# Leaking ENELOOPS!



## viorel00 (Dec 21, 2008)

I had 2 Eneloops in a Braun toothbrush. A couple of weeks ago I noticed a discoloration when I opened the toothbrush, but I though it must be water and toothpaste that got inside. I wiped everything off and put them back.








Today I took them out to charge, again wiped them off to make sure they're dry and put the in my MAHA-C9000. A little later I wanted to check to see if they're charged, one was DONE, was was still charging, and I took the one DONE out and noticed some white powder on the MAHA charger. Like one of those Alkaline batteries leaking except this was a NiMH Eneloop. What the heck?

I took the other eneloop out and cleaned the charger, (I think it's OK), and now I looked at both cells, *I cleaned them up (there was a lot of white powder)*, and you can see a *hole* in the left cell (the one that leaked), and what appears to be a forming hole (not broken though yet) on the right cell.






I have probably 20 enenloop cells, and this is the first time I use them in a Toothbrush, and I cannot figure out what caused this. My first guess would be that moisture caused an electro-chemical between the material in the negative terminal of the cell and the contacts in the toothbrush, but I am not sure what they're made off and if that makes any sense. I think you can also see some corrosion in the positive terminal, but it's not a through hole like in the negative terminal.

has anyone seen something like this?

EDIT: this are genuine ENELOOPS that I got in various places like Ritz camera, HHGregg, COSTCO. No eBay or other dubious places.


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## paulr (Dec 22, 2008)

Sounds like it vented from overcharging or reverse charging.


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## WildChild (Dec 22, 2008)

Are you sure your toothbrush contacts didn't puncture them? I've seen leaking Duracell Pre-Charged (rebranded Eneloop), but it was with the Energizer 15 minutes charger that isn't gentle with batteries at all.


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## viorel00 (Dec 22, 2008)

I doubt it was overcharging, I use a MAHA C-9000 and the first cell stopped after about 1200 mAh.

I looked at the toothbrush, and the contacts are not sharp at all, and they are very flexible. I don't think this could have caused the puncture in the cell.


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## UnknownVT (Dec 22, 2008)

Looking at the pics - with the rust coloring getting under the wrapper - it seems that water had got into the battery compartment of the toothbrush -
which probably means that the eneloops were operating/discharging while wet - this obviously can't be good - this is probably the cause of the malfunction.


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## Lynx_Arc (Dec 22, 2008)

UnknownVT said:


> Looking at the pics - with the rust coloring getting under the wrapper - it seems that water had got into the battery compartment of the toothbrush -
> which probably means that the eneloops were operating/discharging while wet - this obviously can't be good - this is probably the cause of the malfunction.


I have leaking nimh when they are charged but most of the time the white powder is harmless so if it isn't causing any problems with usage or corrosion I would just keep using those two batteries till they quit and check them at times clean up the powder etc.


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## Mr Happy (Dec 22, 2008)

Is this toothbrush designed for alkaline batteries? It is possible that in attempting to extract the maximum capacity from alkalines it is over discharging the NiMH cells, and perhaps reversing the polarity of one of the cells. You might try recharging more frequently.

I have a Philips Sonicare toothbrush that I am running a pair of Hybriloops in. It switches off automatically when the batteries are low, and so far they seem to be working OK without any signs of deterioration.


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## coppertrail (Dec 22, 2008)

UnknownVT said:


> Looking at the pics - with the rust coloring getting under the wrapper - it seems that water had got into the battery compartment of the toothbrush -
> which probably means that the eneloops were operating/discharging while wet - this obviously can't be good - this is probably the cause of the malfunction.


I was going to say the same thing, this likes more like rust than leakage from the cells themselves. 

I use eneloop AA cells in my Spinbrush pro and I coat the rubber ring with Nyogel to help prevent water from getting into the battery compartment. So far, so good.


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## viorel00 (Dec 22, 2008)

yes, there is definitely rust, I agree, but there was also a large amount of white powder (which I cleaned off, I as said in the original post). I think the left cell is definitely leaking.

anyway, no big deal, I just wanted to make sure this is not a general problem with Eneloops, so far I am very happy with these cells, I have probably 20 or so, and plan to buy more.


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## Illum (Dec 22, 2008)

if the toothbrush contacts only in one area [in this case, one point] discharging current through that point while wet with impurities could mean a couple different things, such as regional corrosion either on the toothbrush contact or the battery, whichever is more reactive.

Eneloops have vent holes towards the anode, from the discoloration pattern I believe the vent may have been punctured but not in a forceful manner [you don't see the discoloration jet out in a specific manner] and its simply from the electrolyte flowing out and oxidizing.

It may also be the nature of the toothbrush's electronics
consider this:


Curious_character said:


> I've sometimes seen furry white stuff which came from the cell. I recall reading at manufacturers' web sites that this could result from leaving the cell connected to a very low current drain load which completely discharges the cell. This could happen in flashlights where the on/off function is controlled by circuitry instead of a mechanical connection of the main current path, if you left the battery in the light for a long time.
> 
> c_c



Did you measure the residual capacity of the cells when they were first removed from the toothbrush?

the Cathode end of the metal feels rather coarse [at least to me] by hand, a toothbrush will oscillate the entire assembly while under operation, could there be some sort of protrusion on the contact that is cutting the hole like an ultrasonic blade? Its very unlikely that the hole is being formed from the inside out, more like outside in. 

On the AA cells, here reads [pardon the caps]
Size AA HR6
Model HR-3UTG 1.2V Typ. 2,000 mAh. 1,900 mAh


DO NOT DISPOSE OF IN FIRE, NOR SHORT-CIRCUIT
CHARGE ONLY WITH A SANYO SPECIFIED CHARGER
DO NOT INSERT BATTERIES WITH (+) AND (-) ENDS REVERSED
IF LEAKED LIQUID GETS IN EYES, WASH THEM WITH CLEAN WATER AND CONSULT A DOCTOR IMMEDIATELY
It seems to be that leaking was in design, but heres where it gets interesting
see here: *Dissasemble Enloop gizzard pics*
yes, your looking at that correctly, ENELOOPs are relatively identical in the component assemblies like that of CR123As...they are essentially rolled electrodes like capacitors. If this is the case for all cells...I have no idea what "fluid" might exist. I fail at failing when it comes to chemistry


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## MorePower (Dec 22, 2008)

Illum_the_nation said:


> It seems to be that leaking was in design, but heres where it gets interesting: *THERE IS NO LIQUID ELECTROLYTE IN ENELOOPS*
> see here: *Dissasemble Enloop gizzard pics*
> yes, your looking at that correctly, ENELOOPs are relatively identical in the component assemblies like that of CR123As...they are essentially rolled electrodes like capacitors. If this is the case for all cells...I have no idea what "fluid" might exist. I fail at failing when it comes to chemistry



All cylindrical NiMH cells are built with rolled electrodes.

Also, they all contain liquid electrolyte, in the form of aqueous potassium hydroxide (KOH). They may appear to be relatively dry, but that's simply because the anode and cathode soak up the KOH solution and there is very little free electrolyte left to slosh around. When NiMH cells vent and leak, it is aqueous KOH that comes out, reacts with carbon dioxide in the air, and forms the white crystals that you typically see on leaking cells.


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## Illum (Dec 22, 2008)

MorePower said:


> All cylindrical NiMH cells are built with rolled electrodes.
> 
> Also, they all contain liquid electrolyte, in the form of aqueous potassium hydroxide (KOH). They may appear to be relatively dry, but that's simply because the anode and cathode soak up the KOH solution and there is very little free electrolyte left to slosh around. When NiMH cells vent and leak, it is aqueous KOH that comes out, reacts with carbon dioxide in the air, and forms the white crystals that you typically see on leaking cells.




IIRC KOH has a pH around 13-14...not at all "harmless" as accordance to Lynx_Arc's standards oo:


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## MorePower (Dec 22, 2008)

Illum_the_nation said:


> IIRC KOH has a pH around 13-14...not at all "harmless" as accordance to Lynx_Arc's standards oo:



The white powder is pretty much harmless. It's potassium carbonate, the reaction product of KOH and carbon dioxide. KOH isn't really that bad, either, provided you just wash your hands shortly after touching it.


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## hank (Dec 22, 2008)

One thought -- I've seen nice soft springs that had knife-sharp tips on the (the spring wire was probably cut off a coil). [email protected] for example!

The vibration of a toothbrush could make that kind of tiny sharp edge on a spring work like a power chisel, even with the spring not being very compressed.

Even in ordinary flashlights, I've see this kind of edge carve into the base of a cell.

Another thought --Which model Braun? Is the toothbrush recharging the Eneloops?

If so that's outside their guideline, isn't it? Not that it would have deterred me, but maybe there's a reason (like, a steady charge that doesn't cut off could be a problem)?

You could also try contacting the company and seeing if they want a look at the cells -- I've done this several times with other companies and they've always sent me some credit and usually a mailer to return the cells.


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## h2xblive (Dec 23, 2008)

I have eneloops that look like that as well, and as many have already mentioned, I believe that's rust. I used those eneloops in a toy boat.

However, I did not suffer from white power like the OP.


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## viorel00 (Dec 23, 2008)

OK, I don't want to use the cell in the left ever again, I am 120% sure it leaks, I am going to squeeze it later with a pliers and see if more stuff comes out. I am sure that's a hole.

The cell in the right (the one not perforated yet) I may keep around for various less critical apps


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## zipplet (Dec 23, 2008)

BTW, Not a good idea to squeeze cells because it can short them out, although with a fully depleted nimh I doubt that anything will happen.


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## csshih (Dec 23, 2008)

looks exactly like water got in the battery compartment.. yuck!


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## TinderBox (UK) (Dec 28, 2008)

Hi.

I have slight brown leakage or corrosion on the positive terminal on one of my eneloops, I have wiped away some of the leakage before i took the picture.

It has been in my digital camera for a couple of months, and is totally dry.

I have only used an Accumanager 20 charger and the battery`s only get warm when charging in that.

Regards

John.


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## JWP_EE (Dec 28, 2008)

Is that a nick in the case on the same side as the leak?

If it was dropped and damaged it may be the reason for leaking.


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## TinderBox (UK) (Dec 29, 2008)

Hi.

I suppose it could be possible that it could have been dropped, but i have had a close look at the nicked area and their is no dinting of the metal.

I am usualy very carefully not to drop my battey`s but it does happen for time to time.

Regards

John.



JWP_EE said:


> Is that a nick in the case on the same side as the leak?
> 
> If it was dropped and damaged it may be the reason for leaking.


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## hank (Dec 29, 2008)

I'd suspect that break in the cover; if you don't return the battery to the manufacturer, you might try cleaning off the rust (wipe, not wash!) and putting a bit of glue or paint over the chip in the plastic there at the rim. I'm just guessing there's some current flow somewhere there shouldn't be with that break. Any rough metal edge inside the flashlight for example?

Pure speculation on my part.


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## Bobo The Bear (Dec 29, 2008)

I don't know about the nick on your battery, but ALL of our batteries, whether alkaline or rechargeable, in our electric toothbrushes end up looking like your picture. It's because water gets inside. I really should try to waterproof these better or get new ones.


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## crofty (Feb 1, 2009)

2 of my hybriloops were in garden solar lights for a few months, I would bring them in every sunday to charge them, on the last inspection they had rust on the top and side of the possitive nipple, now their in the TV remote.





Definatly don`t like moisture. I`m tempted to disect and see what it looks like under the white disk :devil:


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## Keatah (Sep 17, 2010)

I wonder if this couldn't be a problem with a slight standby discharge from the device. Devices that don't have a hard switch that breaks the electrical path mechanically when turning off will always have a tiny discharge current of around 50 to 100 uA current draw.

Apparently nimh cells don't like that and that small current draw will cause leakage over time. Is that the case here? Could be.

From the looks of the hole, it seems like something drilled it from the outside in. That could be electrolytic action from moisture on a contact, along with physical vibration applied by a sharp contact spring. The sharp points cut through debris and oxidation, but seems they damage the cells.

It would also seem that the ni-mh cells have a different bottom or negative terminal that is not as durable as an alkaline cell. Is that the problem here? Dunno..!

Please report to me about any other leaking eneloops, anyone!!


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## Sugarboy (Sep 18, 2010)

it's not the Eneloops leaking, it's your toothbrush not being water-tight enough. (maybe the o-ring?):wave::wave::wave:

in short, your eneloops are water-damaged.


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## sgt253 (Sep 18, 2010)

I did the same thing with a pair of Eneloops in my Sonic Care. Disregarded the lack of lube on the o-ring and got water to seep in. Rusted my two batteries and contacts. I saved the batteries but had to throw out the Sonic Care. Good Luck!

Regards.


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## gshack (Sep 20, 2010)

Guys, I am a NOOB here. The water damage explanations sound very reasonable to me. Lots of issues with dissimilar metals and moisture causing corrosion.

With the toothbrush, is there any possibility of the vibration also contributing to the damage? With the vibration, water and other possibile contaminants, seems like a pretty hostile environment for your expensive rechargeables.


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