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Obi Wan Ken00bi

DIY Field battery - plans are ready, should I start?

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No chance of clear skies.  It's more a case of having the telescope there, setup and showing off what I can do with it.  From a nerd point of view...

Meade LX-90 with a SkyFi, being controlled by an iPad.

Skywatcher Synguider attached to an ST80 via a flip mirror, this is mounted on my main OTA.

Canon 70D attached in prime focus via another flip mirror.

Main focus is done by electric focuser.

I think the scope is an impressive sight when it's all setup and running. Should be good for wowing the crowds.  That reminds me.  Need to make sure I have all my astro pics on my ipad.

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That does sound like an impressive set-up, pics plz :)

btw I have upgraded the battery to 45Ah but not charger which is rated for batteries 12-40 Ah, this means its will take longer to charge or should I find a new charge?

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As promised here's the pics.

Here's the full setup

post-46378-0-99266400-1445198134_thumb.j

As you can see in the image, my battery box is the big JCB box at with wheels at sitting on the carpet.  Above that is a box that carries the various bolts that I need to put the scope together.

The silver case on top holds my eyepieces and autostar.

Here's a close up on the battery box.

post-46378-0-31334600-1445198154_thumb.j

Next to the wheel there are two terminals that I can connect to jumper cables, or to a 12v car battery charger to charge the battery.

There is a small plug between them. I can use this to plug into another battery box to extend the capacity (I do not have the second battery box, I have put the plug in so that I don't have to do it in future)

The black and red cable that that is plugged into the side of the box powers my telescope (more on this later)  The plug is an XLR type socket, with a latch so that the plug will click into place and not fall out, I have to release the latch to be able to remove the plug.

Above the cable is a volt and ammeter.  The switch to the right turns this on and off.  The ammeter is apparently capable of 50A.  This is accomplished by using a shunt inside the box for the current, the ammeter takes a sample reading. (Not sure how accurate it is)

On the front of the box, working from the bottom, I have four 12v marine sockets.  They're like the car 12v sockets, but the marine version can be locked into place.

Above the auto socket are two panel mount duel USB charge sockets, giving four USB sockets in total.  Each USB socket is capable of two amps.

Inside the box, I have a fuse box, so that each of the above items are fused.  Each Auto socket has a 15A Fuse.  The telescope socket has a 10A fuse, the USB and volt meter use 5A fuses.   The cabling inside the box is capable of 30A, apart from the jump terminals, they're rated for 110A, not that I'm planning on using that much power at the same time ever.

Today, I was using two of the Auto sockets (one to power my SkyFi, and another to power my EL Panel)

The Telescope cable, does not run straight to my mount, it first goes via this box.

post-46378-0-81460000-1445198172_thumb.j

This little box of tricks does is the start of system that I use to power my scope.  This box has two dew heater controllers, and a 5v DC-DC converter.  It provides power out through the grey cable (It's a 9-pin D-type like those used on Serial cables)

The nine pins (nine seperate wires) are broken down something like this...

1 & 2 unused.

3 - 5V DC

4 - 12V DC

5 - Ground for the 5V and 12V

6 & 7 - positive and negative of dew heater 1

8 & 9 - positive and negative for dew heater 2

The dew heaters are turned on by the switches, and the power is controlled by the knob next to the switch.

The LED  on this box is there to provide some visual feedback that the box is plugged in and powered.

when you follow the grey cable, you'll end up at this box.

post-46378-0-73712900-1445198186_thumb.j

This box provide the means to split the power out to the various devices at the scope. (Means that there's not so many wires runing from the battery to the scope)

Working clockwise from the grey cable.

two dew heater elements (lower silver plugs)

5V output which plugs into my SynGuider

three 12V plugs (on top) one of which is plugged into the scope mount.

This box also has a small fuse board inside to provide a fuse for each of the 12V plugs.

The last picture give a better overview of where all the wires are going.

post-46378-0-06898000-1445198200_thumb.j

Edited by cjdawson
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Hi Obi

Here is an old link to the power box I made for my outings to remote sites , I used insulation in my box & I made an extra long, low power diy dew band wrapped round my AGM 90Ah battery , it maintains almost  room temp. inside the battery housing .

A frosty battery lasts no time at all, keep it snug :) , take time with the design & construction of your power build and it will work for years .

Happy building.

Dave.

http://stargazerslounge.com/topic/162015-building-a-new-diy-power-box/

Edited by Epicyclus Dave

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Epicyclus Dave,  I've been looking at your thread and I'm wondering about a could of things.

Do you really need the dew band for the battery?  or is the insulation enough?

If you do need the dew band, how much power does it draw?  do you leave it on all the time, or just give it a blast once in a while?  And can you provide details of how you made the band?

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Epicyclus Dave,  I've been looking at your thread and I'm wondering about a could of things.

Do you really need the dew band for the battery?  or is the insulation enough?

If you do need the dew band, how much power does it draw?  do you leave it on all the time, or just give it a blast once in a while?  And can you provide details of how you made the band?

Hi , before I built the one in the link above, I used a a couple of Lucas 22Ah golf batteries in parallel in a box with an open top, on a cold January night years ago they sapped pretty quickly.

When I was planning the big box supply, I looked at the battery manufacturers spec sheets online to see the Temp/ time discharge graph curves  and they showed room temp as ideal operating conditions , so I knocked together a simple resistor dew band to run at 3 or 4 watts from one of those led dimmer units ( I had to re-flow all it's solder joints , easy job to do) from hong kong.

It was an article on ice in space website that I looked at for the maths side of working out a dew band, but I adjusted my own pencilled out equations to make a long low power band.

http://www.iceinspace.com.au/63-292-0-0-1-0.html

Since getting a skymax180 I have now started using nichrome wire ,much easier and quicker build of big heat bands.

When I unload the car at a remote site, I switch on the battery warm band to a medium setting on the control dial and leave on for the session, in winter I turn it up a bit more , power wise , everything runs sweet - NEQ6 with diy 13.6V step up regulation / SW ED80 / finder guider / XP laptop / diy dew band control & bands / DSLR supply.

Dave.

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might as well add a dew heater to my battery box. Going to make make a dew strip from nichrome wire, will be interesting to know how much current a couple of turns of nichrome will use. That will probably be enough to keep an insulated battery nice and toasty.

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Hi, if you really need a warming band , I would say 0.5 A would be good for a slight warmth, we are not looking to roast a leg of ham with the band :) :) yum , that equals 24 ohms total resistance or as close as you can get  ( 12V divided by 0.5A) , so if you need 2meters of nichrome wrap around, you would have to get nichrome that is 12 ohms per meter  and if you require 3 meters worth length, it would need nichrome that is 8 ohms per meter, the values will depend on physical size of battery & how many loops needed and what resistance per meter you can purchace

When I made the nichrome band for my Skymax180, I sleeved my nichrome with 2mm heatshrink to ensure no shorting along the length of the band .

In most situations a band for the battery is not really needed if the box is well insulated, but i liked the idea of maximising the battery performance by having it operating at house temp. in Scottish winter time.

Dave.

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Why not just use a heat mat? You can get them online. The my are normally used for keeping reptiles as pets. They are needed as reptiles are cold blooded and usually sit under the floor of the glass vivarium that the pet is housed in. One of those in the bottom of the box, plus insulation and the temp in the box will be fine for the battery :)

Sent from my iPhone using Tapatalk

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Don't vivarium heat mats run off 240Vac?  At least the one that I just looked up does, and it costs £20.    I can make a battery meter for about £5 (cost of a good PWM from ebay) and some nichrome wire, heatshrink and electrical tape which I already have laying around.

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