Dealing with 6V output from LiPo Solar Charger

For other supported Arduino products from Adafruit: Shields, accessories, etc.

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
User avatar
macdonaldtomw
 
Posts: 5
Joined: Thu Aug 28, 2014 12:02 pm

Dealing with 6V output from LiPo Solar Charger

Post by macdonaldtomw »

So, I bought the Adafruit USB/DC/Solar Lipo Charger and integrated it into my project, which is running off of a 2000mAh 3.7/4.2 V LiPo battery. I wanted to be able to charge the battery while it is being used.

It fried my microcontroller.

Upon further inspection, I realized that there was a disclaimer about this charger on the 4th page of the tutorial on how to use it. It states:
The smart load sharing means that the LOAD output can be as high as 6VDC if in direct sun because it will draw current directly from the 6V panel instead of from the battery. If using this with an electronic project, make sure it is OK for up to 6VDC input or use a low-dropout-regulator (LDO) to regulate the voltage down.
Okay, so at least i know why I fried my controller (because it was seeing 6 V from the load-sharing system, and it is only rated up to 5.5V). When it's night-time, the microcontroller will be 'asleep', consuming about 10mA at whatever voltage the battery is at (I'm assuming a max depth of discharge down to 3.5V). I want to have at least 3.3V to my project at all times, and will be powering a GSM modem which spikes during transmission, up to 2A, and which automatically shuts off if the voltage dips down below 3.2 V.

Okay, so that means I need an LDO with max dropout voltage of 0.2V, input range of min: 3.5V to max: 6V, and can handle up to 2A of current.

I can't find one!

What LDO would Adafruit technicians suggest to use with this charger???

So, plan B is to simply connect my entire V+ project bus to the battery directly. The tutorial for this charger states:
To do this, you might connect the project directly to the battery output. This means, however, that the charger is both charging a battery and driving your project at the same time. The charger is working extra hard and the battery is being charged and discharged constantly.
Does this sound like a good idea, or a bad idea?

EDIT:

I've decided to just go with a 5V 0.25 Watt solar panel, so that the solar panel's output won't fry my microcontroller

EDIT:

Just saw this on the solar charger site:
We've tried 5V panels and they don't work. 5.5V panels sometimes work, 6V is really the best!
Looks my 5V solar panel idea isn't going to work? How can it charge off a 5V USB if it can't charge off a 5V solar panel?

User avatar
adafruit_support_mike
 
Posts: 67446
Joined: Thu Feb 11, 2010 2:51 pm

Re: Dealing with 6V output from LiPo Solar Charger

Post by adafruit_support_mike »

Here's a list of 5v fixed LDO through-hole regulators that accept 6v or more as input:

http://www.mouser.com/Semiconductors/In ... ricing%7c0

The next parameter to constrain will be the output current, so compare what you need to what the items on the list can do, then read the datasheets for the ones that catch your interest.

We use a lot of LP2985 and LT1117 LDOs, but those usually come in SMT packages.

Locked
Please be positive and constructive with your questions and comments.

Return to “Other Arduino products from Adafruit”