Powering CVS1454 with batteries

[HenryBryantBigelow]

Hello,

We need to power the CVS1454 with batteries.   We have a 32VDC battery system that has the Watt-hours we need and we expect the CVS and peripherals to draw less than 1.0A (no problem for the battery). When we use a 24V voltage regulator (NTE972) rated to 1A we find that the CVS1454 doesn't even turn on.  Hmm.

Any advice appreciated.

Thanks,
Ben

[AnalogKid2DigitalMan]

Is it wired per page 2-10 in the link for the manual?

http://www.ni.com/pdf/manuals/373610e.pdf

Does it work with the standard NI supply (if you have one)?

[HenryBryantBigelow]

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@AnalogKid2DigitalMan wrote:

Is it wired per page 2-10 in the link for the manual?

http://www.ni.com/pdf/manuals/373610e.pdf

Does it work with the standard NI supply (if you have one)?

---

Hi,



Thanks for the response.

Yes, I can confirm that the input V = 24VDC and matches that described in the manual.

Yes, we do have the AC/DC power brick that NI sells with the CVS and all works fine when we use it.


We can get the CVS to boot-up and run from batteries if we use a Radio Shack voltage regulator
273-1827 (http://tinyurl.com/ppfb) - but I'm not sure if that will be satisfactory for deployment later where we want to keep power consumption low. I can't noodle out why the 24V regulator doesn't work.

Thanks again,
Ben

[AnalogKid2DigitalMan]

Interesting. Do you have access to a multi-meter? If so, I'd verify the current draw by the CVS while using the NI or RS supply (of course you must cut a wire or make a jumper cable to insert the meter in series).

Other than that, have you verified the regulator circuit is actually outputting 24V?. Do you have another regulator to substitute? If it is hot to the touch, the 972 may be going into thermal shutdown (needs heatsinking).

The 1454 manual specs 12-22W power consumption, excluding cameras. This translates to 0.5 to 0.92A, so thermal shutdown may be a possibility (but I think it would take a little time to reach shutdown).

[AnalogKid2DigitalMan]

Ben:

Further investigation shows that the NI supply is rated 50W, the RS supply is rated 60W.

Without an actual current measurement from a working system, I have a hunch the 972 regulator circuit is starving the CVS for current. Can you try a higher power regulator?

[HenryBryantBigelow]

Hi again,

Yes, we have measured the CVS current draw (when powered by the NI brick.) With the camera acquiring and peripherals running (FireWire drives for saving images) the current drawn is 0.9+ amps. That's one reason we went with that particular votage regulator NTE972 - it is rated to 1A at 24VDC. We have a number of these 24V power regulators on hand and we have tried a couple of them. The output on the oscilloscope looks clean -it doesn't appear change when we connect the regulator output to the CVS. The regulator is not getting hot to touch (not even noticably warm for that matter.)

Thanks again,
Ben

[AnalogKid2DigitalMan]

Ben:

I am stumped. Methinks the regulator would be getting warm at 0.9A, but you say it is not. What is the current draw when using the 972 regulator setup?

I know nothing of the CVS other than the brief review of the manual today, hopefully someone else can chime in with suggestions.

-Pete

[HenryBryantBigelow]

Hi,

Yes, I could try a higher power regulator if I can hunt one down. I see a TI μA7800 SERIES is 24V 1.5A (36W) and that might do the trick. Incidently, the power brick that came with our CVS 1454 is a Tri-Mag DT450-6V3 24VDC 2.3A (55W). The batteries we hope to use are good to 6.9A at 28 VDC.

Cheers,
Ben

[HenryBryantBigelow]

We get no current when we connect the 972 regulator. I am 99.44% sure that the connections are fine (I have wiggled and tested everything except my boss' blood pressure). As far as the heat is concerned - I suspect that the CVS internal power regulators are rejecting the input. The status light on the CVS doesn't light (no flicker - no wink - nothing).

It's probably a good thing that weekend has arrived.

Thanks for all your help and suggestions - I very much appreciate it.

Cheers,
Ben

[Bob_Y.]

My guess is that there is more current draw during initial power up than during the steady state.  This is common in many systems.  Initial surge current could easily be twice or more the value of the normal operating current. 

Hope that this helps,

Bob