12VDC Power Conditioning

[moesterl]

Hello All,

I'm new to this forum and the automotive industry... I'm working on a project hooking up a data logging computer to a vehicle (CAN bus) along with an inclinometer sensor. I need to clean up the VDC from the alternator so it operates at a steady 12VDC.

Can anyone recommend a power conditioner to do this?

I appreciate your help!

 

[MacGyverS2000]

What voltage does the logging system work off of? If it's a low-voltage system, it most likely has proper conditioning inside of it. Unless the sensor itself is a self-contained unit, it most likely does not have proper conditioning, and that will be essential to a quality output signal.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[GregLocock]

Any bit of 12V data acquisition gear I have used in a car could handle what came out of the cigarette lighter socket.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[IceStationZebra]

I have used DC-DC converters before for this purpose. One source I used in the past was Calex, but there are others. I just used a PCB version and soldered wires directly to the pins. I also adhered the brick to an aluminum chassis to help with the heat dissipation. There are many voltage and wattage choices.

ISZ

 

[moesterl]

thanks for you help!

The datalogger operates at 12 Volts. It does have internal conditioning, as well as a 10A fuse. However, I've been using an additional external 5A fuse for convenience (I don't want to have to unscrew the datalogger everytime the fuse blows). It never should be drawing more than 1 Amp.

I feel like the easiest solution would be to condition the 10-14V input to a clean 12V, I just don't know if something like that exists.

However, now I'm thinking it might be best to just use an external 10A fuse and an internal 15A fuse for the datalogger and create a simple voltage divider for the inclinometer. Has anyone done something like this?

 

[IRstuff]

huh? What does the fusing have to do with the power conditioning?

And why do you need so many fuses at all? If it really only draws an amp, then having a larger fuse will simply cause more damage before the fuse(s) blow.

What is the specification for the datalogger?

If you're really that concerned, then get the DC-DC converter as suggested by ISZ and be done with it.

TTFN

FAQ731-376

 

[moesterl]

Yeah, sorry for the confusion... Current spikes are blowing the fuses. I'm thinking that conditioning the power will eliminate these spikes and stop the fuses from burning as often as I've been seeing.

The reason for 2 stages of fuses is convenience. The internal 10A fuse is a pain to get to. It's much easier to replace one external to the datalogger.

Here is the datalogger spec:

http://www.somat.com/products/somat_edaq_lite.html

Maybe it would be best to trust the somat power conditioning. I was also thinking of terminating the power input with a capacitor, I don't think it could hurt.

Thanks!

 

[dgallup]

You can put a choke (inductor) in series and a capacitor in parallel to build your own low pass filter.

 

[jbkettler]

Confusion!! The product specification at the link you provided states input power: 10-18 VDC. Your charging system is designed to operate within these parameters. You state that you keep blowing fuses - are you blowing the 5 amp fuses, or have you blown a 10 amp fuse? So....if blowing fuses is your trouble, please elaborate on that problem.

 

[BrianE22]

Maybe the power supply on the Somat has transient voltage absorbers that are pulling big amps through the fuse when large voltage spikes are seen.

 

[IRstuff]

Is this for school?

TTFN

FAQ731-376

 

[LionelHutz]

I read "ELCPU: 10-18 VDC". I can't get any other details from that site without registering and I have no desire to register.

A low pass filter using a reactor in series connected to a capacitor in parallel would probably suffice. Even just a decent sized reactor in series would likely be enough.

 

[theoldwizard1]

Go to a car audio store and buy a large capacitor.

 

[IceStationZebra]

You should not be blowing fuses when connected to a car. Somat data loggers are used routinely on cars and other engine powered equipment, and are designed to handle the power drop and spikes during engine start. My wild guess is that you are creating a ground loop somehow, maybe through the CAN.

Creating a voltage divider will do nothing to maintain a constant 12.0 vdc for your sensor, it will just pass X% of whatever you feed it. You need a voltage conditioning circuit to do that, and one of the easiest ways is the DC-DC converters. Digi-key sells them for $6-40 depending on wattage. As far as trusting the excitation voltage, you didn't say what layer you are hooking it up to. If you let me know I can check the manual.

I have used Somat products for the past 15 years and I can say their products are solid and customer service is 2nd to none. Call them up and see what Lisle has to say. You can also call their local sales rep, the one's I have dealt with work directly for Somat and not some catch-all instrumentation distributor.

ISZ