100NZ (50GBP), seems okay, I thought 'why not?' and figured it would pay to ask, so thanks for the advice, 'not yet' is fine! lol I think buying new is out of my budget for now(!)...

Kiriakos-GR, what link do you mean?

[Kiriakos-GR]

Oups .. sorry mate ,  in my excitement I forgot to write the link 

https://www.eevblog.com/forum/index.php?topic=660.msg7847#msg7847

Its my PSU unit in it , and something that probably you will need too, one Pro AC/DC Amperes clamp.