Calculating Required Amperage For Stir Plate

[thadius856]

Going with the 120mm ThermalTake desk fan for my stir plate build. Four identical ones, to be exact. The rheostat comes pre-wired and it uses USB for power in. I know it's going to cost me a few dollars more per stir plate, but it's worth it to save my sanity.

My confusion stems from the fact that the fan has a voltage, amperage and wattage specified, but the USB A/C adapters come only with mAh ratings. The problem I've having is interpreting the specs to know how large on a wall wort I need to power it. It's been a while since college Physics.

Do either of these options provide enough power?

1- All four one 4-port wAC adapter (rated 500 mAh each port) - $10 shipped.
2- All four on separate 1-port iPhone AC adapters (rated 1000 mAh each adapater) - $2.50 ea shipped.

 

[bdh]

Do you have links for the AC adapters you're looking at? mAh (milliamp-hours) is an energy spec (usually seen more with battery packs and such). It doesn't make sense in terms of power. If it's really mA (milliamps, not milliamp-hours) then either is fine since this fan only draws 300mA max.

 

[thadius856]

Do you have links for the AC adapters you're looking at? mAh (milliamp-hours) is an energy spec (usually seen more with battery packs and such). It doesn't make sense in terms of power. If it's really mA (milliamps, not milliamp-hours) then either is fine since this fan only draws 300mA max.

Ugh. You're right. Just looked at a few models again. I read it too fast and through it said mAh, and that's why I was getting super confused. I could have swore that mAh was a unit of capacity.

1A 5V (iPhone white style) 1-port $2.44 ea shipped - eBay
1A 5V (iPhone black style) 1-port $3.69 ea shipped - eBay
1A 5V (Kodak style) 1-port $2.25 ea shipped - eBay

2.1A 5V 4-port $7.59 shipped - eBay (simultaneous 2.1A, assuming each port is 500mA because they didn't specify)
2.1A 5V 4-port $11.73 shipped - eBay (1 port is up to 2.1A, the others seem to be 500mA, total output is 2.1A simultaneous)

There's many others. But I haven't yet seen one under $20 that gives more than 2.1A total output.

Went with 5 of the black iPhone chargers for under $20 shipped. I figure I can use a power strip, and that way if I don't end up putting them all on the same table, no worries.