Top critical review
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on 6 February 2014
The batteries I received (from "Topwell") are red and grey (as in the current picture), say UltraFire on them and are labelled as 18650 and 3000mAh (no space).
I was surprised at how light they felt so I weighed them. They were 33gms whereas some older 18650 batteries I have are 46.5 gms.
With some NiMh batteries I find it is common for sellers to claim a high capacity where the batteries are actually of low capacity - and have a correspondingly low weight compared with good ones.
Does the same principle apply to Li-ion batteries?
To find out I made a test circuit (discharging though an ammeter and a 2.5 Ohm resistor) to measure capacity. As a control, I also tested one of my old 3860 batteries ("Asucell" and labelled as 3000 mAh and I measured the output at 2853 mAh - quite good for a well used 18 month old battery I'd have thought.
I then tested both of these Fire batteries and the capacity is showing up as just over 800 mAh - so less than 30% of that claimed.
I gather that one of the operations of the protection circuits in Lithium ion batteries is to prevent damage caused by discharging below 5% of capacity. I noticed that the old batteries I have cut out when voltage got too low - presumably the circuit is working, whereas these "UltraFire" batteries did not cut out so I wonder if they have any protection circuits at all.
Lithium ion batteries can be dangerous. As the 3000 mAh label is a lie, don't trust the "protected" label.