Why do the contacts on batteries need cleaning every so often?

Phil2015

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I have a Nitecore tinymonster rechargeable LED touch that uses 18650 batteries, and this is the third time Ive had to clean the contacts in about 3-4 yrs... The light starts dimming and then if you tap the light, it brightens up again. Is this normal as never remove the batteries to charge the light?
 

SYZYGY

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or maybe the plating wore off, and oxide's getting in the way?
 

Sharrack

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My 14500 battery contacts rust over the summer on my EDC ultrafire mini light.
Screenshot_20230112-175227_Gallery.jpg
 

Phil2015

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All the contacts on the light are copper coloured, the light is the TM26.. Theres nothing that I can see on the battery contacts when the light starts miss behaving, but cleaning both ends of the batteries fixes the problem.
 

hamhanded

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Try some silicone paste on the contacts. It'll make a mess of your battery but if it can charge in the light you likely won't notice.
 

SYZYGY

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Try some silicone paste on the contacts. It'll make a mess of your battery but if it can charge in the light you likely won't notice.

i think that's worth a try. clean everything up really well and verify a low resistance connection first, though. also, remove moisture as well as you can.

btw, by paste, he means grease and not sealant (caulk) :)

you could also use a grease specifically labeled for the task. look for "dielectric grease"
 

chillinn

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Try some silicone paste on the contacts. It'll make a mess of your battery but if it can charge in the light you likely won't notice.

Don't do that, because it will never work, and never work again.

you could also use a grease specifically labeled for the task. look for "dielectric grease"

Silicone or dielectric grease is an insulator and will not conduct electricity. What I think was meant was electrical grease.

this is the third time Ive had to clean the contacts in about 3-4 yrs...

My 14500 battery contacts rust over the summer on my EDC ultrafire mini light.

The corrosion is occurring due to the chemicals inside the battery escaping and coming into contact with the conductive metal of the battery terminal and your light's metal spring or contact. Recycle your crappy batteries and get some decent cells produced by, in no particular order, Samsung, Sanyo/Panasonic, Sony, Molicel, Imren, Keeppower, Vapcell or Efest.

Also, not for nothing, in order to not abuse your Li-ion cells, you must never overcharge above 4.2V nor over-discharge below 2.5V. You must never drop your cells or your light. You must always rest your cells after use and before charging and after charging and before use. 1-2 hours is sufficient.

And with such a cheesy Ultrafire light with built-in charger, it likely sucks. Get a decent smart Li-ion charger, such as from NiteCore, they're usually less that $30, often less than $20. While you're at it, get a decent 18650 flashlight: example #1, example #2, example #3, example #4, example #5, example #6, example #7, example #8, example #9, example #10, example #11, example #12, and a decent 14500 flashlight: example #1, example #2, example #3, example #4, example #5, example #6, example #7, example #8, decent 14500 cells (their lights may be ok for some, but Olight labeled cells are notoriously bad at producing current), and toss that Ultrafire in an electronics recycle bin.

cleaning both ends of the batteries fixes the problem.

Not really. Your cells are the problem. Get decent cells from the list I made above, and put your old cells in a battery drop at Home Depot, Builders Square, or Lowe's, etc.i
 
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SYZYGY

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Spray some deoxit gold on the terminals and you won't have these issues as frequently.

^ this is another good suggestion

Don't do that, because it will never work, and never work again.
...
Silicone or dielectric grease is an insulator and will not conduct electricity. What I think was meant was electrical grease.

lol... do you say this from experience? forgive me if i'm incorrectly assuming that you're not, but...

the "electrical grease" you linked to is actually an example of a dielectric grease... further...

it's true that dielectric grease is an electrical insulator (dielectric material), but believe it or not, its use on electrical terminals is the correct application of the product. on a terminal, the grease is displaced enough at high pressure areas of mechanical contact to form a low resistance electrical connection.

the primary purpose of the grease is to keep out moisture and oxygen to prevent formation of oxide (which would give a high resistance connection). it also has some limited ability to prevent seizing and galling, although an anti-seize compound works much better.

the dielectric property is incidental on single-contact, low voltage connections -- as a nonpolar substance, grease just happens to be nonconductive. but on multi-contact terminals or in high voltage applications (well above flashlight voltages), a high dielectric value is critical. you don't want the grease to create shorts between contacts on multi-contact terminals, between the terminal and the environment, or between the terminal and a user.

there are greases impregnated with graphite or metal dust that make them electrically conductive, but they usually aren't used for that reason. they're used to inhibit galvanic corrosion and galling. they're also used to increase heat flux rate through thermal interfaces (thermal interface material/grease).
 

SYZYGY

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The corrosion is occurring due to the chemicals inside the battery escaping and coming into contact with the conductive metal of the battery terminal and your light's metal spring or contact. Recycle your crappy batteries and get some decent cells produced by, in no particular order, Samsung, Sanyo/Panasonic, Sony, Molicel, Imren, Keeppower, Vapcell or Efest.

Also, not for nothing, in order to not abuse your Li-ion cells, you must never overcharge above 4.2V nor over-discharge below 2.5V. You must never drop your cells or your light. You must always rest your cells after use and before charging and after charging and before use. 1-2 hours is sufficient.

aren't the batteries in this thread liions? have you really seen those leak and cause corrosion? i never have.

i figured the corrosion was just caused by contamination from the environment. or from the corrosion-resistant plating wearing off on the spring or something.
 

chillinn

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In fact I have seen, more like smelled, Li-ion vent its electrolyte. They were Coolook 10440 LifePO4, and I actually did see one of them squirting. Take a close look at any Li-ion positive contact, and you will notice it has vents. This is a safety feature to reduce the effect of thermal runaway, so pressure doesn't build up and cause an explosion. Any Li-ion cell will vent under the right conditions, but decent cells won't regularly vent under normal use. Usually gas is vented, but I actually saw the Coolook expel its electrolytic fluid, not all at once but like it was being pumped out.
 
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chillinn

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lol... do you say this from experience? forgive me if i'm incorrectly assuming that you're not, but...

the "electrical grease" you linked to is actually an example of a dielectric grease... further...
Thank you. I put too much faith in Ford Motorcraft's misuse of the descriptor "electrical," to hilarious effect.
 

Robert Crayton

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It sounds like you have been experience some isuues with the contacts on your 18650 batteries in your nitecore tinymonster rechargeable led torch, the facet thta you have to clean the contacts in a period of time is likely due to a buid-up of dirt, corrosion or oxidation on the contacts.

It is not uncommon for the contacts on batteries need to be cleaned. particularlly if the batteries are not used frequently or if they are exposed to environmental factors such as humidity or air. In your describe: since you mentioned that you never remove the battery to charge the light, the batteries are always exposed to the internal environment of the light, and it could be possible that the environment inside the light is causing the oxidation or corrosion.

Cause you noticed that the lights stars dimming and brightens up agian when you tap the light, this is a sign that the contacts are not making a good contaction. Clean the contacts with a pencil earaser or a soft cloth dipped in rubbing alcohol should help to remove any dirt, corrosion and oxidation and improver the connectivity.

If the issue persist after clean the contacts, it could be an indication of a problem with the charging circuit of your light, and it may be time to consider getting it reparied or replaced.:ROFLMAO:
 

chillinn

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These are the batteries I bought with the light and they wern't exactly cheap https://www.torchdirect.co.uk/batteries/nitecore-18650-2600mah-li-ion-protected-battery.html

Do you live on or frequent the beach? Do you live on a boat on the ocean? Because the only environment I know that can cause corrosion on metal is salty moist air.

All cells have vents. That should be the smoking gun. All cells have vents because any cell can get hot enough to vaporize its electrolyte and outgas, and less frequently can even eject some of its liquid electrolyte. If the vents weren't there, and the cell got hot, pressure would increase inside the cell, but it would have no where to go but kaboom.

Do you think your cell ever got pretty hot? If it did, the pressure inside the cell increased, and if the pressure increased inside the cell, maybe it sent out some of its chemistry. I'm not saying it definitely did anymore because there is so much doubt in this thread for some reason. But if your cell did release some chemistry, it would corrode any metal that was exposed to it due to a chemical reaction between the metal and the acidic electrolyte.

Is the corrosion reasonably even across all metal surfaces? Gas will expand to fill the container it is in, and any metal exposed to it would more or less corrode evenly. But often as not, around near the vents of the cell, there may appear to be more corrosion than elsewhere because it was exposed to all the gas as it escaped, if it was released.
 
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