Solar LiPo charging

[Exogenous]

The entry on the solar mintyboost mentions reducing the LiPo charging current if the smaller solar panel is used in order to "keep the lipoly charger from trying to draw too much current from the panel." I assume this is to avoid a voltage drop from the solar panel.

It would be pretty neat to adapt the charging circuit to automatically regulate the output current on the basis of the input voltage to get maximum charging ability, and also to allow a fast charge when connected to USB power.

Then again, perhaps this isn't needed - I ought to measure the voltage produced under different load and solar conditions. I don't know how quickly performance would deteriorate under load, but the bigger panel is nominally 6V at 330 mA so it seems it ought to be able to muster 3.75V (minimum required for the charge controller) at a somewhat higher load under reasonable lighting conditions.

Or maybe a potentiometer for R4 will suffice...

[adafruit]

you mean like this?
http://ladyada.net/make/solarlogger/

[Oby One]

Hi,

I bought the USB LiIon/LiPoly charger - v1.1 http://www.adafruit.com/index.php?main_ ... cts_id=259
Before I install it to my mintyboost .. I have read something about LiPo charghing on wiki: http://en.wikipedia.org/wiki/Lithium_io ... er_battery
During discharge on load, the load has to be removed as soon as the voltage drops below approximately 3.0 V per cell (used in a series combination), or else the battery will subsequently no longer accept a full charge and may experience problems holding voltage under load.

From the tests that I have done so far with my mintyboost... I noticed that it will not stop discharging the battery ....so I am now asking how can I prevent the damage to my lipo battery ... by preventing a discharge bellow 3.0 V ?

[adafruit]

all the lipos we sell have a protection circuit, they will not allow it to be discharged past 3v for safety

[Oby One]

Yes.. but you said that there is a physical connection between the battery in and battery out ports.... so there is NOTHING preventing the mintyboost to get all the juice from the battery.

[adafruit_support_bill]

Unless, as Adfruit said, the LiPo has a protection circuit in it. From the product page: http://www.adafruit.com/index.php?main_page=product_info&cPath=44&products_id=258

The protection circuitry keeps the battery voltage from going to high (over-charging) or low (over-use)

[Oby One]

Code: Select all

The protection circuitry keeps the battery voltage from going to high (over-charging) or low (over-use) which means that the battery will cut-out when completely dead.

Aaaa I got it now.. the battery itself has the protection circuit.
Much more clear now.... thanks

However, even with this protection it is very important that you only use a LiIon/LiPoly constant-voltage/constant-current charger to recharge them and at a rate of 500mA or less

Hmm.. another question
Can I use a li-ion battery with my lipo charger?
They have similar voltage characteristics and I don't see a reason why it shouldn't work.

[adafruit_support_bill]

The Adafruit charger is rated for both LiIon and LiPo. But not all cells are created equal. Make sure you find one with the built in protection circuit.

[Oby One]

I have another question for this USB LiIon/LiPoly charger - v1.1 http://www.adafruit.com/index.php?main_ ... cts_id=259
I want to put a 1000k rezistor so I can boost charging to 1Amp.

Do I have to remove the existing R4 rezistor.... when I install the new one?

[Oby One]

Well ?

[adafruit_support_bill]

You can remove it, or install another one in parallel to create the equivalent resistance.

[wdmarto]

I made solar(small)/lipo/minty exactly like you said and it works!
But, my solar do not charge my battery (medium 1300mAh), even after a full sunny day.
When I charge it with my computer, all is fine and the led Done is on. Immediately after that, I plug my solar panel in, the led Done becomes off and it charge again.
What can I do to solve that?

[adafruit_support_bill]

Can you post a photo showing all of your connections?

[wdmarto]

Here they are

[adafruit_support_bill]

What voltage do you measure from the solar panel when connected as shown?
What voltage do you measure when it is not connected to the charger?

Is your solar panel outside in full sun? Windows (especially modern "Hi-E" windows) reduce the available solar energy by quite a bit.