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noah4x4

Intel NUC with battery power

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Just some helpful information about battery requirements for an Intel NUC;

I have a wireless/cordless EAA set up with large sensor megapixel camera; Hypestar 802.11ac WiFi; Teamviewer to second laptop (in the warm!) etc.  I chose an Intel NUC i5 as the mini-computer at the telescope to ensure I had enough 'ooomph', and built this compact cradle out of aluminium hobby sheet to hold the NUC and batteries. Everything rotates together so no cordwrap. Narrative is continued below the image;

Telescope6.JPG.4ef2fb82cb1dca5147201e54edeed145.JPG

The Evolution mount has its own internal battery (lasts 10 hours).  As can be seen, I am using a 12v 8Ah Tracer to power camera and focuser (about 2 amps) and a '2-Power' 19v 27Ah to power the NUC.  The 2-Power was the only higher capacity power bank I found guaranteed to output 19v for the NUC and guaranteed compatible (see next paragraph). The issue with this set up is that I can enjoy a maximum of 4 hours EAA due to the battery capacity limitations. I don't want to carry around a giant 'brick' given the compact nature of my set up, so unless I double up on these batteries (e.g. as spares) it is not feasible to do a long session at a dark sky site away from mains power.

Then the MaxOak 20v or 12v K2 50Ah was suggested to me as it will offer 8 + hours and costs merely £110. I know people running NUCs on this and so far so good. However, its manufacturer KayoMaxstar contacted me when I placed the order and refused to confirm NUC compatibility (but do confirm OK for 20v rated Toshiba, Dell, HP etc).  Intel Support then expressed concern that the NUC's rating is "strictly 12v to 19v" and the MaxOak's 20v might be too much and 11.6v too low (so potential danger at both ends). A pal of mine then tested his MaxOak 20v output rating and it was 19.3V, the same as the input from the Intel mains adapter!

Whilst tht latter suggests KayoMaxstar and Intel are probably being over cautious, we think there is a simple solution.

https://www.bixpower.com/BX-DD90M-p/bx-dd90m-19v.htm 

This will take any input 9v to 17v and convert it to 19v. Cost $67 (including shipping to the UK). Add that to a £109 MaxOak K2 running at 12v (£109) and it sounds like a decent solution to produce regulated 19V power. I have not yet purchased one but it sounds like a decent solution to a myriad of power problems, given that the MaxOak remains compact (I would need to use 40mm M4 bolts rather than 30mm in my cradle).

EDIT - IMPORTANT!

Further research suggests that my Tracer 8Ah  and 2- Power 27 Ah both have 97 watt hour capacity. The MaxOak despite its claimed 50Ah is 185 watt hours. It's still double the watt hour capacity of the Tracer or 2-Power but its claimed 50Ah is a bit deceiving. That 50Ah applies at its native 3.7v. (it has 8 such cells to give it the higher voltage). At 20v it is nearer 10Ah. The Tracer and 2-Power will each run a NUC for between three and four hours. The MaxOak will exceed seven hours. Watt-hours is evidently a far better guide than Amp-hours.

I also warned caution above with the MaxOak, but confess I have now ordered one, having been further reassured by owners and manufacturer. But it will shut down if above 5A is ever sought and your computer may suffer damage. The MaxOak  is strictly rated 12v/2.5A and 20v/3A typically outputting (when measured) 12.07v  or 19.4v. You must NEVER use both outputs simultaneously. The NUC really wants 19v (+ or - 10%). But if run at 12v and at peak load of potentially 60w it would therefore demand 5A (hence, not good!). Fortunately, for most of our needs a NUC will be running at under 35w, hence at 12v around 3A (but still above the MaxOak 12v/2.5A rating).

In conclusion, I think it unwise to run a NUC on merely 12v using the MaxOak,  and even more unwise to add any additional 12v devices to the same circuit.  But it's watt hour capacity is compelling. I therefore propose to use a MaxOak to power (only) the NUC at its nominal 20v/3A and my Tracer to run camera and Microfocuser at 12v. 

As regards the Bix power converter originally suggested above that precaution does work in one sense, but whilst it will boost voltage from 12v to 19v, it cannot increase the Amps which remain limited to 2.5A (less that being consumed by the Bix). At 19v/2A that might limit the NUC to merely 38w. On reflection it's arguably better to use the MaxOak at 20v/3A hence without a DC to DC converter than use 12v/2.5A with one. Whatever route there is a slight risk with MaxOak, But the alternative is to buy (say) a 264 watt hour 22Ah Tracer for £250. The MaxOak or similar Lithonite appears to be the only budget solution. But adopt either at your own risk.

Edited by noah4x4
Additional important technical data
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On 20/01/2018 at 11:06, fireballxl5 said:

The NUC spec says that they accept 12-19V. Have you tried running yours at 12V?

Yes, and it does work fine with my Tracer that guarantees a steady 12v. But Intel Support recommend 19v and state that at 11.6v "there may be consequences".  So at either end of the range there is potential doubt about the MaxOak K2, hence Intel recommend the use of a DC/DC adapter outputting 19v where there is uncertainty. 

 

EDIT.

Please see update to original post. It is fine with a Tracer (10A) but less wise with a MaxOak (2.5A at 12v). A NUC at 12v at peak 60w might require 5A. So if using a MaxOak use ONLY the 20v/3A output but at your own risk.

Edited by noah4x4
Important technical detail added

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