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eBike Charger

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Time for an upgrade

2014-03-20 21:20:20

My eBike needs some serious batteries to keep climbing steeper and steeper hills. As always I went and found the highest power charger out there and settled on an iCharger 208B 350W 8s. I can charge my 6x 6cell 5AH 25C batteries in parallel at up to 15amps! This gives them a full charge in about 1hr! My current setup has it all stuffed inside a large Tupperware container, now that I have my new laser I think it's time for an upgrade!

After an hour or so In Google Sketchup I came up with the following design, leaving room for another 350w psu and Icharger for future use. They can be charged at 2C each, 5Ax2 = 10A x 6 batteries = 60A max possible charging rate! So room for improvement later.

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First pieces cut

2014-03-20 21:59:12

To remind me why I'm redoing this, I tapped 2 plugs together while connecting the charger and fried a gold bullet connector and some high gauge wire.

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This is why it happened, In my rush to get something happening I really didn't think it through or understand how much these can output in a pulse. Some math 4.2v per cell x 6 cells per battery = 25.2v * 3 batteries in series = 75.6V. Peak discharge 35C = 35 x 5A = 175Amps per battery x 2 packs of 3 in parallel = 350amps!!! 350Amps x 75.6V = 26,460Watts of peak output!!

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Anyhow the pieces I created yesterday were easily exported from Sketchup into Laserworks.
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Time to start cutting!

Woops....

2014-03-20 22:22:40

Still having issues cooling the laser, the due point today is 23C..... almost at the max I should be running the laser at! It just meant I had to cut this 6mm acrylic at 4mm/sec 90% power. After cutting out the first 2 pieces I discovered I clicked the wrong reference point at the bottom while placing the PSU vent slots which are off by 6mm...

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The last few pieces(which all fit, yay!!)

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2014-03-20 23:08:43

All cut out! The best part about laser is the high accuracy and low cut width of < 1mm.
Everything fits so snug! Here I added a few switches to check for size. The 4 switches are for the 1+possible extra Icharger PSU's, the third is for the two bananna plug's to output 24v from the PSU if I ever need it with the last switching the mains to the psu.

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The old Icharger case had the screen flush with the surface, to make that work with 6mm think cover I'm going to have to mill out space for the screen and higher components. Acrylic is very nice to worth with under a mill luckily and took no time at all. The hardest part is trying to clamp it without cracking! With a bit of effort everything fits perfect!

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Finished!

2014-03-20 23:21:55

Completed and fully functioning!!

The top and two longer sides are fixed to the Icharger, the PSU holes the bottom to the side. The end pieces I've left loose to add the second Ichager/PSU at a later date.

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I Connected the larger 12v fan to the 24v PSU via a voltage regulator, It's stuck to the metal casing of the PSU to keep cool.

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Next project... Made a plug to replace all these loose wires!!!