Charger charged reversed battery

[Hawise]

This actually happened a while ago, but I'm wondering if anyone can tell me what the charger thought it was doing. I have an xtar VC4. Like most chargers, it's supposed to recognize a reversed battery. I've given it a few opportunities to do so, and it had always given me the appropriate error up until this occasion.

So, I put my batteries in the charger and, instead of watching to see it start up properly, I unwisely walked away. I passed the charger a few minutes later and noticed the display looked odd. It turned out it had recognized one battery as a NiMH and was happily charging it. Closer inspection revealed the battery was in backwards - positive to negative. I pulled it out, turned it around and put it back in. The charger correctly recognized it as a Li-ion and was about to start charging when I came to my senses and yanked it out of the charger. I watched the battery warily for a while, and when it failed to do anything untoward I disposed of it appropriately.

Several months later, I'm still wondering how on earth the charger recognized a reversed 18650 as a NiMH, and what was going on when it thought it was charging it. Any ideas?

 

[Baditude]

No, but I bet @Mooch has some ideas.

 

[Shadav]

go home charger, you're drunk....
but seriously...maybe time to get a new charger

 

[00jim2]

Recognizing a cell put in reversed is a safety feature. As tempting as it can be I would never put my batteries in backwards on purpose. Sounds like it would have saved you a couple of times. Very curious though how it managed to think it was a NiMH battery. This underscores the importance to check that your charger had started the charge cycle correctly before walking away.

 

[DaveP]

Backwards or forwards it still should been able to correctly assess the cell and should have read reversed potential on a positive post right away and rejected it. I vote for scrambled firmware or damaged electronics.

The charger should have read - 1.3v or lower on the NiMh cell or - 2.5v or higher on a lithium cell and been able to differentiate. A reversed cell pole swap should have been easy for it to catch.

 

[bombastinator]

This actually happened a while ago, but I'm wondering if anyone can tell me what the charger thought it was doing. I have an Xtar VC4. Like most chargers, it's supposed to recognize a reversed battery. I've given it a few opportunities to do so, and it had always given me the appropriate error up until this occasion.

So, I put my batteries in the charger and, instead of watching to see it start up properly, I unwisely walked away. I passed the charger a few minutes later and noticed the display looked odd. It turned out it had recognized one battery as a NiMH and was happily charging it. Closer inspection revealed the battery was in backwards - positive to negative. I pulled it out, turned it around and put it back in. The charger correctly recognized it as a Li-ion and was about to start charging when I came to my senses and yanked it out of the charger. I watched the battery warily for a while, and when it failed to do anything untoward I disposed of it appropriately.

Several months later, I'm still wondering how on earth the charger recognized a reversed 18650 as a NiMH, and what was going on when it thought it was charging it. Any ideas?

Not here. I’ve got one too though. Kind of anyway, an Xp4 plus dragon. I guess I’m going to have to take special flesh based vigilence precautions with it and NEVER EVER put a battery into it backwards until this is figured out. I hate doing that stuff. I’m not particularly good at it.
XTAR will hate it more though if someone pops a battery in one of their chargers and burns their house down. That’s a lawsuit that could take their company down.

It is not impossible that this is a very dangerous error.

Putting this thread on watch.

 

[stols001]

Yeah I have an Xtar too. It has never done what you are describing. Glad you caught it but really.... I might consider a new charger, unless you can warranty it? I might ask, personally.

However the cost of a replacement charger far outweighs the potential cost of an explosion.

But I'm interested in this.... The charger was showing as actually charging the battery? Do you think it actually was? Or just applying current to the back end to no avail? I mean, was it hot or anything like that?

Anyway good luck with it,

Anna

 

[DaveP]

I have the Xtar VC4 also, but haven't reversed a cell to check the polarity protection.

ETA: I put in a fully charged cell reversed and the display said, "ERR". Of course, I don't have a zero volt cell to use for checking that scenario. Zero volts might not even trigger the logic.

 

[Vinnybagodoughnuts]

@XTAR-Justin

 

[BillW50]

I know this charger very well and it is a damn good one too. And the only way this could happen is your cell is at or near 0v. Thus the reverse polarity protection has no clue what the polarity is supposed to be. There is no way I would ever use that cell again.

 

[Hawise]

But I'm interested in this.... The charger was showing as actually charging the battery? Do you think it actually was? Or just applying current to the back end to no avail? I mean, was it hot or anything like that?

It wasn't hot. I'm not sure it was actually charging. It was showing the NiMH display, but the charge indicator was moving up very quickly - too quick for it to be a normal response for charging.

I know this charger very well and it is a damn good one too. And the only way this could happen is your cell is at or near 0v. Thus the reverse polarity protection has no clue what the polarity is supposed to be. There is no way I would ever use that cell again.

Xtar-Justin has been in touch and agrees with your assessment. On one hand, I don't see how it would have been zero because I'd taken it out of my mod where it had been behaving normally only an hour before and hadn't noticed anything peculiar in the mean time. Also, it doesn't explain how it recognized it as a li-ion when I turned it back around. On the other hand, I can't think of another explanation for its behaviour, so I guess I'll have to accept that something weird happened to the battery and its charge somehow collapsed after I used it.

I can assure you that I didn't try to use the cell again. I immediately covered the ends with electrical tape and checked it for heating for a while. As soon as I was relatively sure it wasn't going to blow up, I marched it over to London Drugs and deposited it in the battery recycling bin. I was reluctant to even sleep with that thing in the house!

 

[Fidola13]

If you watch Mooch’s latest video the battery does not need to be hot to be severely damaged internally. It’s rather frightening.

 

[Lordron's_Drag]

Oh boy.