[gta02-core] Backup battery underdimensioned

Rask Ingemann Lambertsen ccc94453 at vip.cybercity.dk
Sat Aug 1 15:43:50 CEST 2009

   I looked at the specifications for the backup battery[1]. The charge
current is specified as 25 uA in the charge/discharge graph, but the
pcf50633 can only be configured for 50, 100, 200 or 300 uA (with 200 uA
being used in the GTA02). Similarly, the discharge current of 5 uA is much
lower than the maximum 50 uA consumption specified for the pcf50633 in SAVE
state. Even if this abuse doesn't damage the battery, with a nominal
capacity of about 300 uAh, it will only last for about 6 hours. At 100%
depth of discharge, battery life is only 100 cycles.

[1] http://speed.sii.co.jp/pub/compo/battery/productSpecBatEN.jsp?recordID=77

Rask Ingemann Lambertsen
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