 | Electronics For All (EFA) | 322 Members |
| About EFA Community: For People around the world, who are interested in Embedded SW/HW, Electronics, Industrial Automation, Robotics, OSH, OSS, Beacons, 3D Fab,Professional N/W'ing, knowledge sharing & discussions on these technologies & engineering. | 35 Servers |
| Sender | Message | Time |
|---|---|---|
| 28 Jul 2023 | ||
 Daniel | V = IR (voltage = current * resistance) Rearrange that to get I = V/R, so current is determined by the resistance (something inherent to the circuit) and voltage | 10:33:45 |
| Daniel | So the current that a given circuit/component will draw will not change if the voltage does not change (assuming no other changes) | 10:35:00 |
| Daniel | If it helps to use the water analogy, the anount of flow (current) through a pipe is determined only by the size of the pipe (resistance) and pressure (voltage), not by the maximum flow the supply can supply (unless the resistance is too low) | 10:37:19 |
| * Daniel was asleep about 5 minutes ago, hopefully this is somewhat articulate/useful | 10:38:20 | |
 rd2 | In other words, the current coming from the battery will step down according to the resistance of the logic board. This resistance determines the maximum allowed current of 14.7A, regardless of the battery's capacity to provide a continuous current of 30A. Have I understood this correctly? | 12:27:50 |
| Daniel | This is not universally true, but as a rule, if voltage is constant current will be too | 12:38:23 |
| Daniel | * The above is not universally true, but as a rule, if voltage is constant current will be too | 12:38:52 |
| rd2 | I have to check the voltage range the bms allows in this batter | 13:00:01 |
| rd2 |  Download image.png | 13:04:57 |
| rd2 | the maximum power consumption of the logic board states maximum continuous watt consumption 185W and the maximum allowed current is 14.7A so the P= IR = 12.6V*14.7A=185.22W I calculate the resistance from above R=V/I 12.6/14.7= 0.857142857 Ohm The allowed voltage range in the battery 14V>=V<=14.2V Calculate the Currents range for the above voltage I1=V/R = 14/0.857142857=16.33A I2=14.2/ 0.857142857=16.56A | 13:16:21 |
| rd2 | * the maximum power consumption of the logic board states maximum continuous watt consumption 185W and the maximum allowed current is 14.7A so the P= IR = 12.6V*14.7A=185.22W I calculate the resistance from above R=V/I 12.6/14.7= 0.857142857 Ohm The allowed voltage range in the battery 14V>=V<=14.2V Calculate the Currents range for the above voltage I1=V/R = 14/0.857142857=16.33A I2=14.2/ 0.857142857=16.56A raise in current is 1.63A-1.86A | 13:18:44 |
| rd2 | * the maximum power consumption of the logic board states maximum continuous watt consumption 185W and the maximum allowed current is 14.7A so the P= IR = 12.6V*14.7A=185.22W I calculate the resistance from above R=V/I 12.6/14.7= 0.857142857 Ohm The allowed voltage range in the battery 14V>=V<=14.2V Calculate the Currents range for the above voltage I=V/R I1= 14/0.857142857=16.33A I2= 14.2/ 0.857142857=16.56A raise in current is 1.63A-1.86A | 13:20:38 |
| rd2 | * the maximum power consumption of the logic board states maximum continuous watt consumption 185W and the maximum allowed current is 14.7A so I calculate the resistance from above Calculate the Currents range for the above voltage I2= 14.2/ 0.857142857=16.56A raise in current is 1.63A-1.86A | 13:22:02 |
| rd2 | Redacted or Malformed Event | 13:23:17 |
| rd2 | In reply to @danielp3344:matrix.orgThe logic board component resistance is unable to handle the increase in current. correct? | 13:24:28 |
| rd2 | * the maximum power consumption of the logic board states maximum continuous watt consumption 185W and the maximum allowed current is 14.7A so I calculate the resistance from above Calculate the Currents range for the above voltage I2= 14.2/ 0.857142857=16.56A raise in current is 1.63A-1.86A | 13:28:45 |
| rd2 | * the maximum power consumption of the logic board states maximum continuous watt consumption 185W and the maximum allowed current is 14.7A so I calculate the resistance from above The Currents range of the above voltage I2= 14.2/ 0.857142857=16.56A raise in current is 1.63A-1.86A | 13:29:25 |
| rd2 | * the maximum power consumption of the logic board states maximum continuous watt consumption 185W and the maximum allowed current is 14.7A so I calculate the resistance from above The Currents range of the battery voltage range =16.33A-16.56A I2= 14.2/ 0.857142857=16.56A raise in current is 1.63A-1.86A | 13:31:03 |
| rd2 | * the maximum power consumption of the logic board states maximum continuous watt consumption 185W and the maximum allowed current is 14.7A so I calculate the resistance from above The Currents range of the battery voltage range =16.33A-16.56A
raise in current is 1.63A-1.86A | 13:32:05 |
| Daniel | Any semiconductor (your entire board) is inherently non ohmic | 13:32:28 |
| Daniel | So behavior at a different voltage is unpredictable | 13:32:46 |
| rd2 | * the maximum power consumption of the logic board states maximum continuous watt consumption 185W and the maximum allowed current is 14.7A so I calculate the resistance from above given Battery's allowed voltage range = 14V-14.2V Calculate the current range from the voltage range =16.33A-16.56A
raise in current is 1.63A-1.86A | 13:34:02 |
| rd2 | In reply to @danielp3344:matrix.orgif we assume that the actual resistance is 0.857142857 Ohm. does that mean this battery can fry the board? | 13:36:14 |
| Daniel | Semiconductors don't have a "resistance" per se | 13:36:38 |
| Daniel | But yes they will tend to draw more current with increased voltage, which can certainly damage things | 13:37:11 |
| Daniel | Just use a buck regulator tho | 13:37:32 |
| Daniel | https://www.ebay.com/itm/124976393245?hash=item1d192c6c1d:g:0LoAAOSwiRdhejzl&amdata=enc%3AAQAIAAAA8HSsPabBxrZDNEicjix5QaeydgsQ1Zv0TXMBSKhlOVMXl951CLKDkomrQWsvUWta8DiELV1sWuH2x%2BgfSLz0oIWpDzDtJny2U4UCYAV3p4Wl2vI6ycYYaF0TsaxirCmzMvEV2ghMkNJdOfl7S1vQmkgH7AFqEyh3Kw%2Fn1ttVw9FO8L0co8Yw0tzZeJ0cdyBLZgjo%2BoXH2QEeU6XrrN7WY8k4udk%2FIb1YFuAAv%2B5fcuxtCIAouN9tjNabpLNjL2QVZywrLsHuu4F47oBvx4cSnqEpVKhboJT6GBm3l4Joe9Wa4BDzwyrA6c38oNPpdCSmwA%3D%3D%7Ctkp%3ABk9SR7Kaw8uzYg | 13:38:30 |
| rd2 | I am trying to get a battery bms that suits the logic board to evade having to install a buck converter | 13:38:33 |
| Daniel | * https://www.ebay.com/itm/124976393245 | 13:39:01 |
| rd2 | there is a dude who is running his m1 mac mini on a v mount battery rated 99W | 13:39:31 |