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Getting a bar/stem mount for my iPhone 6 and would like to use it's GPS capabilities on all day rides. One of the disadvantages of having it running for long periods as a GPS receiver is impact on battery life. I do however have an MTB batteries Lumenator on the bike with its chunky high capacity battery pack not being used during the day.
Is there a way of charging the phone using the battery pack? Thinking of a cable with suitable connectors at both ends and some sort of inbuilt circuitry thing to regulate - is this sort thing available? Seems like a neat solution if possible.
I've no knowledge of electronics so complicated homebrew solutions will be of no use.
The other thing to consider, which has an impact on battery life, is the phone signal itself. Turning on airplane mode will disable this, and makes a big difference.
You can turn it off again, if you need to make a call, so it's no great hardship.
If you have the maps downloaded onto your phone, you don't need data/WiFi either, so that's more battery consumption eliminated.
Probably good to utilise something like a battery bank, or hub dynamo, though, if you're doing a multi-day trip.
Can't help with the electrics sorry. I can also suggest using on airplane mode and a circular halo charger (taped onto underside of bars) which has got me through a nine hour event.
I can help with electronics. What voltage is the battery.
It'll only probably cost you a fiver too.
Thanks piesoup - it would be great if you could. According to the MTB Batteries website the battery spec for the Lumenator is '7.5V 6.6Ah Li-Ion'.
A fiver sounds good too.
Ok great. You can do it yourself if you can get a plug and lead for the battery. Then get one of [url= http://www.aliexpress.com/item/DC-4-5-40V-To-5V-2A-USB-Charger-DC-DC-Step-down-Buck-Converter-Voltmeter/32375059597.html ]these[/url] and connect the battery to the input (blue terminals). Simply plug any usb cable into the other end. The display gives you the voltage of the battery which is handy as the battery may not have undervoltage protection built in.
I've never heard of a 7.5v li ion battery though. Usually in multiples of 3.7v. So presuming yours is a 2S (7.4v) I wouldn't let your battery go below 6v. It's dangerous to let a li ion battery discharge too low.
You could then wrap tape around it or stick it in a little box to keep it safe. I have used one for ages and it's great. Any dramas my email is in my profile.
Have fun!!
Thanks piesoup that's really helpful. The specs for the battery I got from this page where it gives details of the replacement battery for the Lumenator light: http://www.mtbbatteries.co.uk/mountain-bike-lights/spares-accesories/ . The description next to the picture of the Lumenator battery says 7.5v, but zooming into the picture of the battery it looks like it says 7.4v on the neoprene cover, which tallies with what you're saying. I recall reading elsewhere that it's a 6 cell battery pack. I am away at the moment so don't have the bike nearby to check in person.
When you say 'I wouldn't let your battery go below 6v. It's dangerous to let a li ion battery discharge too low' - how likely is this and how do I mitigate against this happening?
[url= http://www.ebay.co.uk/ulk/itm/301827442675 ]Beaten to it (but even cheaper from th'bay)[/url] as above; don't let your voltage go below 3.2v per cell. You won't pull it back if it goes below.
That's a good option too. The one I listed will work up to 40v, so can connect to a car battery if you're really stuck!
You can get 2S lo ion protection circuits that you connect to the battery. Only a few quid at most too. They'll save you from worrying about your battery. I'd connect them in parallel to your new usb charger, so when you unplug the charger and use the battery for the light, it's as intended, with no extra protection circuits potentially interacting with the built in protection in the light and the battery charger.
7.5V is the nominal voltage of the 2S battery. There is no difference between this and a 7.4V. It really depends on how you measure the single cell either 3.7V or 3.75V. The Li-Ion batteries from mtbbatteries contain a protection circuit which will cut the discharge voltage once it reaches its end of discharge limit.
Do not use the Lumenator battery to directly charge you're phone as its a different voltage. You'd be best buying a portable power bank to use. These would be smaller and less bulky to use.
get one of these....
[url= https://www.amazon.co.uk/Veho-VPP-005-EXP-Explorer-Smartphones-portable-y/dp/B00FS6YQWY ]Veho Pebble[/url]
give 3 full charges of my iPhone 6. Great for long days with GPS running on the phone