krobinson103

For a while I've been running Endomondo to monitor my rides. The problem has been that it takes so much energy to keep the screen, gps, and audio running the battery lasts 3 hours at best. Then I was looking through my junk box and found 2 850mah LiPo batteries I used on r/c helis when I had them, a small car usb adapter, and a data/charging cable. Took the adapter and soldered a deans plug to the lighter connector, wrapped that in tape and then took the charging cable and wrapped that around the whole assembly for neatness. More tape to secure it. Took the batteries and soldered them in parellel to give me 1700mah at 12.4v (full charge). Attached the opposite deans to the batteries. Took the whole assembly and put in the pocket of my small top bag with the smart phone installed on the top under the window.

Tested it all out.. and I get a constant charge going to the phone with the storage batteries dropping by 500ma or so in 1 1/2 hours. This means that even applying the 80% rule on Lipo I still get an extra 3-4 hours of mp3/gps/full screen on the phone and have the original battery (1500mah 4.1v) totally charged - which is worth another 2-3 hours run time on its own. If I were to change out the storage batteries to 2 2100mah batteries - there should be room I can see an all day run time as no problem. I also get to use the phone as .. a phone if I need to.

Disposable

That's a pretty cool trick, to filter the voltage thru the car adaptor. I've been wondering how to use some extra cells that way. Thanks for the tip.

krobinson103

No problems. I think though if you want really good run time you will need 4-5000mah at 12v. These batteries got used because I had them and they were small, but a r/c heli 2100mah battery or two aren't that large or heavy and would last a long time.

bud16415

Sounds good do you have any pictures? I did something similar a few years back.

Here was my original set up I built. Worked quite well on the iPhone 3 using the car adapter and a DIY 12v pack. It didn’t work as well when going to the iPhone 4. Most of the car chargers are designed around input voltage around 15 to 25V my plan was to build a higher voltage cell that I could use rechargeable batteries in as well as throw away batteries as I do some touring and wanted the easy access to the AA cells if need be.

Using the car adapter is a great idea though as it has the built in regulation needed.

I now have a mophie battery case on my phone that more than doubles the battery life and works for all my daily around town needs. I also found after a few years the novelty of having the phone bar mounted wore off and it became a bit of a distraction. I do run the apps still but do so in my bar bag with the screen off stretching battery life a lot and pulling over when I need to access the phone.

For longer range back up I use the Tekkeon charger as it uses only 4 AA’s and will take both rechargeable or single use batteries and also when not being used as a charger it becomes a recharger with pass thru to the phone so I can top both off batteries and phone and the USB port also powers a handy little LED lamp.






https://www.tekkeon.com/productcart/p...&idproduct=194 .

krobinson103

Still a work in progress. I'll snap some pictures on tomorrows run when the sun comes up. I still have some heat issues to resolve. The batteries are rated at 30c so I have a 60c capacity with them set up as they are - they can discharge in a few minutes and not get hot. But, the cheap little adapter gets warm - especially with wire and tape around it. Not enough to cause any concern, but more than makes me comfortable with two lipo packs right next to it. I may just run the wire loose and corral it with zip ties or something similar to see if that helps with heat retention.

I found the most awesome little top case that has the smart phone "window" with a pocket under it I can mount within easy reach on the top bar and plug a hands free headset into a small hole I burned into the case. It will let a little water in, but the size is within a few mm of the wire going into it so it should be minimal. I can then get the pace info "x km in x minutes", answer the phone, and if I want to listen to music out on the empty 4am roads (one earbud - lots of debate but it works for me). I tried a blue tooth headset but it just eats more power and its a pain to use. The wired version is better for this application.

I think having the screen off on long rides is better anyway. I have the computer up front giving me speed/distance. The map display and pace etc are great, but I like being able to actually change things on the phone without having to stop a great advantage over pulling it out of the pocket, changing, then putting it back and riding. I also like having it mounted under the bar so that if something bad were to happen its less likely to be damaged being in the dead center of the bike. That and my bars are full with lights etc anyway.

bud16415

I have found the same true with Bluetooth and also find one ear bud not a problem.

When I had my first iPhone bar mounted it was as shown when I went to the iPhone 4 I had a otterbox case on it and the belt clip attached to just a little bracket (tab) thing I made. I also set it a little lower and less likely to get wacked. One concern I had was the phone being out in the sun for long periods of time and of course rain even in a semi protected case. With how my bar bag (re purposed camera bag) is mounted on the inside of my bars it’s really easy to flip open the top and there is the phone, the top also shades the screen some for viewing. I like your idea of a clear window in the top of my bag that might be an idea worth thinking about.

For phone calls I mostly put it on speaker.

krobinson103

The first shot showing the battery and adapter snug in its pocket. It doesn't get hot now that the cable is separate. It also acts as a barrier between the batteries and the adapter. The second shot showing where the phone sits - sadly the phone is the camera so it just has to have a 'virtual' presence. The third is just a gratitous shot of my baby all muddy after this mornings ride. Charger shows 400ma drain for 1 1/2 hours of run time. That was with the phone battery at full charge. Puts the run time on external batteries with a large safety margin at about 5 hours with the phones battery in reserve. I call that successful.

krobinson103

500ma for 4 hours run time on a fully charged phone. That means running screen off, music and gps active its good for 12 hours.

hopperja

I have a small solar charger (Goal Zero) that fits nicely either on my front rack (Nashbar) or on the outside of my saddlebag (Carradice Nelson Longflap). I've never tested it, but I'd bet on a reasonably bright day I could run my Android smart phone all day long with any of the GPS/Speed/energy draining apps running.

krobinson103

https://www.goalzero.com/shop/p/11/No...r%20Panel/17:1

The output potential would suggest you are right. If my testing is correct then running the GPS etc with the screen off is pulling less than 0.2amps an hour and if the sun were bright enough you could indeed run it all day. Not sure where I could put such a large device on my mtb though. The commuter sure, but not the mtb.