Thread: [Thread Closed][Pre-Pre-Pre Announce]Black Aluminium replacement body & backcover for N900
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guylhem is offline guylhem
2012-05-01 , 17:47
Posts: 40 | Thanked: 25 times | Joined on Sep 2011
#77
Originally Posted by Estel View Post
Generally it's good idea. dr_frost_dk's charging port connected to battery isn't bad thing, yet, it have some limitations. First of all, it can be charged only by Li-Ion charger of any kind (not power supply). Second, and more important thing, that it should *never* be left charging to 100% during device runtime - power used by device fools Li-Ion charger, which keeps charging battery more than needed = unhealthy for battery life.
A LiIon charger circuit from 5v/1a (USB) to 4.2v costs around $4, delivered : http://cgi.ebay.com/universal-1A-lit...item35ba49263b

If you go the direct battery route, it is cheap enough and small enough that it might be included in the replacement cover to use direct USB power from a desktop computer to charge the battery by the jack bypass.

Regarding leakage causing overcharge and SoC confusion, these are real problems. A good solution would probably require a circuit sitting between the battery and the n900, to be able to take that leakage into account.

I'm not good in electronics- I don't even know how it could be done. Maybe someone with a good knowledge of charging circuits could help.

Originally Posted by Estel View Post
Considering this, I'm more and more tempted to create some crazy solution for full body replacement, that would mean having external charging port connected to testpads. This way, we would have best of both worlds - charging by any 5V power source, without touching USB port, yet still processed by N900 charging circuit.
Right on. No need for external circuits.

Regarding the USB test pads having all ESD protection (etc.) but missing coils, according to http://electronics.stackexchange.com...-needed-on-usb such coils are only needed for EMI, so yes they should not really be needed - or they could be easily added by modders who would absolutely require them for FCC compliance :-)
 

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