Project: BattBox – A DIY Powertank

A quick scour of Amazon reveals that your average Celestron Powertank, a portable battery box for astronomers, varies in price from around £50 for a 7ah model, through to £130 for a 17ah model, to £150 for a Lithium Ferrite beasty.

Blimey, astro manufacturers know how to hit astronomers right in the bank balance! SCREW THAT. I’ll do it DirtyAstro style!

Total cost for this version: £120

Build time: an hour

Tools: Drill, hack saw / oscillating multitool / dremel

Weight:  Down to choice of battery. For this one, lots!

Shopping List

 

Strap it all together, wire it all up and you have what should last an entire weekend from a full charge of 12v goodness, fully switched and fused.

See attached pics!

Wiring is effectively thus: red on battery [+] to FUSE to POWER pole of switch. ACC pole of switch to + terminal on cigarette socket / USB socket accessory we want to switch. Black from battery [-] to GROUND pole of switch. Black from battery [-] to – terminal on cigarette socket accessory.

Repeat for remaining switch & socket.

For the final pushbutton and voltmeter, red [+] on battery to FUSE to + pole on pushbutton. – pole of push button to + pole of voltmeter. – pole of voltmeter to black [-] on battery.

Just follow the wiring in the Rat’s Nest pix below and the above should make sense.

Doneskis.

Rat’s nest…

IMG_0848.JPGBottom left, momentary switch for centre voltmeter. Top left, on/off switch for left hand cigarette socket. Top right, on/off switch for righthand USB sockets.

 

Other end of rat’s nest… (the two black wires disappearing off down beside the battery are the quick connector for my maintenance charger)

IMG_0847.JPG

Voltmeter… on a 2A fuse

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Momentary switch on rear for voltmeter… hold for a reading.

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Left hand switch is power on/off for left hand locking cigarette socket, on a 10A fuse.

IMG_0843.JPG

And Right hand switch is power on / off for right hand pair of USB sockets, on a 5A fuse

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