Originally Posted by
colleen c
I suggest first taking a look at the internal battery of your Android phone. See what the battery size of the OEM batteries than go from that. Also see if there is any rating listed on the OEM charger. If you can get these spec then you might be able to get an estimate runtime from the 4000mah battery. Do keep in mind that your display will most like be set on the highest brightness level for outdoor use in the sun so that will also use some extra juice. The display is the biggest user of power on a phone and having it to be set on high brightness just makes it that much worst. Even at that, there are times when I wished that my display was even more brighter when I have the sun reflecting on my screen.
These external batteries can be overated just like the bike batteries. I never took on apart (yet) but I suspect these external batteries are parrallel wiring configuration and they are being boosted to get the usb spec of 5v. If that is true, then the 4000 mah battery might be less than the claim rating due to the efficiency loss from boost. I will think something more like the 4000 mah rating will be closer to 3000 mah or less. How and when these pack fall out of the USB spec is anyone guess and that pretty much depends on what the load to the battery happens to be and how much juice is left on these external battery. Usually at this point, you may notice a longer charging rate to the phone or even having the phone drop out of charging mode then back into charging mode repeatly. The lower ampacity of the pack along with the higher current draw might be loading down the pack where the output is falling out of USB specs. Turning off the phone and just let it charge for a while helps. That's why I prefer to just use the larger pack if I know I will have a high constant load drawing from the pack.
There is a company named "Star Tech" that sell short version of USB to micro and mini USB. They have 6 and 1ft length cable. The cable itself are not the thick cable variety which may translate to being more of the fragile species but it also nice in the fact that they don't wiggle around the micro usb connector right at the phone unlike the heavier duty cable that wants to fall out of the connector especially when using micro USB. Star Tech also makes some 90 degree connector. That makes a nice cleaner connection right at the phone connector. The price is around $6 to $8 from Amazon.
Thanks Colleen. Nice to know I've asked the right person. You've given me some things to think about and the "Star tech" stuff is just what I was looking for. Now all I have to do is to try out the upgraded "Cue Sheet" app to see if it's worth me buying the extra phone accessories.
You're right about the screen using the most power. Knowing that I can always power down the screen until needed. As long as you have an audible prompt on the approaching turn it should be no problem. The thing I like about using the phone as a GPS tool is that the screen is nicer to look at ( vs. the Garmin ) and it effectively eliminates carrying a second device ( since I always take the phone on every ride regardless ). It also helps taking up less space in my bag since I can now mount the phone on the stem ( if everything goes as planned ).