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Organized Chaos

Roadside Jumpbox Retro-fit
So, early last year I picked up a Stanley 450 Amp Fatmax start box from Sams. Initially my expectations were for some roadside help, though, after looking at the profile of the little box.. it got me thinking - Camping power.

Out of the box it sports a 17 Ahr battery (with a 700 mA charger), Air compressor, Jumper cables, Cigarette lighter, a LED light, and a 500mA USB charger. 


The 500mA USB isn't all what its cracked up to be. Most modern cellphones wont charge very well on that. Even if they do, Its a long time to charge - Its going to be upgraded soon enough. 

The 700mA charger also isnt all that great either. Besides the fact that its an extremely slow charge, Its not a switched charger either. Its just a standard AC adapter tucked in the side. 

The rest, not so horrible. The only real thing I really didnt like is the fact that everything went strait down to the battery individually, and unfused. Yeah.

So, the first thing I ended up doing is installing a power distribution block on both poles and brought them up to inside the main area of the box and put a main 100A fuse on them. I am thinking of installing an actual fuse block with individual fuse links. For now, its good. 

Second thing I did was install a power inverter. Now, I didn't go crazy. I just internally installed a 75w cigarette lighter plug that i dismantled and ran longer wires for. The primary function of it is not to run anything major, mostly lights. I bench tested this thing and, with its current battery, I can get >5 hrs on a 60w equivalent (10w) LED household light. That was just the point where I said "the heck with it" and turned it off. the battery health indication showed ~50% (after it rested for about 20min), so thats about as much as I should get out of the battery - safely. 

Eventually, i plan on installing a solar panel to this box. Nothing too crazy. I've been eyeballing a 50w panel for its size, but wanting to go with a 100w just because of solar effency and power loss at the controller, I wanted to get the most with what I have. That, and if i want to run anything while charging the battery, i could ;-)


Good rule of (Lead-Acid) battery thumb. Never discharge batteries much past 50%. Here's my math:
17Ahr/2 = 8.5Ahr (real). 
10w/12v = 0.8A, so about 8 1/2 hrs on half the battery when drawing about 1A.

Charging rule of thumb. 1w for every 1Ahr.

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.blog.justin.frieze - Roadside Jumpbox Retro-fit