Battery Design

[Anweniel]

After thinking about making my own more robust powertank and having a look at a few good DIY projects on SGL, I have put together my own very basic design.

I wish to run my mount and laptop from it but keep the system pretty simplistic. I first toyed with the notion of adding resistance to drop the current before the adding fuses but I think I was complicating matters and possibly adding a (very much undesired) potential heat source in the circuit. Am I right in thinking that adding an appropriately rated fuse is sufficient?

Here is my circuit and with the exception of maybe adding a voltmeter should be the complete article, should this be practical or am I missing something fundamental to the design?

Any ideas most welcome

[cowasaki]

You have a master switch which is good.

Yes the design of the outlets is correct. I would use waterproof sockets for each one.

[Anweniel]

Thanks, yes all the components I have are waterproof and from motorcycle spares and will sit in a waterproof casing. Cheers for the confirm its been a while since I had to do any electronics design so wanted it as basic as I could

[woodbob123]

As a final precaution add a fuse next to battery terminal quite a high rating say 20 Amp just in case cable is damaged will avoid a short circuit. I have soldered a car type fuse directly to terminal in the past. If battery is inside box, fuse may not be required but I always like a final fail safe batterys can supply a high currant.

[Anweniel]

Funnily enough I had that thought this afternoon, maybe a 20A in-line fuse in case something goes badly wrong! Thanks for the heads up woodbob123

I ordered a 4 way fuse box for the terminals to sort of future proof it as well so I can have two extra connectors without much extra hassle if I find I need them later.

[woodbob123]

Use a box larger than you need and put in spare sockets or at least the holes as you are sure to need them either for equipment or dew heaters, Led indicators across the socket are also usefull if something does not work you can see if fuse has blown not so easy in the dark with cold hands. Increase the series resistance to give just a dull glow rather than a shining light beacon. If you are not sure pm me and i can sort you out some suitable one's ( have around a thousand various ones here used to sell them and kept what was left) Bob

[Anweniel]

Very kind offer, thankyou. The in-line fuse has an indicator but the fuse box I bought doesn't have LED's. Was the cheaper option although I see the use. The fuses will be kept inside the unit and the handy thing about the switches I bought is that they are the rocker type with a very small LED on them so that should be a good indicator if something is up or has gone puff on that line So essentially doing the same thing.

I have the 7Ah skywatcher powertank as a backup which is great for running the mount and it runs the mount beautifully for long periods of time. This DIY project really came about when I realised that the powertank is inadequate for the laptop (which gets run from mains at home)

I don't intend to install any more sockets as yet - well for the foreseeable future anyway as I have other priorities (such as a much needed flattener!) adding the holes without installing sockets would be detrimental to the waterproofing. You are right though and I have considered a potential for dew straps, cameras etc and hence the 4 way fuse box for a 2 socket system.

The advice is sound so thanks for that and I'll update this thread as I progress, most of the parts should be here by the weekend

[Anweniel]

Made some progress today, inspired by JimS' project http://stargazerslou...re-battery-box/ using the Wickes Toolbox.

Socket and switches have been drilled out and the fuse box affixed. Wiring crimped and soldered (belt and braces I know but I like to be careful) and all fixed together and tidied up with some electrical tape. Tried to keep things neat and simple now I am just waiting to fetch a new 100ah battery so I can build a reinforcing wooden support to keep the battery from moving and to save reliance on the the strength of the plastic walls.

The switches are LED lit so should be good indicators of any localised problems. A voltmeter and inline 20A fuse to be added at a later date if it all works out at this stage.

[stuartjones]

Great build i am planning on trying to build one of these it seems like such a good idea,