RE: New Lipo battery problem
Well, sir, I'll say this. I am an electrical engineer (socially challenged by profession) at a company that designs and builds MRI scanners, and this affords me the opportunity to interact frequently with those in the medical profession. I've seen what you go through to get trained up, and I respect it. Engineers have trouble understanding what radiologists need, and radiologists have trouble understanding what engineers can do. If my post was not clear ... it is my fault ... it has happened before.
If I may, I'll take another try.
The principle thng we have to consider is the equation for power in an electrical system, which is Watts = Volts * Amps. We are doing direct current here, not like the current in your house, so it is easier to do the math. No matter what else is going on, that equation up there holds true. In wattmeters, all that happens is the device measures voltage, and current (amps), multiplies those values together to get watts.
If your wattmeter says 10 volts, and 1 amp, then it MUST report 10 Watts. If it doesn't, it is broken.
One might want to wonder if the esc, or motor/prop, both of which have some adjustments, could be involved in this problem. The answer is no, because you are measuring the output of the battery, which is not effected by the load (esc and motor), other than the fact that the load eats power. Theory, done.
OK, so you said that with the 2S and 3S batteries in series, you got:
"When I tested it I had a drop in power to 386wp and 28.11 ap" (first post)
and
"it showed 20.18v in the right upper corner of the meter with the 11.1v and 7.4v connected in series" (second post)
So, the math says, V * A = W, or 20.18V * 28.11A = 567 W (calculated)
But ... this cannot be, because the meter reported only 386 W.
Our options now are:
1. Your meter is broken (unlikely)
I did the math on the 2 2S battery info you gave which was V =16.3, A = 34, so calculated Watts are 554 W, which matches closely with your reported watts from the meter of 514 W. From this test, the meter looks good.
2. Your measurements are wrong (only option that is left).
What may be happening here is that the 20.18 Volts you are seeing, is when the motor is not turning. Bad cells will show great voltages when there is no load on them ... when they are not driving anything. I'll bet that if you take the measurements again, and record watts, current and voltage with the motor loaded (running), you do not see 20.18 volts. I'll bet you see 14 volts.
There is a possibility that the "lost volts" are in a connector somewhere, but based on the 2 7.4 battery test you ran, that is not likely in my opinion.
Is the 3S 2100 battery a little swollen? Can you push on the plastic on the top and have it give, like a balloon does? Are there any marks on the battery from crashes or being dropped?
Can you try the 3S battery in a plane that uses just the 3S, and measure that with the wattmeter? If you don't see 11 volts, or so, under load ... you have the culprit.
Regards,
Rikk