Thanks in advance. I am in the process of designing a remote camera trap. The project includes a 5v Arduino Uno and (2) 5V IR LED lights. I purchased a 5V/5A voltage regulator designed for RC Heli use to regulate the 11.1v LiPo to 5V (I chose the higher amperage voltage regulator because the LED lights run at 1.5A each).
I have begun researching low voltage cut-off circuits to project my LiPo from over-discharge. Most of my research has involved cut-off circuits that use OpAmps and Zener diodes. I have found little useful information from people with real-world experience using low voltage circuits for Arduino use.
I am curious if anyone has experience designing this type of circuit for Arduino use, or if anyone has explored other solutions, like hacking a low voltage RC alarm to trigger a cut-off relay. Thanks much.
Just wondering if I can supply any additional information. Having trouble getting any responses to this question. Any guidance on low voltage cut-off circuits?
I've used a LM339 voltage comparator cct. with a relay/P Channel MOS fet, however I don't have access to the circuit right now.
Do a google search for LM339 low voltage cutoff
jremington:
You can buy commercial PCBs that protect cells against low voltage and over current quite cheaply from here: Tenergy Battery Pack PCB
You could use 3 cells, each with its own PCB to make an 11.1 V pack, or buy the 3S version.
Thanks, this looks promising. What happens when the battery voltage gets too low? If placed between the battery and 5V voltage regulator (SBEC), current would simply be switched off to the BEC when the battery voltage gets too low? Forgive my ignorance, but how do you connect this PCB to the battery's individual cells? Do you need to open up the battery?
There are a number of options at that site for the different sized battery packs, and you will need to spend some time looking at the details, which are posted.
For a single cell these are 4-terminal modules that go between both terminals of the battery and its output terminals (or the charger input). The PCB removes the battery from the circuit if a low-voltage or short-circuit condition is encountered, but the PCB will still allow you to charge the battery (up to its upper voltage limit). Here are the details for a single-cell PCB: Tenergy Power
Then I will need to construct a breakout cable from the battery's balance plug and connect the appropriate wires to the connections on the PCB. Correct?
jremington:
There are a number of options at that site for the different sized battery packs, and you will need to spend some time looking at the details, which are posted.
For a single cell these are 4-terminal modules that go between both terminals of the battery and its output terminals (or the charger input). The PCB removes the battery from the circuit if a low-voltage or short-circuit condition is encountered, but the PCB will still allow you to charge the battery (up to its upper voltage limit). Here are the details for a single-cell PCB: Tenergy Power
I have purchased one of these PCB's, but it came with no documentation. The website lists the wiring info but the question is, if all connectors on this PCB go back to the battery (either to the balance plug or main output), how could this device affect the battery's connection to a circuit? There is no output on the PCB, so where do you connect the rest of the circuit to be powered by the now protected battery?
Which PCB did you buy and for how many cells? For one cell, the output terminals of the PCB become the new "battery output terminals", that is, the PCB just goes between the battery and whatever circuit the battery is normally attached to.
I've only used the single cell versions, so can't advise you on the multicell version. I assume it operates similarly, though.
It has connections for each balance plug wire (B+, B-, B1-, B2-) and then a P+ and P-, which according to the website go to the battery output or charger. I do not read any voltage on these P connectors so they don't seem to be an output. This labeling scheme seems to be the same as that used on the 1S versions. How did you wire yours up?
More specifics: I measure the total voltage of my battery to be about 11.5v and each cell (measured by the balance plug) to be about 3.8v.
The specs for the PCB list the over-discharge voltages to be a max of about 9v total or 2.6v/cell, so the PCB should not be cutting off current flow yet (ruling this out as the reason I cannon measure voltage across the P+ and P- terminals). Any ideas?
The instructions on the web site seem clear enough, and correspond to how I connected the single cell version. To be sure, I've attached a schematic showing my interpretation of the instructions. If any wire is connected incorrectly it seems likely that the PCB will shut down.
