Electrolytic in Maha charger exploded

[PhotonWrangler]

I have a MaHa C777Plus-II charger. I've been using it for the past year or so with no trouble.

Last night I walked into the room where it was and I noticed a slight burning odor. The odor was a little too faint to pin down it's location so I figured it was nothing. The charger wasn't plugged in nor was there a battery in it, although I had been charging a battery recently.

About 10 minutes after I noticed the odor, there was a loud POW!

Disassembling the unit revealed a small electrolytic cap that had blown rather violently. It was located between the two white power resistors. I'm not sure there's enough of the cap's case remaining to be able to read the value, but if I can, I'll replace it and hope for the best.

Has this happened to anyone else with a MaHa?

 

[Bones]

Disassembling the unit revealed a small electrolytic cap that had blown rather violently. It was located between the two white power resistors. I'm not sure there's enough of the cap's case remaining to be able to read the value, but if I can, I'll replace it and hope for the best.

I would suggest contacting Maha before you undertake repairs.

Who knows, they may find your experience unique and/or troubling enough to offer an exhange so they can attempt to determine the cause.

At the very least, they may be able to explain what happened.

Although a relatively minor burst inside the charger seems innocuous enough, I can't help but wonder what the consequences would have been had it been plugged in.

Just one more reason never to use chargers on or near flammables.

 

[PhotonWrangler]

The metal casing of the electrolytic was blown off the printed circuit board from the force, leaving only a frayed wad of dielectric material and a portion of the outer sleeve on the board. Had this kind of thing happened in the open, the metal casing would've been fired into the air like a bullet.

My first thought is thermal runaway, possibly fueled by some sort of a chemical reaction inside the cap. It was so weird that it was smoldering when everything was unplugged; the reaction must have started while I was charging a battery.

I'll contact the manufacturer and see what they say. Thanks for the recommendation, Bones.

 

[Illum]

bad cap....if the cap was of bad quality it will overload despite what the specs say....theres a couple articles on bad caps on motherboards and some have been about leaking and exploding caps while the computer is at off

the manufacturer wouldn't know about it unless they look through every component by testing them

 

[NA8]

What are they putting in caps these days ?

I remember a lot of electrolytic caps blowing because they were inserted with the wrong polarity and the power was on, but I've never heard of one just going off like that.

 

[Bones]

After reading your first post again, it's obvious that my use of the phrase "a relatively minor burst" was a gross understatment PhotonWrangler.

Sometimes ignorance is bliss though. This incident will no doubt come to mind the next time I'm peering into one of my electronic "necessities".

Mind you, a black humourist would surely then have a endless supply of witticisms about the poor soul shot through the heart by his faithful charger...

 

[SilverFox]

Hello PhotonWrangler,

Interesting...

By all means contact Maha and tell them what happened.

Tom

 

[jrmcferren]

I also say contact maha, they will probably replace the charger at no cost to you. The capacitor should not have failed while the charger was unplugged unless there was a battery in it. Most people forget that their motherboards on their computers have power when turned off to keep the clock and to wait for a power-up command, and battery power when unplugged to keep the clock.
I've seen bulged caps in computer equipment, but none that have blown completely.

 

[PhotonWrangler]

...Mind you, a black humourist would surely then have a endless supply of witticisms about the poor soul shot through the heart by his faithful charger...

Hmm, sounds like a potential segment idea for MythBusters. :huh:

**EDIT** I've just written to Maha Energy Corp and explained the situation. We'll see what happens.

 

[PhotonWrangler]

I received a reply today from Maha which apparently explains the failure. I was charging an 18v battery when the charger is only rated to 14.4v.

Sure enough, that limit is printed on the box and in the manual, although it's nowhere on the unit itself. What fooled me is that the display always starts out at 22v, which lead me to believe that this was it's maximum capacity.

I blame myself for not noticing this in the manual, but I also believe that this limit should also be stamped on the unit itself... especially when going a few volts over the limit can cause an explosion. :duh2:

 

[matrixshaman]

Yeah - that's strange and you only went 3.6 volts over from the battery side? That seems like their circuit should have been able to tolerate that much over and yes that to me would also be confusing for them to have a display start at 22 volts but it won't charge over 14.4 volt. It SHOULD be stamped on the charger - maximum battery voltage. What happens when people throw away the box and lose the manual? What if you sell it without the manual - it's going to blow up based on someone else assuming the same thing?