discussion / Camera Traps  / 2 February 2024

Li-ion rechargeable batteries suddenly drain

I am currently testing a camera trap with rechargeable Li-ion batteries and untill a week ago they were doing much better than the NiMH rechargeable batteries that I used before. The camera has been working for about 5 months, taking on average at least 2 images and 2 20-second videos during daytime ( in fact taking many more, including night time images and videos but I don't have any averages readily available in my head ) and a week ago it still reported three bars out of three on the battery indicator.

Today, I checked the camera trap and the batteries were completely drained. 6 out of 8 were completely drained, down to about 0,015V, and 2 still had a charge of 1 V.

What puzzles me is that it happened in the time of a week. Some hypothesis:

  • It is how this type of batteries behave?
  • The camera trap's indicator is faulty. Could be but it is a new one, so I don't think so ( Coolife H881 old model without any wireless capability, no wifi, no bluetooth, no mobile. ) 
  • This is only the first cycle of the batteries which were bought in July ( Security Zone A2U-22 23000mAh / 3400mWh ). I don't even know if these batteries need to go through a couple of charges before they reach their optimum.
  • The weather ... it has been raining steadily for a couple of weeks. Almost daily, between 3 to 5 or more hours. For sure it has been far more humid in January than in previous months. However the camera has an IP rating of 67. That does perhaps not say a lot about resistance against air humidity, but it should be good for something - or should it not?

 

I would appreciate any and all feedback. 

 




Hi Frank. 

Just wondering but is it possible you got lithium-ion batteries in the AA form factor and voltage? If that's the case, the batteries have an internal switching regulator which will keep the voltage output constant until the batteries no longer have enough charge to meet the minimum operating requirements of the power supply. Then the power supply will shut off. It would look like the voltage drops off a cliff. It sounds like this is what is happening. 

[Updated] Oops, scratch that. I just saw the part number and they are indeed lithium-ion batteries in the AA form factor and outputting the AA alkaline voltage. Hence there is a power supply on them. 

Akiba 

 

Hi Frank, 

Your question has already been answered, but I thought it would be useful to add this plot to the comment section. It shows the expected voltage vs capacity for that battery model.

voltage vs capacity


This is consistent with what you observed and also shows you that battery charge indicators don't even work that well for NiMH batteries. 

I pulled it from this website: https://www.bol.com/nl/nl/p/4-stuks-oplaadbare-aa-li-ion-batterijen-a2u-22-aa-1-5v-usb-oplaadbare-lithium-ion-batterijen-3400-mwh-security-zone/9300000112911034/

So without any further modifications your battery indicator just isn't useful for the Lithium batteries. But now you know how long they will last with that configuration. Expect that the batteries will get worse with age, though. 

If you are using this camera trap model a lot and would really benefit from roughly knowing how long they would last with some arbitrary configuration, it is possible to estimate that. You would need to use a power analyser to measure the idle current as well as energy consumption for each image and video. 

Hope this helps you or others stumbling across this thread. 

Amanda