Suitable charger for li-on 14500 (hopefully not too dumb a question!)

[sunglob]

I've just ordered some AW's P14500 and AW's Dual Bay Fast Charger (AW-139) from Fenix-Store.com. I presume this is the correct charger for these cells, but I don't want to make a mistake knowing what can happen if you mis-handle li-ions. I have no experience of rechargeable li-ons in AA or CR123 formats, and I presume the AW-139 is the same as WF-139?

I've searched the forums and think I'm OK, but would welcome a second opinion.

 

[DM51]

The WF-139 charger will be OK for protected cells such as AW's 14500s. You should know however that problems have been reported with this charger overcharging unprotected cells (they don't have overcharge protection). For this reason it should NOT be used with unprotected cells.

Also, at 450mA output it is underpowered for larger Li-Ion cell sizes. For example, a 14500 cell should ideally be charged at ~1.2A, and an 18650 at ~1.6A.

There are better chargers than the WF-139, although they are of course more expensive. The Pila charger is reported elsewhere by Paul_in_Maryland as being very reliable. The next step up from that would be a Triton or a Schulze.

I suggest you use the WF-139 in conjunction with a multimeter and check your cells' voltage from time to time. Take them off the charger as soon as the light goes green.

There is a lot more to learn about Li-Ion safety, charging etc. Here is a start:

Lithium chemistry is wonderful as long as it is used within its limits. When you get outside of its limits, it has a tendency to "rapidly vent with flame," more commonly called an explosion accompanied with a fireball.

Li-Ion cells need to have the maximum voltage to them limited to 4.2 volts. When you exceed this, you run the risk of an explosion.

Li-Ion cells need to have a low voltage cutoff. Running them below roughly 3.0 volts can ruin the cell, and it has the possibility of creating problems during the next charge cycle.

The current draw from a Li-Ion cells should be limited to twice the capacity of the cell. For example, if you have a 1200 mAh Li-Ion cell, the maximum current draw should be limited to 2400 mA. Exceeding this causes the cell to heat up and results in a reduced cycle life, and if it gets hot enough, an explosion.

The charging current for a Li-Ion cell is usually recommended at 0.7 - 0.8 times the capacity of the cell, with a maximum charge rate of 1C. If you have a 1200 mAh Li-Ion cell, the ideal charging rate would be 840 - 960 mA, with a maximum charge rate of 1200 mA. Faster charging rates cause the cell to heat up, resulting in cell damage. If the cell get hot enough, you end up with an explosion.

And this post by mdocod, although about a different specific subject, is full of good general info:
http://candlepowerforums.com/vb/showpost.php?p=1884574&postcount=30

There no shortage of useful info available on CPF, and no shortage of people happy to help.

 

[sunglob]

Many thanks. What would be the best voltage at which to remove from the charger? And are there any issues with using a multimeter with Li-ions? I have a digital multimeter which has a 20V DC max setting, but also a battery voltage check (9V max)? I presume the battery setting tests the battery under load. Which would be better?

 

[max52]

I disagree with the advice of not using the WF-139 on unprotected cells. There has been hysteria on this site about Lion batteries. The only problem with the WF-139 is that is trickle charges after the charge terminates.(light changes from red to green). As long as you remove them when the light turns green there will be no overcharging problem. On occaision I left some cells in to balance cells. All the cells I have charged have terminated in the 4.1X range.
Belive me when you read some of posts you would never go near the Lion cells. They do require careful attention, but so does most battery charging. The most danger I have run across recently is Meltdown of the BC-900 charger. There are thousands on the market that pose a fire hazard at unpredictable times.

My opinion is that the WF-139 is safe as long as remove the cell when the light on the charger turns green.

 

[DM51]

The protection circuit should not let it go above 4.2v. If it goes above that, the battery will take more charge but its life will be shortened. SilverFox produced these interesting statistics on battery life:

at 4.1 volts, you get over 2000 cycles.
at 4.2 volts, you get roughly 500 cycles.
at 4.3 volts, you get under 100 cycles.
at 4.4 volts, you get less than 5 cycles.

As a guide, at 4.1v, the battery will be ~90% of its max capacity. 4.15v seems to be the ideal compromise between battery life and capacity.

To test this with your multimeter, don't put the battery under load (this would cause the voltage to sag ~0.5v).

 

[DM51]

I disagree with the advice of not using the WF-139 on unprotected cells. There has been hysteria on this site about Lion batteries. The only problem with the WF-139 is that is trickle charges after the charge terminates.(light changes from red to green). As long as you remove them when the light turns green there will be no overcharging problem. On occaision I left some cells in to balance cells. All the cells I have charged have terminated in the 4.1X range.
Belive me when you read some of posts you would never go near the Lion cells. They do require careful attention, but so does most battery charging. The most danger I have run across recently is Meltdown of the BC-900 charger. There are thousands on the market that pose a fire hazard at unpredictable times.

My opinion is that the WF-139 is safe as long as remove the cell when the light on the charger turns green.

We are talking about protected cells here, so sunglob will be safe.

You are probably right about safety IF (big if) you take the battery off the charger as soon as it goes green. The reports of overcharging (no accidents AFAIK) may have arisen because people left them on, and they continued to receive a trickle charge.

 

[sunglob]

Thanks for all the useful information. I presume the same applies to charging protected RCR123A (AW's) in the Nano charger. Specifically does it go on to trickle charge when the light goes green?

I think I'll take the extra precaution of placing all my chargers (not just Li-ion ones) on a metal tray in future. I've left my La Crosse BC-900 refreshing for more than 24 hours unattended on a wooden table, until I read about some melt-down problems here!

 

[DM51]

The same applies to charging all Li-Ions. There have been nasty incidents, though fortunately they are rare. The trouble is trying to get the balance right with warnings - sometimes they can sound over-cautious, but better that than too cavalier IMO. You seem to have taken a very sensible attitude.

As to your question, yes, the same applies to the nano-charger. It should be fine. You can use the WF-139 for RCR123s as well, if you have spacers.

As I say, you are very unlikely indeed to have an accident, but if you do, I am afraid a metal tray won't help much. These things go off with quite a whoosh when they blow, with flames shooting out of them, and they can propel themselves across the room like small rockets.

There I go, sounding like a prophet of doom... seriously, don't be over-concerned about it. If you continue to be careful you will be absolutely fine. All you need is a healthy respect for the amount of power there is locked up inside these small batteries.

 

[sunglob]

I've just checked the voltage of an AW RCR 123A I charged on the Nano a couple of weeks ago, and have not used. It reads now 4.3V. Admittedly I did not remove the battery immediately the light turned green, but is this right? Perhaps I should check frequently before the green light and remove at 4.1V?

 

[DM51]

See my post #5 above. Are you sure your multimeter is accurate?

 

[sunglob]

Are you sure your multimeter is accurate?

No, I'm not sure whether it's accurate. I suppose I should check with a different multimeter.

I've just checked another battery with the original multimeter and a different one. One says 4.1V and the other says 3.9V. Looks like I need a better multimeter.

 

[sunglob]

Just acquired a third multimeter, when I realised the original one (which read 4.3V) was displaying *low battery* symbol. Changed battery and now all 3 multimeters read the same. Seems like the low battery was causing it to read higher than actual voltage. Dohhhh!

 

[max52]

No, I'm not sure whether it's accurate. I suppose I should check with a different multimeter.

I've just checked another battery with the original multimeter and a different one. One says 4.1V and the other says 3.9V. Looks like I need a better multimeter.

Probably not your multimeter. I have Rechargeble Lions in all configurations. They vary in open voltage. They would develop wide variation if left in the WF-139 for various periods of tme after charger light turns green. I check with meter and the new ZTS MBT-1 which tests capacity of Lions cells based on percentage of capacity. It is important to match cells in muti-cell applications.

 

[DM51]

Just acquired a third multimeter, when I realised the original one (which read 4.3V) was displaying *low battery* symbol. Changed battery and now all 3 multimeters read the same. Seems like the low battery was causing it to read higher than actual voltage. Dohhhh!

Don't worry about it, we've all been there!

The other day I was checking a battery that had just come off charge, and it read 0v. I checked another - the same. After a third I was beginning to panic, wondering whether a sunspot or something had hit and all the electronics had been knocked out, when I noticed that.....

......I hadn't plugged the other end of the leads into the multimeter!!

DOHHHHH!!!

 

[cy]

here's a similar thread and a good place to start...

http://candlepowerforums.com/vb/showthread.php?t=157773

 

[combatative31]

I have just brought a fenix tk11 and a aw139 charger am new to all this does any one know how long the 18650 and cr123a rechargable batteries will hold their charge for when not in use?

 

[Illum]

I guess I'm the only one that still uses a DSD charger for all my AW cells :candle:

 

[pobox1475]

the WF-139 is safe as long as remove the cell when the light on the charger turns green.

Does this mean the Pila does not have to be baby sat? I am looking to take the Li-Ion plunge and want a safe, reliable and easy to use charger for 14500's, RC-R123's and 18650's. Is there a charger that will not exceed 4.15v if left unattended?

 

[marschw]

I guess I'm the only one that still uses a DSD charger for all my AW cells :candle:

Just took my AW 14500 out of it this morning... why do people criticise this charger? And the KD all-in-one (SKU 3163)? I've never had problems with either, and they're versatile and cheap...