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#1 TheZ3roCool

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Posted 02 July 2020 - 05:30 AM

Hi all, currently use my setup at home and just plug in to the mains.

 

Planning on taking my setup an hour into darker sky.

 

I need to power my NEQ6, ASI 1600 MM (TEC), guide camera, laptop and possibly dew heaters.

 

I am not an electrical person but am I right in thinking that I could use something like this:

 

https://www.amazon.c...3685013&sr=1-14

 

and a Deep Cycle battery (Connect with clips) or Power Tank (Use cigar connector) work okay?

 

Cheers for any info.

 

Tom.



#2 james7ca

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Posted 02 July 2020 - 06:18 AM

I suspect that most of your equipment runs on 12VDC (except the laptop) so for power efficiency it's better to skip the conversion from 12VDC (battery) to AC (inverter) and then back again to 12VDC (power adapter).

 

Your mount will probably run directly from a 12VDC battery, same with the dew heaters, and the camera's TEC. That leaves only the laptop and you can probably find a suitable power supply for that device that can be connected directly to the 12VDC battery.

 

For the laptop, here is a power regulator that MAY work (you'll have to check the power requirements for the laptop's input voltage and watts):

 

  https://www.amazon.c...U_ecC.EbTZ658TJ  (about $30 U.S.)

 

For the other devices you can purchase a simple fused, female power connector that will run between the battery's +/- terminals and the DC power plug for the device itself. Something like the following (you'll need one of these for each device):

 

  https://www.amazon.c..._U_LgC.Eb2WHDXZ (less than $10 U.S.)

 

Or, you can use the above with a simple splitter:

 

  https://www.amazon.c...U_DjC.Eb41A5059 (less than $10 U.S.)

 

As for a battery power source, don't use your car's battery. Either purchase a few small deep cycle 12VDC AGM batteries (or a full-sized battery if you don't mind the weight) or spring for a more expensive but better performing Lithium ion or LiFePO battery. If you get small batteries you can use one for your mount, one for your laptop, and another for the dew heater and/or camera TEC/cooler.


Edited by james7ca, 02 July 2020 - 07:20 AM.


#3 Sandy Swede

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Posted 02 July 2020 - 06:57 AM

Not sure about UK electrical, but will you be able to set up within, say, 15 ft. of your vehicle?

The one you linked is not pure sine wave, only modified.  Some mounts and sensitive electronic gear may not like that.

Although the brand name sounds like it may be made in Japan, is it made in China?  Doesn't have high consumer rating.

Not a fan of the Celestron Power Tank.  Check out some of the comments on CN concerning the single mode limitation.

 

Take a look at the Jackery (MSQL for 220v)  I have the 240 model.  Pure sine wave made in America.  Highly rated.  $250 USD.  Higher capacity models available as well.  You will not be tethered to your vehicle.

https://www.amazon.c...,aps,188&sr=8-2

https://www.amazon.c...93690245&sr=8-8

 

I think another key is not to drain your vehicle battery beyond its ability to start your vehicle.  Also, if voltage or amps drop below a certain level, the Jackery will shut off, eliminating the possibility of your damaging sensitive electronic gear.  No guaranty if you have a direct connection to your vehicle battery.

 

These are only my opinions. 



#4 dapalmer

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Posted 02 July 2020 - 12:53 PM

Yes you could do what you proposed, but I will agree with James that it is not the best solution.

 

The only thing I would differ with James on is I would not get a Lithium Ion battery. They don't last very long unless you charge and discharge them at the recommended rates. They are less forgiving than your other options.

 

LiFePO4 is the way to go if you can find one you can afford. Shop around there are huge differences in prices. I expect 16aH would likely last one evening. Also, a LiFePO4 battery will weigh about a 3-4lbs versus 15-20lbs for an equivalent AGM. 


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#5 james7ca

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Posted 02 July 2020 - 06:34 PM

There is nothing particularly wrong with Lithium Ion batteries and they are used in most mobile devices and electric cars. However, they need to be used and charged correctly but that's true with any battery. That said, Lithium Ion is probably not the number one choice for powering a mount/camera/computer. But, how often can you afford or even find the absolute best in anything?

 

If I had to rate battery technologies regardless of price then the ordering would be (from worst to best):

 

A typical lead acid automotive battery (I don't recommend this under any circumstances, although it can work)

Deep cycle AGM lead acid

Lithium Ion

LiFePO4

 

Now, each of these technologies comes in at various price points when looking at capacity. Generally speaking, Lithium Ion and particularly LiFePO4 are the most expensive (YMMV) but each of these battery types has a higher energy density than lead acid batteries and that means they can be both lighter in weight and smaller in size than an equivalent capacity lead acid battery.

 

Also, you shouldn't choose any of these batteries without doing a bit of your own research on things like charge cycles, true capacity at 12VDC, and safety. LiFePO4 may be the current favorite in terms of charge cycles and safety but it can also be the most expensive (again, YMMV). For that matter, deep cycle sealed AGM lead acid batteries are easy to use and very safe but they are much heavier per unit capacity than the lithium or LiFePO4 batteries. Lithium Ion can be nice because there are generally more product types with that battery type than with LiFePO4. 

 

A few years ago based mostly on price and easy availability I decided to go with small (34Ah) deep cycle AGM batteries that I could array in various configurations (one for the mount, one for the computer and cameras, and a third either as a spare or for dew heaters). In terms of capacity one of these batteries can keep my mini PC and cameras (with cooling) running for at least 8 hours and if I need more than that I can easily hook two of these batteries in parallel.

 

Today, however, it looks like it is possible to go with LiFePO4 for only about a 50% increase in total cost over a similar capacity deep cycle AGM battery (except that high capacity LiFePO4 is still very expensive -- think $500 to nearly $1000).

 

In any case, I'm pretty close to trying a smaller capacity and inexpensive LiFePO4 that can currently be found on Amazon for only $50. It might not provide the same runtime as one of my 34Ah AGM batteries and it might require some additional circuits to run in parallel (only with another LiFePO4) but the price is certainly attractive and it is much lighter in weight than any similar capacity lead acid battery.


Edited by james7ca, 02 July 2020 - 11:13 PM.

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#6 dapalmer

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Posted 04 July 2020 - 11:49 PM

I pretty much agree with what you have said except my preferences are bit different.  Lithium Ion batteries typically last 3-4 years or 300-500 discharge/charge cycles. AGM batteries typically last 4-7 years or 500-1000 discharge/charge cycles. LiFePO4 batteries typically last 5-10 years or 2,000-3,000 discharge/charge cycles. For this reason on the cost associated with each battery - I am not a fan of lithium ion batteries. 

 

AGM batteries can be connected in parallel without much fanfare. Lithium based batteries should not be connected in parallel unless they have matching internal resistances and matching starting voltages. A good quality lithium based battery from the same manufacture and same design should be reasonably consistent in construction (i.e. internal resistance), however the cheaper battery manufacturers can have varying internal resistance from battery to battery.  True, it is not unheard of to hear about amateur users connecting lithium based batteries in parallel, but it can be a poor idea if not done correctly. It is very important that the batteries be at the same voltage when they are connected. The reason it is risky  is that the internal resistance of a LiFePO4 battery might be as low as 5-6 milliohms, so if we connect 2 batteries with say 0.1 volt difference then the lower voltage could pull as much as 20 amps (0.1volts / 0.005ohms) from the higher voltage battery trying to get the voltages to match. This could be higher than the recommended load on some cheaper batteries, while it may be fine with the more expensive brands. The high current draw could in turn cause the battery voltage on the initially higher voltage battery to drop below the lower and reverse the process and start a tug of war.  What that ultimately means is that you could shorten the life expectancy of both battery significantly and potential cause excessive heat in your system. 

 

These are some of the reasons the manufacturers almost always say you can connect up to four batteries in series, but do not connect in parallel. That being said, it can be done if care is taken to insure the batteries are a matched set and properly charged. Just don't be surprised if your batteries don't last as long as you expected or suddenly you notice things are getting hot.  If you are dead set on connecting batteries in parallel you should always used a balanced wiring method.  For example, if two batteries are connected in parallel - connect both positives together and both negatives together, then connect the load to the positive of one battery and the negative of the other battery. This will ensure that the entire current passes through both batteries and they both perform half the work. If more than two batteries are connect, the balance wiring method is a bit more complex but should still be used.  (There are more complex ways of protecting the system with diodes and other circuitry but I will not get into those here.)

 

My recommendation to most people would be to split the loads instead of wiring in parallel. This is what I do. For example, let one battery power the mount and dew heaters and let the other battery power the cameras, focuser and computer - or some other method to split the loads to match your battery's capability. This way, the batteries do not have to match in any way.

 

Oh, I should add that it is recommended that LiFePO4 batteries be charged individually instead of while wired in parallel. The reason is the BMS in the battery is not designed to protect the battery during charging if it is connected to another battery.  This complicates the matter of getting both batteries to the voltage level, but does not make it impossible.

 

Certainly there are some who will disagree and/or not follow this advise, but you should at least know the risk and reasons why the experts say don't connect in parallel. It's not so much that it can't be done, but rather we don't trust you (Joe Amateur) to do it properly. Hence the manufacturers may not warranty the battery if they find out you wired LiFePO4 batteries in parallel.  Honestly, I think the risk of catastrophic failure is low but as a professional cannot recommend it.



#7 whizkidcat

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Posted 29 July 2020 - 08:18 PM


 

Quote

In any case, I'm pretty close to trying a smaller capacity and inexpensive LiFePO4 that can currently be found on Amazon for only $50. It might not provide the same runtime as one of my 34Ah AGM batteries and it might require some additional circuits to run in parallel (only with another LiFePO4) but the price is certainly attractive and it is much lighter in weight than any similar capacity lead acid battery.

 

Can you add a few links of the products you recommend please?
I don’t know enough about batteries to make an informed choice but I do know I’m looking for something “Plug and Play”

 that comes with all the necessary cables, plugs, adapters, something that gives somewhat constant power without dropping Out and shutting off etc.  Not something that looks like a car battery. ;)

 

Thanks for your help!



#8 james7ca

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Posted 02 August 2020 - 03:43 AM

Here is a $50 LiFePO4 on Amazon:  https://www.amazon.c...p_4UNjFbE2N7NQG

 

Note, I have not tried this particular battery or brand, but another user on CN apparently purchased one or more of these about one month ago.

 

Here is a link to the original thread on CN:

 

  https://www.cloudyni.../#entry10287204

 

You can send a PM to that user to see how he likes them. If so, please report back on what he said.

 

[UPDATE]

I decided to PM the user that purchased this battery, so I'll report back what he says.

[/UPDATE]


Edited by james7ca, 02 August 2020 - 08:08 AM.


#9 james7ca

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Posted 03 August 2020 - 08:21 AM

...

[UPDATE]

I decided to PM the user that purchased this battery, so I'll report back what he says.

[/UPDATE]

He said that the Miady batteries that he purchased from Amazon worked "great." Unfortunately, they don't seem to be available on Amazon any longer. The link I provided earlier now only shows a larger and much more expensive version and a smaller, lower capacity one.


Edited by james7ca, 03 August 2020 - 08:26 AM.


#10 dapalmer

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Posted 04 August 2020 - 10:41 AM

I would have recommended the same one as James, but see it isn't available right now. I use two TalentCell LF120A1. They are a little more expensive and little less capacity than the original Miady that is not available. I really like the TalentCell battery but would have went with the Miady if it was available.

 

Link to TalentCell:  https://www.amazon.c...2dDbGljaz10cnVl




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