Tracer, particulary the LiFePO 22ah ones was ideal and was on top of my "buying" list. But i had an issue. With those airline restictions about battery transfer, delivery to Greece was impossible. The funny thing was that i bought the MAXOAK from Amazon UK without any problem!!! But that's not the case with Tracers. Go figure...

I am no expert, but believe this is the explanation; it is to do with discharge curve...and watts/watt hours...

The Tracer 8Ah 12v is the largest in that range that is airline friendly (under "100 watts"). It will pump out around 12v (actual 11.7v) and support multiple devices up to 8 Amps, hence "96" watts (8 × 12), but will last only one hour at that maximum rate. But devices only draw what Amps they need. Most mounts draw around 2 Amps, a camera perhaps draws 2 Amps, so at a total rate of 4 Amps drawn a Tracer "8Ah" will last around two hours.

By contrast, the 22Ah Tracer would support 4 Amps for around five hours (or at 8 Amps for around three). If a mount draws only 2 Amps it will work dusk until dawn (outside of the Arctic Circle!). You can visit the Tracer website where there are graphs that show the comparitive discharge curve for each Tracer unit at 50 watts load. However, the claimed Amp-Hour (Ah) rating or milleAmp Hour rating (mAh) can be misleading if the actual output is lower in real terms.

The MaxOak K2 offers only 20v (19.3v) discharging at merely 3 Amps so is rated merely 60 watts, hence under the airline limit (but do prior check with airline!). The manufacturer's marketing advertisment claim of "50,000 mAh" is misleading and is calculated (I believe) by taking the rating of each individual cell rather than the output as as whole. Whatever the calculation employed, it will never support more than circa 20v x 3 Amps (60 watts). But if the airline took the 50,000mAh claim as correct I suppose it might get confiscated.

However, the MaxOak K2 is genuinely rated "185 watt-hours", so if discharging at (say) 36 watts (12v x 3 Amp) will last around five hours at its maximum output of 3 Amps. Its potential 60W can support an Intel NUC i5 that peaks at around 45 watts at 19v, but it might choke at 12v (where at its 11.4v falls below the NUCs operating voltage range). Here, my theory is that fewer individual cells are employed to serve the 12v output compared to the 20v.

The MaxOak K2 at around £120 is fantastic to support a small rig drawing no greater than 3 Amps. But if you get into more serious Astrophotography or EAA my advice would be invest in the Tracer 22Ah that will consistently pump out 11.7v for a longer discharge curve at up to 8 Amps.

**Edited by Noah4x4, 18 December 2018 - 03:10 AM.**