2014 Crush the Commonwealth

← Back to Forums


stefb
Participant
#

I have a garmin 810. I also have a small charger that allows a USB out so I can take turns charging my phone and my gps with their own respective cords. I put it in my bento box feeder that is behind my stem on top of my top tube and run the cord to the gps


reddan
Keymaster
#

@kristopher: a GPS won’t hurt, but it really isn’t necessary for CtC. The route is marked very well; a basic comp to track miles traveled (average speed is nice too) is really all you need.

That said, for keeping one running, you will probably need an external battery pack or a dynamo hub with a USB power adapter of some kind.

Locally, Jim Logan has used GPS devices on many of his rides…you can contact him via email or the Pittsburgh-Randos mailing list, if you have any questions.

[Edited to add:] Yeesh, Stef. Think we watch this thread too closely?


Kristopher
Member
#

Thanks stefb and reddan!

Question about the power pack ……..power seems to be measured by “mAh”. How much do you recommend? Would 2400 be enough or would I need 4000.

My basic computer is fine and I’ve got plenty of experience with maps, charts, etc (I was a navigator in the Air Force for many years…..even using a sextant when flying over the ocean…man, that dates me a bit) but I’m ready to tool up to the 21st century.

Suggestion……we’re still using the 2014 Crush thread. Not having given it a go yet I don’t think it’s my place to start a 2015 thread….maybe on of you vets could start it?


Mikhail
Member
#

Kristopher, it depends on your equipment.

On one hand, power is P=V*A, on other hand, power is energy (Joel) per second. So total amount of energy battery could supply is Power*Time. Battery is supposed to be stable in term of voltage (there are some changes during discharge time but those are not much from our point of view). So for a given battery V is constant. E=P*T=V*A*T where V=const. So A*T is used to indicate battery capacity.

2400 mA*h means that this battery is capable (roughly) to produce 5 Volts (this is USB stansard), 2.4 Ampere DC current during an hour. Or 5 V, 1.2 Amp during two hours. Or 5 V, 0.12 A during 20 hours.

I have Garmin Edge 500. It typically works around 18 hours non-stop with new battery. I think it has something around 400 mA*h internally — based on the size of the device. So 2400 mA*h would be enough roughly for 18*6=108 hours plus th first charge of Garmin itself. But this device is old with very small and primitive screen.

Garmin Edge 510, 810, 910 have a bigger screen and they can show maps. Those devices are more powerful and 810 is more powerful than 510. This increases energy consumption. They have bigger internal battery. According to 810 manual it has 1100 mAh rechargable, built-in lithium-ion battery. With typical work time 15 hours 2400mA*h pack would provide additional 32 hours so total time would be around 47 hours.

Take into account that very rare 2400 mA*h are real 2400. Most often it would be 2300. And chinese version would about 2000 (if you buy from AliExpress, DX, or even Amazon, Newegg if goodies shipped from mainland China).


reddan
Keymaster
#

@kristopher: good idea, here ya go: http://bikepgh.org/mb/topic/2015-crush-the-commonwealth

(But, next time, feel free not to wait for us codgers and curmudgeons. We’re cranky, reactionary, and set in our ways. If this thread was good enough for 2009, it’s good enough for 2015. Now get off my lawn.)


Kristopher
Member
#

Wow! Thanks Mikhail for the EE lesson. I’ll check out some brands and may just go for the 4000 as I may be using it for the phone too.


Vannevar
Participant
#

yes, thanks Mikhail !

← Back to Forums

You must be logged in to reply to this topic. Click here to login.

Supported by