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MAXOAK K2 50000 mah

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#1 DIMITRIS K.

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Posted 17 December 2018 - 12:44 PM

Just purchased this powerbank and put it to the test. I powers a Sony Vaio without it's battery and a skywatcher AZ-GTI. It seems that this little beast have plenty of energy to give!! I'll make some stress tests and I'll come back with my review. But I'm already impressed!

Stay tuned

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Edited by DIMITRIS K., 17 December 2018 - 12:45 PM.

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#2 Conor Maclaud

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Posted 17 December 2018 - 01:29 PM

I was lucky to buy this powerbank during sale last year for $99 on amazon for powering my Celestron Advanced GT mount and laptop. And it works really well !

Single laptop(Dell latitude e5430) can be powered around 12 hours on the full charge. Mount, I believe, can work for at least 4-5 times more.

I think this is much better decision than Celestron Powertank comparing dimensions, weight and, of course, capacity.

 

Regards,

 

Oleksandr. 


Edited by Conor Maclaud, 17 December 2018 - 01:33 PM.

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#3 Noah4x4

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Posted 17 December 2018 - 01:55 PM

Great power bank if you understand it's limitations.

 

1. Whilst quoted at "12v or 20v" it actually outputs around 11.4v and 19.3v.

 

11.4v is fine for most astro gear, but I also (for EAA) use an Intel NUC i5 mini-computer with Iris Plus Graphics rated at "12v to 19v". As the i5 NUC peaks at around 50W (see next) it stuttered at '12v' (merely 11.4v) but worked fine at 20v (19.3v).  I ended up using the MaxOak K2 for NUC and a seperate Tracer 12v for astro camera and autofocuser. 

 

2. Whilst it has "12v and 20v" outputs it is unwise to attempt to use both simulataneously. 

 

It is actually a series of 3.75v batteries in parallel and that is how the 50,000 mAh is derived (e.g. naughty, misleading Chinese claim!). However, it will offer 12v (11.4v) and a genuine 3 Amps. But 3A possibly isn't enough for multiple devices (my camera alone demands 2A). However, it will genuinely offer 185 watt-hours, so will power (say) a mount for around eight hours.

 

In summary, it's a fantastic value unit if your total power demand isn't excessive. However, I eventually switched to a single 22Ah 12v Tracer as it offered the power (consistently exceeding 11.7v) to run my NUC, camera and focuser for around four hours. 



#4 DIMITRIS K.

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Posted 17 December 2018 - 03:17 PM

Great power bank if you understand it's limitations.

1. Whilst quoted at "12v or 20v" it actually outputs around 11.4v and 19.3v.

11.4v is fine for most astro gear, but I also (for EAA) use an Intel NUC i5 mini-computer with Iris Plus Graphics rated at "12v to 19v". As the i5 NUC peaks at around 50W (see next) it stuttered at '12v' (merely 11.4v) but worked fine at 20v (19.3v). I ended up using the MaxOak K2 for NUC and a seperate Tracer 12v for astro camera and autofocuser.

2. Whilst it has "12v and 20v" outputs it is unwise to attempt to use both simulataneously.

It is actually a series of 3.75v batteries in parallel and that is how the 50,000 mAh is derived (e.g. naughty, misleading Chinese claim!). However, it will offer 12v (11.4v) and a genuine 3 Amps. But 3A possibly isn't enough for multiple devices (my camera alone demands 2A). However, it will genuinely offer 185 watt-hours, so will power (say) a mount for around eight hours.

In summary, it's a fantastic value unit if your total power demand isn't excessive. However, I eventually switched to a single 22Ah 12v Tracer as it offered the power (consistently exceeding 11.7v) to run my NUC, camera and focuser for around four hours.


I had a consern using those two inputs (12v and 20v) simultaneously so I contacted maxoak to ask about. They replied me the following:

"Yes, you can use 12V and 19V output simultaneously, but if the total output power exceeds 130W, it will cause an interruption."

My laptop draws max 3a and my sxd2 max2.5a. I calculate about 110w combined with cameras, heaters etc. So I'm in safe range. In worst case scenario the power bank have a cut off circuit that prevents the overcurrent. So i play safe I suppose. In any case, I don't want to risc any damage to my vixen mount so I bought another powertank to feed my setup except my laptop. An einhell 28000mah.

#5 Noah4x4

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Posted 17 December 2018 - 05:52 PM

Exactly Dimitris.K.  It is a brilliant power bank for around £120. But although it offers 185 watt-hours and is very compact you probably need one MaxOak K2 to run two 12v devices and two if running more devices or if requiring both 12v and 20v. However as (say) a 22Ah Tracer is around £250 you have to pay a lot of money to get better in a compact format. But is easy to work out the ideal combinations from the information in my post. 


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#6 DIMITRIS K.

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Posted 18 December 2018 - 12:19 AM

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...   



#7 Noah4x4

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Posted 18 December 2018 - 03:07 AM

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.

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#8 DIMITRIS K.

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Posted 18 December 2018 - 08:51 AM

With a laptop and AZ GTI it last minimum 10 hours. Not bad. Next time I'll measure the outputs with multimeter to see how it performs in voltage as it discharge.

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#9 Noah4x4

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Posted 19 December 2018 - 03:51 AM

Measuring both 12v and 20v outputs simultaneously would be interesting as there seems to be conflicting advice from the manufacturer. Earlier advice was don't use both. But maybe that is merely where a rig is likely to exceed its Amp limit.

#10 DIMITRIS K.

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Posted 20 December 2018 - 01:08 PM

I measured 19.32V 4.30A on the 20V port and 12.50V 4.30A on 12V port. I pluged my laptop and measured again the 12V port. Values remained the same. 12.5 and 4.30A. Combined we have an output of about 130Watts. I'll leave it until distarge to measure again.

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Edited by DIMITRIS K., 20 December 2018 - 01:11 PM.


#11 DIMITRIS K.

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Posted 20 December 2018 - 11:53 PM

After 11 hours it had 2 leds on (i estimate about 25% - 30% of "juice") and i measured again. 12.52V 4.30A on 12V port and 19.39V 4.33A on 20V port. A very flat disgharge curve all right! 


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