I've been working on a quadruped project, and need some help determining the... safety... of my power system.
To start, there's two packs, a larger "main" and a smaller "reserve"
the two packs are built from the same type of battery: Coolplay 3.7V 500mAh LiPo
the smaller pack is two of these wired in series to get 7.4V 1Ah, and the larger one is 8 of these wired to 7.4v 2Ah (4 packs in parallel to make 4x 3.7V 1Ah, in which they are series paired into 2x 7.4v 1Ah, which in turn are wired in parallel to get 7.4v 2Ah)
I've done the prerequisite searching, and can only find safe current to apply to parts and IC's, not the safe current to pull from the battery. So, my question is, what would be a "safe" amount of current to pull from either of these packs?
At idle (all IC's powered, but servos not powered), the build pulls about 0.2A, and the packs don't heat up at all, but when the build enters a "pose" such as standing (all servos powered up and under load), the load jumps up to 2A usage, and the pack temperatures start to rise, and my overcurrent kicks on and shuts the packs off (I have it set very low because, well I don't trust LiPos).
So, is it safe to run my pack under these conditions? and if so, for how long? I have adjustable overcurrent protection and temperature monitoring installed, so I can utilize those as well.
And if its not safe to run like this, what could I change?
One of these packs powers a Syma X5C drone for 7 minutes. So some quick and dirty math tells me that the drone pulls around 4.5 amps from the packs for the duration of the 7 minutes, and the packs are pretty warm from this. So with the new information that these individual batteries get 4.5A pulled from them, what is the verdict on this?
**EDIT: RESOLUTION So, thanks to @MarcusMUller and his insight, I've determined that the packs should be safe to run in these conditions but should be monitored more closely (as marcus pointed out, cheap batteries are unreliable and inconsistent) and should be housed better. Thank you @MarcusMuller for the feedback and insight
**NOTE: Batteries are dangerous, but I dont need to say that. As marcus pointed out (more or less), batteries with poor documentation should make you nervous. Good batteries are a good investment, and shortcuts should only be taken by those that know the path, and even then it should make you nervous. Be safe with batteries