Short answer: a swollen LP-E6 must come out of service immediately. It cannot be repaired and it must never be punctured to vent gas. Fast drain is usually a rise in internal resistance from aged cells, cold conditions or long storage at full charge. When the body refuses to recognise a pack, check contact oxidation and the decoder circuit first. Each of the three has a completely different remedy, so identify which one you have before deciding to repair or replace.
All three share one trait: none of them happens suddenly. Swelling is usually preceded by long periods stored full or used in high heat; fast drain is often preceded by charge levels that jump; a pack the body will not read has often been dropped, exposed to water, or left with blackened contacts. Watching for those early signs is far more useful than reacting afterwards.
Swelling: the only correct response is to stop
The physical cause of swelling is gas generation inside the cell. Overcharging, over-discharging, high heat and simple ageing all break down the electrolyte and release gas, which pushes the foil pouch out and bows the casing. The process is irreversible, and no household method reverses it.
How to check. Lay the pack flat on a table or a sheet of glass and press gently on the corners. If it visibly rocks or lifts, it has swollen. If it feels tighter than usual going into the body, or the door needs force to latch, suspect swelling too. A slight bulge is invisible to the eye but changes how the pack seats.
Three things never to do. Do not pierce it to release gas — lithium reacts violently with air. Do not put it in a freezer — condensation inside raises the short-circuit risk. Do not put it back in the camera to “use it a few more times”. None of these is excessive caution; each is a common origin of real incidents.
What to do instead. Stop using it, cover both terminals with insulating tape, keep it alone in a metal container away from anything flammable, and get it to a hazardous-waste point or battery collection bin promptly. Do not put it in household rubbish and do not leave it sitting at home for months.
One related note: if a swollen pack is already jammed in the bay, do not lever it out with tools. Take it to a repair centre — damaging the bay or puncturing the cell both cost more than a new battery.
Fast drain: rule out the environment, then suspect the cell
| Symptom | Most likely cause | How to check | What to do |
|---|---|---|---|
| Full pack drops to half in a week | Standby drain inside the body | Remove it and repeat the week | Take the pack out when not in use |
| Drains very fast outdoors in winter | Cold raises internal resistance | See whether charge partly returns once warm | Keep spares against your body |
| First 70% is fine, last 30% shuts down | Aged cell, steeper voltage curve | Watch whether it repeats | Replace the pack |
| A new pack is worse than the old one | Overrated capacity or poor cells | Compare charge time and heat | Return it, buy one with clear ratings |
| Gauge jumps from 3 bars to 1 | Inaccurate decoder estimate | Run a full charge/discharge calibration | Replace if calibration does not help |
Cold deserves separate treatment. Below freezing, electrolyte viscosity rises and lithium ions move more slowly, so usable capacity shrinks — you see two bars left and a warning after a handful of frames. The pack is not broken; capacity partly returns once it warms up. For how much is lost at different temperatures, the data in this minus 10°C battery test comes from another pack, but the trend is the same.
A pack the body will not read: start at the contacts
When the body reports a communication error or an unrecognised battery, work through the following in order. Eight out of ten cases are solved by the first two steps.
- Clean the contacts. Take the pack out, rub the terminals and the metal tabs inside the bay with a clean pencil eraser, then wipe with a cotton swab and anhydrous alcohol, let it dry and refit. Oxide layers and fingerprint grease are the most common cause.
- Cross-check with another pack. Fit a known-good pack into the same body. If it behaves, the original pack is the problem; if the error persists, the fault is in the body contacts or firmware.
- Check the firmware. Some bodies change how they handle third-party packs after an update. If you upgraded recently and the pack used to work, read the official release notes first.
- Check for water damage or a drop. Corrosion on the protection board after moisture, or cracked solder joints after a fall, both break communication. Damage of that kind usually comes with a deformed casing or an odd smell.
If cleaning and cross-checking both fail, the decoder circuit inside the pack has failed. Such a pack will often still supply power, but the body cannot read its charge and treats it as unknown. That is acceptable for unimportant work, but do not take it out for anything that matters — you have no way to predict how much is left.
Making one last longer
- Do not store packs at full charge. Around half is the most stable state; top up before you go out.
- Do not run them to shutdown. Swap at the last bar, because deep discharge damages the cell cumulatively.
- Avoid heat. Do not leave packs in a car in summer, and do not charge them on a duvet or a sofa.
- Use a matching charger. The LC-E6E will charge all four LP-E6 generations; unbranded chargers with inaccurate cut-off voltages are a common cause of swelling.
- Run a full charge and discharge every so often so the body can recalibrate its curve — every three to six months is enough.
For how the four generations differ in capacity and discharge, see the LP-E6 family section. Owners of smaller bodies face the same logic but a different pack, covered in the LP-E17 section.
FAQ
Can a slightly swollen pack still be used?
No. Swelling means gas has formed inside and the casing has lost mechanical strength; continuing to charge and discharge risks rupture and fire. “Slight” only means it is not yet visible — a tighter fit in the bay is already the signal. Retiring it is the only recommendation.
Does fast drain mean the pack is failing?
Not necessarily. Rule out three external factors first: was it left in the body on standby, was it used in the cold, had the firmware just been updated. If none applies, run a full charge and discharge to recalibrate. Only if it still drains fast should you conclude the cells are aged.
Can a third-party pack damage the body?
A properly built compatible pack will not harm the camera in normal use. The risk comes from two kinds of product: cheap cells with no protection board, which can overcurrent, and casings with poor dimensional tolerance that are hard to insert and wear the contacts in the bay. Choosing a brand with clearly stated specifications keeps the risk manageable.
What is the safest way to store an old pack?
Charge to about half, store it separately, keep it away from metal objects and top it up every three to six months. Once a pack has swollen or leaked, treat it as hazardous waste rather than keeping it at home. Store it away from radiators, balconies and anywhere children can reach.