Nano RCR123 charger, charging times??

Is this charger supposed to take 8 hours to charge a 750mAh cell? Wondering if this is a normal average, or do I have a defective unit.

Any recommendations for a good, faster charger for home use? Thanks..

Dan C

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I got a Nano a few days ago and my first impressions were that it was a very nice little compact charger, but...... The cells come off at only 4 volts, while my DSD pushes them to 4.16 volts.

Its susposed to trickle to 4.2 volts eventually.

Even after the green light comes on? I dont know why MFG's have the trickle mode kick on after the light says the charge is done, its just dumb. They should do red for normal charge, yellow for trickle, and green for full cell.

I heard (Remembering a post off the top of my head)
Charge, to 90%ish, light goes green. Then a hour or so passes and you remove the battery (Or else if you leave it on the charger for a day or two, it spikes to 4.3 to 4.5 eventually leaking.)

Well, damnit, I dont think I want to use this Nano now!

Navck said:

I heard (Remembering a post off the top of my head)
Charge, to 90%ish, light goes green. Then a hour or so passes and you remove the battery (Or else if you leave it on the charger for a day or two, it spikes to 4.3 to 4.5 eventually leaking.)

Click to expand...

Thanks for the tip,
I have two of those chargers coming and although I don't leave batteries on chargers... good to know that I should NEVER leave my RCR123's.

Hello Navck,

I think you better review the information on the Nano charger. A Li-Ion charger that regularly charges to 4.5 volts would result in a rapid venting condition which can be accompanied by flame. I have not heard of anyone catching their wall on fire...

If you have a Nano charger, the first thing you should do is plug it in and measure the voltage across it. Mine comes in at 4.224 volts. That indicates that if there is no internal resistance in the battery, the maximum voltage the battery can come to is 4.224 volts. Since most batteries have some internal resistance, they will come off the charger a bit lower.

The next thing to notice is that the charger charges at 450 mA. This tells me that if you have a 450 mAh Li-Ion battery, it will charge in around 1.5 - 2 hours, if the battery is in good condition.

I believe the green light comes on when the charge current levels off. I am not sure what that current value is, but it should be around 45 mA. With a brand new 450 mAh battery, that brings the voltage up to around 4.21 volts, and removing the battery from the charger will see the voltage drop to very close to 4.2 volts.

Dan mentioned that it seems to be taking a long time to charge his battery. It could be that the charger is not operating properly... It could also be that his battery has been damaged.

Li-Ion batteries become damaged by over charging, over discharging, hard use, heat, cycle fatigue, physical damage, and age. It is usually recommended to replace a battery that has fallen to around 80% of its initial capacity. With Li-Ion batteries, this reduction in capacity can present itself by the battery not being able to be fully charged.

It is interesting to read specification sheets. Cycle life testing is usually done at a 5 hour discharge rate and a 0.7C charge rate. When you use these batteries at the maximum current rate, it is not unreasonable to expect the cycle life to be reduced. Given a proper amount of abuse, I have seen a quality battery suffer damage in as little as 5 charge/discharge cycles.

I have not done extensive testing on the Nano charger, but it seems to operate within the proper range of specifications for charging Li-Ion batteries. It may be better to question the condition of the battery being charged...

The major complaint I have with the Nano charger is that it does not fully shut off the charge current. Continuing to apply a small amount of current to a fully charged Li-Ion battery can degrade the battery condition. This compounds itself when your battery does not seem to be fully charging and you leave it on the charger for an extended period of time hoping it will trickle charge to more capacity.

My suggestion is to remove the battery as soon as the green light comes on. If the battery does not deliver the "normal" capacity, or if the green light does not come on in a reasonable amount of time, replace the battery.

Tom

The major complaint I have with the Nano charger is that it does not fully shut off the charge current. Continuing to apply a small amount of current to a fully charged Li-Ion battery can degrade the battery condition. This compounds itself when your battery does not seem to be fully charging and you leave it on the charger for an extended period of time hoping it will trickle charge to more capacity.

Click to expand...

I thought someone mentioned that their Li Ions were hitting 4.3 on their Nano from that. Must be my memory, my bad.

Silverfox, thanks for the info. The batteries in question (4) are all brand new, purchased with my FF3. I didn't pay much attention to the charging times of each one, but I know at least a couple of them took 7-8 hours until the green light came on. I charged a partially discharged one yesterday and it too took about the same amount of time.

I just checked my charger, and it's putting out 4.09 volts. The three charged cells show 4.03 to 4.05 volts.

I think I'm in the market for another charger. Any recommendations? How about the Batterystation one? I'd like a two-slotter. Thanks for any help.

Dan C

Hello Dan,

The advantage to charging to a lower voltage is that you will get more cycle life from your cells. 7 or 8 hours seems like it is too long though...

I do almost all of my Li-Ion charging on my Schulze. I have not done much testing, or spent much time with the other chargers, so I can not comment on them. I can, and do, recommend the Schulze...

Tom

My NanoCharger charges my RCR2 cell in about 2 hours. I have read in previous threads about the danger of leaving a cell in the NanoCharger for an extended period of time. I purchased a protected RCR2 from AW in an attempt to minimize any danger.

I just ran a test with my Nano charger...

I took an empty (3.6 volts resting) 650 mAh R-CR123 cell and charged it.

In around 3 hours, the light changed to mostly green and the cell voltage was 4.106.

I left it in charging and at 4 hours the voltage was 4.127, and after 5 hours it was 4.175 volts. That is close enough for me.

This cell has been subjected to a wide battery of tests including repeated discharge rates up to 4.5C and one run up to 7.5C. I do not recommend using these cells beyond 1C, but I was testing to see if there were any current limiting safety devices built into the cell. I am surprised this cell works at all, but it just seems to keep on going. It seems to charge up just fine on the Nano charger.

The green light at 4.106 volts is a bit low for maximum capacity, but just right for extended cycle life.

The 650 mAh cell is about 44% more than the 450 mA charge rate, so theoretically if it takes about 2 hours to charge a 450 mAh cell, it should take around 2.9 hours to charge a 650 mAh cell. This is pretty close to the 3 hours it actually took.

Tom

Hello HighLight,

The protection circuits limit the voltage extremes of the cell, but they do not protect against low current charging degradation. I still feel it is best to pull the cell off the charger when the green light comes on.

Tom

SilverFox said:

...The next thing to notice is that the [Nano] charger charges at 450 mA. This tells me that if you have a 450 mAh Li-Ion battery, it will charge in around 1.5 - 2 hours, if the battery is in good condition.

Click to expand...

Hi SilverFox,

Thanks for all the info about the Nano charger. I've been thinking about getting one for charging RCR2's and your post was very informative.

I was just reading AW's old sales thead about the Nano R123 charger ( here). AW posted that it has a charging current of about 150mA, "The charging current of the Nano is actually 150mA so it is safe to charge a 300mAH RCR2 LiION battery."

From what I understand, it is recommended that the charging current be less than the capacity (C) of the LiIon cell being charged. If the Nano were providing 450 mA, then it would not be appropriate for small batteries like the RCR2. However, I believe the Nano is the recommended charger for the smaller LiIon cells like the RCR2 so I would question whether it is really 450 mA, or perhaps there is more than one version of the Nano R123 charger. I've read that the larger DSD charger has a current of about 350 mA, which seems closer to the 450 mA you mentioned. Would you please clarify the source of the 450 mA number that you mentioned (for the Nano R123 charger's current). Thanks.

Hello Vortechs,

On the back of my Nano charger it states that the output is 4.2 volts and 0.45 amps. If you look closely at the pictures AW put in the first post of that same thread, you will see that it is the same as what is on the charger he is showing.

I am not sure what AW is referring to in that particular post, but if you read on, you will find that he says that the Nano charger is charging at 420 mA (post #50). Not sure where he gets that figure either, but perhaps there are some losses in the system...

Tom

Thanks SilverFox,

I've been trying to make sense of all the threads about LiIon batteries and chargers, since I recently got a JIL CR2 light and now need some RCR2 batteries and a charger. I've been attempting to learn more about how to handle LiIon batteries and their chargers, since there are a number of comments about LiIon batteries potentially being dangerous if mishandled. If you have any good references you could point me towards, I would greatly appreciate it.

I've been trying to figure out the differences between the most common chargers I've seen mentioned on CPF, the Nano and the DSD. I understand that the Nano charger isn't designed to reset protected cells that have had the protection circuit tripped (I have read that you have to manually reset the circuit by applying 6V DC), while the DSD will automatically deal with this. I've been trying to make sense of which charger is appropriate for the 300 mAh unprotected and the 350 mAh protected RCR2 cells that are currently available. Any clarification or advice you could offer would be appreciated.

I just came across this thread. The Nano charger is labelled with a 420mA charging rate but the actual rate is somewhere around 240mA to 150mA, depending on the state of charge of the battery. This has been confirmed by a number of CPF members already.

Hello AW,

I see what you mean. My charger starts out at 450 mA, but the current quickly drops off as the voltage climbs. I agree that there is little time spent charging at 450 mA. Once the cell gets to 3.5 volts, the charge current has dropped to around 300 mA, and at 3.6 volts, it is closer to 200 mA, and it continues to taper off from there.

Tom

Thanks AW and SilverFox, you've helped me understand this better.

I just ordered a Nano charger and some protected RCR2's.