VRTC Battery Recommendation

Hardware UNO R4 UNO R4 WiFi
1

Hello!

I understand that the VRTC pin will work with voltage in the range 1.6 - 3.6 V DC. While there are many, many batteries to choose from, does someone have a recommendation for one (or two) that can be easily attached? Apologies for this lame sounding question. Thanks.

Regards.

2

That voltage range sounds perfect for a LiPo.

3

Thanks for the quick reply. Wouldn't LiPo be overkill for RTC use? A very small coin battery with an appropriate holder that I could attach to the bottom is my search path.

I cannot locate a holder even for the common 2032 let alone the smaller ones.

Regards.

4

Yup. You can get LiPo in a coin cell can't you

1 Like
5

I was looking for a holder similar to that on the DS3231 board. I'm uncomfortable with the RPi 5 solution (which I want to avoid, and hence my initial request for guidance).

Regards.

6

Have a look through the listings here:

https://www.digikey.com/en/products/filter/battery-holders-clips-contacts/86?s=N4IgjCBcoMwGxVAYygMwIYBsDOBTANCAPZQDaIMAnHHAKwgC6hADgC5QgDKrATgJYA7AOYgAvoTAAWSfWggUkDDgLEyFGACYADJUohCMTWC1b96jcY1m4lGAHY7epiDYdu-YWImUAHHrkKSniEJJDkpgyi4iCyoMxQYCzxkBq0UUA

Even if you aren't going to buy it through DigiKey, if you see something you like there you can surely find the same part from other sources once you know the model number to search for.

1 Like
7

I use these CR2032 holders. If there's any difference between them and the ones on the DS3231 RTC modules, you'd be hard pressed to see it. Google CH224-2032LF.

8

Thanks! Appreciate it.

Regards.

9

Agreed. My problem is solved thanks to the replies here.

Regards.

10

So how long will a battery last before it dies? How many amps does the VRTC pin consume?

11

From the datasheet:

Vbatt Current
Vbatt Current1988Ɨ1220 257 KB

Guglielmo

2 Likes
12

Thanks, @gpb01!

This table is helpful. The numbers are aligned with my expectations for RTC batteries.

I refer to https://docs.arduino.cc/resources/datasheets/ABX00087-datasheet.pdf but obviously you have a different datasheet that I should have looked at.

Regards.

13

I'd start posting links but I might miss something. Just hit this thread. The link to the Users Manual for the R4AM1 is on the first post. I'm pretty sure that table is in there.

1 Like
14

OK, thanks! I missed that one previously.

Regards.

15

I looked up some of the 3v coin batteries. They look like they are rated for ~35maH to ~100+... so at 1 or 2 uA it looks like we get a ~couple years of life out of a battery.

16

I am referring to this: Renesas RA4M1 Group.pdf (1.7 MB) :slight_smile:

Guglielmo