Re: Request comments on simple solar charger

On 25 Jul 2005 08:33:36 -0700, larwe@xxxxxxxxx wrote:

>> assuming you are right about your project using 1A only 5 minutes a day.
>
>Ah! Now I understand where you're coming from - but I guess you missed
>the part where I said:
>
>>>During the night, the device runs various lights, and motors and other
>>>actuators, not on a 100% duty cycle by any means. A 5Ah battery, fully
>>>charged, could handle the required tasks - so I speced in 7Ah.
>
>So the device does more than just run that 1A motor and do the comms
>session.
>
>> panels, you'll need 36 * 51 = 12.75 sq feet of panels! Also, you can't
>> even charge your battery at more than 2.1A, so why do you need 6A?
>
>This is part of why I was asking the question in here - the cells are
>speced under ideal solar conditions, so I don't know how far to derate
>them for real life. Considering the cost of the device, adding another
>$300 to $600 in solar cells is money well spent if it significantly
>improves the chance that the device will last for its intended
>lifetime.
>
>Thanks for your comments - I'm back to the drawing board.

If you do go the DC-DC step-up and SLA reg, I highly recommend the UC3906 in the
latter role. If you have trouble locating the Unitrode/TI data *** just post
back here - it is found under some arcane name.
.

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