Electric bike talk 2

This post is for all the nerds out there who keep sending me emails with technical questions. Consider it an update to my update.

I designed a new battery holder out of PVC sheet to replace the wooden box used on my first prototype. I also replaced a fried switch with one that has a higher current rating and designed a new wiring harness with quick disconnects. My lead-acid battery pack is already starting to take less charge and I have now relegated it to back-up status.

The parallels between an electric bike and a plug-in hybrid car are very close. These new batteries have taken the bike to a whole new level. The lead-acid batteries do not have the range I need to get to the far corners of Seattle (and back). They also take too long to charge (up to six hours). If I wring them out on a long ride I am done riding for the rest of the day. They also weigh too much. I once dropped the pack on my finger, which emphasized just how frickin' heavy they are. Like a lot of electric car enthusiasts, I was frustrated for want of a decent battery. It took a lot of time and effort to incorporate these nano-phosphates, but it has been well worth it.

They also have an unbelievably flat voltage discharge curve. As a lead-acid battery discharges, its voltage drops. Your bike gets slower and slower. With these nano-phosphates, the voltage curve remains almost flat until the battery is done. The bike does not get slower and slower. It just craps out all of a sudden when the battery is out of energy. They can also put out the power. According to A123 Systems, they are good for 30C continuous and over 50C in ten-second bursts. Add to this the fact that they do not blow up or catch fire and we are finally on to something here.

I took a few minutes to build a website with pictures of the improvements. You can print them out and pin them on your bedroom walls.

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