Thread: hotswap of battery possible!
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joerg_rw is offline joerg_rw
2010-07-22 , 20:43
Posts: 2,222 | Thanked: 12,651 times | Joined on Mar 2010 @ SOL 3
#15
Originally Posted by joerg_rw View Post
In The Field Hotswapping:

You need a dongle *) that has two slots for contacting 2 BL-5J batteries, a 2way switch, and a 1000uF 6.3V capacitor. And a USB-A-receptacle with D+/- short plus CA-101, or a charger-cable stub.
[edit] Depending on component variance this might not work with voltage of empty battery, so some sort of booster might be needed to step up voltage of even an empty battery to a reliable V-IN(min) level of >4.0V for BQ24150
According to my tests the CA-146C charge adapter dongle that comes (or came?) with N900, serves nicely for such boosting purposes. Continues charging N900, when I switch electronically stabilized power supply plugged in to it, to 3V. So should be OK with even comlpetely nominally discharged cells, which still should have >3V.

So - in theory - replace the USB-receptacle or cable stub in the DIY instructions by a cable plus barrel type plug fitting one of the CA-146C receptacles - minus=outer,+=inner. And you should be done. Alas in real tests it didn't work for me yet, maybe needs tighter control of maximum current taken by device, as it seems the CA-146C can provide only ~150mA on 3V input power, and also has no big capacitor to buffer spikes. So might work, but needs further R&D.

cheers
jOERG

(if some users might bother to click thanks on this post, I might bother to build a prototype and publish a video)
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