Ok lets talk voltage

[corybrown40]

pulled out the old volt meter and tested some bats and what do ya know.....

XL manual 3.85v
standard manual 4.22v
shortmatic 4.19v

I believe that is higher than 3.7

 

[Davo]

Hmmm CB, that's interesting; I've been meaning to do the same but it hasn't occured to me when I'm in the shop where my meter(s) are. Assuming they're all fully charged, I'm curious why the decrepancy. Maybe some others will supply some answers and I'll try yo remember to check mine when I get home this evening. --- Welcome in by the way!!

 

[Adrenalynn]

At what charge state?

It's higher than 3.7 because it's under no-load and relatively fresh.

3.6v is typically nominal. The range of the cell is permissibly 2.8-4.2v under load. In a consumer device, shutoff should be 3.0-3.1v under load. Under no load, I wouldn't be surprised to see 4.4v... You really want to drill the battery housing, splice off the switch, and graph voltage and current draw over time to get a really effective picture. (It's on my to-do list. )

 

[corybrown40]

Hmmm CB, that's interesting; I've been meaning to do the same but it hasn't occured to me when I'm in the shop where my meter(s) are. Assuming they're all fully charged, I'm curious why the decrepancy. Maybe some others will supply some answers and I'll try yo remember to check mine when I get home this evening. --- Welcome in by the way!!

well 2 are basically the same. The XL neverdid work real great. Not many people realize also that Mah is not how powerful it is but the realitive length of time it keeps a charge. Wish i had more batts to test hint hint Steve. j/k

 

[Adrenalynn]

errr - I've gotta differ with you a bit.

mAh is the number of millamps that can be delivered for one hour before the cell is entirely dead. Alas, we can't drain them entirely, so the number is somewhat misleading, hence the need for "duty cycle". But if we figure a battery has a 50% duty cycle and 500mAh capacity, that means that it can deliver 250 milliamps continuously for one hour before it's no longer able to deliver adequate current to power the device. Or 500mA for 30mins. Or 125mA for two hours, and so on. Over that period, the voltage will ramp down, but far less for a Li* chemistry battery than for a lead acid or seal lead or nicad, etc.

Not to be confused with the battery's ability to deliver burst power, or it's maximum deliverable current which may be incredibly much higher. Even 30x or more. Although I believe these batteries are 2C max discharge.


So it IS, technically, how "powerful" it is. Noting that power = work/time, and the amount of power we can deliver into a circuit equates to how much work can be accomplished.

Edit to note: And this is the reason I suggest measuring the discharge cycle, because we're dealing with the internal resistance of the battery in this calculation - typically 320-360ohms in a LiIon cell

 

[corybrown40]

errr - I've gotta differ with you a bit.

mAh is the number of millamps that can be delivered for one hour before the cell is entirely dead. Alas, we can't drain them entirely, so the number is somewhat misleading, hence the need for "duty cycle". But if we figure a battery has a 50% duty cycle and 500mAh capacity, that means that it can deliver 250 milliamps continuously for one hour before it's no longer able to deliver adequate current to power the device. Or 500mA for 30mins. Or 125mA for two hours, and so on. Over that period, the voltage will ramp down, but far less for a Li* chemistry battery than for a lead acid or seal lead or nicad, etc.

So it IS, technically, how "powerful" it is. Noting that power = work, and the amount of power we can deliver into a circuit equates to how much work can be accomplished.

aahhh ok so it is how long it will last.

 

[Paranoyed]

the hell with all you electricians yall are making me feel dum D U M dum.

 

[corybrown40]

the hell with all you electricians yall are making me feel dum D U M dum.

I was tryin to keep it simple but yes adrenaline is correct in what he said also I am not a electrician I am a auto mechanic same thing really these days.

 

[Paranoyed]

I know I appreciate anybody with more knowledge than me I just had to point out how lost I got reading this thread.

 

[corybrown40]

I know I appreciate anybody with more knowledge than me I just had to point out how lost I got reading this thread.

I think your just being paranoid

 

[Paranoyed]

I think your just being paranoid

Might be the whole knife thing.

 

[Adrenalynn]

I edited to clarify and expand. And fix the silly "power = work" which would have hanged me instantly over in the physics forum... (and it's "she" - but I'll let you slide this time. )

 

[corybrown40]

I edited to clarify and expand. And fix the silly "power = work" which would have hanged me instantly over in the physics forum... (and it's "she" - but I'll let you slide this time. )

Oh snap I am sorry she. My bad. would explain the ar-15 though

 

[Adrenalynn]

[shrug] No big. Common mistake. Less so in person. RocketVapor probably suffers from the same thing.

 

[Davo]

Yeah CB Adrenalynn is techy and I love it. Actualy I believe she (please correct it wrong) is an engineer, which tells you why there is that level of knowledge. And just for fun... that would be electronic eng or tech as oposed to electrician (which does wiring and such for buildings). I'm not up to spead on Li battery technology but I suppose the voltage level tolorance is acceptible within those ranges (and especially without a load applied, kind of like a car idleing as oposed to being in gear). I may have to cut an old cart into so to measure the voltage across the heating element while in operation. Inquiring minds want to know... right?

 

[corybrown40]

yep knowledge is everything, with out it we are nothing

 

[Adrenalynn]

eYup - I'm an EE, but also the RMO for our electrician's license - so kinda both.

I'm not that strong in analog electronics though, I'm more on the digital design and programming side of the equation.

You should be able to measure voltage and current under load with a modified battery. As soon as my lab is back together I plan to dig into these a little further. I haven't spent ANY time on the modding forum, but certainly those folks have done this work anyway. (I just enjoy it. )

 

[Scottbee]

Edit to note: And this is the reason I suggest measuring the discharge cycle, because we're dealing with the internal resistance of the battery in this calculation - typically 320-360ohms in a LiIon cell

Ummmm.. don't think so.

With a load resistance in the 3 Ohm range.. you best not have a source impedance in the 300 Ohm range!

 

[Davo]

I'm glad I got it right, I don't want to offend... My technical background was a two year tech colllege for "electronic technician" (soooo would have like the EE route... envious!!!) but that led me into computers though and I've made a good living so I can't complain; but I prefer analog stuff when tinkering (Ham Operator KI4OZY). That wraps it up for me, I'm going home... Later guys (and gals LOL).

eYup - I'm an EE, but also the RMO for our electrician's license - so kinda both.

I'm not that strong in analog electronics though, I'm more on the digital design and programming side of the equation.

You should be able to measure voltage and current under load with a modified battery. As soon as my lab is back together I plan to dig into these a little further. I haven't spent ANY time on the modding forum, but certainly those folks have done this work anyway. (I just enjoy it. )

 

[Adrenalynn]

Ummmm.. don't think so.

With a load resistance in the 3 Ohm range.. you best not have a source impedance in the 300 Ohm range!

Good catch. R_B should be 300 MILLIohm range. 320-360MILLIohm