How LOW Can U GO???

[recDNA]

Jack be limbo, Jack be quick
Jack go unda limbo stick
All around the limbo clock
Hey, let's do the limbo rock
Limbo lower now
Limbo lower now
How low can you go

Ok, I'm not really talking about the best party song ever written...

IMR cells are not protected so the voltage can drop pretty quickly. I just wonder how low the voltage an IMR16340 or IMR18650 drops to that it is still OK to recharge them? Of course I know not to go below 3.7 volts but if I do at what voltage should I just throw them away rather than trying to recharge them?

I assume my protected AWRCR123 can't drop to a point that would make them dangerous due to the protection circuit but again if they do at what voltage should they be considered TOO LOW to recharge safely?

 

[old4570]

Very personal ....

For me I try and stop @ 3v , but usually I charge them up way before that .
I only go down to 3v when testing batteries ..

Protection Circuits are set at 2.7v or 3v depending on where / what battery you buy , even many lights have protection set at 3v ..

Many a CR123A EDC wont work with primaries as the protection is set to 3v and they are made for rechargeables ..
I have quite a few CR123A lights that wont even turn on with primaries ...
The other thing is , voltage under load , and voltage at rest ...
So I guess Im talking voltage under load ...

 

[VidPro]

IMR cells are not protected so the voltage can drop pretty quickly. ?

When the voltage "drops Quickly" they are done, after resting they can bounce back up a bit from the "LOAD" you had on them.

so how low should you go? RIGHT THERE, where you said, when the voltage starts to take its dive, the cut-off is right before that.

loaded, or resting, and what is the load, is all conciderations.

because Cut-Off point is the state of its charge , or the "capacity" drained not actually the "voltage". UNDER LOAD, the actual cut-off voltage as SEEN with the combined battery & load curcuit. the cutoff point varies depending on the load.

also robust li-ion like this type your referring to hold voltage better, and the capacity is done at a slightly higher voltage than a normal 2C type li-ion. (if both have the same load)

So all you gotta do is ask yourself:
what is the load, and how does it effect the visualised voltage?
what is the cell type? robust, depending on the load it is mostly depleated at a slightly higher voltage, or generally will start to voltage tank a bit higher , compared.

the biggest problem being when in series, with incans, or using boost drivers, you dont nessisarily see it start to drop. especially if the use is intermittant.

You know you CAN actually put protection on them, nothing really stopping that other than the general use of them is on devices that draw more current than cheap easy to grab protection can do. and when used with great currents, the protections added minor resistance isnt helpfull.

soo terminate "early" and re-top off, or again just like the other ones, right before the voltage starts streaking downhill. (precognition

A person could potentially make a protection alogrythm that detects a sharp decrease in voltage , that being the end of its capacity, almost everytime. but there are probably many things that would get in the way of that being as simple as i said it.

 

[old4570]

Sorry , many consider 2.5v as being the danger zone ...
The PTC would need to fail with a protected battery to get down that low .

 

[recDNA]

And so at 2.4 volts you would throw the battery away? That's what I need to know...the resting voltage (rule of thumb) at which you would pitch an imr rather than even trying to recharge it?

 

[old4570]

And so at 2.4 volts you would throw the battery away? That's what I need to know...the resting voltage (rule of thumb) at which you would pitch an imr rather than even trying to recharge it?

Sorry , if you head on over to the marketplace , and check out the IMR sales thread , it say's the IMR is rated to 2.5v max discharge , so 2.4 is not that far from 2.5v ...
If you were talking about a regular 18650 , id say toss it . But since its an IMR , I would throw it in the charger but very carefully monitor the cells temp and make sure it was accepting a charge .
I have an IMR , but have never taken it bellow 3v , but the IMR is supposedly a more robust battery capable of more than your regular 18650 .
Since its at resting voltage , you may have taken it to as low as 2v under load , its up to you , I would try it , but keep a very close eye on it for the first hour and pull it every now and again and check to see if the voltage is going up .. Its your call ..