18650 Battery Safety

[Shit Snacks]

Thx for clearing that up--I really needed to hear that! It seems that buying name brand batteries from a reputable dealer and treating them with care (proper charging, not dropping them on the table and keeping them in battery cases) are the best ways to use them safely.

Speaking of charging, are chargers such as the Nitecore and Xtar better than charging by micro usb cable (which came with the Ace) to the computer in battery longevity or are they just faster?


Yeah, that's a good point! Those plastic battery cases are worth having.

Haha yes never carry loose batteries! I always store them in cases, and if not being used for a while, around 3.7 volts, 4.2 volts is maximum fully charged... They can go down to three or less safely though!

And yeah best to get an external battery charger, those brands are fine, I like something with a digital display so you can see the stats, mainly that voltage number so I know the charge level exactly... USB charging is typically slower, not useful if you want to have spare batteries ready to go!

 

[oldfool]

Speaking of charging....or are they just faster?

Why is everyone always in such a hurry?
I charge my batteries at a half an amp.
I only charge up to 4.1 volts instead of 4.2
I usually charge when they get down to 3.75V.
I'm only using 60 or 70 percent of the capacity but they will last much longer.

Heard good thing about the SkyRC MC3000 charger, pretty pricey.
I picked up an XTAR VC2. Seems to work fine. I like the info displayed.

 

[Shit Snacks]

Why is everyone always in such a hurry?
I charge my batteries at a half an amp.
I only charge up to 4.1 volts instead of 4.2
I usually charge when they get down to 3.75V.
I'm only using 60 or 70 percent of the capacity but they will last much longer.

Heard good thing about the SkyRC MC3000 charger, pretty pricey.
I picked up an XTAR VC2. Seems to work fine. I like the info displayed.

Yeah you are style is the way for best battery longevity, that's pretty much how I keep all of mine and why they have held up so well over many years! Molicell honestly I have often been taking to lower voltage, just because their performance seems to hold up so well!

 

[fifty_shades_of_green]

Haha yes never carry loose batteries! I always store them in cases, and if not being used for a while, around 3.7 volts, 4.2 volts is maximum fully charged... They can go down to three or less safely though!

I remember reading about some poor guy that did that! His pants burst into flames and he suffered serious burns and ended up being taken to a hospital!

Heard good thing about the SkyRC MC3000 charger, pretty pricey.
I picked up an XTAR VC2. Seems to work fine. I like the info displayed.

Your XTAR looks incredible! I guess you can choose which current to charge at and I'm also not in a hurry to get them charged up as quickly as possible. I guess each battery will have different optimal charging rates and half an amp sounds like a good way to prolong their life. I guess the slower one charges, the better it is for the cell or is there a thing as too slow charging?

Yeah you are style is the way for best battery longevity, that's pretty much how I keep all of mine and why they have held up so well over many years! Molicell honestly I have often been taking to lower voltage, just because their performance seems to hold up so well!

Is it good practice to keep them .1 or .2 volts below their full capacity? I also don't run down my battery but charge it up when it's half way empty but I'd have to buy an external charger to have that kind of control over the volts...

 

[Shit Snacks]

Is it good practice to keep them .1 or .2 volts below their full capacity? I also don't run down my battery but charge it up when it's half way empty but I'd have to buy an external charger to have that kind of control over the volts...

Yeah, first time I charge them brand new I let them sit on the charger a while after being fully charged, minimum 6 hours total, but yeah usually more like 8 or so? Sometimes more, I don't even think it's necessary, but I have so many now I don't even mind doing it the first time anyway! Maybe the second time also they can get to a full charge, but yeah I try to pull them off the charger a little earlier than fully charged if I can... However often I miss it, these are just small things that may not even make any kind of noticeable difference honestly! Plenty of people discharge their batteries down to 2.5v and some always charge them full to 4.2v, the nice thing about replaceable batteries is well that they're replaceable!

But yes the leg is not replaceable! The same way lol so check the battery safety thread and follow advice from people like @RustyOldNail @cybrguy @KeroZen me and oldfool^ many others here, there are risks but it is not difficult to be safe, good thinking

 

[cybrguy]

Thx for clearing that up--I really needed to hear that! It seems that buying name brand batteries from a reputable dealer and treating them with care (proper charging, not dropping them on the table and keeping them in battery cases) are the best ways to use them safely.

Ding ding ding. This is the key to battery safety. Only buy from vendors you can trust, not ebay or even Amazon. You may get good batteries from them, but you also may not. And it isn't worth the risk. A trusted battery vendor will be sure he is selling the real deal and saves us from having to worry about it. I usually keep using batteries until they start to show significant degradation, and then I just recycle them. If there is any question in my mind they go. I always rewrap any battery that starts to tear from being removed and replaced in my devices. Rewrap sleeves are very inexpensive.

Most of what I have learned about batteries I have learned in these groups or by reading Mooch's reviews and explanations. He is the guy we all trust. And people like @KeroZen who is kinda our inhouse expert. (Thanks @KeroZen) The "Don't blow off your face" link in my sig is just a cute reminder from one of our favorite vape makers.

Until recently I have been using Nitecore battery chargers. I ALWAYS charge my batteries in an external charger just to be sure it is safe. Device chargers may be fine, but this saves any worry for me. The Nitecore chargers I was using (D series) never went over .75 amps while charging and were kinda slow, but I trusted them to assess the battery condition. I have recently bought the new 4 channel version of the one above, the XTAR VC4L, and it charges up to 1 amp on it's 2 outside channels so it charges a little faster, but still safely. Some chargers go up to 3 AMPs, but that seems kinda high to me and I'll stick with the 1 AMP. I always have enough extra batteries around that I am never in THAT much of a hurry to charge them.

There are better chargers out there then the typical around $30/$40 spent on the Nitecore or XTAR (there are a few other vendors), but they are noticeably more expensive and I don't feel the need to invest in them, but if the $$ doesn't matter to you they ARE better so that is a decision for you. These $30 chargers are meant as hobbyist chargers, not professional chargers.

As long as you buy from reputable sources, watch for tears in the wrappings, treat them carefully and in cases (never loose in the pocket) and replace them if they get squirrely, you should be fine. I have never had a battery vent on me. It IS important if you use a device with 2 or more batteries that you keep them in pairs (or triples) so that they keep at the same relative charge so they deplete evenly.

 

[fifty_shades_of_green]

Ding ding ding. This is the key to battery safety. Only buy from vendors you can trust, not ebay or even Amazon. You may get good batteries from them, but you also may not. And it isn't worth the risk. A trusted battery vendor will be sure he is selling the real deal and saves us from having to worry about it. I usually keep using batteries until they start to show significant degradation, and then I just recycle them. If there is any question in my mind they go.

Thx for the great advice! I'll have to check out some of @KeroZen's posts and your sig really sums things up nicely.

 

[RustyOldNail]

Thx for the great advice! I'll have to check out some of @KeroZen's posts and your sig really sums things up nicely.

Read all the posts in this thread, it’s only 4 pages. If you truly want to learn about lithium battery safety, browse the link in my sig at your leisure. The Battery University site is a great source of info if you are willing to dig deep, and the information will be more accurate then most of the advice you get on public forums and strangers, like me!

EXAMPLE: Some like to baby their batteries, don’t fully discharge them, don’t fully charge them. And technically that advice for lithium batteries is CORRECT, if potentially longer battery life is your goal. But, in MY opinion, it’s chasing “fairy dust”. At $3-5 for a quality battery, I use them to their limits, as I’m not concerned with getting a few extra life cycles out of a inexpensive battery. The device will cutoff the voltage when it reaches its preset, usually 3.0-3.3 volts, depending on how the manufacturer programmed it. Battery capacity is usually tested by the manufacturer with a discharge down to 2.5 volts, these specs are usually published so you can check against the tests you do to confirm you bought an original. 2.5 volts is as low as one can safely go on a manual discharge on a charger/analyzer like a SKY MC3000. Any decent device will shut down when the low voltage cutoff is reached, so not something you have to even consider. Since I’m only interested in getting top performance from my devices, I charge them to the limit of 4.2 volts, though on my SKY charger, I can manually choose any voltage, and most any other available setting.

So, as you can see from the example above, you are presented with two opinions, and neither is wrong, choice is yours!

I don’t own the mod you use, but if the batteries are actually getting too hot to hold right after a session, that’s not a good sign. In my Davinci IQ2, they never get hot, just warm. The HEATER in the device is what WARMS them, they should not get hot by themselves when in use. This is one of the reasons it’s recommended to charge batteries on an external charger, the batteries are are air cooled during charge/discharge, not trapped in a closed device.

Battery basics: HEAT is the major ENEMY of a battery!

That’s the main reason HEAT in the MOOCH tests, that define how many AMPS a battery can SAFELY deliver. Look at his VTC-6 tests, the SAFE rating is a 15 amps, but 20 amps if the temperature of the battery does not go above 80c. Since most of use don’t have the special equipment to measure battery heat temperatures at 15-20 amps or higher, we trust an independent battery reviewer like MOOCH, as many of the published specifications as well as those printed directly on the batteries are either overly optimistic, or blatantly FALSE!

So..... BUYER BEWARE. For a minimal investment in a quality charger/analyzer, I can test for battery resistance, this is one of the main indicators that a battery is reaching EOF (End Of Life), and test for MaH rating = the actual capacity of a cell. The SKY MC3000 also monitors the batteries temperatures while charging. I can’t tell the temperatures of a cell at HIGH AMP DISCHARGE RATES, that requires more specialized equipment, but that’s the KEY in determining the safest amount of AMPS a battery can deliver. With the information I can get from my charger, I can at least determine with a fair amount of confidence, that I have an original battery, and not a fake or rewrap.

I don’t recommend chargers that are full AUTO charge settings, but I’ve posted the technical reasons for that in this thread already, sorry don’t have the time or interest to repeat the same info as it comes up repeatedly. If you have specific questions after learning the basics, I’ll try to respond. Good luck, vape SAFE!

 

[fifty_shades_of_green]

Read all the posts in this thread, it’s only 4 pages. If you truly want to learn about lithium battery safety, browse the link in my sig at your leisure. The Battery University site is a great source of info if you are willing to dig deep, and the information will be more accurate then most of the advice you get on public forums and strangers, like me!

There's some great info on this thread and I really appreciate all the advice that people have given here. I checked out the Battery University site and there's a wealth of information there but it's a bit too techical for me. One thing that made an impression on me is that fully charged batteries are potentially more dangerous and that's why vendors can only ship batteries that are 70% charged or something like that. If a battery can hold 3.6 V, I guess it makes sense to only charge it to 3.4/3.5 V to prolong its life but I really don't want to split hairs about this kind of thing. More importantly is that the battery is safer when not fully charged things correctly.

One quick question about the Nitecore and XTAR charger. Can you charge multiple batteries with different capacities at the same time--I mean set each battery's voltage and charging speed or is it best done with the exact same cells? Is it better to charge individually or in pairs? I feel like they should teach this stuff in school--that might be a way to get the kids in HS interested in Chemistry and Physics, m'kay.

 

[cybrguy]

If a battery can hold 3.6 V, I guess it makes sense to only charge it to 3.4/3.5 V to prolong its life but I really don't want to split hairs about this kind of thing. More importantly is that the battery is safer when not fully charged things correctly.

One quick question about the Nitecore and XTAR charger. Can you charge multiple batteries with different capacities at the same time--I mean set each battery's voltage and charging speed or is it best done with the exact same cells? Is it better to charge individually or in pairs? I feel like they should teach this stuff in school--that might be a way to get the kids in HS interested in Chemistry and Physics, m'kay.

I know it seems weird, but the usable range is really between about 3.4 and 4.2 volts. When a regulated device gets down around 3.4v it will shut off.

The hobby chargers WILL charge different battery types together with no problems. And they don't really care how many slots are filled other than they will reduce the charging voltage per slot when more batteries are loaded.

On my XTAR 4 banger, for example, the charger will charge at 1 AMP if I use just the 2 outside slots, but will reduce to .5 amps for all slots if there are any batteries in the middle 2 slots.

 

[Shit Snacks]

There's some great info on this thread and I really appreciate all the advice that people have given here. I checked out the Battery University site and there's a wealth of information there but it's a bit too techical for me. One thing that made an impression on me is that fully charged batteries are potentially more dangerous and that's why vendors can only ship batteries that are 70% charged or something like that. If a battery can hold 3.6 V, I guess it makes sense to only charge it to 3.4/3.5 V to prolong its life but I really don't want to split hairs about this kind of thing. More importantly is that the battery is safer when not fully charged things correctly.

One quick question about the Nitecore and XTAR charger. Can you charge multiple batteries with different capacities at the same time--I mean set each battery's voltage and charging speed or is it best done with the exact same cells? Is it better to charge individually or in pairs? I feel like they should teach this stuff in school--that might be a way to get the kids in HS interested in Chemistry and Physics, m'kay.

Yeah you are confused, the 3.6V rating of a battery is different than what we are talking about, the charge level is also volts, and 4.2 volts is fully charged, perfectly safe, and like I said you can use it down to 3 volts safely but 3.7 is typical shut off for a lot of vapes and good storage voltage...

All new batteries I have bought arrive without any charge at all, so they will be like 2.6v fresh on the charger, so it does take about four or five hours to get fully to 4.2 volts and like I said I then let them sit there charging extra a bit before I use them the first time...

You only need to think of volts in this terminology, otherwise the ratings you want to pay attention to are the amps as we said, and the mah for capacity.

Yes if you are using paired batteries, a device that requires two batteries, you should charge them together and discharge them together always like they are one battery. But the ace only takes one battery, so this does not matter for your needs!

Charging multiple batteries at the same time of different specs is fine, that's what a good charger is all about, it knows what it's doing.

 

[RustyOldNail]

There's some great info on this thread and I really appreciate all the advice that people have given here. I checked out the Battery University site and there's a wealth of information there but it's a bit too techical for me. One thing that made an impression on me is that fully charged batteries are potentially more dangerous and that's why vendors can only ship batteries that are 70% charged or something like that. If a battery can hold 3.6 V, I guess it makes sense to only charge it to 3.4/3.5 V to prolong its life but I really don't want to split hairs about this kind of thing. More importantly is that the battery is safer when not fully charged things correctly.

One quick question about the Nitecore and XTAR charger. Can you charge multiple batteries with different capacities at the same time--I mean set each battery's voltage and charging speed or is it best done with the exact same cells? Is it better to charge individually or in pairs? I feel like they should teach this stuff in school--that might be a way to get the kids in HS interested in Chemistry and Physics, m'kay.

You are OVER thinking things, don’t be concerned with how your batteries are shipped. Buy the brands and types that have been recommended, at the trusted vendors, also listed. A good multi-bay Charger will allow different charging settings for each bay. Charge them to the standard of 4.2 volts at 1amp or higher if you are in a hurry, and when your device shuts off, recharge them.

There are millions of lithium batteries in use every day, 6-7,000 21700 lithium’s in electric cars, in battery sleds, yes individual cells, same as the ones I buy for some of my ECig mods. So in general, very safe. It is smart to be safe, just don’t handcuff your mind on using them. I don’t charge my batteries unattended, and as you’ve seen in my earlier photos, I recently bought fire extinguishers specifically designed for lithium batteries, just added safety.

 

[cx714]

Thanks everyone for a solid Q&A. Feel like I just requalified on 18650 handling.

(Also bought some Molicels. FC strikes again!)

 

[fifty_shades_of_green]

Thanks everyone for your patience with trying to help me get a grasp of all this battery stuff.

You are OVER thinking things, don’t be concerned with how your batteries are shipped. Buy the brands and types that have been recommended, at the trusted vendors, also listed. A good multi-bay Charger will allow different charging settings for each bay. Charge them to the standard of 4.2 volts at 1amp or higher if you are in a hurry, and when your device shuts off, recharge them.

The only reason I mentioned that they ship with 70% capacity is that I read it's for safety reasons. Would it make sense to only charge them up to 70% at home for this reason? I read somewhere that it's best to keep phone batteries between 60-80% full and never fully charge them but don't know if this applies to 18650 batteries too. According to the specs for the Samsung 26 JM 2600 battery mAH, the nominal voltage is only 3.63V and most batteries seem to be around 3.7V too. Isn't charging them up to 4.2 volts a bit too much for most of them--sorry if I'm missing something here...

I'm thinking of getting the XTAR VC4 charger but am worried that it might be a bit complicated to use correctly. I don't have the best track record with electrical household wares. I remember an old middle school project where we made a lamp and did the wiring ourselves--the teacher didn't do a good job checking our work. It was supposed to be a present for my parents but when we plugged it in, smoke came rushing out of the socket! Talk about almost burning down the house! I've also had two close calls with vacuum cleaners plugged in--once there was a mini explosion and it blew all the fuses in the house and the second time, smoke started coming out of the motor. I feel like I've used up a few of my "nine lives" already, so I definitely want to play it safe.

One last thing about batteries. I've noticed that some come with steel plates on top or maybe "solder caps" is the correct technical name for them. Do most vendors simply remove them to sell individual cells or are some of the 18650s manufactured without these caps in the first place?

 

[oldfool]

I'm thinking of getting the XTAR VC4 charger but am worried that it might be a bit complicated

If it's the same as my VC2 there's nothing complicated.
Plug it in, put batteries in slot, watch display. No buttons or knobs to adjust.

 

[cybrguy]

The only reason I mentioned that they ship with 70% capacity is that I read it's for safety reasons. Would it make sense to only charge them up to 70% at home for this reason? I read somewhere that it's best to keep phone batteries between 60-80% full and never fully charge them but don't know if this applies to 18650 batteries too. According to the specs for the Samsung 26 JM 2600 battery mAH, the nominal voltage is only 3.63V and most batteries seem to be around 3.7V too. Isn't charging them up to 4.2 volts a bit too much for most of them--sorry if I'm missing something here...

Well, kind of. The part you are missing is that most regulated devices will shut down at 3.4 to 3.7v, so if you only charged them to 70% you couldn't use them. The devices would not work. 3.4 to 3.7 v is where they stop working. While not fully charging them (lets say to 4.0) may extend their life, it will also reduce their usefulness. You can STORE them at 3.4, but you can't use them.

The hobby chargers are very simple to use as @oldfool says. They are designed for use by hobbyists who don't have a lot of battery knowledge. Some of the "professional" chargers (or at least better chargers) may be more complicated to use and do more than just charge, but the basic XTAR and Nitecore chargers (and other vendors in that class) are pretty plug and play.

 

[Shit Snacks]

Thanks everyone for your patience with trying to help me get a grasp of all this battery stuff.


The only reason I mentioned that they ship with 70% capacity is that I read it's for safety reasons. Would it make sense to only charge them up to 70% at home for this reason? I read somewhere that it's best to keep phone batteries between 60-80% full and never fully charge them but don't know if this applies to 18650 batteries too. According to the specs for the Samsung 26 JM 2600 battery mAH, the nominal voltage is only 3.63V and most batteries seem to be around 3.7V too. Isn't charging them up to 4.2 volts a bit too much for most of them--sorry if I'm missing something here...

I'm thinking of getting the XTAR VC4 charger but am worried that it might be a bit complicated to use correctly. I don't have the best track record with electrical household wares. I remember an old middle school project where we made a lamp and did the wiring ourselves--the teacher didn't do a good job checking our work. It was supposed to be a present for my parents but when we plugged it in, smoke came rushing out of the socket! Talk about almost burning down the house! I've also had two close calls with vacuum cleaners plugged in--once there was a mini explosion and it blew all the fuses in the house and the second time, smoke started coming out of the motor. I feel like I've used up a few of my "nine lives" already, so I definitely want to play it safe.

One last thing about batteries. I've noticed that some come with steel plates on top or maybe "solder caps" is the correct technical name for them. Do most vendors simply remove them to sell individual cells or are some of the 18650s manufactured without these caps in the first place?

As I said they don't usually arrive even 70%, they're usually lower, and there's no reason to not charge them full honestly, they'll still last plenty long doing so, there's really no reason to not do that, you are overthinking it still!

 

[RustyOldNail]

The only reason I mentioned that they ship with 70% capacity is that I read it's for safety reasons. Would it make sense to only charge them up to 70% at home for this reason? I read somewhere that it's best to keep phone batteries between 60-80% full and never fully charge them but don't know if this applies to 18650 batteries too. According to the specs for the Samsung 26 JM 2600 battery mAH, the nominal voltage is only 3.63V and most batteries seem to be around 3.7V too. Isn't charging them up to 4.2 volts a bit too much for most of them--sorry if I'm missing something here...

Think of “nominal”, as the AVERAGE voltage the battery delivers during one discharge cycle.

ONCE AGAIN: Charge them 100%, to the standard of 4.2 volts at 1amp or higher if you are in a hurry, and when your device shuts off (device dependent 3.0-3.x volts), then recharge them.

The ONLY time I DON’T FULLY CHARGE them is for “long term storage”, batteries sealed for refrigerator. My charger has a “STORAGE SETTING”, which charges the batteries to 3.8 volts, about 40% (considered best storage voltage).

Most are NOT “storing” batteries long term, so don’t worry about it.

 

[cybrguy]

Most are NOT “storing” batteries long term, so don’t worry about it.

Just out of curiousity, what do you consider long term? As I don't use my 2 battery mods as much as I used to due to the TM, I have a couple pairs I could probably store.

 

[RustyOldNail]

Just out of curiousity, what do you consider long term? As I don't use my 2 battery mods as much as I used to due to the TM, I have a couple pairs I could probably store.

Long term, is when you have a lot you don’t think you will use in a year or two. I put some Sony VTC5 18650’s away for a few years in bottom of FRIG (not freezer), well wrapped. Took them out, let them warm, then charged, perfect. The shelf life of lithium batteries is about 10 years, so if you not using them for months, no problem. Most vapor users don’t need to do long term “cool” storage, unless you have more then you can currently use in a year or so. Also most specs on 18650 batteries will claim 300-500 recharge cycles. So, if you only used ONE battery, once a day, it could last 1-2 years. If you rotate more batteries, they all have longer life.

BATTERIES = CONSUMABLES

 

[cybrguy]

Yeah. It won't be years so I will leave them available. They aren't THAT expensive. I may just end up breaking the pairs down the road. I had a triple for the RX 2/3 that I never used in triple mode so I just pulled one out of the pairing. 3 batteries was too heavy a mod for me.

 

[RustyOldNail]

Yeah. It won't be years so I will leave them available. They aren't THAT expensive. I may just end up breaking the pairs down the road. I had a triple for the RX 2/3 that I never used in triple mode so I just pulled one out of the pairing. 3 batteries was too heavy a mod for me.

Indeed, I have a bunch in a room temp box that I’ll probably never use, but aren’t worth the effort or space for long term storage. I do keep records of my battery purchase dates, and log their specs when new so I have a baseline of them for future reference. It’s also a pain to try to manually charge or discharge a battery to the proper storage voltage of 3.8v, unless the charger has a “storage” preset, it’s doable, but you have to factor the voltage sag when battery is removed from charger. Much simpler to use them as designed....

 

[fifty_shades_of_green]

Wow, what a great discussion! It seems that everyone here is so knowledgeable about batteries and I'm in the dark ages!

If it's the same as my VC2 there's nothing complicated.
Plug it in, put batteries in slot, watch display. No buttons or knobs to adjust.

That sounds like my kind of charger. I really don't want to complicate my life any more. Having said that, are the "professional" chargers safer or is it just for people that really want to maximize how long they use their batteries?

Btw, any opinions on how the SC4 Nitecore compares to the XTAR VC4? Are they both about the same in quality and what they can do?

As far as the discussion about how long to keep batteries goes, I read somewhere that it's good practice to replace them every 6-12 months if you use your device every day. I don't use mine that often but would rather spend a bit more on batteries if it means staying safe, so maybe 1 year is a good rule for battery replacement.

 

[RustyOldNail]

Wow, what a great discussion! It seems that everyone here is so knowledgeable about batteries and I'm in the dark ages!

That sounds like my kind of charger. I really don't want to complicate my life any more. Having said that, are the "professional" chargers safer or is it just for people that really want to maximize how long they use their batteries?

Btw, any opinions on how the SC4 Nitecore compares to the XTAR VC4? Are they both about the same in quality and what they can do?

As far as the discussion about how long to keep batteries goes, I read somewhere that it's good practice to replace them every 6-12 months if you use your device every day. I don't use mine that often but would rather spend a bit more on batteries if it means staying safe, so maybe 1 year is a good rule for battery replacement.

If by “professional chargers”, you mean HOBBY chargers, you are not in that market, as you’ve already stated you are fairly non technical. You get all the manual settings you could dream of, my SKYRC MC3000, is an in between charger, as it’s a 4-bay, still more tech then you seem ready for.

I don’t have the time to compare products for you, but in terms of brands, I prefer Xtar over Nitecore chargers, though I own many Nitecore flashlights.

 

[fifty_shades_of_green]

The SKYRC MC3000 looks amazing but is really more than I need and much more expensive than the XTAR VC4. I've come across one other charger that seems to have good specs--the EverActive UC4000. Has anybody used it or am I'm better off getting an XTAR?