What do I need for a portable 12v deep cycle battery

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Old 08-15-18, 05:42 PM
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What do I need for a portable 12v deep cycle battery

I'm going to buy a 75 Ah 12V deep cycle battery soon, and I'll need to use it as a portable 12V power supply. The build should be quite simple, but I'd like to ask a few questions to make sure I'm doing everything the best and safest way I can.

So I'm planning on getting some sort of battery box, so it will be easy to carry and have all the cables sorted inside of it, I thought of having the following cables: I'd have 2 cigarette sockets, 1 for the main 12V output I'd need, and one more extra in case I'll need it in the future, 2 USB outputs, and a voltmeter so I'll know where I stand.

I'll also want to connect an on/off switch, for more safety etc. The last thing I'd maybe want to have, and I don't know if it's even possible, but some sort of charging port. I have a battery charger, but it has those crocodile clips, which means I'll need to open the box and connect it directly. That's not really hard or even messy, but I think that if I'll manage to make some sort of charging port, it will be easier, safer, and better overall.

Now I can sort of see in my head how I want to connect everything, doesn't seem too complex to me, but what I want to know is if there's something else I need, maybe a fuse? Or just anything else that you can think of that I might need for that, some general tips it's important to know, and just everything else that pops to you mind. Thanks!
 

Last edited by pardovot; 08-15-18 at 06:51 PM.
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Old 08-15-18, 09:47 PM
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what I want to know is if there's something else I need, maybe a fuse?
YES. That is must. Install a fuse for each cigarette lighter sockets of whatever your socket is designed to handle. It will be no more than 20A. Use 12AWG stranded wires. 14 probably will do, but 12 would be better.
Also, add a fuse for 5V chargers.

You can use in-line fuse holders, but probably better to use a fuse block.

Adding a current meter might be a worthwhile to see your current draw.

There are battery chargers with ring terminals that you can nut down to the battery terminals. Look for one of those or just cut alligator clips off your current charger and put ring terminals.
You might want to just install some short of quick disconnect terminal outside of your battery box so that you don't have to carry charger with the box all the time.
 
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Old 08-16-18, 06:16 AM
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I would forget cigarette lighter outlets. They are large, bulky and outdated. I would get another socket and put corresponding plugs on your equipment. There are many to choose from that will take up a lot less space and be able to handle the current load. You can also install a socket for plugging in your charger though you can just use one of your power out sockets. Just remove the alligator clips from your charger and install a new connector.

Installing a fuse is a judgement call. Generally they are used to protect the wiring from overload and they are not a bad idea but a fuse won't protect any of your connected equipment. A fuse could will protect your battery and the wiring inside your battery box.
 
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Old 08-16-18, 07:01 AM
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Originally Posted by Pilot Dane View Post
I would forget cigarette lighter outlets. They are large, bulky and outdated. I would get another socket and put corresponding plugs on your equipment. There are many to choose from that will take up a lot less space and be able to handle the current load. You can also install a socket for plugging in your charger though you can just use one of your power out sockets. Just remove the alligator clips from your charger and install a new connector.

Installing a fuse is a judgement call. Generally they are used to protect the wiring from overload and they are not a bad idea but a fuse won't protect any of your connected equipment. A fuse could will protect your battery and the wiring inside your battery box.
The battery is quite big as it is, so I'll probably need quite a large box, so I think space is not really going to be my problem, and from what it seems, there are so many uses for a cigarrete socket such as usb, 12v cables, voltmeter and many many more things you can connect it to, which is more common than other connectors, but which socket you'd use? And can you explain about the charging port? Lets say I have a cigarette socket, and I remove the alligator clips, what socket/cable do I connect instead to plug it in?
Regarding the fuse, I think I'll get a fuse, I don't think it can do worse and it can only protect my battery and wires, so it seems like a good idea to me.
 
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Old 08-16-18, 08:11 AM
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Most of your punchlist is found on booster packs. Could you make do with something pre-made?

 
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Old 08-16-18, 08:29 AM
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Originally Posted by guy48065 View Post
Most of your punchlist is found on booster packs. Could you make do with something pre-made?

Well yes I can, but I'll never be able to buy something that will be as strong as a 75 AH deep cycle battery for the same price Im buying the 75 AH battery, so its totally not worth it, buying a box and all the cables/sockets etc is really something cheap, and making it myself doesn't really seem too hard as well, so I guess it will be better, I made a sketch here:
https://imgur.com/a/DdV03Bl
Im not an expert so its very possible I have mistakes there.
 
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Old 08-16-18, 12:29 PM
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you could install a cigar lighter to your charger cord and just charge from one of those ports, probably would not install a master switch myself as your looking at a possibly very heavy duty switch to handle the current, would also just install the switch to the positive side only if your do decide to put a switch on it.
 
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Old 08-16-18, 01:03 PM
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Originally Posted by alan73 View Post
you could install a cigar lighter to your charger cord and just charge from one of those ports, probably would not install a master switch myself as your looking at a possibly very heavy duty switch to handle the current, would also just install the switch to the positive side only if your do decide to put a switch on it.
If I correctly understood what you meant, so instead of the alligator clips, I connect something like this:

And then just connect it to the female cigarette socket and it will charge?
And can you explain more about the master switch? What do you mean by heavy duty? I ordered this switch: https://www.aliexpress.com/item/Free...56704c4dPPOZN7
That should be good enough I'd think, and can you wire only the positive to the switch? It has 3 connections and as far as I know its 1 for the positive, 1 for the negative and 1 for the load. Correct me if Im wrong please :]
 
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Old 08-16-18, 01:54 PM
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that switch is probably not going to hold up as a master would probably work fine for the usb ports though you never really said what your going to be using this for but just having fuse protection should be plenty safe the ground is hooked up to the switch only because the switch has a led light built in.
it has a 16 amp rating and your have 2 cigar lighters plus the usb ports you could easily exceed that amperage and if your was even running even close to the rated amperage it probably would not last that long.
 
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Old 08-16-18, 03:53 PM
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I don't think we're dealing with heavy amperage. I think pardovot is powering a telescope and some accessories all night long so it will be lower amperage but for a long period of time.

How much current will you be drawing? I guess the scope's drive will take less than an amp. A dew heater will probably be less than 2 amps. A CCD/camera will be less than an amp. A computer might draw a amp or two.
 
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Old 08-16-18, 05:01 PM
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Originally Posted by alan73 View Post
that switch is probably not going to hold up as a master would probably work fine for the usb ports though you never really said what your going to be using this for but just having fuse protection should be plenty safe the ground is hooked up to the switch only because the switch has a led light built in.
it has a 16 amp rating and your have 2 cigar lighters plus the usb ports you could easily exceed that amperage and if your was even running even close to the rated amperage it probably would not last that long.
Well, I don't think I'll actually reach 16 amps, so I should probably be safe..

Originally Posted by Pilot Dane View Post
I don't think we're dealing with heavy amperage. I think pardovot is powering a telescope and some accessories all night long so it will be lower amperage but for a long period of time.

How much current will you be drawing? I guess the scope's drive will take less than an amp. A dew heater will probably be less than 2 amps. A CCD/camera will be less than an amp. A computer might draw a amp or
two.
Correct, and even your estimations are way off, it is to power a telescope mount, and thats it for now really, the mount might take up to around 2A, but the average would probably be 0.5-1A, Im not planning on connecting any computer/camera/anything else for the time being, so thats really should be more than enough, I just rather be safe in case I'll need anything in the future, so I got 2 cigarette sockets and 2 usb sockets, which maybe in the future I might use, but still, I don't think it will be that much, and even if it will, I can just change the switch, or maybe put 2 switches and divide the current between them? (I really don't know if its even possible ^_^)
 
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Old 08-16-18, 06:03 PM
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Yes, you can divide the circuit and use two separate switches.

What scope do you have? My old wedgepod Celestar 8 can go for many nights on it's internal 9v battery. I have a permanent mount so all I have to do is carry the scope and base out and it slips right onto the mount and very little aligning is required. Unfortunately light pollution has gotten much worse so the viewing from my yard is nowhere near as good as it was 20 years ago.
 
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Old 08-16-18, 07:03 PM
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Originally Posted by Pilot Dane View Post
Yes, you can divide the circuit and use two separate switches.

What scope do you have? My old wedgepod Celestar 8 can go for many nights on it's internal 9v battery. I have a permanent mount so all I have to do is carry the scope and base out and it slips right onto the mount and very little aligning is required. Unfortunately light pollution has gotten much worse so the viewing from my yard is nowhere near as good as it was 20 years ago.
Can you tell me how I wire up the 2 switches together? And I just recently bought a SkyWatcher 200p with EQ5 goto mount, I don't think I can use it with batteries, only 12v so I don't think I have much choice here, and yeah, light pollution is getting bad, I can see some objects from my back yard, but I can't wait for my first trip to a really dark place, I only bought my scope about 2 weeks ago, so its still all new to me etc.
 
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Old 08-17-18, 06:08 AM
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So I got a fuse block and fuses, any other recommendations?
 
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Old 08-17-18, 07:09 AM
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I would wire the switches in parallel. For example if you want two switches I would run two red + wires from the positive terminal of the battery to one side of the switch. If you wish you can install an inline fuse. Inline fuses and switches are commonly available at auto parts stores. Then from the other side of the switch I would run red + wires to your cigarette lighter socket. Then from the negative terminal of the batter run two black - wires with one going to each cigarette socket. Using red and black wires isn't required but it helps keep the wiring easily identified as to what is + and -. You could install a third switch, wired like the others, and use it to control your USB outlets.

---
A couple years ago I sailed to Anegada Island with is a sparsely populated island to the north of the British Virgin Islands. I timed it with the new moon and it was a very dark place at night. The stars were incredible. I borrowed a friend's telescope with a computer controlled mount so I could even track the International Space Station when it flew over. It was very cool to be able to see it and all the solar panels with my own eyes. Sort of odd though trying to look through the eyepiece with the telescope slewing so quickly.
 
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Old 08-17-18, 07:31 AM
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Light pollution

With the popularity and low cost of LED bulbs many of my neighbors now feel it's acceptable to run 100W lights all over the outside of their house, all night.
 
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Old 08-17-18, 07:47 AM
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Originally Posted by Pilot Dane View Post
I would wire the switches in parallel. For example if you want two switches I would run two red + wires from the positive terminal of the battery to one side of the switch. If you wish you can install an inline fuse. Inline fuses and switches are commonly available at auto parts stores. Then from the other side of the switch I would run red + wires to your cigarette lighter socket. Then from the negative terminal of the batter run two black - wires with one going to each cigarette socket. Using red and black wires isn't required but it helps keep the wiring easily identified as to what is + and -. You could install a third switch, wired like the others, and use it to control your USB outlets.

---
A couple years ago I sailed to Anegada Island with is a sparsely populated island to the north of the British Virgin Islands. I timed it with the new moon and it was a very dark place at night. The stars were incredible. I borrowed a friend's telescope with a computer controlled mount so I could even track the International Space Station when it flew over. It was very cool to be able to see it and all the solar panels with my own eyes. Sort of odd though trying to look through the eyepiece with the telescope slewing so quickly.
Im actually thinking about going to a different direction with this, Im going to build something similar to this:
https://www.youtube.com/watch?v=torSEtjPZ2I (its super long, sorry, but the build of this box seems really good to me, so I think I'll go with it.
And that sounds really cool, I don't think I'll be able to see ISS any time soon ^_^ but hopefully I'll learn enough to control everything as soon as possible, and after I'll get my battery etc, Im planning on going to the desert for a nice observation :]

Originally Posted by guy48065 View Post
Light pollution

With the popularity and low cost of LED bulbs many of my neighbors now feel it's acceptable to run 100W lights all over the outside of their house, all night.
LOL, can't you just ask them to turn it off?
 
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