Tomo Power bank M2



Official specifications:

• Input: 5.0V/ 1A
• Output: Dual USB: 5V/ 1A; 5V/ 2A
• 2-in-1: 18650 Battery Charger + Smart Power Bank
• Compatible Battery: 2 x 18650 battery (Not included)
• Weight: 68g
• Size: 130mm x 49mm x 25mm

I got it from Banggood

How does it look



The power bank is delivered in a cardboard box with a window and some specifications on the back.



It contains the power bank, a usb cable and a "instruction sheet".



All connectors is placed at one end

• Micro usb: Charge input.
• 1A and 2A usb output.
• Power on button.

On the other end of the box is a display.



There is no doubt when the power bank is turned on.



This is the power status display,



When charging a mains cord is shown to the left and the bars in the batteries are animated.



When current is drawn the display will show voltage and current for each slot. The display will not indicate charging.






The box do not include any batteries, it is up to the user to supply one or two batteries.
The length of the batteries can be from about 58mm to 69mm.



Measurements

• Usb output 1A is coded as usb charger (DCP)
• Usb output 2A is coded as Apple 2.1A
• Power consumption from battery when off is 2.2mA
• Power consumption from battery when on is 16mA
• Power consumption from battery at 1.9V is 0.7mA
• Limit for detecting current draw or not is about 45mA load on 2A usb and 60mA on 1A usb output.
• The two battery slots are independent, i.e. no problem mixing full and empty batteries.
• It is possible to use both outputs simultaneous, but the total current is only 2A, this is enforced.
• Can be used as UPS
• Size: 100 x 48.0 x 26.4mm
• Weight: 52g (Accessories and batteries not included)

The specification sheet says the box can deliver 1.5A on the 1A output, this is a bit optimistic, overload trips at 1.4A



The 2A output is rated for 2.2A, but again the overload protection kick in a bit early at 2A and also a bit early for a 2.1A coding.



The output looks the same with connected charge power.



Running both outputs in parallel gives slightly more current, but the current limit also works here.



The current display is not a precision meter, but it will easily show if the connected device is charging and give a very good idea on how fast charging is.



Nice stable output voltage until the battery is about empty.



AT higher current the output voltage is a bit lower, but again very stable until the battery is empty.



Two batteries gives about double time.
Note: I am only measuring current and voltage on one battery.





At 2A the output voltage is fairly low, but stays stable until the batteries are empty.



Noise is 8mV rms and 76mVpp



Noise is 11mV rms and 85mVpp



Noise is 16mV rms and 129mVpp, all noise values are very low.



It uses a nice CC/CV charge algorithm, but do not really stop charging, instead it will pulse the current when the voltage drops slightly.



The box will draw nearly 1A from usb when charging two batteries, this means about 0.4A for each battery.



A 0.5ohm resistor in series with the usb supply to simulate a weak power supply or long cable do not prevent the box from charging at about the same speed.




Conclusion

This power bank has many good details:

• Long battery slot, i.e. can handle some protected batteries.
• Can be used as UPS
• Independent slots
• The display with current on each port
• Fairly low noise
• Over load protection
• Easy battery replacement, i.e. this makes it possible carry spare batteries or use it as 18650 charger.

But the standby current is a bit on the high side, i.e. the batteries has to be charged every few months even when not using it. I would also have like a bit more current on the 2A port and auto coding.

I will rate it as fairly good.



Notes

The power bank was supplied by Banggood for a review.

Read more about how I test USB power supplies and chargers