[Lenny400] Replacement batteries

Daniel Glöckner daniel-gl at gmx.net
Mon Apr 6 16:18:50 CEST 2015


On Mon, Apr 06, 2015 at 02:23:28PM +0200, David Boddie wrote:
> What constraints on the battery, other than 7.4V, the size and maybe also
> the capacity do I need to be aware of? I'm mostly thinking about issues
> related to the recharging circuit in the minibook itself.

The capacity is not a constraint.

The Letux 400 uses a TI BQ2057W for charging. It will stop charging
when the battery reaches 8.4 V:
http://www.ti.com/product/bq2057w/description

The sense resistor is 0.2 Ohm and it uses high side sensing, so the
battery must sustain being charged with 0.7 A.

Both R_T1 and R_T2 (see BQ2057 datasheet) are 1.5 kOhm resistors,
if you want to add a thermal protection circuit to the battery.

Best regards,

  Daniel


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