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Mintyboost & Solar Charger?
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Mintyboost & Solar Charger?

by coding1227 on Fri Nov 08, 2013 3:54 pm

Hi Adafruit team et al.

I have two quick questions related to using the Mintyboost with the new Adafruit solar lipoly charger (http://www.adafruit.com/products/390).

1. Would it be ok if I was to connect the mintyboost + and - terminals (where these would connect to the 2 AA battery holder) to the "load" of the Adafruit Solar Lipoly Charger (which sometimes can output +6v)?

2. Would there be a difference in charge rate if I was to connect my solar panel to the solar charger via the mini-USB port instead of the barrel plug jack?

Thanks!

coding1227
 
Posts: 32
Joined: Tue Apr 30, 2013 5:00 pm

Re: Mintyboost & Solar Charger?

by adafruit_support_bill on Sat Nov 09, 2013 12:23 pm

We haven't heard of any problems with connecting the minty directly to the load outputs. Under load, the solar panel output will tend to drop down to levels that are safe for the Minty.

The USB input does not have diode protection for polarity, so if you connect that way, be sure to get the polarity correct to avoid damage to the charger. Bypassing the diode will avoid the diode voltage drop and give you a slightly higher effective input voltage. The max charge rate however will still be limited by the programming resistor.

Bottom line: You might be able to charge a little further into the twilight hours, but your max charge rate will not change.

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Re: Mintyboost & Solar Charger?

by coding1227 on Sat Nov 09, 2013 2:05 pm

Oh, I see. Thank's for the great explanation.

One last question. So, if I wanted to change the charge rate for the solar charger, would it be ok to add a 2.2k resistor to the solar charger's circuitry to raise the charge rate to 950mA when using EITHER a medium 6v 2W solar panel (http://www.adafruit.com/products/200) OR a large 6v 3.7W panel (http://www.adafruit.com/products/417)?

Thanks so much :)

coding1227
 
Posts: 32
Joined: Tue Apr 30, 2013 5:00 pm

Re: Mintyboost & Solar Charger?

by adafruit_support_bill on Sat Nov 09, 2013 2:27 pm

Charge rate is independent of panel selection. The panel will either supply enough current to reach the max rate or not. The main consideration in setting the max charge rate is to pick a rate that does not exceed the safe charge current for the cells you are charging. Most of the cells we sell should be charged at no more than 1/2C rate.
http://batteryuniversity.com/learn/arti ... the_c_rate

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Re: Mintyboost & Solar Charger?

by coding1227 on Sat Nov 09, 2013 2:44 pm

Awesome! This was super helpful :)

Thanks again!

coding1227
 
Posts: 32
Joined: Tue Apr 30, 2013 5:00 pm

Please be positive and constructive with your questions and comments.