Hi all,
I am developing a wireless sensor system to be embedded in yacht sails. I now just have to solve the powering issue. Each sensor array draws 100mA at 5V on average, (300mA peak). I would like to power it via a 3.2V 600mAh LiFePO4 battery. This would be charged via a parallel network of solar cells delivering at least 3.5V 200mA (max Voc = 5V).
Much of the time the system will be in low lighting (when the sail is dropped, possibly in a translucent bag) and I would like to harvest as much energy as possible during this time. I am therefore looking for ideally a single chip that will:
- provide maximum power point tracking
- efficiently charge the battery
within the parameters above.
I can find energy harvesters and battery chargers but not a combined one at this stage:
BQ25505 / BQ25570 / BQ25504 - energy harvesters, all limited to peak input power < 0.5W compared to my >0.7mW
bq25071 - LiFePO4 battery charger with Vin min 3.75V
This application is weight critical, so I don't really want to go for a heavier battery. It needs to be as safe as possible as the unit will get heavy handling, so no LiPo batteries. If the battery is depleted, it needs to start up within a few minutes of getting decent lighting, so needs a decent solar input (space is no problem on the sail).
Can anybody suggest either a single IC or combination of 2 that will do the job? The solar panels could potentially be paralleled and fed to multiple energy harvesters, so that the input stays below the power threshold. The drawback of this is that a larger solar panel is more space-efficient and needs fewer hookup wires that are susceptible to damage.
Many thanks,
David
