Use one big table or multiple small tables for described scenario I have a question regarding my database scheme: 

Lets assume I have 100+ measurement devices, each of them is equiped with a  voltage and current sensor. Multiple (50-100) of those devices are aggregated in a bigger device (DEVICE)
Shall I create a mysql table for each device and each quantity and store the values like:

DEVICE1_voltage:
Timestamp, sub_device1_value, sub_device2_value, sub_deviceX_value...

DEVICE1_current
Timestamp, sub_device1_value, sub_device2_value...

DEVICE2_voltage:
Timestamp, sub_device1_value, sub_device2_value, sub_deviceX_value...

DEVICE2_current
Timestamp, sub_device1_value, sub_device2_value...


...

Or is a relational scheme like:

DEVICES:
id, name

sub_devices:
id, DEVICE_id


voltage_reads:
id, timestamp, sub_device_id, value

current_reads:
id,timestamp, sub_device_id, value


more appropriate? The advantage I see with version 2 is that my scheme will never change, as with version 1 I get two new tables with each new device. These Tables then have different numbers of colums as they differ in sensor setups.

The big disadvantage of version 2 is see is when I get a lot of measurements and the table grows very big....plus that when I query Data this is already the format I need later

Which scheme is better in "theory"? 

Thanks in advance!

Edit: Renamed tables and colums, to make more clear that each device can have multiple sub devices
You definitely should not have one table per device. That means you'll have to create dynamic SQL to merge the device name into the query, and create a new table every time you add a device. So version 2 is much more appropriate than version 1.

But you don't necessarily need separate tables for voltage and current. You could have a single table device_log, with columns:


id - primary key
sub_device_id - foreign key to sub_devices table
timestamp
type - 'voltage' or 'current'
value 


Or if you don't need so much generality, and always read current and voltage at the same times:


id - primary key
sub_device_id - foreign key to sub_devices table
timestamp
voltage
current