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DIY Field Battery HELP ?

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Hello all,

   I'm looking at putting together my own Field battery for my setup but not sure where to start.


So Here's my current Kit:

NEQ6 Pro Mount

Moonlite Focuser with Mini V2 controller

QHY8L Camera (usually sits approx. 27 - 29% power at -25 below ambient)

Orion Starshoot Autoguider (from the Awesome autoguider package with the Orion ST80)

12V Anker USB3 7 port Hub to connect it all up

No Dew straps yet but intend on adding one to the ST80 in the future (any recommendations ?)


Main Stumbling Block :- Laptop MSI GP72 2QD-062UK

I'd like it to also be able to power my Laptop but the battery pack is built in so I cant see the credentials of it, I know the mains adaptor

is rated at 19.5v and 6.15Ah which equals approx. 119W but im sure this is overrated. I contacted MSI and they say they couldn't tell me

an approximate W per hour the thing used fully loaded, half loaded and at Idle but suggested a piece of windows software called BatteryMon.


On running BatteryMon on my Laptop with PHD2 Simulated guiding, Sequence Generator Pro running and all my kit connected and running a

simulated capture, and Stellarium running too, BatteryMon reported battery Voltage at 12v and approximate discharge rate of 1612000 - 1712000 mW

with it all running. Interestingly, If you pan around in Stellarium, the mW figure shoots up to approx. 3312000 - 3512000 mW, likewise, when the mount

slews via EQMOD EQASCOM the mW figure short up to 3312000  3512000 mW also


Primarily, I usually image in the back garden with the laptop inside and plugged into the mains so most of the time I will be looking to just power all the

equipment outside but not the laptop, on the other hand, should I go to a star party I'd also like the power so I can run the laptop off of it too foe something

like 6 to 8 hours at an absolute maximum.


So could anyone help me work out what 'Ah' battery capacity I would need to power all the above (inc Laptop) for a good 8Hrs  ?????


I have a charger like the following rated for a battery up to 80Ah:



Could these type of batteries be any good and also be chargeable with the above charger:




Was looking at this but will it be overkill or not enough (19Kg is really heavy and its really big, if smaller was possible that would be MUCH BETTER):




Any help would be gratefully appreciated


Many Thanks












Edited by Pscammp
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Hi mate,

My advice would be to get the biggest battery you can. I have a 85 ah deep cycle battery running my azeq6, dew straps x3, ccd camera, USB hub & my laptop when needed. I could really do with a 110ah battery, especially when it's cold outside to guarantee enough juice for a whole night of imaging. My laptop really sucks the life out of the battery. The ctek chargers are really good & you can leave them on the battery for long periods of time where they maintain the charge. It is important to keep the charge topped up when the battery is not in use. There are lots of threads on here for diy battery packs,  usually mounted in some kind of toolbox. Have a look through some of them to get some idea of what people are using.



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  • 2 weeks later...

Yes, Deep Cycle batteries are a good choice.

Typically, I only plan on using 50% of the battery's AH capacity.

I use a single 110AH Deep Cycle battery, but it weighs 50 lbs / 25 kg +/-.

A 110AH  battery will give you 6 amps for 8 hours and will discharge 50%.

For your AC Powered equipment - purchase a $20 Kill-a-Watt and actually measure the watts consumed.

For  DC equipment - measure the DC Amps using a $10 volt-ohm meter.

You need to KNOW your power requirements, we can only guess-timate.

I think , a 75AH battery (from your LINK) , fully loaded with ALL of your gear, will not last 8 hours.


I suggest running everything directly from 12 Volts, no inverter for best efficiency.

Mount = 1 amp

Computer = 2 amps

Dew Band = 1 amp EACH

QHY8L Camera = 2 amps (4 max)

AutoGuider = 1 amp

Focuser = 0 amps

USB Hub = 1/2 amp


I guess-timate 7.5 amps already


75AH battery x 50% / 7.5 amps = 5 Hours +/-

110AH battery x 50% / 7.5 amps = 7 hours +/-

If weight is an issue then purchase two 75AH batteries and split the loads.

Batteries with built-in handles or batteries-in-a-box are great to store and carry.


And the charger must be configured properly for your battery type.


How to kill a battery in less than one year ...

1) Chronic over-charging

2) Chronic under-charging

3) Discharging too deeply, too many times


Edited by mvas
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