Griffin Reserve 6000mAh Power Bank Review

I bought this Griffin Reserve 6000mAh Power Bank from Sainsbury’s supermarket for £15.99. The box claims that it comes Pre-charged and that it can deliver “Max-rate tablet & phone charging”. Neither of these claims are true. I DO NOT recommend this power bank.

Video Review

In the box

The box that the powerbank comes in

The box contains the power bank, a 30cm USB to Micro USB cable and a small warranty leaflet.

The contents of the box


  • Dimensions: 104 x 65 x 20 mm
  • Weight: 177 g
  • Micro USB cable length: 30 cm
  • Input: 1 micro-USB
  • Output: 1 USB A - 5V up to 2.4A (but not really 5V)

Power supply

Initially seems to deliver up to 2.4A, but only at 4.8V rather than the expected 5V which is just barely within the allowed minimum (5V ±5% or 4.75V to 5.25V). When you add in cable loss this means that the power bank is not delivering sufficient voltage to the device. In fact this is the peak voltage that the device delivers and during the capacity test things get even worse…

Cable test

The cable is 30cm long. It has some strain relief but it’s not very flexible. I would not expect this cable to last long with heavy use. At 2.1A it drops 0.21V which is 4.2% of the power being delivered. For a 30cm cable this is nothing special, but it’s ok. At 2.4V it drops 0.25V or 5%. Again, this is ok.

Capacity Test

This is where the power bank really fails. The claim on the product page and on the box is that it will deliver 2.4A. The starting voltage at 2.4A after the first few seconds was 4.7V, and by the time the power bank was empty had dropped to under 4V. This is not just the usual dropout right at the end either, this is a steady decrease in the already low output voltage.

The output voltage during the discharge test.

It did cut the power off cleanly at the end, but this is hardly a great victory given the output voltage had been lower than 4.5V for the last 13 of the discharge test!

Display Accuracy

The display consists of 4 LEDs. They show the available capacity with a short press of the power button and while charging. I have not specifically tested their accuracy, but during the test their output seemed consistent with the state of the power bank.

Standby Power Loss

Utter rubbish. The box claims PRE-CHARGED. READY TO USE™. Just one of the 4 power indicators lit when I first unboxed it, and it delivered power for a few seconds before turning off. This power bank was effectively empty on arrival. I did not specifically test the standby loss any further than this.

Passthrough power

I didn’t test this in the video, but it seems to cut the output power when the input is plugged in, so this doesn’t support passthrough.