nssdiver

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Research Chemist

R/C enthusiast (Plane & Boat); Cyclist (Cannondale Synapse); Watersports Enthusiast (Water skiing, wake boarding, swimming...); Motorcyclist (Honda VFR800A)...


nssdiver

's contributions
  • 04.11.2017
  • Teardown: Debugging a faulty MacBook Pro battery
  • Looking at the data in the Unknown Terminal measurements, in hindsight I can see that the voltage output to ground appears to be the drop across the 0.020Ohm shunt resistor. VIR calculations show very good correlation for pins 4 and 6 with pin 5 showing a slightly higher voltage (and hence, calculated current). The bulk of my experience with high power LiPo batteries lies in their proper treatment. And with that, all roads lead to temperature. (Charging above design voltage (4.2V), Charging at a higher rate (current) than the battery can handle and discharging at a rate higher than the battery is designed for.) On the charging side, this is often handled by specialty chargers for electric R/C enthusiasts. They are designed to monitor each cell during charge and prevent any individual cell from charging to an excessive voltage or current. On the discharge side, this is typically handled by the Electronic Speed Control (ESC) which typically provide many functions including: Power control, inverter (DC to 3 ph AC), and low voltage converter to power the receiver and servos. They are also typically programmable. Integrated cell/battery protection is uncommon in R/C as it adds an additional failure point for your power system. Also, an inadvertent battery shutdown could be catastrophic, depending on the craft and maneuver that it is in. (Inverted helicopter, airplane performing low altitude 3D stunts, etc.) Most ESC's can detect a bad battery and alert the pilot and still give them time to land. The battery may get ruined, but that beats crashing a (potentially) expensive "toy."
  • 05.27.2016
  • 10 drones you’ll want to own
  • Those of us who have been into R/C aircraft for our entire adult life (and half our childhood) look at drones as a way of "cheating" your way into R/C. Cameras, gyro's, GPS... Really?!? That doesn't stop me from wanting one, though...
  • 11.09.2016
  • What's wrong with this MacBook Pro battery?
  • We have too many unknowns here: What temperature environment has the battery been experiencing?; We know nothing of the charge control circuitry, and; We cannot monitor the individual Vpc (voltage per cell). There are probably others, but as an R/C abuser of Lion and LiFe batteries, these are what matter to us in the rather expensive hobby field. I have a 4 cell 5Ahr battery that I pull 100A burst and 60-80A constant out of. What matters to me? 1- TEMPERATURE, 2- Max Vpc (during charge) and 3- min Vpc during discharge. I have no battery protection circuitry in my battery, but [we] do have rather expensive charge stations. I watch all of the three above parameters like a hawk during both charge and discharge. My batteries last me 100's of cycles. My educated guess is that if your wife is not using her laptop on a pillow that either: 1- the battery has a bad cell that the computer can't detect and the charge control circuitry is shutting the battery down to protect it, or; 2- the charge control circuit sucks, or is not functioning properly. Now that the battery is out of the computer, do you feel comfortable tearing into it and getting the battery and individual cell voltages? An interesting experiment would be if you could find a local R/C club (Plane, boat or car - ask at a hobby shop) and see if there is someone willing to look at your battery with a precision Lithium balance charger.
  • 01.19.2013
  • Proper Lithium-Ion battery charging and safety
  • Lithium ion batteries are routinely charged to 4.2V/cell safely. Both your assertion that the 32V to the pack is too high is wrong as is the author's 4.3V/cell claim for a safe charge voltage. None the less, it always comes down to temperature. Temperature (high) comes from: VENTILATION (or, lack thereof); Overcharge (voltage); Overcharge (current), and to likely a lesser extent; Over discharge (voltage &/or current).
  • 06.21.2016
  • Apple MacBook gets a new battery
  • I have an app (the name of which I cannot remember for the life of me) on my Mac Mini at home that gives me greater control of the cooling fans. I use it to spool up the fan in my Mini prematurely when I do gaming, like, every other month. Installing it and trying it out might be an interesting test to see if keeping the computer cooler may extend the life of this next battery. I do electric R/C and aside from over & under charging, battery temperature is likely the next most important variable in the cycle life of the battery. The charging is controlled by the computer. The temperature you have some control over. I agree with markkonijn - keep everything as cool as possible.
  • 06.08.2015
  • Charging batteries rapidly and safely
  • Not paying attention to my own typing - I can calculate Id, but not Ic or any of the Times. Is this milliseconds, seconds, minutes? Are the times proportional to the graphs? Also in the statement "The time duration is a fraction of the charging current." is not only vague, you have a time variable relating to a current variable. At least on my Granite Digital charger I can watch the current pulses and see the current and ON duty cycle change when I am too lazy to hook up a data acquisition module to it...