32 replies to this topic

[Volta55]

(before I begin, using my cars cigarette port is not an option)

 

I got one of these Power banks and I am wondering if its enough to power my setup 
https://www.amazon.c...product_details

Camera Nikon D5200:       1A

Mount Iexos 100:       2.0A

Dew Heater from ebay: 2.0A

Guidescope QHY miniscope: 0.5A

Mount USB:  0.5A

Laptop Dell Windows 10 2.0A

 

total of 8 amps, and the amazon power bank has 24000mah or 24 AH
24/8

3 hours? 

 

Basically, did I just waste my money? lol 

 

[NearVision]

Read the specs a little deeper.

 

Here are the important things.

1 x DC Output 12-16.8V/10A, 10.8A Max This tells us that it can supply your maximum expected current draw of 8 amps with some room to spare. A lot of these types of power pack only have 3 - 5 amps output at the 12v jack. Something else to keep in mind is that this type of jack is not rated for high current usage. 10 amps is the highest I've seen for these jacks, so having more than 1 of these is a better setup. You would still have the 10.8A limit but it would be distributed across 2 or more jacks. If you try to draw too much current through a wire or connection it can overheat and burn up.

 

Up to 6Ah/14.8V (equivalent 24000mAh, 3.7V) This tells us that you really have 6Ah of power. The 24Ah is at 3.7 volts which is the output of the individual cells. This power pack is made of multiple LI-Ion batteries which is very common. Advertising it as 24Ah @ 3.7V is also very common and very misleading. You will be using the 12 volt output so you get 6Ah of power or about 45 minutes of use at full power.

 

That being said, keep in mind that most of the equipment will draw a LOT less current when in use. Most of those current specs you have listed for your equipment are probably the manufacturers recommended power supply size. For example the mount is rated  at 2 amps. If it's anything like my AZ-GTI, which is a similar size and capacity, it probably draws around 0.1 amps most of the time and 0.5 - 1 amp when slewing. Realistically you will probably get 2 or maybe even 3 hours out of a charge but it will depend on the actual current draw of the equipment in real use. You may not need the dew heater most nights. You may do more slewing between objects some nights. If you plan on the worst case scenario (45 minutes at maximum draw) then anything above that is a bonus.

 

But! It's always good planing to have a safe margin, meaning don't plan on having regular sessions of over a hour with that battery. Run some tests with everything hooked up and running at home to see how long you really get before going out to a dark site for a night of AP and having it cut short by a dead battery. Try different scenarios, dew heater running full time because of heavy dew, Slewing to 10 different stars because you changed your mind, having both cameras capturing at high speed and the laptop processing it all... These tests will give you a good idea of what to expect and a comfort level for real life expectancy in the field.

[MarMax]

The battery inside the unit is 6Ah at 12V so it's not going to cut it for your 8A load. I agree that your load estimate is probably worst case and you will likely be closer to 4-5A. Still that 80W power station is inadequate.

 

At say 5A continuous load I'd want a 30Ah battery. Buying the power stations is tricky because they throw a bunch of numbers at you and try not to tell you the Ah rating at 12V when that is what really matters. A 300W power station weighs about 8 pounds. A 30Ah LiFePO4 battery weighs 9 pounds. I think the $500 Jackery power station has a 24Ah battery.

 

I think you'd be better off with just a 30Ah battery and it would give you a solid 4 and maybe up to 6 hours.

 

My 12V load is around 3A for my mount and cooled camera and I use an 18Ah battery. I run the laptop off an extension chord since it's the power hog in my kit. I can usually get up to 5 hours with the battery.

[CA Curtis 17]

As Nearvision said, your mount will draw less than 0.5A while tracking and only ramp up to less than 1A during slews.  So that's about 6W.  I have measured the power draw on a bunch of different mounts and found this to be true for all of them except my SB mounts which draw around 1A tracking.  Guide scopes taken even less, maybe 0.2A - so low they are hard to measure.  That's 2-3W.  The Nikon likely draws another 2-3W unless you have the screen on all the time.  You don't say the size of your dew heater but for something big enough for a 9.25" to 14" SCT I have measured anywhere from 10W to 20W at 12V for half and full power.  Less for a small refractor.  The USB port may be 0.5A but that is at 5V so the power draw is around 2-3W.

 

Adding that up without the laptop you should expect 25 - 35W with the dew heater being the biggest power hog.  Laptops are the biggest power hogs which can draw upwards of 100W if the battery is not charged.  My Dell 15.4" draws 30W if I start with the battery fully charged so I am not wasting power recharging the battery in the field.

 

So you might be around 50 - 60W mostly because of the laptop.  I put together a video showing how you can measure the power draw of you own equipment without much difficulty.  You can find it here https://www.youtube....LIdo7zsU78&t=1s

 

Best Regards,

Curtis

 

 

[CA Curtis 17]

 I think the $500 Jackery power station has a 24Ah battery.

The Jackery 500 is a 518Wh solar generator which supplies 518Wh of power which I have measured to be 42 - 43Ah. The 24Ah number is at 21.6V which is very confusing to folks and not particularly relevant since the DC output is voltage regulated at ~12.8 to 12.9V.  I know this from my own testing.

 

Regards

Curtis

[carolinaskies]

(before I begin, using my cars cigarette port is not an option)

 

I got one of these Power banks and I am wondering if its enough to power my setup 
https://www.amazon.c...product_details

Camera Nikon D5200:       1A

Mount Iexos 100:       2.0A

Dew Heater from ebay: 2.0A

Guidescope QHY miniscope: 0.5A

Mount USB:  0.5A

Laptop Dell Windows 10 2.0A

 

total of 8 amps, and the amazon power bank has 24000mah or 24 AH
24/8

3 hours? 

 

Basically, did I just waste my money? lol 

6ah @14.Xvolts, will run your system for only a couple hours.  Drop out the laptop and mount and you may get 3-4hrs true performance before voltage drops below safe levels.  Always run a mount drive on separate power from other equipment to reduce the chance of the mount loosing tracking.  All other equipment can be easily restarted/reset, re-aligning a mount in the middle of the night is a sure headache and frustrating.  Full blown laptops should be run on their own power until they reach 25% and then recharged, rather than being a constant drain on the battery they can run several hours on their internal battery.  

In general I don't recommend imaging sessions be powered by anything less than 17ah minimum and more depending on how long the imaging session is expected to last.  Lets remember that unlike a tank of gas which you can run 'dry', batteries are NOT meant to be depleted 100%.  Lead based batteries including deep cycle, can be run to 50% before they should be recharged.  Lithium Ion batteries can be drawn safely to 20%.  These are buffer % to ensure life expectancy of the battery is 'normal'.  

For simple rigs a 17ah is typically sufficient, for complicated rigs 34-48ah @12v is much more reliable so that power issues don't ruin all the time you've spent to setup. 

 

[jesse 3]

I have similar equipment and Jackery 500. After 3 hour session, displayed capacity reduces to 60%. It will get worse when battery ages or when weather gets really cold.

Use WattHour to compare these products.

Edited by jesse 3, 23 January 2022 - 11:18 AM.

[MarMax]

I'm always wondering when someone posts a question like this if the respondents just read the OP's post and respond or read the entire thread then respond. Clearly there is a little of both going on here.

 

Three responses have stated the load estimation is high and two recommend not powering the laptop (power hog). Two have recommended a 30-40Ah capacity battery (@ 12V).

 

And the 500W Jackery is rated at 24Ah at 21.6V which translates to about 42Ah @ 12V. Someone with a Jackery 500W has used a similar kit for three hours and the capacity was 60%. This says that a 42Ah battery will be good for about 6 hours, or a 30Ah battery will be good for about 4 hours.

 

Summarizing (and repeating), the minimum recommended battery is 30Ah. So if you feel the need to purchase a power station you need to read all the specs and find one with a 30Ah at 12V (minimum) battery.

 

All the gobbledygook about power stations is useless for the way we use power at night. Yes, out in the desert for days with a solar panel and a power station is useful. But if you are just at home or travelling to a local dark site for the evening you don't need a power station you just need a battery.

 

I know the OP said no cigarette lighter power but it is the best and cheapest option if you have your car nearby. With 100's of Ah's available it's the way I'd do it if I were spending my viewing time away from home. And I would not use the cigarette lighter, I'd rig up a separate fused connector (Anderson or Deutsch) just for this.

 

 

[Procyon]

https://www.celestro...#specifications

 

https://www.ebay.com...BAAAOSwmLBg5FD4

 

https://www.celestro...or-all-nexstars

 

I use the first one, love it. Can probably find better nowadays.

Edited by Procyon, 23 January 2022 - 12:11 PM.

[jesse 3]

OP’s product idea will be a waste. It is 24AH at 3.7V, or 8AH at 12V. Energy-wise it is 80WH. It may not last an hour.

As reference, Jackery 500 is 500WH. There is a cheaper version at 300WH. It costs $1/WH.

Car battery is an cheap alternative. Buy a battery powered jumper in case of emergency.

[Noah4x4]

I will offer a practical example as it might be easier to understand. I have a similar AllPowers device, but that offers 288 watt-hours. I use it for off-grid power when sports broadcasting. My camera and transmitter kit draws around 2 amps and therefore my unit comfortably lasts longer than the ten hours I need for a full day of cricket.

However, your 80Wh is less than a third of this capacity. This technology is lightweight, compact and generally excellent, but you need to do the maths to ensure that you buy a device with sufficient watt-hours capacity. Just multiply your required voltage x required amps to determine watts. Then, multiply that by the number of hours of power required (hence watt-hours). Then, allow a margin for the manufacturers over optimism and cold weather!

If powering telescope, camera and other devices, one might potentially need between 5 and 10 amps (do the maths for your kit, suggests 8). Hence 12v x 8A = 96w. Hence, optimistically, my 288Wh device might then last merely 288/96 = under three hours, despite it being fine for over ten hours for my less demanding 2 Amp (24Watt) professional needs. I deduce that your mere 80Wh is unlikely to be enough unless your sessions are very short, or you are merely powering one single device such as telescope.

Edited by Noah4x4, 23 January 2022 - 02:00 PM.

[CA Curtis 17]

The aforementioned Jackerys work great.  I have a 500 and 1000 and use them in the field.  As was mentioned, these go for ~$1 per Wh.  But, if you do not need the built in features (AC inverter, USB charging, solar charge controller, etc.) a simple LiFePO4 battery is the best alternative.  LiFePO4 batteries go for $0.60 per Wh (100Ah Battleborn Battery) to as low as $0.29 per Wh (100Ah Ampere Time) based on my own capacity tests.  Slightly more per Wh for the 50Ah versions.  One is made in the US and the other in China.  Both seem to be very good from my own experiences so far and from the reviews on line.  

 

Regards,

Curtis

[Volta55]

I REALLY appreciate all the info and tips guys. Thankyou. Fantastic info 

 

I just did a trial run inside ( a comfortable 72*F ) and it lasted alittle over 2 hours

Laptop running APT, SharpCAp, and Ascom config programs.

Nikon running

QHY guide camera running

Mount connected via serial 

and NO dew heater

 

 

 

Def not enough juice, simply put. 

So, maybe I will try to resell this or give it to one of my nieces lol

 

Bummer. 

 

[Noah4x4]

I have 'liked' your previous post as it is a salutary warning to all. But you are definitely not the first down this path. Guess why we are experts in underestimating everything from battery to computing power!

[Volta55]

I have 'liked' your previous post as it is a salutary warning to all. But you are definitely not the first down this path. Guess why we are experts in underestimating everything from battery to computing power!

I felt like I was in the movie Apollo 13 when they were calculating all the amps being used in the test environment scene
https://www.youtube....h?v=Ju-OBU7uTyc

[Linwood]

Just to add one additional comment on capacity:  Different technologies have different USABLE amp hours.  Lead Acid should generally not be used below 50% or they pretty quickly die.  LiFePO4 are good down to near zero, say 10-20% is a good, easy-on-the-battery target that also gives you a bit of reserve.  

 

LiFePO4 is the best choice now, IMO, in particular since many will keep them indoors.  Other Lithium battery chemistry is not as safe (think fire) or as long lasting.

Lead Acid is the cheapest to buy (arguably not the cheapest if you figure long term lifecycle cost, but for many you may not ever wear one out).  They are also twice as heavy per amp hour, and roughly half the usable capacity. 

 

Solar Generators have a lot of stuff most astronomy setups do not need: Inverters, built-in solar charging controllers, etc.  Buying just a battery, if you do not need AC, may be much cheaper.  Like 1/2 to 1/4 as much.  Keep in mind you need a special purpose charger for LiFePO4, you can't use your old car charger.

 

Final comment: Almost no one who stays in this hobby stays static in your equipment over time, and rarely does one end up with LESS equipment.  It may not be wise to buy a battery just barely big enough.

[Noah4x4]

One further comment.

Batteries have a discharge curve. They might start at 12v, but many cheaper batteries progressively drop to around 9v. Hence, if you try to run an Intel NUC at 12v it might stop if this happens as their typical range is 12v to 19v plus or minus 10%. Laptops also tend to require 19v. I hence initially used a 20V Maxoak battery with my NUC. Although that too will progressively deplete, it stays within the NUC range and 185Wh capacity gave me decent run time for a single NUC (I used a regular 12v battery for other devices).

But this is where the emergency generators discussed in this thread with a built in inverter are helpful. You can then use your regular AC/DC adapters that offer steady volts/Amps at exactly the desired rate. I now use AC/DC mains at home and have two 288Wh AllPowers devices should I travel. Two of these still weigh much less than a single Lead Acid battery of like capacity. I can see the appeal of 500Wh to 600Wh models. It is probably not electrically efficient to take 12V up to 220v (USA 110V) and back down again, but this route does guarantee steady levels of power even with cheaper battery devices.

Like I said, many if us have trod this path before and off-grid power requires a good deal of planning or the physique of a weight lifter. It's the biggest barrier to extending the range of electric cars. As laptops typically prefer 19v, these AC outlet power banks are notably good to extend their run time beyond internal battery.

Edited by Noah4x4, 24 January 2022 - 01:35 AM.

[Wow!]

One further comment.

Batteries have a discharge curve. They might start at 12v, but many cheaper batteries progressively drop to around 9v. Hence, if you try to run an Intel NUC at 12v it might stop if this happens as their typical range is 12v to 19v plus or minus 10%. Laptops also tend to require 19v. I hence initially used a 20V Maxoak battery with my NUC. Although that too will progressively deplete, it stays within the NUC range and 185Wh capacity gave me decent run time for a single NUC (I used a regular 12v battery for other devices).

But this is where the emergency generators discussed in this thread with a built in inverter are helpful. You can then use your regular AC/DC adapters that offer steady volts/Amps at exactly the desired rate. I now use AC/DC mains at home and have two 288Wh AllPowers devices should I travel. Two of these still weigh much less than a single Lead Acid battery of like capacity. I can see the appeal of 500Wh to 600Wh models. It is probably not electrically efficient to take 12V up to 220v (USA 110V) and back down again, but this route does guarantee steady levels of power even with cheaper battery devices.

Like I said, many if us have trod this path before and off-grid power requires a good deal of planning or the physique of a weight lifter. It's the biggest barrier to extending the range of electric cars. As laptops typically prefer 19v, these AC outlet power banks are notably good to extend their run time beyond internal battery.

Depends on the chemistry.

Lithium NMC? Yeah, they can drop voltage but not a lot. The Jackery's use this and so provide a regulated DC output to compensate. You won't lose voltage until the battery is near dead.

LiFePO4? You won't really need a regulator. That'll maintain voltage until very low charge is left, and then voltage drops off a cliff.

 

I have lots of lithium batteries.

 

My favourite: Bluetti EB70 which uses LiFePO4, and weirdly has regulated DC output.

Jackery 240 was my first "all in one" and still going strong.

And I've got several naked LiFePO4 batteries (12Ah, 15Ah, 20Ah) that I used to use to top up the Jackery during the night, but since going with the Bluetti, I don't do that. Maybe when I get a second rig sorted..

[Linwood]

But this is where the emergency generators discussed in this thread with a built in inverter are helpful. 

Yeah, I'm 99% sure you mean "solar generator" not "internal combustion generators", but just as a side comment: don't become "that guy".  First time at a dark site about 30 or so are set up, it's quiet, some birds and frogs, everyone wandering around chatting, very pleasant... except this one guy with his generator going, probably would not seem loud in the city, here it was more like someone banging cymbals at a funeral.  

 

Yeah, I know at larger groups this is fairly common, the generator endowed often self-isolate, I should not judge.  But if you are the only one making noise and smelly exhaust, it may be embarrassing.   Or should be.  

 

Also: while a lot of laptops require 19v, some also require a specific branded adapter (my Dell is one), so just a buck converter to 19v won't work.  Check before assuming a plug/buck is all you need.  110v from an inverter will work.  HOWEVER, the better solution is often to go to a mini-computer or Intel NUC.  Many of those allow 12v.  All my gear except the laptop runs off of pure 12v, and the laptop I only use briefly during setup to have the large screen, the rest of the night my phone is all I need.

 

Get an accurate power meter, do some trial runs at home; it's annoying to drive hours, get set up, and then find out for want of some minor part, or adequate power, you cannot image. 

[Procyon]

That Jackery sure looks great....There's a 240 and 300 model.

 

You need a regulator though?

Edited by Procyon, 24 January 2022 - 11:10 AM.

[Linwood]

That Jackery sure looks great....There's a 240 and 300 model.

Bear in mind unless they changed, it's not LiFePO4, but Lion NMC - The latter do not last nearly as long, and have a greater (still not great) fire danger. 

 

Watch for vendors who advertise "Lithium" as opposed to "LiFePO4" or "LFE" or "Lithium Iron" (not "Ion")  batteries, if they don't mention Iron it's likely because they use the NMC form.  NMC can charge faster and I think are more energy dense, so claims of super-fast charging also often point to the NMC variant, but personally for safety reasons alone I like LiFePO4.   Not that NMC are all that likely to catch fire -- but if they do it's like a little explosion (google for video of battery tests to destruction).  2-4x the lifetime is just a bonus. 

[CA Curtis 17]

Bear in mind unless they changed, it's not LiFePO4, but Lion NMC - The latter do not last nearly as long, and have a greater (still not great) fire danger. 

 

Watch for vendors who advertise "Lithium" as opposed to "LiFePO4" or "LFE" or "Lithium Iron" (not "Ion")  batteries, if they don't mention Iron it's likely because they use the NMC form.  NMC can charge faster and I think are more energy dense, so claims of super-fast charging also often point to the NMC variant, but personally for safety reasons alone I like LiFePO4.   Not that NMC are all that likely to catch fire -- but if they do it's like a little explosion (google for video of battery tests to destruction).  2-4x the lifetime is just a bonus. 

Linwood, I mean no offense but I think you are greatly overstating the fire danger for LiNiMnCoO2 (NMC).  For the record:

 

1.  NMC has a high energy density to weight ratio, nearly 2X that of LiFePO4,  so it is used in applications where weight is a constraint.  This includes electric cars (Tesla is one), ebikes, electric tools and most solar generators like those from Jackery.  LiFePO4 is commonly used for Li batteries which look like car batteries.  As such, their biggest use case is RVs and boats where weight is not so critical and number of cycles is more important.

 

2.  With a thermal runaway temperature of 518 deg , LiFePO4 indeed has a higher temperature than the 410 deg F temperature of NMC.  But, both are considered high and safe.  It is some of the other Li chemistries that came to consumers much earlier that had the biggest fire risk and have thermal runnaway temperatures much, much lower.  This has given Li batteries a bad name.

 

3.  All of these NMC solar generators and stand alone LiFePO4 batteries come with an internal BMS which is there to protect the battery from unsafe operating conditions, including thermal runaway.  

 

4.  LiFePO4 batteries are rated for >2000 full discharge cycles.  Some manufacturer's like Battleborn say 3000-5000 cycles.  NMC is typically rated at only 500 full discharge cycles.  However, think about what that means.  You could run the Jackery down to zero state of charge (the BMS will cut off once the internal lithium cell voltage reaches the lower safe limit to avoid damage to the cells) 500 times and after that, you will still be able to get 70 - 80% of the original capacity out of the battery.  If I spend 5 nights a month running the NMC supply down to empty that is 60 nights a year which gives me about 9 years of life at 100% capacity.  If I don't need to run the generator all the way down to empty, I will get even more cycles.  And then I still have a generator with a lot of juice left in it.  I'd say that's pretty good and not necessarily a reason to shy away from NMC.

 

6.  Solar generators with NMC cells are great if you want all the additional features that are built in.  I use them and appreciate the built in pure sine wave inverter to supply power to my Dell XPS which must use its AC charge to be powered.  I then re-charge the generator during the day with a simple solar panel since the solar charge controller is built into the generator.  I like that the voltage output is regulated and stays fixed until the unit shuts down.  I like that the dc and ac power ports are built in.  I also like the USB charging ports for my phone.  But, you pay ~$1 per Wh for all of this compared to ~$0.30 per Wh with a stand along LiFePO4 battery which I have also used.  When using the LiFePO4 battery I have to carry an inverter for my laptop and a solar charge controller to recharge with the solar panels during the day.  I like and use both depending upon the situation.  Both are reasonable options for anyone needing power in the field.

 

I gave a talk on all of this at the NightFall Star Party last Nov.  Anyone can download my presentation from my web site if interested.  https://www.weebly.c...itor/main.php#/

 

 

Regards,

Curtis

[Linwood]

@CA Curtis 17, everything you said is true.  I think everything I said is true.  It's all about one's tolerance for risk, priorities, and desire to get more life out of a purchase (and maybe irrationally so if it's going to outlive its usage anyway). 

 

And cost as you say. 

 

I think there is also a tail vs dog and which wags whom issue. I think most people imaging with a laptop will eventually reach the conclusion it is better with the computer and everything at 12v and attached to the tripod or OTA, whether a NUC type arrangement, ASIAir, Eagle or similar.  Lower power needs, less cable tangle, less cable length issues (USB cable problems are endemic in this hobby).  If you don't follow that path, and remain needing AC power for laptops or other devices, generators stay more attractive.  If everything is 12v anyway, plain batteries can be a much more cost effective solution. 

Except: you make a good point about solar charging.  I do not.  If one does, then having the charger/controller built in is very handy, and another dog-wagging aspect. 

 

But to my real point: people should be informed.  Know which flavor of Lithium battery you are getting, its pros and cons.

[CA Curtis 17]

Linwood - agreed.

 

I also have moved to a mini-pc at the mount for the reasons you mention and to keep the power drain low.  I do use my 15" laptop to wirelessly connect to the mini-pc to check in on what is happening and to make changes as needed.  Unfortunately, Dell has decided with some of their latest laptops to put a device into their AC charger that the laptop must recognize to draw power.  That means I cannot use a dc charger like I did with my old HP laptop and that is where the inverter, either built into the solar generator, or added to the stand along battery, comes in.

 

Regards,

Curtis

[TelescopeGreg]

Isn't the issue with Lithium batteries mostly around the Lithium Polymer ones?  LiPo.  Those were the ones used in the flaming hoverboards, phones, and tablets.  They're often still used in drones, because of the high energy density.  Charging is often done in a flame-proof container.

 

The NMC batteries from what I've read aren't all that riskier than the LiFePO4.  The iron-based ones have a lower energy density than NMC, but can cycle more with less reduction in capacity. 

Edited by TelescopeGreg, 24 January 2022 - 03:02 PM.