50 replies to this topic

[CA Curtis 17]

Well, if the laptop screen is kept off and the laptop is modest (and it can be) the power draw might not be very much for most of the night. Personally I was more dubious about the cooler running "at max power" because there's no reason to cool that chip to less than -10C and that would be a very low power draw on a cold night. 

Rgrds-Ross

Some good points.  My headless mini-pc draws less than 20W compared to 65W for the laptop with the screen own at lowest brightness.  

 

Would like to hear from MTC given these questions

[mtc]

Sure.

Yes, the 52W includes the power draw for my laptop through the 300w AC inverter and when my TEC cooler was running at 100%, and all of my power needs. This value was the PEAK, not the average.

I always set my TEC cooling at -10C and it didn't take long to cool it to that temp, but it briefly ramped up to use 100% power to get there - and that's when I measured peak wattage (I was interested in what the max value would be)

 

Also, I leave my laptop display ON - the entire time.

On the laptop, I run:

N.I.N.A - for plate-solving and for my all of my imaging sequences.

ASCOM/EQMOD

PHD2 for guiding

Stellarium for planetarium/target/goto

 

My laptop is a Lenovo T440s and while on battery only, with all this running - the battery only lasts ~2hrs - so I never run it on battery, I just plug it in.

 

Here's a pic of the power meter display during my imaging run - with everything on & running (after TEC power usage started to taper off) - it reads:

3.27A, 41.7W

 

 

[RogerM]

Sure.

Yes, the 52W includes the power draw for my laptop through the 300w AC inverter and when my TEC cooler was running at 100%, and all of my power needs. This value was the PEAK, not the average.

I always set my TEC cooling at -10C and it didn't take long to cool it to that temp, but it briefly ramped up to use 100% power to get there - and that's when I measured peak wattage (I was interested in what the max value would be)

 

Also, I leave my laptop display ON - the entire time.

On the laptop, I run:

N.I.N.A - for plate-solving and for my all of my imaging sequences.

ASCOM/EQMOD

PHD2 for guiding

Stellarium for planetarium/target/goto

 

My laptop is a Lenovo T440s and while on battery only, with all this running - the battery only lasts ~2hrs - so I never run it on battery, I just plug it in.

 

Here's a pic of the power meter display during my imaging run - with everything on & running (after TEC power usage started to taper off) - it reads:

3.27A, 41.7W

 

 

battery-drawl90.jpg

mtc, a buddy of mine modified his laptop (using a guide he found on Reddit) to add a USB-C port so that he could run directly off his battery bank, saved almost 10W of power.  You might save upwards of 15W not having to use the AC brick and the 300W inverter.

 

I ditched this little (only 36W) AC brick on my rig using a 12V USB-C 'trigger' cable and saved about 7W.  Since I'm only able to run off a slightly less than 100 Whr battery its a significant power savings for me.

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[mtc]

ok - that's cool & intriguing... with all the clouds these days, I should look into that..

Part of the thinking behind the ac-inverter was for a dual-purpose power bank.. I also have a dual port usb fast changer in there.

DC is always the better and more efficient path.

Of course, with 10 hours of run time - that's more than enough for an evenings imaging session.

Thanks!

[Linwood]

Check your laptop.  Some are locked by the manufacturer to their own supply (my XPS_15 was that way, thanks Dell). 

[mtc]

My lenovo has a usb-a shaped power plug (with a positive pin in the center).... would be neat to leave the brick behind and be a bit more efficient on energy use. Any ideas on cable options?

[rgsalinger]

Anderson Power Poles plus a buck converter if you need one.  Cut the wire and replace the exposed ends with power poles. Now add in a wire with power poles one end and whatever you need on the other end. I use a cigarette lighter power pole accessory that takes power poles input and plugs into my battery. 

Rgrds-Ross

[CA Curtis 17]

Sure.

Yes, the 52W includes the power draw for my laptop through the 300w AC inverter and when my TEC cooler was running at 100%, and all of my power needs. This value was the PEAK, not the average.

I always set my TEC cooling at -10C and it didn't take long to cool it to that temp, but it briefly ramped up to use 100% power to get there - and that's when I measured peak wattage (I was interested in what the max value would be)

 

Also, I leave my laptop display ON - the entire time.

On the laptop, I run:

N.I.N.A - for plate-solving and for my all of my imaging sequences.

ASCOM/EQMOD

PHD2 for guiding

Stellarium for planetarium/target/goto

 

My laptop is a Lenovo T440s and while on battery only, with all this running - the battery only lasts ~2hrs - so I never run it on battery, I just plug it in.

 

Here's a pic of the power meter display during my imaging run - with everything on & running (after TEC power usage started to taper off) - it reads:

3.27A, 41.7W

 

 

battery-drawl90.jpg

Thanks for the details.  Based upon what you replied and my measurements it looks like you laptop is pretty efficient and draws something like 25W which is way better than mine.  Much of that difference I am sure is in the display size difference, 15.4" vs 14".

 

I agree with Ross, running everything dc is best if we are power limited.  Unfortunately my Dell XPS is designed to only work with a Dell power brick so I am stuck, hence the mini-pc as the main computer.  My travel mount is a MyT and SB mounts use 48V so for that I use a DC-DC up converter which avoids the SB power brick.

Edited by CA Curtis 17, 18 February 2021 - 10:05 AM.

[Linwood]

I agree with Ross, running everything dc is best if we are power limited.  Unfortunately my Dell XPS is designed to only work with a Dell power brick so I am stuck, hence the mini-pc as the main computer.  My travel mount is a MyT and SB mounts use 48V so for that I use a DC-DC up converter which avoids the SB power brick.

That's identical to mine, I tried all sorts of things to get the Dell to run on 12v, even 19v, no luck. Disappointing act on Dell's part.

 

So I switched to a NUC on the mount.  If I really need the laptop at the mount itself I connect wirelessly to the NUC and use the laptop for the display only while I need it.  Most of the time I connect from my desktop at the house, or for something like polar align adjustments I connect with a cell phone.

 

The NUC is both lower power consumption and also more predictable without a display and with dedicated software (many of us with general use laptops have tons of stuff running in background which can affect power consumption). 

[Phil Sherman]

.........

 

I agree with Ross, running everything dc is best if we are power limited.  Unfortunately my Dell XPS is designed to only work with a Dell power brick so I am stuck, hence the mini-pc as the main computer.  My travel mount is a MyT and SB mounts use 48V so for that I use a DC-DC up converter which avoids the SB power brick.

You can get DC power adapters for your Dell. I purchased, for $30 from Amazon, a PWR+ "CAR Charger for Dell Inspiron Laptop: 90W 65W 45W". It worked perfectly with a Dell computer because it includes the communication chip that Dell computers check to verify that the power supply is compatible with the computer.

[Linwood]

You can get DC power adapters for your Dell. I purchased, for $30 from Amazon, a PWR+ "CAR Charger for Dell Inspiron Laptop: 90W 65W 45W". It worked perfectly with a Dell computer because it includes the communication chip that Dell computers check to verify that the power supply is compatible with the computer.

Dell says you can't. There are some for other XPS, but they say they won't work for mine.  They of course could be wrong and these might work, but stopped trying after I found how nice the NUC was. 

[SonnyE]

I do simple. It isn't rocket science.

I used an AGM Group 24 12 volt battery for years to power my mount in the field.

To power my Laptop, I used a 350 watt inverter plugged into my truck dash 12 volt power socket. If I felt I needed to (but mostly if I wanted to warm up) I'd start my truck and let it idle charging up the truck battery, and providing the inverter power for my laptop.

 

I would usually just leave the AGM battery in the truck bed and run the mount with my power cords. (One for the telescope equipment, and one for the mount itself.)

 

Doing it this way easily lasted 3 nights for me out in the desert. During the day, I hooked up a 50 watt solar charger to freshen up the AGM battery.

 

No muss, no fuss, no headache, no worries.

 

Unless you got there on horseback and pack mules, never forget the potential of your car. 

Edited by SonnyE, 18 February 2021 - 01:53 PM.

[CA Curtis 17]

You can get DC power adapters for your Dell. I purchased, for $30 from Amazon, a PWR+ "CAR Charger for Dell Inspiron Laptop: 90W 65W 45W". It worked perfectly with a Dell computer because it includes the communication chip that Dell computers check to verify that the power supply is compatible with the computer.

Phil - not so for Dell XPS.  This was raised in another thread somewhere and I provided the link to the Dell forum which stated this clearly.  They have something inside the power brick that the laptop has to communicate with and if it is not there it will not draw power.  I used a dc power supply for my old HP laptop just like you say but cannot do the same with these new Dell XPS laptops.

[Phil Sherman]

You can get DC power adapters for your Dell. I purchased, for $30 from Amazon, a PWR+ "CAR Charger for Dell Inspiron Laptop: 90W 65W 45W". It worked perfectly with a Dell computer because it includes the communication chip that Dell computers check to verify that the power supply is compatible with the computer.

 

 

Phil - not so for Dell XPS.  This was raised in another thread somewhere and I provided the link to the Dell forum which stated this clearly.  They have something inside the power brick that the laptop has to communicate with and if it is not there it will not draw power.  I used a dc power supply for my old HP laptop just like you say but cannot do the same with these new Dell XPS laptops.

I'm not sure about that. The Dell computer I was setting up for use in a DC only observatory didn't work on a power supply I had that that put out the correct voltage for the Dell. The PWR+ one I purchased worked perfectly. This particular one has the communications chip in the power supply that the Dell computer is looking for. Dell also has a car adapter that includes the communications chip and works perfectly with Dell computers. The Dell unit is, of course, a lot more expensive that the one I purchased.

 

The Dell computer was installed in the observatory around a year ago and has worked perfectly since it was installed. It's an always powered on system and its been very happy running off of the PWR+ car adapter.

[phototech]

The wild card in my estimates is how much power the ASIAIR itself uses to power its internal Raspberry PI.  Since I do not have one, I cannot measure it myself.  My BeeLink mini-pc only used ~19W so maybe the ASIAIR will use similar instead of the 35W.  Keep in mind, you can run these Lithium units down to about 20% SOC without shortening the life of the unit which is a heck of a lot better than a wet lead acid battery.  So estimate only 400Wh as useable power from a 500Wh unit.  For 8 hrs you should be able to draw 50W and be safe.  If you were to use the Jackery or similar for the dew heaters as well, you would have to move up to a higher capacity power source.

 

This is the problem with so much equipment.  The key is to stay d.c. and not use inverters, turn the camera cooling to the minimum necessary, use only the dew power needed to keep dew at bay (this is good practice anyway to avoid creating air turbulence by overheating the optical tube), use some reflectix around the dew heater to direct all the heat to the OTA instead of to the air, use short cables with higher gauge wires (18AWG instead of 20 or 22) to minimize power loss due to cable resistance, etc.  For those using a pc turn off all unused software, turn down the screen brightness or use a headless mini-pc or NUC.

 

Good luck

Curtis

The depth of discharge does affect the live of the battery. The lower the charge, the more cycles (some manufacturers will show the DOD verses cycles)

 

To reduce the consumed power on a dew heater (ie. just enough power to prevent dew) use a dew controller that will keep the area under the dew heaters just above the dew point - ie. they have a sensor that sits under the heater (very close but not directly under the hot bit) and they have a sensor to measure the ambient temperature as well as humidity and perform the appropriate calculations. 

The dial control heaters will invariably use too much power as you can't really manually control the temp to be just above the dew point.

A compromise controller is similar to dew point without the humidity measurement. These keep the controllers supply the heaters with enough power to keep them above the ambient temperature.

[CanadianLoki]

Ok so with the help of you all and several videos online, I made my own powerbox. I wanted endless power and don't mind the building part.

However ... would anyone be willing to look at these pictures and perhaps point out what I might have missed here? When I fired it up all switches are lighting up, my voltage meter works but no power to any outlet? Wondering if its a wiring issue or if the fuse box is bad? Any help would be appreciated. I don’t have a multi-meter handy but will tomorrow to try and narrow this down. Posting this in case it’s something simple I’m missing.
Negatives were chained starting on the right side and then all the way up and around to the left then back to the battery neg terminal. Positives were - battery out to bolt on fuse box - pos out to switch, switch to accessory. All fuses are in good shape.

 

Album: Power Box

3 images

0 comments

[CanadianLoki]

Before anyone spends time thinking of this the answer has been pointed out to me. It turns out not all 12v DC components ordered on amazon adhere to the rule of "negative/ground on brass coloured terminal". My bad for assuming some kind of consistency and for not examining every component more closely. Turns out the polarity on the accessories was reversed from that of the switches. Thanks to Brynn from Saskatoon for pointing it out. Now it's all working I will report back on how long this system lasts if anyone is interested.

[mtc]

Done. Dropped the ac/dc brick for the laptop and added a 20V DC port to my PPS. Thanks! 

 

Anderson Power Poles plus a buck converter if you need one.  Cut the wire and replace the exposed ends with power poles. Now add in a wire with power poles one end and whatever you need on the other end. I use a cigarette lighter power pole accessory that takes power poles input and plugs into my battery. 

Rgrds-Ross

 

Edited by mtc, 24 February 2021 - 09:55 PM.

[SkyETC]

I use a deep discharge battery that I got at the auto parts store for a FRACTION the cost listed here.  It's already 3 years old and it is 38Ah.  I use it to power all sorts of things.......clay pigeon thrower, sprayer for my fields, telescope stuff (G11 mount, dew heaters, etc).  I used it for observing 3 nights in a row last month and it was only down to 12.2 volts.  I don't have to charge it very often for observing.  A good deep discharge battery and some DIY skills are all you need.  If you don't have much DIY ability, there are plenty of people who put good information on the Internet...LOL, there is also some pretty bad info out there.  

Ross, with all due respect I have to disagree. 

 

Look at the technical specifications of the Goal Zero power stations carefully compared to others like the Jackery.  First, both use LiNMC for light weight.  Both have regulated voltage output.  Both have MPPT charge controllers built in for easy solar re-charging.  Both have pass through charging. Both have several USB output ports and pure sine wave AC outputs. Both have 2 year warranties, although my Jackery increases that to 3 years when you register the product.  An so on.  Very little difference of significance based upon these attributes. 

 

Now, here is where they differ.  Cost per unit of Amp-Hour (or watt-hour if you prefer).  The Goal Zero 505Wh specifies 505 watts (46.9Ah) only at 10.8V.  Nothing we use wants to work at 10.8V.   Let’s figure out how many Ah at 12.7V which is the voltage of a fully charged lead acid battery.  That would be 40Ah or 508Wh.  At a base cost of $699.95 you are paying $17.5 per Ahr at 12.7V.  Next, look at the Jackery 518Wh unit.  It specifies 518Wh at 21.6V and 24Ah.  Don’t ask me why all of these solar generator companies use these different voltages and not 12V or 13V for consistency.  Anyway, the Jackery will supply 40.8Ah at 12.7V which is 518Wh.  The price is $500 so you are paying $11.41 per Ahr at 12.7V.  You can do the calculation at any voltage you like, the Jackery will come out to be 30% cheaper.

You can do the same calculations for the Goal Zero 200Wh  ($20.4 per Ah) and 1500W ($16.93 per Ah) models to compare with the closest comparable Jackery  models, 240Wh ($12.17 per Ah) and 1002Wh ($11.41 per Ah).   For these models the Jackery is even a better buy by comparison.

I see absolutely no reason to buy the Goal Zero over the Jackery.  And Jackery has an excellent reputation on Amazon. 

 

Now there are other very good solar generators out these besides the Jackery that have comparable tech specs and competitive price points, but I have only had hands on experience with the Jackery and feel quite comfortable recommending it.  I would certainly recommend it over the Goal Zero given the significant cost differential

 

Regards,

Curtis

[CA Curtis 17]

I use a deep discharge battery that I got at the auto parts store for a FRACTION the cost listed here.  It's already 3 years old and it is 38Ah.  I use it to power all sorts of things.......clay pigeon thrower, sprayer for my fields, telescope stuff (G11 mount, dew heaters, etc).  I used it for observing 3 nights in a row last month and it was only down to 12.2 volts.  I don't have to charge it very often for observing.  A good deep discharge battery and some DIY skills are all you need.  If you don't have much DIY ability, there are plenty of people who put good information on the Internet...LOL, there is also some pretty bad info out there.  

That's the advantage of a visual observer.  Much less power needs compared to an astrophotography or camera assisted viewier, aka EAA'r.   38Ah or ~450Wh might last 1 night for an astrophotographer but they would need a low power laptop to make that happen.

[Linwood]

That's the advantage of a visual observer.  Much less power needs compared to an astrophotography or camera assisted viewier, aka EAA'r.   38Ah or ~450Wh might last 1 night for an astrophotographer but they would need a low power laptop to make that happen.

But I think the theme remains.  It really is about weight vs cost generally.  While it is possible one might wear out a deep discharge battery eventually (especially if you do not keep it charged between sessions), for the frequency most of us use for remote observing, they will last many years.  Many.

 

They are CHEAP in comparison, not to mention almost everyone has chargers for them, but they are HEAVY.  I've got two.  Together they weigh what a small person does.  But... CHEAP.

 

It's really about how much saving that weight is worth.

[CA Curtis 17]

I have been doing the calculations for a blog on my web site about power solutions for astronomy and it is actually not the case that Lead Acid, wet or AGM, are the cheapest solutions.  I don't want to repeat everything that I am writing for my web blog here (expect to publish this Sat) but it is much cheaper to use a 100Ah LiFePO4 battery than the cheap 100Ah lead acid or more expensive AGM batteries.  The up front cost is absolutely higher for lithium.  But most people forget that a wet lead acid is good for ~250 cycles to 50% DOD and an AGM ~ 350 cycles to 20% DOD while LiFePO4 is good for >2500 cycles to 0% DOD.  And at half the weight per battery.  A quarter of the weight for the same useable capacity given the DOD limits on the lead acid batteries.  And, lead acid batteries need much more regular maintenance to keep the 250 to 350 cycle lifetime.

[Linwood]

The thing missing from that math is that use of batteries for many of us vary widely.  I suspect some might use it 100 nights a year.  If I use it 6 I'd be surprised (in the last 4 months I've been out once). 

 

The hugely greater cycle life is only relevant if one ever gets there.  Which some will.  Many?  Most?  Few?  Not sure. 

[JMW]

The surest way to destroy a lead-acid battery is to discharge it or let it self-discharge over a long period and then leave it discharged for a long time.

 

When I used lead-acid batteries I always connected them to a battery-minder type charger after each use and left them hooked up until the next use. When I used them in my cargo trailer I had solar on the roof and an MPPT charge controller to keep them topped off daily. My flooded lead-acid batteries would get water topped off every few months. My smaller AGM battery just needed to be plugged into the battery minder charger.

 

I am a fan of LiFePO4 batteries and feel they are worthwhile over their 10-15 year usage period. They charge fast all the way to 100% SOC, support high current when required and are much lighter. The BMS (battery management system) helps protect them from abuse. My pair of 50 amp-hour LiFePO4 batteries weigh 17 pounds each. I recharge them with the 265 watt panel on my truck's Leer cap using a MPPT charge controller. I also have a 30 amp smart charger when I want to charge them from my house. 30 amps is the recommended maximum life charge rate for my batteries. This allows them to fully charge in less than 2 hours.

 

I use a battery shunt on my travel trailer's 700 amp-hour battery system to compute real time amperage in and out of the battery. For small systems there are many inline battery monitors that should volts, amps, peak amps, max and min voltage and amp-hours.

Edited by JMW, 25 February 2021 - 01:59 PM.

[Phil Sherman]

My lenovo has a usb-a shaped power plug (with a positive pin in the center).... would be neat to leave the brick behind and be a bit more efficient on energy use. Any ideas on cable options?

Search Amazon and ebaY. I was able to locate a car adapter that has the correct power plug for my Lenovo that uses the same power plug. I cut off the cigarette lighter plug and replaced it with PowerPole connectors to connect to my portable power box.