Powering my equipment

[Baskevo]

Hey guys,

So I am thinking of using the Celestron Rechargeable Power Supply PowerTank 17, 12v 17Ah, and then this generator:

I was thinking of using the Celestron PowerTank for solely my mount, and then the generator for my laptop, guidescope, camera, etc. Any thoughts?
Thanks!

[dritter]

Many public dark sites don't allow generators, or at least they are frowned upon. This is due to the noise. A generator is handy for recharging the batteries the next day if you're camped out though.

And the 17AH power tank is most likely not going to be enough to run all the gear all night all by itself.

For full night of imaging, most of us end up with some kind of high capacity battery system that can run all the gear for the entire night. In my case, it's 2 x 12V RV batteries.

These are group 24 size and roughly 60 AH each. For me, on a long night where the dew heaters are running and the camera cooler is on high, one RV battery is not enough. And two of these batteries is more than enough. But these are lead-acid deep cycles so running them down to empty is not a good idea anyway since doing that substantially reduces the battery life. So the two battery solution works for me and after several years, they are still working very well.

Other than large and heavy deep cycles, there are also lithium and other types as well. Some can safely be discharged almost to empty. Some cannot. Prices vary all over the map.

Regardless of what kind you get, you will want high capacity. My guess is that 60 to 80 Amp-Hours should be plenty with the gear you have now. But I'm not sure since you are running a different mix of gear.

And besides the battery you will also need a charger.

The powertank and similar all-in-one packages have the charger circuit built-in. But RV or other bare batteries do not. I'm using a stand alone 10A fast charger when in the field and charging off the generator. At home I use a 2A slow charger when I can leave it on the grid for hours. The slow charge seems to put a little more juice in the tank but the fast charge is better to use when making noise in the campground.

[Baskevo]

Okay good to know. Thanks Dritter. I was looking at the specs and the reviews, and it says that generator does not take gas b/c it is solar charged, and does not produce any noise. But I am open to the RV battery if that is the way to go. Those are the same as deep cycle marine batteries?

I'm really bad with electrical stuff lol would this be okay? It is 75AH, group 24M Deep Cycle Marine & RV battery
https://www.batteriesplus.com/productde ... 7EEALw_wcB

I will be running my mount, I believe I will have to plug in my AutoGuide camera, and then my DSLR camera. My laptop should give me enough battery life , so it would just be the cameras and mount for most nights as of now. That should be fine right? And I can keep my current PowerTank as a back up?

Do I need a converter? And the chargers are confusing... There are some that are $15 and some that are $300. What's the difference?

[dritter]

I didn't realize you were considering a solar based generator. Yes, that would be fine, well except at night I guess...

The batteries I am using are indeed deep cycle marine batteries, very much like the one in your link.

If you're only running the mount and auto guide camera, a much smaller batter will do the job though. Adding in your camera is an unknown since I have no idea how much power it will draw. I'm guessing it's not much but hard to say without having used one like it myself.

If you're going to power the laptop and dew heaters though, that's where the big batteries come in. They also are needed for cooled cameras, the cooler circuit takes a fair bit of power.

So for the upcoming trip, a smaller battery will probably work but even so, the 17Ah power tank is probably still marginal

Having said that, if you already have the powertank, you could always try a dry run at home first. Run everything off battery as you plan to at the dark side. If it works all night, you are good to go, well at least for now. If not, then a big battery is probably high up on the shopping list.

Not sure what you mean by a converter, I will assume it's an AC inverter you are referring to. This would be a box that converts 12V DC to 120V AC, ie: a portable wall outlet. These can be very useful if you have stuff that does not run directly off 12V but does plug into the wall. I have a small one, 100W or so I think and it's worked fine for me. The cost was well under $100.

But over time I was able to get a couple of DC-DC converters going and so now I don't need it. Most astro stuff works directly off 12V so it plugs in to the battery just fine.

But my mount does not, it's 24V DC so I got a DC converter for it. And I also got a converter for the laptop to convert 12V to 20V. This was much smaller and more efficient than using the giant wall wart and an inverter. There are lots of these available now and most people use them to charge their laptops off the car. Just need to make sure the one you get will work with your laptop.

[dritter]

As for charging the battery, any car battery charger will work fine, as long as it has a deep cycle mode (most do).

My current favourite one is a small one from with 2A, 4A and 6A range switches. Its much smaller than the old fashioned car chargers and has an intelligent charge controller circuit built in. This is the one I use from home, typically on the 2A range. Got it on sale for about $30 or so.

The other charger I use is a dedicated 10A fast charger made for deep cycle batteries. It was around $50 or so, so still not too bad cost-wise.

I got it at a DC power specialty shop and it's the one I use in the field so I don't have to run the generator all day. I actually use both chargers in the field for nights when I use both batteries. When the big charger finishes the first battery, I switch it over to the second battery to complete it's charge a little more quickly.

[pakarinen]

Many people use non-astro-specific power tanks like those from Harbor Freight. Cheaper and supposedly just as good as C-tron.

I have no personal knowledge though since everything I use is USB charged.

[Lady Fraktor]

Hey guys,

So I am thinking of using the Celestron Rechargeable Power Supply PowerTank 17, 12v 17Ah, and then this generator:

I was thinking of using the Celestron PowerTank for solely my mount, and then the generator for my laptop, guidescope, camera, etc. Any thoughts?
Thanks!

At 20Ah at 12V it would be great if only running the telescope and dewheaters, for an imaging setup I agree it will not be enough power.

[Baskevo]

Dritter, I totally meant to say inverter! Lol Thanks for all of the help guys! I think I'm going to head over to harbor freight and just grab a battery and everything else I need (I'm sure I can ask the workers for help to lol) Y'all are the best!

[Star Dad]

Be careful of inverters. Most of them available in stores are square wave. These can wreak havoc on sensitive electronics. I tried three different ones of increasing capability. I was trying to use my deep cycle battery and solar panel to recharge an electric lawn mower battery and though way over rated they failed to work - constantly alarming out. I finally gave in and bought a pure sine wave inverter. It works great, and does not require near the power of those cheapy ones at Wallyworld. Here's a possible source for you to look at: https://invertersrus.com/product-catego ... e/12v-psw/ . I ended up buying the 1500 watt AIMS model for our old (and sold) camper direct from AIMS. Been using it for about 5 years so far. Makes cutting the grass and blowing the snow with free energy so nice. Yeah, I'm a bit smug about that.

[Baskevo]

Dude how do you guys use a deep cycle marine battery? I went to Walmart to pick one up, but they are heavy!! I literally couldn't pick one up. lol. How do you guys take them out to a dark site??

As you can tell, I'm pretty ignorant when it comes to the more mechanical part of this...

[chicagorandy]

A handcart or wagon with large diameter wheels should work to transport the truly weighty large deep cycle units.

[Baskevo]

Thanks randy.

hmm... Wouldn't it be better just to get a silent, portable power supply with a lithium battery that doesn't use gas? For example, a portable generator that uses a lithium ion battery with 300W continuous power, 350W peak power, 60000mAh battery capacity, and only weighs 5.6 lbs. (
That was the first one I pulled off of amazon... It says you CAN power it with solar energy, but also with an AC charger and a DC charger, so it doesn't require solar. And it is completely silent since it doesn't use gas. I feel like 2 of these things would be plenty for most people, maybe 3 if you use dew heaters?

So I'm confused why a 60 lb. RV battery, along with a battery box, an inverter, and a charger/maintainer would be a better option for most people... Am I totally missing something here?

[dritter]

Yes, lead-acid marine/rv batteries can get really heavy for sure. An observing partner of mine has a giant one that I can barely budge.

For mine, I bought the plastic marine cases for the batteries and they have handles on the sides. Carrying a battery is a two handed affair. And I don't carry it far. At home, I use a dolly (hand truck?) to shuffle them from the garage to the vehicles outside.

As for the lithium system, indeed they are much lighter. But what you have to look out for is misleading capacity claims. Often the AH or mAH rating is not the 12 V rating. It is at some other, meaningless voltage that is chosen to make the capacity look much larger than it is.

Car batteries and marine/RV batteries are generally honest. If they say 60AH it means 60 amps for one hour at 12V. Or 30 Amps for 2 hours at 12V, or 10 amps for 6 hours and so on. The main point is that these capacity figures are all rated at 12V, which is important since that's the voltage we actually use.

So when checking the specs on other batteries, you need to ensure that the rated amp-hour capacity is for 12V and not 5V or 3.3 or some other voltage.

As for the the battery pack in the link, I think they are amping up the amps.

Consider, a 60AH marine/RV battery can deliver 60 amps for 1 hour at 12 volts. So power = current x voltage which means the power output = 60amps x 12V which is 720 watt hours for a 60AH lead-acid that is really heavy.

But the much smaller and lighter lithium battery pack in the link says it's only rated for 222 watt-hours. So 222W / 12V = 18.5A. Which means that battery is really an 18.5 amp-hour battery if rated for 12V usage.

The rated capacity in the ad in the link says 60000mAH, which is just a fancy way of saying 60AH. Yet, the actual power rating in watt-hours says 222WH. So, its actual capacity at 12V is much less than 60AH (its 18.5AH by my math). Before buying that particular battery pack, it's probably best to get this discrepancy sorted out.

It might be best to visit a DC power specialty shop and ask them. They should know far more than a person at a big-box store would and should make sure you get a battery that delivers the capacity you are looking for.

(I hope this makes sense... explaining math was never my strong point. Neither was doing it, so if someone out there spots an error, please post a correction)

[Baskevo]

I knew it was too good to be true! Haha silly me to question the collective knowledge of everyone who's ever done AP ever...
thanks, Dritter. Looks like I'm going back to Walmart to get a 60 lb. battery

[OleCuss]

Well. . .

Do remember that the performance of a 60AH battery may not work out just as expected.

You don't get all those amps at 12 volts and running them dead is not good for them.

Lithium-type batteries can actually be run until they are dead without rapid destruction and thus deliver a bit better at the end.

Yeah, I've still got several big deep-cycle batteries but I'm trying to move more toward lighter and less finicky Lithium. Lithium isn't really cheap. . .

[Hankmeister3]

Actually, I use a 600/1200 amp EverStart automotive battery "jumper" I bought at Walmart for $79. It uses a lead-acid battery but works great and I've probably already recharged it 50 times and it runs my Skywatcher EQ6-R Pro for at least six hours non-stop with still more battery in reserve. I've even recharged some Vivitar batteries at the same time in the field which I use in my two Canon DSLRs. The USB port certainly came in handy several times when I forget to recharge my camera batteries. However, I may go to Lithium-Ion. The Skywatcher mount is a real power hog and I think you need a powerbank that can support a 12amp/hr draw for an extended period of time. The EQ6-R Pro lets you know when it's unhappy about power availability.

[Baskevo]

Actually, I use a 600/1200 amp EverStart automotive battery "jumper" I bought at Walmart for $79. It uses a lead-acid battery but works great and I've probably already recharged it 50 times and it runs my Skywatcher EQ6-R Pro for at least six hours non-stop with still more battery in reserve. I've even recharged some Vivitar batteries at the same time in the field which I use in my two Canon DSLRs. The USB port certainly came in handy several times when I forget to recharge my camera batteries. However, I may go to Lithium-Ion. The Skywatcher mount is a real power hog and I think you need a powerbank that can support a 12amp/hr draw for an extended period of time. The EQ6-R Pro lets you know when it's unhappy about power availability.

Thanks for sharing, Hank! I actually just did this! I found out that the dark site I will go to has AC outlets, so apparently I don't need a battery. Just in case it gets super packed and I can't get access to AC, I bought a jumper power supply from Harbor Freight, 17Ah, to power my dew heaters, and I have a 7ah Celestron that I know can power my mount for at least 4 hours or so, and my laptop and camera have batteries already, so I'm hoping that if I miss out on AC I can use those as backups