LG HG2 Review (20A, 3000mAh) August 17 2015, 59 Comments
This is LG's new brown battery - the LG HG2
A post on the HG2 is long overdue.
While the original release of the LG HG2 was in 2014, production has become available in Summer 2015. A 20 amp, 3000 mAh milestone is, in some way a holy grail of stats. A battery that can both be high-drain, and high-capacity is just what everyone wants. The LG HG2 can be seen as a 500mAh capacity upgrade from its predecessors the HE2/HE4 which also have a 20A discharge limit.
LG Chem is on a rolling schedule of releases and research, all planned years in advance. An average of between 6% and 10% increase in battery performance is expected, compounding yearly. That means, taking into account the battery specs and LG Chem's release schedule, the LG HG2 will likely be a good contender for one of the best 18650 batteries for some months to come for high-drain applications.
That said, there are many cases where the newest 18650 battery with the latest specs never gains mass adoption. That can be due to a number of reasons including a quick upgraded release, unforeseen safety problems, supply chain insecurity, market ignorance, and so forth. It's for that reason I am not crowning the HG2 as the new king on specs alone.
To test that claim, I'll do the standard Battery Bro review:
- Take a look at the HG2 specification sheet
- Visually inspect the battery
- Do three discharge tests
- Unwrap the battery
- Determine whether the HG2 deserves a noble title
HG2 Spec Sheet
My comments on the HG2 specification sheet:
3,000 milliamp hours is the highest capacity ever for a true high-drain (20A+) cell. If you are interested in maximizing both amperage and capacity you should consider this cell because it doesn't get better at the moment.
2.2 Nominal Voltage
This is the standard voltage for all 18650 batteries. (3.7V 18650 batteries are older, a standard of measurement was changed but actual voltage remains the same.)
2.3.1 Standard Charge
A 1.5A standard charge is good.
2.3.2 Fast Charge
A 4A fast charge is also good. However keep in mind that fast charging will decrease the cycle life of the HG2.
2.4 Max. Charge Voltage
Standard, no comment
2.5 Max. Change Current
2.6.1 Standard Discharge
These are normal standard discharge values. The nominal capacity of the HG2 is determined while discharging at these values. When discharging at its max. continuous discharge rating the capacity will be slightly reduced (watt hours more so).
This has likely led to the claims that the HG2 under performs. However many of these tests neither distinguished between the standard discharge vs. max. discharge testing conditions, nor did they take into account fast discharging conditions outlined by LG Chem in the spec sheet (see next section).
2.6.2 Fast Discharge
The Fast discharge has been tested at both 10A and 20A. What is important to note is the cut-off voltage of 2.0V. LG Chem’s testing conditions for rating Fast and Max. discharge values are as follows:
Cells shall be charged at constant current of 4000mA to 4.2V with end current of 100mA. Cells shall be discharged at constant current of 10000mA and 20000mA to 2.0V. Cells are to rest 10 minutes after charge and 30 minutes after discharge.
2.0V is considered the lowest possible safe cut-off voltage for discharging any 18650 cell. Most 18650 cells cut-off at 2.5V. This 0.5V difference translates to a higher milliamp hour rating, but at expense of utility. (We see a similar parallel between the LG HE2 and HE4 fast discharge conditions).
Most people do not want to go below 2.5V for safety concerns, and if they do the low voltage environment does not provide ideal performance.
2.7 Max. Discharge Current
A 20 amp cell - very good.
Note that this is the cell's maximum continuous discharge rating. Some people seek pulse ratings, which are often fabricated.
Remember: a pulse is defined as current over time. Without stating time, pulse lacks meaning. An example of a proper pulse rating would be 30 amps for 2 seconds. A cell rated at anything above 30A, without an attached unit of time is, in essence meaningless. None of the big three (Panasonic, LG, Samsung) make an 18650 battery rated at over 30A.
2.9 Operating Temperature
Standard, no comment
2.10 Storage Temperature
Standard, no comment
- Never charge below freezing (important for the solar readers: always keep your batteries in a temperature controlled environment.)
Visual Inspection & Basic Measurements
Here is the top-cap, or positive terminal of the HG2. Note there are four top-cap connection points on LG 18650 batteries.
There should be no rust, discoloration, spots, burn-marks, excessive scratch marks, or anything else out of the ordinary. As this cell has been recently produced (Summer 2015 batch), they are new and the steel will reflect that. If your new HG2 has any of the abnormalities listed above, request a return with your vendor and suspect a counterfeit battery.
This is the negative terminal, or bottom of the LG HG2. Nothing abnormal here. There are a few scratch marks (usually circular) on the bottom even on brand new cells. This is normal and from production, as the cells are tested and charged and the steel scratches easily.
Height: 65.1mm - check. (Do not do this with metal calipers as you may short-circuit the cell.)
Width: 18.5mm - no problems here. If you are making a pack, note they are a little bigger than 18mm.
Weight: 44.86g. Let's call it 45g from measurement error. Where does that leave us? With a max. specified weight of 48g - it leaves us just fine. Albeit I will weigh a few more later just to confirm, a 3 gram discrepancy from maximum value does not cause alarm.
Discharging the LG HG2
Accounting for the test's environmental temperature. This is five points off an ideal temperature (LG Chem's test opted for 25 degrees C), but at this difference the efficiency loss is negligible and I will go ahead.
I enjoy charging my 18650 batteries on the VC2. The big display just makes my life better.
This is our 18650 discharging unit. The readout is volts (that last digit is a V and not a U if you were wondering). As you can see this battery is running out of juice, and the discharge test is almost complete. This unit runs off of USB power and as such it has an unfortunate current limit of 3A.
For the first discharge test I used a 2.50 amp current with a cut-off voltage of 2.50V. The capacity is 40mAh hours short of the rated capacity of 3000mAh. Does this mean the battery is not meeting its rated stats?
Yes and no.
Here's what I mean.
For one, the cell in this test is a few months old. A lithium-ion battery will lose some capacity every month it sits in storage. When we are concerned about 40mAh, some of that is attributed to its age.
I could also tweak my testing environment to fit LG's testing conditions by:
- bring down cut-off voltage
- change the environmental temperature
- change amp discharge rate
- reduce the charging rate
- match end current
Having said that, calling this a true 3000mAh battery is stretching the truth. It is more accurately stated as a 2960mAh battery.
Discharge test two confirms the HG2 capacity at ~2960mAh.
For discharge test three I changed the current to 0.50A. As you can see, at lower amperage discharges, the capacity goes up. (In this case, about 6 mAh were gained).
In this image I overlapped the 2nd (2.5A) and 3rd (0.50A) discharge test so you can see what is really going on.
If you look at the bottom-right of the chart, the difference along the X-axis (mAh) is small.
However the Y-axis of Voltage shows a bigger difference. You can think of this as the batteries lasting about the same amount of time, but the low amperage one gaining more working power. A higher voltage for longer results in more watt hours. The watt-hour rating can be argued as just as important as the capacity (mAh) rating.
Unwrapping the PVC
There are three markings to be found on this particular LG HG2 battery.
These are quality control markings and likely batch identification codes. If you unwrap your HG2 and notice it has very different markings please leave a comment describing them.
Here is another look at the top-cap in all its glory, this time without the heat-shrink PVC or washer.
In the beginning I claimed the HG2 may be the best high-drain battery available right now. Unfortunately the cell I tested does not quite meet its mark at 3000mAh. It however does clock in at 2960mAh.
Even if we call it a 2900mAh, or a 2800mAh battery - it still surpasses the Samsung 25R (2500mAh) and the LG HE2 (2500mAh).
There are cases which this can be shown wrong, in particular in high-drain tests at 20A which I did not perform. It is however, highly unlikely that the capacity will be effected enough so that it can not exceed 2500mAh.
It is for that reason I am fairly comfortable claiming the HG2 is quite a beast, and I crown it as the current king of high-drain.