Solar charger help

[paul gb]

Hi there,
I'm not sure I should have started a new thread here as it's similar to the " constant 5v regulator " but I did not wish to confuse things.
I too am new to the Forum and electronics so hi and sorry for any silly questions.
Here's my problem -

I have rigged up a solar phone charging setup for a forthcoming backpacking trip. I am carrying all my food and equipment for 18 days, therefore weight is a premium.
I need a reliable power source as I will be navigating using digital mapping.
So far it consists of a 12v 6.5w flexible solar panel charging a MiLi power crystal 2000mAh Lithium-Polymer Battery (5v 1A max in/out), through a 12v - 5v phone charger.
My phone stays connected to the battery so is constantly charged, with the battery there for backup.
I reallise there is power wastage here but my thinking was a large panel would provide more juice in low light.
As this system stands, it works well in good conditions but in low light the voltage drops to between 6-10v and as the charger needs 12v, no power is available.
My question is how can I utilise this low light power, I was thinking maybe just using a 6v diode but this is probable way too simplistic.
I would appreciate any help available.
Thanks in advance,
Paul

 

[ben7]

Charger input voltage rating?

You can use a DC to DC voltage converter-which might take 6v to 13v input and provide a stable 12v output, or more solar cells in series IF the 12v to 5v phone charger can take the extra voltage. Is the phone battery charger from a car? And what do you mean by a 6v diode, are you thinking of a zener diode? In low light, a 20v solar panel could put out 12v, but in bright light it would put out around 20v. Also, be careful with the batteries beacause if you charge them incorrectly (without a voltage or current limiter, such as a charging controller chip) they can blow up. Don't be overwhelmed if this seems complex, or too hard !!!

 

[colin55]

Have you proven that the 12v to 5v charger does not deliver any energy when the input drops below 12v?
Many car chargers are buck converters and can work down to 6v. I have seen these in the $2.00 shops for $3.00 - $5.00