My HEM15 has arrived

[Elp]

You can change it whilst it's imaging, think it's on the guide graph if you expand it, bottom right. You'll see an instant change. A lot depends on if there's any faint cloud around and whether the guide camera can pick the stars up.

Edited February 12 by Elp

[Ags]

Thanks, I tried 1s and 0.5s but didn't see much difference in the numbers, maybe there were fewer extreme excursions at the shorter guiding exposures.

I will need a higher capacity battery with a regulated 12V output. The battery ws pretty drained after 2 hours and the Air was only getting 10.7V.

[bomberbaz]

Just bought this myself a few months back but still sat in box, following for when my mojo returns. 

peace all.

Edited February 12 by bomberbaz

[Ags]

I had a great first evening with the HEM15 and AIR. The setup was highly portable. Polar aligning was very easy, both from a hardware and software point of view. Plate solving is addictive and a great help in severe light pollution. Selecting targets from a planetarium view was great. The mount is silent and easily capable of handling my scope. Guiding required a little focussing and then just worked. 

Quick question about adjusting the alt axis when polar aligning. I had to loosen a couple of bolts with allen key before making adjustments. Do I need to do this every time or am I over-tightening the bolts?

Regarding the battery, thinking about this:

https://www.amazon.nl/Grideto-Oplaadbare-Lithium-Battery-Draagbare/dp/B0B3WRFDWP/ref=mp_s_a_1_3?crid=16ZVWC9X1JH9P&keywords=battery%2B24%2B%2F%2B12v&qid=1707779876&sprefix=battery%2B24%2B%2F%2B12v%2Caps%2C78&sr=8-3&th=1&psc=1

 

[Elp]

Maybe the bolts in the slots in each side are over tightened. I just checked mine as well as the bolts next to them and they weren't very tight at all. You should only need to turn the front/centre altitude adjustment bolt which is connected to the two vertical brass threads by hand. But I suppose the side ones can be a bit tighter, with my gem I need to use the Allen key in the holes on the altitude adjustment bolt to make the altitude adjustment, I think it's like that so you can adjust the tightness to your liking, PA my gem is exceptionally easy as a result.

Regarding battery, your listing is quite confusing as to how they've listed the item, this is the one I use, bit difficult to give run time with it ATM because it's cold so I use mains power at the moment but my fully autoguided and cooled azgti setup runs around 2-3 hours off this one battery, 5-6 hours plus if I'm only using the azgti in alt az mode (I'm probably confusing the times with my Celestron LTs, but this TC is better than the Celestron one):

https://www.amazon.co.uk/TalentCell-Rechargeable-11000mAh-20000mAh-Portable/dp/B06Y5G3C8Z/ref=mp_s_a_1_1?crid=16XLVX0VBTJDG&keywords=talentcell&qid=1707781574&sprefix=talentce%2Caps%2C1513&sr=8-1

 

Edited February 13 by Elp

[Ags]

Looks very similar, but I am looking at a 24/12/5V unit as the 12V will be regulated. In the one you list I think the top voltage is 12V and I suspect that is unregulated and less in practice?

[Elp]

2 hours ago, Ags said:

unregulated and less in practice?

I've never measured it. What I do know is if I try to power my air then the mount via the airs 12v out my "regulated designed for astro" Celestron Lithium LTs will fail to power the mount (hem15 or gem28), the mounts just won't turn on. No such issue with this talentcell.

[fwm891]

On 10/02/2024 at 21:11, Ags said:

Whew! Adjusting the mount to 52 degrees latitude was more fiddle than expected. I didn’t expect the doodad to disassemble into 5 pieces, and the tiny washers hiding behind the whatsit took me by surprise. There was a dark moment when I thought it wasn’t going back together!

Same with HEM27...

[Ags]

2 hours ago, Elp said:

I've never measured it.

All I did was look on the power/network status of the Air - the power dropped rapidly to 10.7 and stayed there.

[Elp]

I think as long as it doesn't cause issues with the equipment it's fine. External temperature will have an impact too. I'd take the asiair reporting with a pinch of salt.

[Ags]

I just checked with a full charge and indoors, so ideal conditions for the battery. The Air says the battery is offering 12.4V which sounds about right.

[Ags]

Found a good write up about talentcells and their limitations.

https://www.californiaskys.com/blogs/archives/11-2023

[ST_Steve]

Interesting read @Ags thanks for sharing 🧐

[Ags]

A couple of nights ago I had a brief opportunity to play with my beautiful machine. 

Polar aligning did not go well - hundreds of stars detected but plate solving failed and failed. Eventually, I remembered to take off the lens cap 😀

Whenever the mount slews around I am enchanted by the obvious precision of the mount and its smooth unruffled whir, nothing like the multi-tone grinding of my AZ-GTi!

I didn't have time to do much, but it tracked the Moon very nicely, and I took a few test snaps of double stars. 

 

[Celerondon]

Curtis provided some great information in the blog post that Ags linked.  My take on the power choices is that the 24/12/5V power supply that Ags likes will be acceptable because the 12V output is regulated.  It wouldn’t be my first choice though, for two reasons.

• Unless I needed 24V that capability would be superfluous.
• The 2A limit on the 12V port is barely acceptable for a minimum setup.

The 8.3Ah TalentCell that Elp linked is more attractive because of the robust 6A rating on the 12V port.  In fact, my first Li-on battery was a similar 11Ah TalentCell.  However, neither of these battery types is currently my favorite.  If you carefully review the information posted by Curtis, you may see why I prefer LiFePO4 battery packs for my astronomical equipment.  Our portable electrical power storage solutions are created by binding together a group or “battery” of cells to form a battery assembly.  Because of the intrinsic cell voltage values of different battery chemistries, some types can produce 12V when grouped in threes (3S) but others with slightly lower cell voltages do better when combined in groups of four (4S). 

LiFePO4 cell nominal voltage – 3.2V

LiFePO4 cell fully charged voltage – 3.65V

LiFePO4 4S nominal voltage – 12.8V

LiFePO4 4S fully charged voltage – 14.6V

What these numbers mean is that a fully charged 4S LiFePO4 battery will start out in the mid-14V range, quickly dip into the mid-13V to mid-12V range and stay above 12V until it is down to near 5% capacity.  The kicker is that a 4S LiFePO4 battery will do this while maintaining a flat voltage curve through about 80% of its rated capacity without requiring voltage regulation!    

So now, my TalentCell is a backup battery and a high capacity LiFePO4 battery is my main source.  Like Elp suggested, I verify the voltage readings reported by my equipment with an inline power meter. 

Don

Inline Power Meter

 

LiFePO4 - Flat Discharge Voltage Curve

 

 

DC5521 to Powerpole Adapter Cables

 

 

 

Edited February 21 by Celerondon

[Ags]

Next time I am out I will use the Air to make a graph of Volts and Amps over time. From what I have seen so far the measurements it gives seem quite close to the expected values.

The 24/12/5 battery looks like a good upgrade for me as the Air was measuring my current draw at 1.0 A, so well within the 2A envelope.

[Celerondon]

59 minutes ago, Ags said:

Next time I am out I will use the Air to make a graph of Volts and Amps over time. From what I have seen so far the measurements it gives seem quite close to the expected values.

The 24/12/5 battery looks like a good upgrade for me as the Air was measuring my current draw at 1.0 A, so well within the 2A envelope.

Right, that battery will power the mount and ASIAIR Mini just fine.  Neither device draws more than 1.0 amp while working. With a regulated output, your voltage should remain constant over time.  However, your equipment seems ideal for a portable astrophotography rig.  Begin adding features like cameras, dew heaters, and autofocus and you may soon be juggling multiple batteries to meet your system’s current demands. 

Don

[Ags]

Currently I only need to power two uncooled cameras, the HEM15, and the Air Mini, all that only seemed to draw 1A. But there's a cooled 8300 CCD coming to me on the next family visit. When I set up my C6, I guess I really will need to think about dew strips if I am imaging with it for a few hours. So power requirements will go up...

The mount will travel! I've flown a few times with the AZ-GTi and the HEM is only a little heavier. That does impose limits on the size of the battery. This one give 3A on the 12V output:

Celestron Lithium 7.2 Ah LiFePO4 Powertank | First Light Optics

 

[Elp]

I hope you realise you can only use ZWO astro cameras and certain Canon/Nikon/Sony camera bodies with the air.

[Ags]

Yes I know, but I had a generous offer of a excellent mono CCD and spectro grating. When I am using the CCD I will have to do a slightly complicated arrangement with an AIR and a laptop running in parallel.  I rather think that I will use the CCD mostly for photometry and spectro, as it will be much more convenient to run everything from the AIR. Besides, the laptop doesn't have the battery life for an extended session.

Edited February 21 by Ags

[Celerondon]

51 minutes ago, Ags said:

Currently I only need to power two uncooled cameras, the HEM15, and the Air Mini, all that only seemed to draw 1A. But there's a cooled 8300 CCD coming to me on the next family visit. When I set up my C6, I guess I really will need to think about dew strips if I am imaging with it for a few hours. So power requirements will go up...

The mount will travel! I've flown a few times with the AZ-GTi and the HEM is only a little heavier. That does impose limits on the size of the battery. This one give 3A on the 12V output:

Celestron Lithium 7.2 Ah LiFePO4 Powertank | First Light Optics

 

That 7.2Ah Powertank is a nice battery with good features.  As you mentioned, it is also great for air travel.  FLO also sell its big brother.  The Celestron Lithium 13.2Ah Powertank Pro is the largest battery that meets the size limitations imposed by airline and government regulations. 

Don't do what I did during my power hunt.  I was about to press the "Purchase" button on a Powertank Pro but then I got distracted and bought something so large that it will never fly.  Now, if I need to fly my setup, I will have to use my 11Ah TalentCell or purchase another battery.    😉

Don

[Ags]

Aperture fever applies to batteries too  

[fireballxl5]

9 hours ago, Celerondon said:

The Celestron Lithium 13.2Ah Powertank Pro is the largest battery that meets the size limitations imposed by airline and government regulations. 

Not so if flying under CAA regs,  limit is 100Wh for  "Spare batteries for portable electronic devices (including metal devices) containing lithium metal or lithium ion cells or batteries carried for personal use". See

https://www.caa.co.uk/passengers/before-you-fly/baggage/items-that-are-allowed-in-baggage/

 

[Adam J]

I just use this type of battery: 

https://www.amazon.co.uk/ECO-WORTHY-Rechargeable-Phosphate-Emergency-Fishfinder-8AH-Lithium-Battery/dp/B08ZSBS1ZY/ref=pd_aw_ci_mcx_mh_mcx_views_3?pd_rd_w=m2RAD&content-id=amzn1.sym.42c045e2-bd09-44b6-b445-e4140e05d91f%3Aamzn1.symc.acfafb1d-071f-4fdf-beff-aca206a47be9&pf_rd_p=42c045e2-bd09-44b6-b445-e4140e05d91f&pf_rd_r=7ADW105Z7QZ6CT4RAESY&pd_rd_wg=OYmeH&pd_rd_r=e7fab86d-47e1-4e5b-bfb3-8f9602426e0e&pd_rd_i=B08ZSBS1ZY

cheep and it works really well. Sized for airline travel with a battery management system included. All you need to do is make sure the terminals are covered for air travel and also buy a suitable charger. Why pay more. 

Adam

[adyj1]

12 minutes ago, Adam J said:

I just use this type of battery: 

https://www.amazon.co.uk/ECO-WORTHY-Rechargeable-Phosphate-Emergency-Fishfinder-8AH-Lithium-Battery/dp/B08ZSBS1ZY/ref=pd_aw_ci_mcx_mh_mcx_views_3?pd_rd_w=m2RAD&content-id=amzn1.sym.42c045e2-bd09-44b6-b445-e4140e05d91f%3Aamzn1.symc.acfafb1d-071f-4fdf-beff-aca206a47be9&pf_rd_p=42c045e2-bd09-44b6-b445-e4140e05d91f&pf_rd_r=7ADW105Z7QZ6CT4RAESY&pd_rd_wg=OYmeH&pd_rd_r=e7fab86d-47e1-4e5b-bfb3-8f9602426e0e&pd_rd_i=B08ZSBS1ZY

cheep and it works really well. Sized for airline travel with a battery management system included. All you need to do is make sure the terminals are covered for air travel and also buy a suitable charger. Why pay more. 

Adam

£39! - that's an excellent price. I have similar 12v 8AH LiFePO4 batteries that I bought last August and paid £48. I was allowed to take two on a Virgin flight to the US - they had to carried in hand luggage, so just as well they are very light.

I also got a dedicated LiFePO4 charger from Amazon for £30.

I'll be using it to power my HEM27 in the field (bought after the US trip).   [ weak attempt to get things back on topic 😉 ]

Ady 

Edited February 22 by adyj1