Voltage drop on 18/2 wire

[chrisexv6]

I originally intended on powering my Uplink unit with the built in power board on the P983 enclosure. However, since my current draw needs require an aux power supply, I was thinking about getting one large enough for the aux needs in addition to the Uplink.

Uplink specs its max draw (communicating during alarm) at 2A@12VDC. I ran 18/2 solid wire up to the P983, to feed the power board that was included (P624 I think?)

Will the 18/2 wire suffice to get the Uplink enough of the 12V, or will the voltage drop be too much?

Im estimating about 20' run from where the aux supply would be to where the Uplink unit is housed. I checked a couple voltage drop calcs on the net and they are saying about 11.5V at the Uplink unit. Is that enough to keep it going?

Thanks in advance.

-Chris

 

[video321]

I calculated 11.49V, which should be within range - check the manual it should list a working range.

 

[chrisexv6]

I calculated 11.49V, which should be within range - check the manual it should list a working range.

Didnt see it in the manual, although it could be on the unit itself (Im at work right now).

Oddly enough, Uplink responded to my question from the website within 2 minutes of submitting it (how often does that happen!!!???)

Their reply was that the unit will work down to 10.2V at which point it will transmit a low power signal to the station.

 

[gizzmo]

My understanding of uplink is that the max power is only needed during a short lived "data burst " for about a second. 18/2 should be fine.

Sent from my Galaxy Nexus using Tapatalk

 

[Del91574]

18 AWG has a resistance of .00751 ohms/foot. In your case, as a complete circuit, that is doubled. Less than 1/3 ohm based on distance cited. If you calculate a continous 2A load, then yes, you'll lose 1/2 a volt at the unit, but there's more parts to the equation, without overthinking items here.

Also, most 12V supplies push out about .5-2V above their listed outputs, and when on battery, that is dependent on the supply being installed, if there's a voltage loss when running on battery only vs. AC, but normally that is around 1-2V difference, and the battery itself would be the starting point of that, based on age and condition, as most SLA's typically put out around 12.5V or higher when in decent shape, barring a voltage sag over time.

In your case specifically, the 2A listed for the uplink is very brief, 400mS. The real item to be concerned about is total continous load, which is really 28mA, not 2A. You simply need to have enough headroom on the supply to provide this.