AW Protected Cell Question

[recDNA]

If I use an AW protected 18650 in an unregulated flashlight will the protection circuit prevent me from discharging it to a dangerously low voltage?

Will the protection kick in and shut down the battery if it is overheating?

If the flashlight is well regulated for the 18650 does it prevent over discharge or overheating better?

If there is no protection against the battery voltage dipping too low how do you know when to recharge? I cetainly don't want to have to dig out the multimeter every time I use the flashlight.

Since the protection circuit is supposed to prevent overcharging isn't a cheap charger safe anyway with AW protected cells? Thats how the WE charger works with WE protected cells. It just keeps charging until the battery protection prevents further charging.

 

[Marduke]

The protection circuit is a failsafe. You should never rely strictly on it. You should normally recharge a cell long before it trips the protection circuit, and use a charger that does not rely on it to terminate.

 

[lolzertank]

One reason the protection circuit is only a failsafe is that it doesn't always work. AW's cells are pretty reliable, but the protection circuit can be shorted out from drops and too much pressure from the spring. Then you have no protection. However, you'll THINK you still have protection which is worse than having unprotected cells.

The other reason is that with LiCo cells, the more protection the better.

 

[45/70]

Marduke and lolzertank are absolutely correct.

I think many who use protected Li-Ions don't realize that the protection circuit added to protected Li-Ions is not a convenience added to to make the cells easier to use, but a last resort failsafe installed to protect the user from bodily harm or injury in the event that the user neglects to follow proper Li-Ion battery usage guidelines, and should be treated as such.

Dave

 

[Bullzeyebill]

Best to never depend on a "failsafe" solution re LiIon's. I treat all my LiIon's, protected or unprotected, the same. Monitor, monitor, monitor.

Bill

 

[Chodes]

In an unregulated light, the protection circuit may not activate anyway.
Particularly for a lower power LED , as the battery voltage slowly drops , so does the current. You can end up with very low battery voltage as the low current may not trip the protection circuit.

When a laptop, for example , is being designed , cells without protection circuits are built into a pack with a protection circuit specifically for the intended application. The same cells could be found in power tool and the same designers may chose very different parameters when designing the protection circuit.

AW ( or Ultrafire etc) has no idea what light you will use is cells in and all the variables. They can only provide a circuit that will provide some level of safety while allowing flexibilty for us to use in various applications.

To me , using a regulated light without built in low voltage shutoff or warning is like driving a car without a fuel gauge. Not saying it's stupid. But you have to maintain awareness to avoid inconvenience and possible danger.

 

[wapkil]

In an unregulated light, the protection circuit may not activate anyway.
Particularly for a lower power LED , as the battery voltage slowly drops , so does the current. You can end up with very low battery voltage as the low current may not trip the protection circuit.

I believe it is a (common) misconception that the protection circuit needs a high current to trip. It does not but if the current is low, the voltage in the battery will drop really slow. It will eventually drop to the level that would activate the protection but it the protection is set to a low level (like ~2.5V in AW batteries) at this time the battery will be overdischarged. I wrote a bit more about it here.

When a laptop, for example , is being designed , cells without protection circuits are built into a pack with a protection circuit specifically for the intended application.

[...]

To me , using a regulated light without built in low voltage shutoff or warning is like driving a car without a fuel gauge.

I don't know if it is obvious but laptop batteries actually use a circuit called "battery fuel gauge" to monitor how much energy is left :)

 

[wapkil]

If I use an AW protected 18650 in an unregulated flashlight will the protection circuit prevent me from discharging it to a dangerously low voltage?

It depends on what you mean by "dangerously". The protection circuit used in AW's batteries AFAIK will let them to go down to ~2.5V. Except extremely high loads, this level means that the battery will be overdischarged. I don't think it will be dangerous but I think it will affect its life.

Other protection circuits may have different cutoff voltage. For example EagleTac cells, according to the specification, stop at 2.8V. At lower currents it is much better for batteries although probably also not recommended.

Will the protection kick in and shut down the battery if it is overheating?

I don't know, you can probably find it in the AW batteries description somewhere. I think it should. Actually it is not always necessary to have a protected battery for that. Many unprotected cells have a PTC switch inside that will cut off the current if the battery is overheating. I think though that the inner cells in AW batteries don't have it.

If the flashlight is well regulated for the 18650 does it prevent over discharge or overheating better?

The regulation by itself won't protect you. Quite the contrary - in an unregulated light when the battery voltage lowers you can see the brightness drop. With current LEDs, the light will merely glow at the end of the discharge and you'll see that it's time to change the battery. A regulated light will keep the output constant and it can overdischarge the battery without you noticing it.

Since the protection circuit is supposed to prevent overcharging isn't a cheap charger safe anyway with AW protected cells? Thats how the WE charger works with WE protected cells. It just keeps charging until the battery protection prevents further charging.

Once again, this is the result of the differences in protection settings. I think that WE batteries, similarly to EagleTacs, have it set to 4.2V. This a safe level, although it is of course better to have both the charger and the battery to keep an eye on it. AW's batteries apparently (according to user reports on CPF) have an overcharge level set at 4.35V which is too high and unhealthy for batteries. They won't explode, but the lifetime can be drastically reduced.

EDIT: I believe that the protection levels in AW batteries are set, as frequently described, to provide only a last resort failsafe. I think it is a trade-off. If they were set more conservatively, like e.g. in EagleTacs, under really high loads the batteries would cutoff earlier than necessary. The overcharge protection circuit would also prevent the batteries from being charged in many chargers that are unwise enough to rise the voltage above the recommended level. These more conservative setting, on the other hand, would provide longer battery life for users with an "abusive" devices (e.g. lights without the overdischarge protection). For my needs these conservative settings seem more suitable.

 

[LuxLuthor]

Wapkil, Chodes and others answered it, and referred to the most important downside of relying on the low voltage protection to break the circuit. In low current applications (LED's & some Halogen bulbs), the cells start to get progressively damaged as voltage drops below 2.8-3.0V. The farther the cell dips, and the longer it spends at too low of voltage determines the degree of irreversible damage to the cell's life and capacity.

In low current applications (<1-2A), IMHO, a 2.5V cutoff is too low and I would prefer a 2.8V protection circuit. In higher current (>4-5A), when the cell is empty, its voltage will drop like a stone, trigger the 2.5V cutoff, and quickly rebound back into a safe 3.2-3.3V zone with practically no damage done, unless you keep clicking an empty light back on.

Since AlanB, JimmyM, and wquiles have come out with their programmable protection circuits, I generally use that to choose a 3.1V per cell average cutoff of the pack, since some cells may be higher and lower. I may not get every last mAh of stored energy out of the cell, but the cells will last longer.

 

[lolzertank]

I think 2.75V is a good cutoff for very high drain DD lights. My 12xRebel Mag drains about 4A from 2x18650 and even fully charged the batteries sag to ~3.3V. By 2.75V, the tint shifted very heavily to the red end of the spectrum showing that the white LEDs were dimming significantly. This dimming continued for about a minute before one cell decided to cutoff, leaving me with only my Fenix E01 to take out the trash. :D

 

[recDNA]

I think 2.75V is a good cutoff for very high drain DD lights. My 12xRebel Mag drains about 4A from 2x18650 and even fully charged the batteries sag to ~3.3V. By 2.75V, the tint shifted very heavily to the red end of the spectrum showing that the white LEDs were dimming significantly. This dimming continued for about a minute before one cell decided to cutoff, leaving me with only my Fenix E01 to take out the trash. :D

Why did you have to throw away the flashlight?

 

[recDNA]

Wapkil, Chodes and others answered it, and referred to the most important downside of relying on the low voltage protection to break the circuit. In low current applications (LED's & some Halogen bulbs), the cells start to get progressively damaged as voltage drops below 2.8-3.0V. The farther the cell dips, and the longer it spends at too low of voltage determines the degree of irreversible damage to the cell's life and capacity.

In low current applications (<1-2A), IMHO, a 2.5V cutoff is too low and I would prefer a 2.8V protection circuit. In higher current (>4-5A), when the cell is empty, its voltage will drop like a stone, trigger the 2.5V cutoff, and quickly rebound back into a safe 3.2-3.3V zone with practically no damage done, unless you keep clicking an empty light back on.

Since AlanB, JimmyM, and wquiles have come out with their programmable protection circuits, I generally use that to choose a 3.1V per cell average cutoff of the pack, since some cells may be higher and lower. I may not get every last mAh of stored energy out of the cell, but the cells will last longer.

Where would I buy batteries with programmable protection circuits? Are they preset at a level I request or do I actually do it somehow?

 

[recDNA]

From what I've read here I would deduce Wolf Eyes 18650's and even the Eagletacs are safer than AW's yet AW gets the best reviews. Is there anything wrong with the Eagletacs or W.E.'s?

 

[45/70]

From what I've read here I would deduce Wolf Eyes 18650's and even the Eagletacs are safer than AW's yet AW gets the best reviews. Is there anything wrong with the Eagletacs or W.E.'s?

I think you missed the point that a lot of the posters were trying to make, recDNA. If you regularly trip the protection circuit in your cells, you the user, are the largest safety risk.

As for AW's cells, they may/may not have better protection cicuits, but they are some the most consistant cells available. You don't have to "weed out" the bad ones like with others.

Dave

 

[recDNA]

I think you missed the point that a lot of the posters were trying to make, recDNA. If you regularly trip the protection circuit in your cells, you the user, are the largest safety risk.

As for AW's cells, they may/may not have better protection cicuits, but they are some the most consistant cells available. You don't have to "weed out" the bad ones like with others.

Dave

I don't believe I missed the point.

I don't even own a rechargeable flashlight battery. My goal is to select the safest battery - not challenge the limits of it.

Are there tests that show Eagletac and W.E. are of inconsistant quality?

I would prefer the circuits to trip sooner rather than later if a failsafe is ever needed.

 

[45/70]

I don't believe I missed the point.

OK, fair enough. :)

There are tests of both of those brands, I believe. Try the "Google Search" near the top of the page. It works a lot better when you're looking for a specific result. One thing you want to look for is a test that includes more than one sample of each of the cells being compared.

Dave

 

[lolzertank]

Why did you have to throw away the flashlight?

So the garbage collector man would join CPF... why else?

I didn't throw it away, I was using it while taking the trash out and it ran out of juice. :cool:

 

[Bullzeyebill]

Here is a link to some 18650 tests. Wolf Eyes are not included. I believe that Wolf Eyes are unprotected, not sure though. http://www.candlepowerforums.com/vb/showthread.php?t=235025

Bill