Radio batteries: Li-ion vs Ni-MH, capacity, storage and safety

The battery is the one part of a radio that ages even when you aren't using it. A great handheld with a dead battery turns into a brick that "lasts ten minutes" and then swells up in the cabinet on top of it. And yet 90% of power problems aren't about hardware — they're about habits: how we charge, how we store, and what marketplace nonsense we believe. Let's break it down in plain language: how Li-ion differs from Ni-MH, why "9800 mAh" on a cell is a lie, how to extend battery life, and what to do if it swells (spoiler: don't charge it and don't puncture it).

What's actually inside your radio

There are three chemistries on the market today, and the difference between them is fundamental:

In practice: if a radio was bought in the last decade or so, it almost certainly has Li-ion inside (often one or two 18650 cells, or a flat LiPo pack), rated at 3.7 V per cell, usually 7.4 V in the pack. Ni-MH today is either retro gear or an emergency holder for ordinary AA cells that's handy to keep in a backpack "just in case", because Ni-MH isn't damaged by deep discharge and won't start a fire. Ni-Cd is only found alive in very old hardware and is no longer considered a sensible replacement — cadmium is toxic and has to be disposed of separately.

The capacity myth: where "9800 mAh" comes from

Visit any marketplace and you'll see 18650 cells labeled "9800 mAh", "8800 mAh", "6000 mAh". Remember this number: the real ceiling for an honest 18650 cell today is around 3500 mAh, with the top cells (Panasonic, Samsung, LG, Sony/Murata) at 3400–3600 mAh. Anything above 3600 is either a marketer's typo or an outright scam. You can't cheat the physics of volume: you simply can't fit more lithium into a standard 18×65 mm cylinder.

How brazen are the lies? Independent measurements of "9800 mAh" cells from these platforms give a real 800–1100 mAh — that is, 8–10 times less than printed. Inside such a "cell" there is often a stub of a real cell, packed with sand or cement for weight. So the first honest test is a scale.

• A proper 18650 cell weighs 43–50 grams.
• If it's labeled "3000+ mAh" but weighs 25–30 grams, it's a fake with ballast or a dead cell.
• The same rule applies to flat radio batteries: a suspiciously light "extended" pack with a giant number is a reason to be wary.

You can measure capacity precisely with a cheap battery analyzer/capacity meter (such as XTAR, Opus BT-C3100, LiitoKala and similar). It discharges the cell at a controlled current (usually 0.5C) down to a cutoff threshold of ~2.8–3.0 V and shows the real mAh. You can also estimate roughly without an instrument: a new brand-name 3000 mAh cell in a radio that draws, say, 1.5 W on standby receive should give you many hours of operation; if "6000 mAh" dies in an hour and a half, you were cheated by two or three times.

Correct charging and storage

Li-ion lasts longest when it works in a "comfortable" mid-range state of charge and doesn't overheat. The main rules:

1. Don't run it flat. Deep discharge is the number-one killer of lithium. Put it on the charger when the radio shows 20–30%, not when it has already shut off.
2. Don't keep it at 100% forever. A constant full charge speeds up aging. If a radio sits in a cabinet as a standby unit, both zero and a hundred are bad for it.
3. Store at 50–60%. For long-term storage (a month or more), the optimum is exactly the middle. Studies show that storing a cell at around 50% charge in a cool place dramatically slows degradation — over years the cells lose a few percent of capacity instead of tens of percent.
4. Cool (but not freezing) is the friend of storage. The ideal storage temperature is 5–20 °C. Rule of thumb: every ~10 °C rise in temperature roughly halves the service life. A car glovebox in summer is the worst place.
5. Don't leave it on the charger for months. "Drop it in the cradle and forget it for half a year" means a constant 100%, heat from the board, and risk if the charger is junk. Charge it, then take it off.

Degradation: when to replace

Every Li-ion ages two ways: from charge-discharge cycles (cyclic aging) and simply from time (calendar aging). It's generally held that after 300–500 full cycles a cell drops to about 80% of its initial capacity — still a working state, but the "lifespan has shortened". Signs that it's time for a replacement:

• The radio "dies" twice as fast as a year ago under the same load.
• Under transmit load (TX "eats" current) the voltage drops sharply and the unit goes into protection/reboots, even though the indicator showed a charge.
• The cell gets hotter than warm during normal charging.
• There's play/bulging in the battery casing and the compartment won't close — this is no longer "wear", it's a hazard, see below.

A small honest test without instruments: fully charge it, run it in normal mode, and time how long it takes to reach 20%. Compare with what you got when new. A drop by half — replace it, especially if the radio is your workhorse on the network.

18650 cells and the USB-C charging mod

Many radios (and almost all "extended" battery packs) have standard 18650 cells inside. That's handy: the pack can be opened and rebuilt with fresh brand-name cells if the holder shell is intact and you have spot-welding skills. But this is exactly where fake "high-capacity" cells turn up most often — don't fall for the numbers, buy name-brand cells.

One pleasant trend is batteries with built-in USB-C. Manufacturers (Baofeng BL-5, BTECH and others) ship factory packs of 1500–3800 mAh with a Type-C connector right in the housing: charge it with a phone cable, no cradle needed. This is more convenient and safer than homemade mods, because the charge controller is already built in and matched to the cell.

Li-ion safety: the essentials

No jokes here. When damaged or overheated, Li-ion goes into so-called thermal runaway: the internal chemistry starts heating itself, flammable gases are released, and it ends in a jet of flame or an explosion. Swelling is already a signal that gas generation has started inside and the cell has degraded.

What to do with a swollen/damaged cell:

1. Remove it from the charger and the device without pressing or deforming it.
2. Place it in a non-flammable container (metal, ceramic) or a special fire-resistant bag, away from other batteries and belongings, in a cool ventilated place — ideally outside the living space.
3. Don't throw it in the regular bin. Li-ion is hazardous waste; hand it in at a battery/electronics collection point. Many electronics stores and service centers accept batteries for recycling.