AW 3100 & hobby charger

[erich]

So, I recently got ahold of a Turnigy Accucell 6 hobby charger, and have been using it to charge some AW 3100mAh ICR batteries (I have 2, always using/charging 1 at a time in rotation). I'm questioning the results I'm seeing, though, and was hoping someone could shed some light on it.

According to this thread, the recommended charge rate is max. 2.1A
AW's LiIon Batteries Sales Thread *Part 12*

And I found the following thread that concurs with my understanding that the "charged capacity" effectively means "how much capacity was added to the battery"
http://www.candlepowerforums.com/vb/showthread.php?293505-Turnigy-Accucell-6...Am-I-missing-something&p=3560835&viewfull=1#post3560835

When charging a single one of these batteries from the point at which my provari starts blinking (battery reads ~3.6v at this point), charging takes about 120 mins. However, the "charged capacity" only reads 600-900mAh, far less than the supposed capacity of this battery. After reading some other posts recommending to charge at significantly less than the maximum, I've also tried 0.5A. Oddly, this didn't run for all that much longer, running around 170 mins with similar results for charged capacity.

The vast difference between the battery capacity and the charged capacity suggests that I'm either undercharging the battery, or that the voltage is dropping long before it has discharged its supposed capacity.

 

[WillyB]

Well first off is your charger the real deal, or a knock-off?

I would say you are over thinking it, forget what the "charged capacity" reads. Just charge a cell till it stops and check the voltage. It should be around 4.18-4.21V or so. Set the cell aside and recheck it a few hours later. With new cells and a charger that somewhat follows proper charging the readings should be about the same. If it 'stays' at the initial reading (a tiny drop is OK) the cell is fully charged. As cells age you may start noticing a gap.

Unless you have need for for it (you got lotsa different type cells and various packs) a more traditional charger would suit you better.

You read the CPForums. There are a few that pretty much follow the correct CC/CV charging algorithms in the $20 - $45 range.

As far as current you can't just go by some number like 500mAh. The Pila claims 600mAh, but the way it chooses to use it results in a rather quick result.

 

[erich]

It's supposed to be the real deal. News to me if it's not...
HobbyKing R/C Hobby Store : Turnigy Accucel-6 50W 6A Balancer/Charger w/ accessories

Previously I was using a WF-188. I ended up going with this instead of something like the Pila for the ability to charge with CC/CV both 3.7v I[CM]R and 3.2v LiFePO4 RCR123.

I could well be over thinking it. It definitely follows the "charged battery works" model. The battery I charged this afternoon came off the charger at 4.17v and now reads 4.14v. I suppose my concern is just that the 3100mAh ICR doesn't seem to "hold more" than a 1600mAh IMR, at least by the "charged capacity" reading from the charger. I should do a discharge test to assuage this concern, but was just wondering if this seemed out of the ordinary.

 

[WillyB]

The battery I charged this afternoon came off the charger at 4.17v and now reads 4.14v. I suppose my concern is just that the 3100mAh ICR doesn't seem to "hold more" than a 1600mAh IMR, at least by the "charged capacity" reading from the charger. I should do a discharge test

No offense, but who cares what the charger reads. Does the Panasonic last longer than the IMR in your PV? I imagine you want longer vapetimes, are you getting them?

FWIW 4.14V sounds a little low for a new cell. Can that thing be calibrated/adjusted?

 

[erich]

I found the calibration menu:
Calibrating the Turnigy Accucell-6 Battery Charger - YouTube
but it's spot on.

It's longer, but doesn't seem like twice as long. As far as caring what the charger reads, it's just the most obvious quantifiable measure. If I pulled through a gas pump and it said it only dispensed 8 gallons for a 31 gallon tank, I'd be similarly skeptical. I trust your input, though. If the charger reading is meaningless, fair enough.

 

[Mylt1]

if im not mistaken that is a smart charger, which means one the battery hits a preset voltage it drops down to a trickle charge to finish topping off the batter. the problem is, 3.6v on a 3.7v battery is almost fully charged so the charger is only trickle charging the battery and is making the mAh prediction off that voltage. next time your provari starts blinking keep vaping till it shuts off. not sure why the voltage is set so high for it to start warning you since 3.7v batteries arent drained till around the 2.5v range.

 

[erich]

Not quite. "smart" generally refers to CC/CV (Constant Current/Constant Voltage), also sometimes referred to as its "charging algorithm". Loosely, this means that the charger maintains a constant current while bring the voltage from the battery's current voltage up to the *max voltage* (not the nominal), and then maintains constant voltage while gradually reducing the current (to roughly 10% of the original constant). I believe what you're referring to as "trickle charging" is the latter of these. It's at the 4.2v maximum, however, not the 3.7v nominal that this transition takes place.

Some chargers will "trickle charge" after a complete CC/CV charge, but for the sake of proper terminology, it's an important distinction that this is after the entire CC/CV charging process has finished.

While 2.5v is the cut-off voltage of the AW ICR (and possibly others, but I haven't checked) batteries, this value is while under load, which is generally how people with a multimeter (or the provari) test the battery.

This looks to be a great guide:
MDs Rechargeable Compatibility chart/guide for popular flashlights!!

An excerpt:

LiCo02 cells should not be discharged below ~3.0V under a load, (varies by manufacture). A good rule of thumb is that when the cell reaches ~3.5V open circuit, it is dead and should be recharged. Over-discharging a cell will increase the rate of internal oxidation leading to reduced capacity, reduced cycle life, and increased likelihood of explosion/fire.

It's interesting to note that this is probably the rule of thumb applied by the provari. However, the variance of voltage between open circuit and under load of a larger size like the 18650 is probably less than that ~17%. Even if it weren't, 3v when open would probably be more appropriate for a battery with a 2.5v cut-off.