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Using rechargeable lithium ion batteries?

I'm wondering if AudioMoths will accept rechargeable lithium ion batteries and if anyone has tried using them already? I'm curious how long they last compared to NiMH rechargeable or regular lithium ion batteries. Thanks!

18 comments

18 Comments

hinojosalangosto

Nov 24, 2021

I use packs of four 18650 batteries. And work very fine, I can record all the night 1 month without problems. In the test I used a 512 Gb Sd and the audiomoth can record 480 Gb of wav files, and it had remaining energy.

Alex Rogers

Nov 24, 2021

Replying to

Wow, that's definitely the most energy intensive deployment we've seen. What sample rate are you recording at and at what schedule?

hinojosalangosto

Nov 24, 2021

Replying to

@Alex RogersHello Alex, We use some audiomoth because the others devices are to much expensive to our budget. The biggest trouble we had in the beginning was the battery duration, because of thar we put the 4 Sanyo 18650 battery pack (13600 mhA more or less, 3.7v).

I always configure our audiomths at 256Khz rate, or 250 in the lastest App version. I don´t remember the exact number of hour per night, but at least was eight hours per night without sleep- record cicle.

The audiomoth worked 27 days.

cbatist

Oct 14, 2021

No I'm talking about rechargeable lithium-ion, not the NiMH. I've used NiMH before, a couple different brands. But I wanted to try rechargeable lithium-ion because they should in theory last longer.

cbatist

Oct 14, 2021

Great, thanks! Just wanted to make sure they were at least compatible before I tried them. I'm going to have them run continuously at a high sample rate just to see how long they end up lasting.

Wim van Dam

Oct 14, 2021

Replying to

Yes I have been using standard AA NiMH batteries fore my AudioMoth and they worked out fine. You probably want to take care that you pick a proper brand with reliable performance. I have been using the ones from Eneloop/Panasonic.

Alex Rogers

Oct 14, 2021

Ah, I’d forgotten these existed. We’ve never tried them but they should work fine. I can’t find a decent discharge curve plot for them but they claim to maintain close to 1.5V over their capacity. They have some additional voltage regulation inside them which might create some additional noise but worth trying.

cbatist

Oct 14, 2021

Hi Alex, Thanks for the reply! I'm just using 'regular' Audiomoths, and meant rechargeable lithium-ion AA batteries, like putting 3 in to the battery pack (I'm not electronically knowledgeable to figure out attaching external batteries or messing with the board).

Something like these - https://smile.amazon.com/EBL-Battery-Batteries-Capacity-Rechargeable/dp/B08RZ5NDMM/ref=sr_1_6?dchild=1&keywords=rechargeable+lithium+ion+aa+batteries&qid=1634215073&sr=8-6.

chris

Mar 05, 2023

Replying to

Hi cbatist,

I just ran a test with the EBL rechargeable AA lithium batteries you mentioned. The config specs were:

- 64 GB SanDisk Extreme

- 24 hour recording schedule

- 55 sec recording with 5 second sleep

- 48 kHz sampling rate

With this I was able to get 118 hours (4.9 days) of consecutive recordings every minute, and it continued on for another day with increasing gaps (up to several hours) between consecutive recordings. For comparison, when using EBL NiMH 2800 mAh AA rechargeables I would typically get under a day before it completely stopped recording.

Alex Rogers

Oct 14, 2021

Yes, small rechargeable Li-Ion batteries (commonly now LiPo batteries) work really well with AudioMoth. They spend most of their life at a voltage between 4.2 and 3.7V which matches well with AudioMoth’s requirements so you get the full capacity from them. Both the AudioMoth Dev and uMoth boards have JST-PH connectors so you can typically buy a LiPo battery with the correct connector and plug in straight into these boards. There is no standard on the polarity of the connectors and the development board and radio controlled car communities typically use opposite polarities. It’s easy to swap the wires over on the connector though with a small screwdriver to lift up the plastic tab that holds the crimped wire in place. We use these batteries with AudioMoth Dev for short deployments.

https://www.adafruit.com/product/258

Alex Rogers

Sep 21

Replying to

In the spec it says 250mA output so maybe even slower.

We use Adafruit chargers which have the correct polarity for AudioMoth batteries. You can adjust their output up to 1A.

https://www.adafruit.com/category/575

Mike Bennett

Sep 22

Replying to

What would be the lowest voltage that would trigger some kind of error or problem writing to the SD card? Minimum listed in the datasheet for AMDev is 3.3V. Does the device run better with voltages above 4, but less than 5?

Alex Rogers

Sep 22

Replying to

The supply voltage to the microcontroller and SD card is regulated to 3V. However, SD card write currents can peak at 100mA and you then normally see a drop in the battery voltage due to their internal resistance. When the batteries are depleted, the internal resistance is higher and the supply voltage will drop below 3.0V. We stop recordings when it goes below 2.8V.

The regulator is effectively just a voltage controlled resistor so excess voltage is turned into heat. If the supply voltage is too high it gets too hot. Any input voltage from 3.3V to 6.0V works okay. The upper voltage is limited by the temperature of the regulator, and lower voltage by the minimum 0.3V voltage drop across the regulator.

A single Li-Ion and three series NiMH batteries spend most of their time around 3.7V and work well. As do three series alkaline batteries which start at a higher voltage but show a more continuous voltage drop over their lifetime.

Edited