> pondering away on my latest project here which is a
> remote GSM based telemetry device. Got my current consumption
> under control with an average of about 5ma.
>
> So, now to how to power the thing and keep it self sufficient.
>
> My idea at this stage is 600mAh NiMh 3.6V battery pack (as
> the circuit runs at 2.7-4v) and charge this via a 6V solar
> cell. (about 3-4days with no sun I hope..)
>
> I intend to use 2 fixed resistors as a trickle / fast charge
> cct, with the fast charge one switched in when battery falls
> below 3v, and switch to trickle when fully charged. (fast charge
> at about 60ma) also given that max charge will only be when
> the solar cell gets the good sunshine (plenty of that in Aus at
> the moment..)

NiMH batteries don't like long term trickle charging.  You also want to
discharge them almost fully before recharging them.  I think a lead-acid
battery is more approriate here.  Look into "sealed lead acid" or SLA
batteries.


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