Northern Tier 2010

June 22, 2010

Final Overnight Tune-up Ride

Filed under: Gear, Preparation Rides — Tags: , — Henry Scott @ 10:15 pm

I joined my friends Matt and Bruce for another overnight ride to Potato Creek State Park last Sunday. The bike is very nicely dialed in, but I still need to get smarter about how I pack, and definitely more efficient at pitching my tent! But, overall, I feel ready. If I just set aside an evening to tweak my packing I should be all set. My legs feel great, and I think that is the most important thing.

Two brief gear updates: I tried using the E-Werk to directly charge the iPad during this trip, and I was very disappointed to see that very little charging occurred. I’m not sure why that is the case. That said, I’ve also learned that charging a “hot” iPad is very bad for it’s battery, which has me thinking that perhaps I’d be better off using the APC battery to store energy and charge the iPad overnight.

In other news, although my iPad Camera Connection Kit still hasn’t arrived, my friend Matt’s did, and he’s letting me test it — he’ll even let me take it on the trip if mine doesn’t arrive in time. So, this post, including the photo of Matt and Bruce at Potato Creek, is being done entirely from the iPad — pretty cool!

Advertisements

4 Comments »

  1. I am loving the blog, but you probably shouldn’t have announced to the world that you stole your iPad.

    Comment by Erika — July 6, 2010 @ 11:32 am

    • It took me a while to get your comment, but afterrereading the post I do! 🙂

      Comment by Henry Scott — July 6, 2010 @ 12:57 pm

  2. hello. I am planning a tour and want to order the ewerk to charge the iphone and ipad. I wonder if you could clarify for me if the ipad can be charged via the cache battery used by the ewerk or exactly you are charging it.

    I’d really appreciate your help.

    Seth

    Comment by Seth Dominguez — September 23, 2010 @ 5:47 am

    • Hi Seth,

      I haven’t used the E-Werk cache battery, just the battery made by APC that I mentioned in the following post:

      https://hpscott.wordpress.com/2010/06/10/ewerk/

      I believe the key things to find out are the capacity of the E-Werk battery and the current it can deliver. The iPad’s battery is 25 Wh, so hopefully the E-Werk battery is a significant fraction of that. The APC battery is 10 Wh, and that was enough energy for my daily usage and about the most I could store from riding each day anyway. So, I’d say it was about the perfect capacity.

      For the fastest charging of the iPad, you’d want to battery to be able to put out 2 amps — that’s what the charger that comes with the iPad delivers. The APC battery could do 1.7 A, and that was enough that it could deliver its charge to the iPad within a few hours. By specification, all USB-powered devices, such as the iPad, operate at 5 V.

      Note: a Watt is the product of current and voltage, i.e., Watts = Volts x Amps, and you can estimate the amount of time to charge the battery by multiplying both sides by hours (h): Wh = V x Ah, and then solving for the hours on the right side to use the quantities relevant here: Wh / (V x A) = h.

      If the APC battery is able to deliver the entire 10 Wh to the iPad, a rough estimate for charge time would be 10 Wh / (5 V x 1.7 A) = 1.18 hours (about 1 hour and 12 minutes). In reality I imagine the current it can deliver drops off considerably as the energy stored within it drops, so the real charging time is longer.

      Some batteries, however, are limited to lower currents, perhaps only 0.5 A (500 mA), so the same capacity would take several times longer:
      10 Wh / (5 V x 0.5 A) = 4 hours. Again, the real charging time would likely be even longer because I think the current will drop off as it discharges, but I bet it would be okay if you can leave it charging overnight.

      So, ultimately I’d think the most important piece of information to know would be the capacity of the E-Werk battery, and I’d want it to be at least 10 Wh, but I haven’t seen the specification.

      Comment by Henry Scott — September 23, 2010 @ 9:56 am


RSS feed for comments on this post.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Blog at WordPress.com.

%d bloggers like this: