What is the maximum current draw of a ESP32 development board? (e.g., Lolin D32)

Hardware
1

I plan to have 2 sets of ESPHome devices on a ESP32 placed close by:

  • The first ESP32 controls an 8 channel relay board (5VDC coil)
  • The second ESP32 controls a 4 channel relay board (also 5VDC coil)

I plan to power the boards using the 24V battery array I use for my solar panels and connect it to a buck converter board like the XL4015 to step it down to 5V to power the 2 ESP32s and 12 relays. The question is, how much current could an ESP32 possibly draw at maximum?

I tried googling this and couldn’t find a straight answer. I just want to make sure that the 5A stated maximum current output of the XL4015 is enough to power 2 ESP32s and 12 relays reliably and in a stable manner. If it turns out that a 5A buck converter isn’t enough, I might have to use a 10A buck converter. Or maybe 5A is too much? Maybe I could just use a 3A buck converter?

Thanks in advance for the replies, folks. I appreciate it!

2

This is pretty comprehensive:

You can design on 160~260mA when active. The higher current peaks are short (wifi Tx) and can be averaged out by a capacitor.

3

The ESP will likely consume less than the 12 relays.
Not actually sure how much a relay consumes. Google tells me around 100mA @ 5V, but I actually have no clue.

4

It depends on the relay. There’s no standard coil power, could be anything from 50 to 500mW.

1 Like
5

Thanks for the replies! I read the link @tom_l sent which is certainly a great resource, but to be safe I ended up using 3 XL4015 boards since I have some spare XL4015 boards lying around anyway. So that’s 2 XL4015 boards for each of the 2 ESP32 boards, and another XL4015 just for the 12 relays.

Relays turn out to draw a lot of current since in my experience, using one XL4015 to power an ESP32 + 8 relays would cause some of the relays to fail to switch on when trying to turn on all 8 relays because there isn’t enough current to actuate all the coils.

6

I think switching all 12 relays at once should be some kind of rare event, and then going for 5A may be overkill, I would just go 3A or even less and add some big capacitors for each relay, so that the current draw is mainly taken care of by the capacitors when switching the relays

7

I don’t think a capacitor would do anything. When the coil turns on, the capacitor has no charge… charging it as the coil turns on would cause a bigger spike, not smooth it out. A capacitor on the always-on power rail would help, but the 5V supply likely has one already. I guess a cap on the fuse might be what you need?