OMG!!!! My battery justn now EXPLODED

[MorpheusPA]

I just Googled very quickly to make sure. NiMH cells are 1.2V each, so what you had was a battery of four cells. Apparently big cells are expensive and rare. Seems like charging should also be slow, around 8 hours minimum and if they are overcharged they can be dangerous too.

To a point. They dislike taking charge at high amp ratings and throw away any excess amerpage as heat. This is not as dangerous as it sounds.

NiMH tolerate overcharge fairly well so long as the current isn't excessive, and they're quite happy being overcharged as much as 0.1C (I don't recommend doing this as a matter of course, naturally). Excess current is discharged as heat, and does not harm the batteries over the short term. Long term overcharges will shorten battery life or destroy the battery (very gracefully, there will be no fire).

For that reason, they're commonly used in unmoderated solar applications. They'll easily toss the excess current as heat and no charge circuitry is required. Simply apply a reasonable voltage and trickle charge.

I do that all the time, actually, and battery life is measured in years. My applications don't stress the battery under load, however, and I'm always careful to trickle at well below 0.1C. 0.05C is somewhat common for me, 0.02 is not unheard-of.

Your experience with these does not sound good Baditude. I was actually hoping Nikkel might be able to shed some light on the intricacies of NiMH batteries since he's obviously vaping them.

Personally, I'm kind of neutral on the concept. Lithium is going to tolerate higher drain well. NiMH is unarguably safer, but I wouldn't expect excellent output consistently, and I wouldn't expect the battery lifespan to hold up to spec.

 

[MorpheusPA]

"Three 18650 NiMH 4.8v batteries used back to back couldn't last a entire day. In comparison, an AW 18650 IMR lasts me an entire day."
Most reports I've seen claim 4AAA last a day, and 4AA last several days. The discharge curve for NiMH is flatter than Li-ion.

AAA is around 1,000 mAh, AA around 2,500. I could kill a set of four AAA batteries in about 4 hours. AAA would last all day.

Discharge curve doesn't matter quite so much if the device is moderated, the internal chip will shift the voltage to the setting given. In a mechanical mod, your NiMH would tend to spend a long time at 1.2 volts (4.8 total assuming series batteries), which would actually mean I'd prefer to use 3 (my sweet spot is right around 3.6 V).

 

[Nikkel]

"Forget theory, let's get PRACTICAL"
Let's also get strategic. One of the reasons Uncle Sam wants to regulate us is public safety concerns regarding our batteries. The OP's exploding battery is evidence that some public safety concerns are legitimate. If we vaped NiMH, exploding ecig batteries would be unheard of, or almost so. Uncle Sam would have one less (legitimate) reason to rain on our parade.

 

[Myrany]

"Forget theory, let's get PRACTICAL"
Let's also get strategic. One of the reasons Uncle Sam wants to regulate us is public safety concerns regarding our batteries. The OP's exploding battery is evidence that some public safety concerns are legitimate. If we vaped NiMH, exploding ecig batteries would be unheard of, or almost so. Uncle Sam would have one less (legitimate) reason to rain on our parade.

And it would not matter one whit to Uncle Sam.

The safety crap is another mokescrean. Uncle Sam's campaign against vaping is about MONEY make no mistake about that.

Tax revenue, BT settlement money, and donations from BP

 

[Ryedan]

AAA is around 1,000 mAh, AA around 2,500. I could kill a set of four AAA batteries in about 4 hours. AAA would last all day.

Discharge curve doesn't matter quite so much if the device is moderated, the internal chip will shift the voltage to the setting given. In a mechanical mod, your NiMH would tend to spend a long time at 1.2 volts (4.8 total assuming series batteries), which would actually mean I'd prefer to use 3 (my sweet spot is right around 3.6 V).

Thanks for all the good information Morpheus! A few more questions for you. How safe are these? Do they simply never burn? Shorts, the wrong charger used, heat, cold, etc.?

 

[Fisheeboy]

nice cheap asian batterys do that sometimes. it's called a runaway.
the chemical reaction just goes nuts randomly
and the cheap ones dont have any much protection from this.
a good battery will have a circut that prevents this.
wait until you get one that goes nuts in your backpack.

There was definitely a run away. Everything inside that battery ran away from its casing really quickly. I couldn't say whether or not the batteries(well one battery left now) are Asian, Chinese, whatever. I'm having difficulty with thinking the battery itself was the problem here. I way more inclined to think and say it was operator error on my part simply because of mixing and matching charging devices. I would love to dodge the blame on this if I could but if I did that then I wouldn't be comfortable with myself knowing that there are others making the same mistake and therefore I feel that no matter what is said on this thread I want there to always be a fixed topic of battery safety come from it. People are people and they will deviate to other issues and that's fine but if I decide to add anything to this thread again I want to try to discipline myself by sticking to that point, Safety. And if that kind of battery energy were to ever happen inside of my backpack then I would be called Rocketboy instead of Fisheeboy Thanks for your input, I appreciate it

 

[Nikkel]

Neither. It's a secret. The secret of NiMH is here.

It's over here:
NIMH · Home

 

[MorpheusPA]

Thanks for all the good information Morpheus! A few more questions for you. How safe are these? Do they simply never burn? Shorts, the wrong charger used, heat, cold, etc.?

NiMH safety is excellent due to their overcharge tolerance, self-limiting output (although larger NiMH packs delivering 10 A at higher voltage can be a bit dangerous when shorted), and much lower energy density.

Use the wrong charger, however (put it on your lithium charger) and prepare to see some fireworks. NiMH batteries absolutely CAN vent and will (Wikipedia has a photo of a popped cap: Nickel)

Short it and that sucker is going to get hot--both from internal resistance, and from the metal shorting it getting very hot. That's true of any battery, really, except maybe zinc-air (where reactions are so slow that only milliamps are available at any one time). The price of having good energy supply and a battery that can power reasonably complex and power-hungry electronics is some risk.

Like lithium, they have a safety valve (so do my lead-acid gel cells, they're pretty much universal). Said safety valve will open if pressure becomes too great, which will happen during charging if it's going to happen at all. Venting hydrogen is flammable, of course, so fire wouldn't be out of the picture if you apply a spark.

I've never seen an NiMH fail in years of working with (and, I confess, sometimes abusing) them. I also've never seen a lithium vent, but I'm very careful with them. It's wise to treat any battery with respect as even the weakest store a fair amount of energy.

Power output varies somewhat by temperature, but NiMH function fine under warm, cool, and cold conditions. My ultraviolet solar design functions fine in a Pennsylvania February (15° F) and July (can hit 100°; in the UV light, where the box is black, temperatures undoubtedly hit 120+). I spec the electronics I build to be tolerant of very wide ranges (usually -45 to 150), I expect the battery to keep up without doing anything nasty.

 

[Nikkel]

AAA is around 1,000 mAh, AA around 2,500. I could kill a set of four AAA batteries in about 4 hours. AAA would last all day.

I think watt-hours is a better predictor of vape time than amp-hours.
How many mL of juice [do you] vape daily?

 

[MorpheusPA]

AAA is around 1,000 mAh, AA around 2,500. I could kill a set of four AAA batteries in about 4 hours. AAA would last all day.

I think watt-hours is a better predictor of vape time than amp-hours.
How many mL of juice to vape daily?

Watt-hours and amp-hours are essentially just two sides of the same equation-- Watts = Volts * Amps. Or, a 2,000 mAh lithium battery contains right around 7.4 watt-hours.

Both measures are strongly influenced by the battery drain rates, and batteries will underperform spec if they're drained at high rates (quite apart from manufacturers sometimes inflating specs). In some of my electronics, the batteries actually over-perform by a fair amount, but I make every mAh I'm drawing from the battery count and keep the drain as low as I can figure out how to do!

I whirl through 10 ml of liquid a day, so I'm a chain vaper to the extreme. I can drain a 1,300 mAh battery in 5 to 6 hours.

For a light vaper, AAA NiMH might last all day, but for the given (and relatively reasonable) average of 100 mAh per hour vaping, they'll supply about 10 hours of power to the average vaper.

 

[Nikkel]

"2,000 mAh lithium battery contains right around 7.4 watt-hours."

A 2,000 mAh pack of 4AA batteries contains about 9.6 watt-hours. With the higher voltage, you would want a higher resistance atty to get the same thrill as when vaping at lower voltage with Li-ion.
10 mL per day seems like a heck of a lot.

 

[Nikkel]

"100 mAh per hour vaping"

Undoubtedly that estimate is based on 3.6 or 3.7 volts from Li-ion. When ecig batteries are mentioned, Li-ion are assumed. NiMH are assumed to be non-existent.

 

[Nermal]

I am glad you started the thread, Fisheeboy I hope you haven't come to regret it as nearly all have learned something even if we did drift from the main topic. For myself, I learned that Blu chargers have a polarity opposite to everything else on the market. I don't think I'll ever need the information, but you just never know.

 

[Fisheeboy]

I am glad you started the thread, Fisheeboy I hope you haven't come to regret it as nearly all have learned something even if we did drift from the main topic. For myself, I learned that Blu chargers have a polarity opposite to everything else on the market. I don't think I'll ever need the information, but you just never know.

I don't regret this thread. There has been some really great information shared here. The safety awareness being the most important imo. But any info that can be used from this thread is valuable and is beneficial to the forum.
One of the things that has impressed me about this thread is that so far there have been zero posts deleted.

 

[Robino1]

I don't regret this thread. There has been some really great information shared here. The safety awareness being the most important imo. But any info that can be used from this thread is valuable and is beneficial to the forum.
One of the things that has impressed me about this thread is that so far there have been zero posts deleted.

Hahahahaha!! Looked like it could've been close for a couple posts.

 

[Vapor Vinny]

I actually gave the NiMh 5 volt batteries a try in an 18650 mechanical mod well over a year ago. Battery life was poor and quickly declined over a couple of weeks use. They required a special battery charger. I became so frustrated with them I stopped using them and purchased a regulated mod which uses high drain Li-Mn batteries. Much better performance and battery life.

I don't think we're taking about the same thing. My mod uses 4 rechargeable AAA batteries you can find at Walmart and requires no special charger. The mod is smaller than most other box mods. The batteries last a good long time. It's certainly cheaper than LIPO batteries in my experience. The drawback with using AAA batteries is you are limited in what you can build in terms of cosmetics.

 

[LEDBETTER122]

I happened to read this right before I was going to test my first Sub-Ohm coil...........lol

 

[Fisheeboy]

I happened to read this right before I was going to test my first Sub-Ohm coil...........lol

I don't really know anything about sub-ohming. It sounds kinda interesting(maybe a little intimidating too for some reason) but I'm in no hurry to try anything like that. I'm still figuring out chargers

 

[edyle]

"Forget theory, let's get PRACTICAL"
Let's also get strategic. One of the reasons Uncle Sam wants to regulate us is public safety concerns regarding our batteries. The OP's exploding battery is evidence that some public safety concerns are legitimate. If we vaped NiMH, exploding ecig batteries would be unheard of, or almost so. Uncle Sam would have one less (legitimate) reason to rain on our parade.

Right; so; which of the common NiMH batteries can I get to work in my common VAMO.

Or maybe there's a regulated mod out there made for the 26650 size battery that has enough room to rig something up;;

actually maybe the vamo v5 working on a fat telescopic mech might be workable?

 

[edyle]

I don't think we're taking about the same thing. My mod uses 4 rechargeable AAA batteries you can find at Walmart and requires no special charger. The mod is smaller than most other box mods. The batteries last a good long time. It's certainly cheaper than LIPO batteries in my experience. The drawback with using AAA batteries is you are limited in what you can build in terms of cosmetics.

Hmm.. What to say about that;
... ah ok how about....

I think you mean the drawback for YOU is cosmetic because you don't care for VV, VW etc; YOU are happy with a plain mech.