I use several low-end trail cameras for monitoring wildlife. All of them are powered with 4 x 1.5 V AA batteries. Replacing non-rechargeable cells in several trail cameras starts to generate more electro-waste than I like (and it also costs money). All cams have external 6 V DC input, so I am starting to think about options I have in order to get rechargeable source of 6 V. Regarding current, it only takes few mA (maybe les than 1 mA) in stand-by and this usually takes most of the battery life.

As first, I have asked a manufacturer of my recent trail camera (Suntek Mini300) about using 7.4 V (2S li-ion cells) as external power source. As I expected, they do not recommend it, because "the infra LED will not work" (no more details to this statement). So I will probably need source of 6 V. Below, I sum options I came with. There is a need to say, all of them will be really "external" - can not be fitted to 4xAA compartment in trail camera.

  1. 5xAA Ni-MH 1.2 V cells - probably the simplest solution, but re-charging 5 cells is really uncomfortable.
  2. 4xAA Ni-MH 1.2 V cells + step-up converter - I know very little about it, but stepping up 1.2 V might not be very efficient.
  3. Li-ion 3.7 V cell / 2P cells + step-up converter - I have no experience with li-ion cells in outdoor conditions + uncertain efficiency. 1 cell might not have enough capacity, and connecting 2 cells in parallel may be dangerous.
  4. Li-ion 2S cells @ 7.4 V + step-down converter - low voltage difference -> might not be very efficient (?)
  5. Li-ion 3S cells @ 11.1 V + step-down converter - voltage difference is higher, so conversion might be more efficient(?)
  6. Above mentioned with Li-po cells - no experience, aware of cold conditions
  7. 6V Pb cell - can have enough capacity, but is too bulky & heavy and especially not very eco-friendly.
  8. Lion 2S @ 7.4 v directly :) - should I try it despite the fact it is not recommended? It is needed to assume 8.4 V when fully charged.
  9. Other suggestions?

Personally, I mostly like first 2 options, but maybe I have not mentioned some obvious solution, that is why I am asking here. I will be very grateful for any suggestions or discussion of above stated options. thank you.

  • \$\begingroup\$ You realize that the "most energy and space efficient" solution is likely to also be the most expensive, don't you? Is that acceptable? It sounds like "eco-friendly" is important to you...can you explain what your criteria are for that? \$\endgroup\$ Commented Apr 15, 2020 at 20:19
  • \$\begingroup\$ @Elliot Of course that was needed to state in my original question, I am not willing to invest more money in battery than whole trail camera, lets say 30 €. So it should be low-cost solution :) I use cheap trail cameras because there is high risk of getting stolen. Anyway, I am still interested in your suggestion, so do not get limited by my budget. And that "eco-friendly" was maybe too hasty statement, as I do not believe that other battery types (than Pb) is more friendly to nature when damaged. \$\endgroup\$
    – Oki
    Commented Apr 15, 2020 at 20:39
  • \$\begingroup\$ Have you tried using LSD (Eneloop or equivalent) NiMH cells? \$\endgroup\$ Commented Apr 16, 2020 at 2:13
  • \$\begingroup\$ @BruceAbbott not yet, as they only supply nominal 4.8 V when 4 of them used. I believe the trail camera will operate at the beginning, but I guess as the cell will get discharged a bit (or during cold night) the operation will start to be very unreliable. Currently, all my traps are in a terrain, but I can try it in home in a few days and let know here. \$\endgroup\$
    – Oki
    Commented Apr 16, 2020 at 4:16
  • \$\begingroup\$ For the "other" category: amazon.com/Capacity-1850mAh-Blackube-Rechargeable-Batteries/dp/… They look like AA batteries, and they fit in an AA battery compartment, but each one contains a Li-ion cell, a step-down circuit that supplies a steady 1.5V to the appliance until the cell is almost depleted, and a charging circuit that lets you re-charge the cell from a USB source. I have had good luck with the AAA-size product made by this same company. Haven't personally tried their AA-size. \$\endgroup\$ Commented Apr 16, 2020 at 7:17

3 Answers 3


You should try checking out LifePO4 batteries as an alternative solution. They have a nominal voltage of around 3.2V, so having 2 in series is 6.4V, which is really close to what your camera needs. You will require a (tiny) BMS circuit on it though since discharging them below its recommended minimum voltage will permanently damage it.


I have actually first come across similar cameras about a month ago, possibly the same model or manufacturer.
A customer was confused as to why they worked on batteries but not on an adapter. He thought some electronics failed on the board. I discovered that the camera actually needed a specific voltage range or it wouldn't even turn on. I don't remember exactly, I think it was from 4.5V to below 9V. He actually had a power supply whose voltage was outside of this range (I think 12V).

Anyway, first to correct you: connecting 2 cells in parallel can be dangerous only if their charge levels vary greatly (like more than 0.2-0.3V I think), so all you need to do is make sure their voltages are within 0.1-0.2V of each other when connecting them together and they will just work great afterwards.
If you are using a DC-DC converter, make sure that it has a VERY low quiescent current (the amount of current it uses with no load whatsoever, for running its own circuitry).

Before trying anything else, I would suggest you measure a camera's current consumption at 5, 6, 7 and 8V and see if it varies significantly (especially with the IR LEDs turned on).
Your solution might be as simple as 2 Li-Ion cells in series, without any conversion. You would just have to make sure they disconnect before the voltage of either cell drops too low (below 3.2V; depends on its chemistry). If the cells have circuitry on them, that's good, but you may want to have your own adjustable, micro-power monitoring circuit.

One tip: lithium cells can be recharged many more times if you use only 50% of their capacity (from 30%-80% charge level), so you could employ that tactic.
Another tip: You could include a ~7.2V mini solar panel to charge your batteries. It wouldn't be much larger than the camera.

  • \$\begingroup\$ Thank you, very informative answer. But need to clarify some points. 1. Are you suggesting to hook the camera on variable-voltage supply and try the range from 5-8V, while measuring current? Should not I be afraid of the overvoltage? I hope that both internal and external (AA bateries, DC jack) are somehow regulated, but It is just my wish. 2. I already have some protection circuits for li-ion cells. They should also protect cells against over-discharge. But I do not know If I should also use them while charging, or rather charge indiv. unprotected cells in charger. But this is off-topic. \$\endgroup\$
    – Oki
    Commented Apr 16, 2020 at 4:30
  • \$\begingroup\$ The one I looked at contains PWM DC-DC converter. If you start at 5V and slowly increase the voltage to 6V, you should notice a DECREASE in current if yours has PWM circuit as well and that means your input voltage can go from around 4.5 to around 9V. I don't remember if it has conversion on the battery side (I think it does), but it should have it on the DC input side. \$\endgroup\$ Commented Apr 16, 2020 at 7:39
  • \$\begingroup\$ As for your second question, you should use that protection circuitry both while charging and discharging, but you should check its current consumption. \$\endgroup\$ Commented Apr 16, 2020 at 7:40

remember you get a robust 0.6 or 0.7 volts drop across silicon diodes.

consider 1n4001 for your current level


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.