Recommend a long-lasting battery

Hardware
41

@syrinxtech Woww. 2 years!! This is surprising!

Now, let’s do some calculations. One Energizer battery is rated 1.5V nominal voltage and 3500 mAh. When fully charged, it gives around 1.7V. Hence, 4 batteries in series should give 6.8V when fully charged. Here is the discharge curve from the official document:

image

Now, you are saying that it has never come down below 6.6V, it means that (as per the curve) it has only consumed about 2000 mAh of its total capacity of 3500 mAh.

Now, this is only possible if both these 2 conditions are satisfied:

  1. Sleep State current consumption at VIN is NOT 2.4 mA and 130 uA. Does it mean that the consumption on the thread Electron Deep Sleep current when powering from VIN without LiPo is wrong?
  2. You are transmitting data VERY infrequently (say, once a week).

Let me know @syrinxtech. I am actually thrilled about this. If (1) is true, then you must have special settings in your firmware/code which actually brought down the current. And let me know about (2).

42

The JST-PH2 connector has a similar Deep Sleep current (130uA) as well, doesn’t it? You could always do what I did, and attach wires with this connector type to a battery holder.

43

@Vitesze Yes. It has 130 uA deep sleep current. This is also mentioned in the documentation. And there is no need to use JST-PH2 connector at all. You can directly connect the battery holder to the Li+ pin, which is shorted to the JST connector.

However, which batteries are you using then? The Li+ (or JST-PH2) has voltage limitation from 3.6V to 4.4V. See documentation: https://docs.particle.io/datasheets/electron-(cellular)/electron-datasheet/

Surely, 3/4 Energizer in series lie beyond this range.

44

I use a 3.6V battery, so no 4 x AA setup. If you use a voltage regulator you can make it work, but it’s probably more complicated than simply connecting it to VIN…

45

If you want to solar charge, the Energizer Lithium & LiSOCl2 non-rechargable batteries are not an option for you.

46

@shivams, wow, you did a lot of work. Actually, the MCU is not a Photon but a Moteino which has a built-in 915MHz radio. The radio and MCU both sleep until they are wakened by the interrupt from opening the mailbox door.

47

@syrinxtech Okay. Then the calculations clearly break down :grin: I am not aware about Moteino, though. Will look it up.

@RWB We are not talking about using solar panel here (in this thread). Surely, non-rechargeable batteries wouldn’t make in that case.

@Vitesze Could you tell me which brand and model of the 3.6V battery you’re using.

48

@shivams I use a single LiSOCl2 D-cell (ER 34615M), produced by GEBC. Voltage fluctuates between 3.2 to 3.6V (depending on current draw), so I use a regulator to get a fixed 3.6V output from it.

49

@Vitesze Thank you.

However, a regulator usually adds its own quiescent current. Could you tell which regulator you’re using?

50

Here it is

1 Like
51

@shivams, regarding transmission frequency. Since there is only a transmission when the mailbox is opened, on average there are 3 times a day, Monday - Saturday. Usually no transmissions on Sunday.

52

@syrinxtech Yeah I got that. My calculations were based on Particle Electron, which has higher current consumption during sleep as well as transmission, as compared to Moteino.

53

That boost regulator I found for Vitesze has a super low quiescent current of 1uA which is perfect for these long-term applications.

54

Based on some super quick/terrible maths, it looks like you’d need roughly 26Ah a year, so at least 80Ah to last the full 3. As I think others have said, regular lithium-ion cells definitely won’t like -25C, and though NiMHs, some of the newer lithiumy chemistries, and lead acid batteries can handle lower ones, most seem to only be rated to -20. On the other hand, if you need to lower the voltage I’m a big fan of Pololu’s voltage regulators.

55

For the record, we were testing the Moteino with the TPL5110. We were able to get a sleep (radio and MCU) current draw of 6-8 uA.

I have seen reports on the Moteino forum of getting down into the nA range with special settings and careful coding.