Dungbeetle
New Member
- Joined
- Feb 10, 2021
- Messages
- 4
If I take say a 12v 10ah battery, and attach one of those 12v usb hubs, would I technically be getting 20,000mah+ at 5v or still 10,000mah? Thanks!
How many mah will I get at 5v from a 12v battery?
- Thread starter Dungbeetle
- Start date
Welcome to the forum, oh roller of poo...
Ah is tied to the given voltage. If you change the voltage, the Ah adjusts.
12v * 10Ah = 120Wh
120Wh / 5V = 24Ah
The above assumes perfect conversion, which you won't get, so your 20Ah is probably more realistic.
Ah is tied to the given voltage. If you change the voltage, the Ah adjusts.
12v * 10Ah = 120Wh
120Wh / 5V = 24Ah
The above assumes perfect conversion, which you won't get, so your 20Ah is probably more realistic.
Dungbeetle
New Member
- Joined
- Feb 10, 2021
- Messages
- 4
Thank you!
As @snoobler says
Generally, a switching convertor has an efficiency of 80-90%, 0.8 x 24 = 19.2Ah
A few notes:
- This is the battery capacity, not the actual usable capacity.
Depending on the type of battery(Starter, AGM, LFP), you can only use 50-80% of the rated capacity without sacrificing the life.
- These calculations are based on a switching power supply. A lineair power supply only lowers the voltage and will convert the remaining into heat.
In those cases, the 10Ah will remain 10Ah at 5V. If using eg 5V / 1A, you will also generate 7V x 1A = 7W of continous heat, which requires a heatsink. For some applications, a switching powersupply might not work (but generally it works)
Generally, a switching convertor has an efficiency of 80-90%, 0.8 x 24 = 19.2Ah
A few notes:
- This is the battery capacity, not the actual usable capacity.
Depending on the type of battery(Starter, AGM, LFP), you can only use 50-80% of the rated capacity without sacrificing the life.
- These calculations are based on a switching power supply. A lineair power supply only lowers the voltage and will convert the remaining into heat.
In those cases, the 10Ah will remain 10Ah at 5V. If using eg 5V / 1A, you will also generate 7V x 1A = 7W of continous heat, which requires a heatsink. For some applications, a switching powersupply might not work (but generally it works)
