Description: This is the Sunny Buddy, a maximum power point tracking (MPPT) solar charger for single-cell LiPo batteries. This MPPT solar charger provide you with the ability to get the most possible power out of your solar panel or other photovoltaic device and into a rechargable LiPo battery. Set-up is easy as well, just plug your solar panel into one side of the Sunny Buddy and your battery into the other and you are good to start charging!
The output of the Sunny Buddy is intended to charge a single polymer lithium ion cell. The load should be connected in parallel with the battery. By default, the Sunny Buddy comes set to a maximum charge current of 450mA with a maximum recommended input of 20V (minimum 6V). It’s recommended that batteries not be charged at greater than their capacity rating; thus, the smallest battery that should be charged with the Sunny Buddy is 450mAh.
Each Sunny Buddy comes equipped with a LT3652 power tracking 2A battery charging circuit and pre-installed barrel jack and 2-pin JST connectors with unpopulated areas to install your own personal 3.5mm screw terminals for added input/output options. This revision also adds a potentiometer to the input to set the holding voltage for MPPT and we’ve also tweeked the feedback resistors on the output to change the float voltage.
Based on 5 ratings:
9 of 9 found this helpful:
I originally bought this for a project specifically running off solar, but I knew I was going to make multiple ones, so cost is a bigger factor than just a one-off.
I had to read up on various charging methodologies and how they impact charging speed & battery longevity.
On the surface MPPT seemed perfect, but after doing a few sample runs, I settled on a non-mppt solution.
Did this board work? Absolutely.
Did this board work well? Absolutely.
Would you recommend this board? For someone needing MPPT charging, Yes.
The board I bought is in service, and doing it’s job, and doing it well. I wish it had some better monitoring on-board. (ie: battery status). If you’re building one unit and need to pick a charger, this is a great choice, if you’re looking to build a bunch where price can add up; mppt might not be the cure-all. Personally, I like the rocketscream boards for when solar charging is needed.
4 of 4 found this helpful:
I bought this board to use with the Large Solar Panel from this site. It’s been really interesting to experiment with. The flexibility of the footprints on the board is really nice because it allowed me to attach terminal blocks to the inputs so I could connect the panel voltage to one and a current sensor to the other. Great!
One suggestion for this board: consider adding an independent voltage input to the set pin so that the MPPT can be managed by a controller.
1 of 1 found this helpful:
This charger was great for me - one feature not described in many chargers is whether the charger will always output 3 volts even if the solar panel voltage goes above that. I tried a few other chips which all listed passing through the panel voltage as a feature. This is actually big design annoyance for 3v devices. However, the sunny buddy will always output max 4v even without the battery plugged in, even when charging , even when the solar panel voltage goes to 15v. Great!
The big issue for me with this device is the NTC pin for the thermistor is NOT broken out. For weather stations and things which are outside (where you would use this device) you should not charge below 0C. The chip has a pin deticated to reading a 10K thermistor to prevent charging above 50C? and below 0C. Even if this pin went to a small via it would be great, but it is actually just a pad. TL;DR; if you want to connect a thermistor be prepared to solder some small stuff. http://i.imgur.com/9qU4mYC.jpg
While I haven’t used it extensively so far, preliminary testing seems to confirm that it does what it says it does, and quite well.
There are a few minor inconveniences though. The first one being that the jumpers for configuring the amount of panels attached aren’t actual jumpers, but pads that are solder-bridged. While it certainly keeps the cost down this way, it makes it somewhat of a hassle to change the setup quickly (unless you’re the kind of person who always has a hot soldering iron nearby).
The second minor annoyance is that for tuning it right, you have to hold the multimeter probes onto the SET and GND pads, but the pads are so small it’s easy to slip off with the probes in one hand while trying to tweak the little knob with the other. Though this could also be the fault of my probes, or my hands.
While a bit bare on the side of soldered-on components, it definitely does what you want it to do.
In the education, how the use solar energy in consumer applications it a very compact device with excellent instructions