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DIY Battery Pack Suggestions


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So I have had my trusty battery pack that is one of those camper ones with the big light, 12v car plugs, regular wall plug and a couple other gadgets. It worked very well and I love it. I has lasted 2 night without recharging but that was when I only had my mount and dew strap hooked up to it. Now I have aquired a guide cam and a CCD and laptop I'm pretty sure I'll drain it in under an hour with everything hooked up to it...or it might just melt in a pool of acid when it explodes. So before that happens I'm going to need something a bit more powerful and longer lasting.

I'm not sure what to look for though. Should I get just a car battery or are there better options? I prefer to keep it as light weight as possible since this will be traveling with me to my dark sites. I am keeping my surrent battery pack as I have used it more than once to jump a car already so its just handy to have around. So I could use it to run the mount a dew strap as before and then get another battery to run everything else. 

Do people tend to have multiple batteries when going to dark sites or just take one big one to run everything? I'm not opposed to that either. Some suggestions or telling me what you use would be great help. Thanks.

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I use 2 x 50 ah leisure batteries. One for the mount and one for everything else. It means that the mount can continue tracking as long as needed without the draw of dew bands etc. if it is at Dalby then i always carry a spare "just in case".

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Yes, leasure batteries work the best, they are expensive and so are the chargers, but unlike the normal car batteries then can last waaaaaay longer.

The problem with regular car batteries is that they don't like much to be fully discharged and loose a lot of voltage with cold nights, you will see them die and last fewer and fewer month by month.

But hey, they are relatively cheap :)

Or...get a generator :D LOL

Cheers,

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Thanks. I'll look into the leisure (deep cycle) batteries. What stats are considered a good for AP purposes? As I've seen the Ah and Amps and volts range all over the place.

Also what connectors do you prefer to hook up to the battery to allow the equipment to hook up to it?

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Depends how far you want to go but the best option for power vs weight / size would be a LiPO pack. I am considering using some RC hobbyist lithium packs in parallel - probably would use 2 or 3x 4cell 8Ah packs and a 12v regulator. Should work out as a 24Ah pack that I can easily fit in my camera bag :)

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Depends how far you want to go but the best option for power vs weight / size would be a LiPO pack. I am considering using some RC hobbyist lithium packs in parallel - probably would use 2 or 3x 4cell 8Ah packs and a 12v regulator. Should work out as a 24Ah pack that I can easily fit in my camera bag :)

Please, please be careful with LiPo packs as there have been a few fires due to miss-use.

Also they do not like the cold and will loose a fair bit of capacity when cold.

And you MUST use a charger that is suitable for LiPos.

You may find some 'special prices' on a web site such as Hobby King if you root around.

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FLO sell LiPo batteries which should be suitable for this purpose (it's what they sell them for :D) :- http://www.firstlightoptics.com/power/tracer-12v-22ah-lithium-polymer-battery-pack.html  Seems a bit low in capacity for a whole night's AP though, to my way of thinking.  Not that I use batteries and go away for my imaging but I am aware of how much current things take.

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Thanks for the suggestion everyone. How do you plug in your equipment to your battery? What connectors do you use. I've only been able to find the cigarette lighter ones. 

Edited by nmoushon
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I brought a 5 way cigarette type hub, the hub connects to the battery with large croc clips. The cigarette types have the benefit of hold a fuse but some type move over time due to the spring tension and break the circuit until you push them into place again.

On equipment that comes in different connector like the 2.1mm pin I will convert to cigarette type.

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I use XLR connectors for my power them the 2.1mm standard type for distribution.  Some cig plugs and sockets are alright but many are not - I don't like them.  I use fuses and overvoltage crowbar circuits in my power box.  But that is with main supply you won't get overvoltage from a battery.  However, any voltage reducers can fail and OV circuits are a good idea there.  It's worthwhile protecting some of this mighty expensive astro gear like mounts and cameras.

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Please, please be careful with LiPo packs as there have been a few fires due to miss-use.

Also they do not like the cold and will loose a fair bit of capacity when cold.

And you MUST use a charger that is suitable for LiPos.

You may find some 'special prices' on a web site such as Hobby King if you root around.

I know, they can be lethal when you start charging cells over 4.2v. They are not too bad when cold if you insulate them, could even make a simple dew strap type heater to keep them at optimum temperature :)  Agree about the charger, depends what you have though because I sometimes charge my packs with a bench supply, just make sure I set the voltage to 4.2 x number of cells and a sensible charge current!

I really think they are the way forward though, especially for observing in the field :)

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I know, they can be lethal when you start charging cells over 4.2v. They are not too bad when cold if you insulate them, could even make a simple dew strap type heater to keep them at optimum temperature :)  Agree about the charger, depends what you have though because I sometimes charge my packs with a bench supply, just make sure I set the voltage to 4.2 x number of cells and a sensible charge current!

I really think they are the way forward though, especially for observing in the field :)

I am sure LiPo or even LiFe radio control packs would lend themselves to powering astro kit,  using LiPo in radio control cars over the years I have seen a few packs swell/puff when badly charged, yet to see one randomly catch fire but there are stories, radio controllers had problems with NiMH cells.  Dedicated chargers for these batteries are cheap enough and should be used.

The packs for flight are soft cased and would need to be boxed, car packs have hard plastic casing with hard wired cables or bullet style connectors.  Lipo's need a voltage cutout in the circuit that switches off before they are over discharged, dedicated lipo chargers will refuse to charge a battery if the volts are to low, assumption is the battery/cell has been damaged.  We love our LiPo car packs.

Hope this is helpful,  jcjc's dad.

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