So I've been thinking about what batteries I'm going to use in my Skeletor when I get it, and there's something I'm not sure I fully understand. Hopefully
@Pipes or someone else can clarify. Does the unit perform differently using batteries with different discharge ratings? For example, will 30A Sony VTC4s provide a faster heat-up than 20A LG HG2s? I know they need to be rated for at least 20 amps.
I was originally planning on getting VTC4s because I had seen them mentioned here and figured the 30A rating was more than good enough, but if I can use LG HG2s instead I would be increasing capacity by almost 50%, right? (3000 mAh vs 2100)
Thanks in advance for any insight.
Those ratings are for continuous discharge, not an issue to go over a bit for a few seconds now and then.
I don't think you'll need to pull more than 10A anyway, so 20A rating is sufficient.
There may be a slight heat up time differences due to internal resistance of the batteries.
The LG's appear to have a (marginally) higher internal resistance, meaning the voltage loss inside the batteries is slightly higher, and the portside will have slightly less power. Only slightly.
Like you mentioned, the HG2's have a (much) higher capacity, and that would be a much bigger advantage. besides, I think slower heat up time is advantageous too. It allows heat to spread in the tip and is a little more forgiving in time to char.
On specs alone (since I haven't used either of these cells), I'd choose the VTC4s for applications that require the higher discharge rate, say anything needing more than 20 amps for extended periods. Otherwise, the HG2s look like a better choice due to higher capacity, specially with a <10A load for a few seconds every now and then.
I have some samsungs, seem to work well.
BTW, I'm guessing the best spec to look at is the capacity the batteries have when their voltage gets down to 3v, when the BMS circuit will cut them off.
From the HG2 chart below, we see that to if we want to keep the battery healthy and avoid deep discharge (we are using a BMS, which cuts off at about 3v, so we are), the capacity available to us at 10A discharge with voltage limited to 3v, is about 2500 mAH, not the stated 2925mAh.
under these conditions:
HG2: 2500mAH
25R: 2350mAH
VTC4:1950maH
Spec sheets:
https://www.powerstream.com/p/INR18650-25R-datasheet.pdf
https://www.powerstream.com/p/us18650vtc4.pdf
https://www.nkon.nl/sk/k/hg2.pdf