My battery system only cost USD 35!

[babamamagogodede]

http://www.talkaboutsleep.biz/cpap-acce ... y-pack.htm
The cost was 324.6USD
----------------------so expensive!
Background:
It is a good option to use DC power on your CPAP but not use UPS system
( It converts 12V lead battery to 110V) and the internal converter in your CPAP converts 110V to 12V--> It wastes more than 80% energy!
The battery was 14.4AH 12V
However , how expensive the system
---------------------------------
I bought a deep-cycle 12V 12AH lead battery and it cost only 400NTD(12USD)
A adjustable charger: 750NTD(23USD)
A DC connecter ( connects lead battery and CPAP) DIY: free

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It runs OK~