Hi, What is the maximum operating temperature of Wipy3.0 and Expansion Board3.0?

[melbinmanuel]

Hi, I am planning to use WiPy3.0 + Expansion board3.0
I will be connecting both USB and battery as a backup to the module. Will the battery able to provide a continuous power to board in the time of power loss from USB?

[robert-hh]

@melbinmanuel That's the intention of the design. But are you really interested in the operating temperature, as the title tell?
According to the data sheet the range is -40°C to +85°C.That is the range the components of the board as specified at. But the actual temperature of the chips depend on the use case. I would consider the ESP32 and the regulator as the components subject to create some internal heat. The ESP32 itself is good for up to 125'C. That give some margin. The LM3281 is specified at +150°C max. That sounds a lot, but the chip can easily get to that, if the current draw at the 3.3v output is too high. The WiPy itself should not cause a chip temperature of 25°C beyond the environment, assuming a 100mA average current. Given that, +85°C sounds reasonable.

[melbinmanuel]

@robert-hh Will the temperature be a problem for the battery also?
Can you please suggest me a battery to use here in the temperature up to 60-degree Celcius

[robert-hh]

@melbinmanuel I have no knowledge about that besides a general one. A quick search in internet and a scan in battery vendor data sheets did not reveal a lot besides what can be expected form the nature of batteries:

• at high temperatures self discharge increases
• the typical max. temperature is between 55°C (alkaline) and 60°C for opeartion and not above 40°C for charging.. LiPo seems critical, since using it increases the internal temperature, and beyond 75°C it gets critical.
• Lithium-Thionyl chloride (Li-SOCl2) Batteries work for up to +150°C, but are horribly expensive and not rechargeable,

So you have to go into the data sheets of the respective vendors. Battery types alone do not tell much. But 60°C should still be fine for Lithium batteries, at least for operation. Charging may also be OK, if the current is low. But that is outside the specs.

[melbinmanuel]

@robert-hh I could understand that for a 500mAh LiPo battery to charge in the temperature up to 60 degrees Celcius, the charge current should be as less as 50mA. Can we change the charge current to 50mA on the expansion board?
For the battery charging IC BQ24040, current can be set by changing Iset resistor value. Can you help me to find the same resistor in the expansion board

[robert-hh]

@melbinmanuel Sorry, I cannot. Pycom does not publish any substantial technical information, and I do not have that board here for analysis.