station240
Member
- Joined
- Oct 9, 2016
- Messages
- 177
As per HBPowerwall's recent video, where he raised concern about the power drawn by the tiny LED volt meters you get from ebay, aliexpress, amazon etc.
If the values displayed are different for each series pack, due to voltages differences, then the number of led segments lit is also different. Hence the current drawn by each LED volt meter varies depending on what numbers it displays.
Lets assume worse case for the last digit.
Pack 1 displays 3.51V
Pack 2 displays 3.58V
Each segment draws ~ 20mA each,
Pack 1 is drawing 100mA+100mA+40mA = 240mA
Pack 2 is drawing 100mA+100mA+140mA = 340mA +42% extra power
breakdown of value vs segments lit and current draw.
1 2s 40mA
2-5 5s 100mA
6 6s 120mA
7 3s 60mA
8 7s 140mA
9-0 6s 120mA
Aside from value 1 and 7, the current drawaverages between 100 to 120mA.
I've got one of these voltmeters myself so I can do further test if anyone wants.
I don't have the version with the extra wires that has a separate 5V input to power the device, but obviously it drains very little from batteries.
If the values displayed are different for each series pack, due to voltages differences, then the number of led segments lit is also different. Hence the current drawn by each LED volt meter varies depending on what numbers it displays.
Lets assume worse case for the last digit.
Pack 1 displays 3.51V
Pack 2 displays 3.58V
Each segment draws ~ 20mA each,
Pack 1 is drawing 100mA+100mA+40mA = 240mA
Pack 2 is drawing 100mA+100mA+140mA = 340mA +42% extra power
breakdown of value vs segments lit and current draw.
1 2s 40mA
2-5 5s 100mA
6 6s 120mA
7 3s 60mA
8 7s 140mA
9-0 6s 120mA
Aside from value 1 and 7, the current drawaverages between 100 to 120mA.
I've got one of these voltmeters myself so I can do further test if anyone wants.
I don't have the version with the extra wires that has a separate 5V input to power the device, but obviously it drains very little from batteries.