SparkFun Forums

[dsegel]

What exactly does the fault pad on the sunny Buddy represent? My Sunny Buddy seems to be intermittently failing, and I'm registering a 3+V voltage between the fault pad and ground. I don't actually have an LED installed, but if I did I think it would be lit up. Is there any troubleshooting I could do, or should I just replace it?

[jacquelbot]

If the charging chip is seeing a problem, it'll pull the fault line LOW. If you're seeing a positive voltage on that pad, the LT3652 (U1) thinks everything is a-ok. Here's the relevant snippet from the datasheet: "FAULT (Pin 5): Open-Collector Charger Status Output;
typically pulled up through a resistor to a reference voltage.
This status pin can be pulled up to voltages as high
as VIN when disabled, and can sink currents up to 10mA
when enabled. This pin indicates fault conditions during a
battery charging cycle. A temperature fault causes this pin
to be pulled low. If the internal timer is used for termination,
a bad battery fault also causes this pin to be pulled
low. If no fault conditions exist, the FAULT pin remains
high-impedance"

[Valen]

The datasheet of the LT3652 chip explains what it means. Basically if a fault occurs during battery charging, like overheating (NTC resistor) or charging takes too long, that pin goes high. But it is to be read in combination with the notCHRG pin.

Why don't you connect leds to it? Better to be sure than make assumptions.

You'll have to describe "intermittently failing" a bit better. In what way does it not work? What do you have connected to it? What panel? What battery? What other load? Under what conditions does it fail?

[jacquelbot]

The datasheet of the LT3652 chip explains what it means. Basically if a fault occurs during battery charging, like overheating (NTC resistor) or charging takes too long, that pin goes high. But it is to be read in combination with the notCHRG pin.

Why don't you connect leds to it? Better to be sure than make assumptions.

You'll have to describe "intermittently failing" a bit better. In what way does it not work? What do you have connected to it? What panel? What battery? What other load? Under what conditions does it fail?

All good advice except for the highlighted word. According to the datasheet, the fault line is pulled low when there's a fault. You should be able to guess that too from the schematic - the line drawn over the word "FAULT" on the chip means that the line is "active low" - i.e. if the name is true (in this case "there is a fault"), the line will be pulled low. Without the line, you'd expect the line to go high when a fault occured.

[dsegel]

The Sunny Buddy is connected to a Large Solar Cell (PRT-07840) and a 6Ah LiPo battery (PRT-08484) and is powering an Arduino Uno with an Electric Imp shield and a few light (UV and IR) sensors. It worked fine for a week or so, then the battery went dead (despite plenty of sun) and when I pulled it inside to check it out there was no voltage present on the Load or charge pads of the Sunny Buddy even when connected to a bench power supply. I left it for a few days and when I came back it seemed to be working again. It's possible there's a temperature dependent failure going on - it was close to freezing when it failed outside, and is obviously warmer inside. I did verify that the solar cell is working as expected.

I'm going to test it for several days on my bench and then stick it outside again and see what happens.

[UhClem]

The Sunny Buddy is connected to a Large Solar Cell (PRT-07840) and a 6Ah LiPo battery (PRT-08484)

What is the open circuit voltage of the PRT-07840?
What is the voltage of the PRT-08484?

[Valen]

All good advice except for the highlighted word. ...

Thanks for the correction. I'm aware of how that distinction works but somehow I got the high and low mixed up in my mind.