Unstable Solar Charger at renovation

It’s shocking that we found Solar Charger might have +/-1V ripple while supplying 5V DC from Li-Po battery.The ripple varies according to the load, most project might run OK, but having high potentiality that ADC applications might have unstable read or other unexpected errors.

Possible Reason

External Charging Circuit for sp6641 does not meet requirement and caused huge ripple. Changed to AIC1896 and ripple is within 200mV

Solution: Please notify us (depot(at)seeedstudio.com) with Your order and address, and let us know if you like to A) ship you free fixed replacement  or B) sell you the next generation charger with half price. (please help choose only one option if you bought multiple)

We are so sorry for such irresponsible Engineering! The next revision is planning. We would also revise it with better functionality.


It would be charging from AC(?-?, screw terminal) and DC (4.5-6.5V, JST 2 pin connector) supply.

It would be able to charge normal 3.7v Li-Po with up to 500mA

It would be output 5VDC to USB host

Please let us know if you have any suggestions too, we will send out the prototypes as usual. Thanks!

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11 thoughts on “Unstable Solar Charger at renovation

  1. I would like to see this board get a nocturnal option. I would switch so that it charges during the day and runs the arduino at night. This might already be an option I have yet to purchase (out of stock) but if not this would make a great addition.

  2. In my opinion in ANY good solar charger there should be at least a “working” green LED indicating by its intensity the quantity of charge it is getting. Next to the green LED there could be, you guess, a red LED for the “charge complete” message…
    I agree on the feature of charging info readability from microcontroller too, anyway.

    I also hope you will put some more info on the kind of Solar Cells to be used best, together with the infos on rechargeable batteries; also, i don’t think AC input to be truly necessary

    really waiting for it… i’m sure i’ll buy many!

  3. If you are going to add an AC input then I’d recommend a max. input of 14V (AC and DC) as 110/230VAC –> 12VAC transformers are used in many applications and the charger could be used in cars as well (13-14VDC).

  4. the DC-DC converter(SP6641B) is fixed output 5V, Maybe the unreasonable components placement and layout cause the 1V Ripple.

  5. Hi, according to your comment I imagine myself than this charging system of battery, which works with a system of commutation this governed for a converter DC-DC, the reason for this charger generate a RIPPLE of more a 1 volt can be because the frequency of operation of the converter DC-DC isn’t the adequate according to the load, maybe exist a problem in feedback (Detection of level of current consumed in the load ) what it makes the frequency of the converter DC-DC not be the correct, therefore a big RIPPLE is generated.

    Best Regards.

    Sergio Quiroga.

  6. When can we expect the new revision? I would really like to have on for my standalone ‘Survive for 90 days autonomously’ Robot!

    1. The plans is 3-4 weeks. The latest stock has the problem fixed, you could use it for now. The next version might not be Arduino form factor but a standalone power add-on, smaller, convenient, and also for other boards.

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July 2010