18650's Care and Maintenance

[Ag76]

Would it be wise to discharge an 18650 to the appropriate (storage voltage) or is it okay to just keep it as is after charging?

I'd also like to know the answer to this question. I just received new 18650 batteries...4 x Sanyo NCR18650GA, all read 3.52V with my DMM, 3 X Sony 18650 VTC6, 2 are 3.50V, 1 is 3.49V, and 2 X Panasonic NCR18650B, both read 3.54V. Can I store these batteries at their current volts, or should I charge them first?

 

[Torchmee]

I'd also like to know the answer to this question. I just received new 18650 batteries...4 x Sanyo NCR18650GA, all read 3.52V with my DMM, 3 X Sony 18650 VTC6, 2 are 3.50V, 1 is 3.49V, and 2 X Panasonic NCR18650B, both read 3.54V. Can I store these batteries at their current volts, or should I charge them first?

If you want to do it right for long term storage charge or discharge them to 3.6 - 3.7v and store in a cool place, the fridge being an option if the wife will allow it. This will give you max storage life. If they are going to be used in a week or two leave them fully charged. Of course be sure your DMM is reasonably accurate. Some of the top end chargers have a storage mode to adjust the voltage for you.

 

[Ag76]

If you want to do it right for long term storage charge or discharge them to 3.6 - 3.7v and store in a cool place, the fridge being an option if the wife will allow it. This will give you max storage life. If they are going to be used in a week or two leave them fully charged. Of course be sure your DMM is reasonably accurate. Some of the top end chargers have a storage mode to adjust the voltage for you.

I went ahead and fully charged them with the VC4, but it doesn't look like it has a storage mode to adjust voltage. I've thought about running each battery in a light until I lower the voltage to 3.7V, but that seems like a lot of trouble. Maybe I should look for a charger that has a storage mode. Thanks for the help, Torchmee.

 

[Torchmee]

I went ahead and fully charged them with the VC4, but it doesn't look like it has a storage mode to adjust voltage. I've thought about running each battery in a light until I lower the voltage to 3.7V, but that seems like a lot of trouble. Maybe I should look for a charger that has a storage mode. Thanks for the help, Torchmee.

Wow I just looked up the VC4 specs and I see it doesn't discharge battery's. So unless you plan on purchasing another charger you could just go ahead and use them in a light and when you are recharging pull them off when they reach the voltage you want.

If you are going to be doing it often and want to spend the money then a different charger would be handy. There are a couple available that have an automatic storage function or some allow you to set a desired voltage and then discharge to that voltage. If you get one that will discharge, and there are many, but will not do it automatically you will have to monitor as its discharging and pull the battery when it reaches your desired voltage. All depends on how much you want to spend. Myself or others on here can recommend one if you give a price range you are willing to spend.

 

[Ag76]

Wow I just looked up the VC4 specs and I see it doesn't discharge battery's. So unless you plan on purchasing another charger you could just go ahead and use them in a light and when you are recharging pull them off when they reach the voltage you want.

If you are going to be doing it often and want to spend the money then a different charger would be handy. There are a couple available that have an automatic storage function or some allow you to set a desired voltage and then discharge to that voltage. If you get one that will discharge, and there are many, but will not do it automatically you will have to monitor as its discharging and pull the battery when it reaches your desired voltage. All depends on how much you want to spend. Myself or others on here can recommend one if you give a price range you are willing to spend.

Torchmee, can you recommend a good charger that will discharge to a preset voltage? I almost went ahead and purchased an Opus BT-c3100/3400 since it seems to be highly recommended on the forum, but I decided to hold off buying more stuff until I can learn enough to be sure I'm getting what I really need. I would probably budget whatever it takes to get the right charger. I don't think I could figure out how to operate the SkyRC M3000, so I probably wouldn't consider that one. After finding this forum, I've been on somewhat of a spending spree, and my wife thinks I've developed an obsession with flashlights. I had no idea it could be this much fun! Thanks for the help.

 

[Torchmee]

Torchmee, can you recommend a good charger that will discharge to a preset voltage? I almost went ahead and purchased an Opus BT-c3100/3400 since it seems to be highly recommended on the forum, but I decided to hold off buying more stuff until I can learn enough to be sure I'm getting what I really need. I would probably budget whatever it takes to get the right charger. I don't think I could figure out how to operate the SkyRC M3000, so I probably wouldn't consider that one. After finding this forum, I've been on somewhat of a spending spree, and my wife thinks I've developed an obsession with flashlights. I had no idea it could be this much fun! Thanks for the help.

The Opus is a great charger and I wouldn't ever get rid of mine but unfortunately it will not auto discharge to storage voltage so you would have to manually monitor it and pull them. However it would be significant a step up from the VC4. Right now as far as I can tell the MC3000 is the only non hobby charger that has an actual storage mode that will discharge to the proper voltage unattended. You can also use the discharge mode and set whatever cut off voltage you want and it will do it unattended as well.

The MC3000 is the most versatile advanced charger/analyzer out there IMO. Yes it is more complicated, expensive and has a greater learning curve than the other chargers but it does so much more! It will be the last charger you ever buy for cylindrical cell battery's. Don't sell your self short on being able to operate it. If you like computers and gadgets, have a little patience and are willing to sit down with the manual and practice you can master it in no time. You have this forum for help and there are lots of Youtube videos. The manual details every mode and setting and a forum member has made a nice cheat sheet for us.

I suggest you download the manual and study it first to get an idea of what it will do. Watch the videos (search SkyRC MC3000 on youtube) and remember it will be easy when you have it to practice on. It does have a "dummy mode" that operates as easy as say the Opus and other less advanced chargers to get you started. As you study up on it you will find comments about teething problems found on the early models but they have been corrected on the latest production ones. I love mine and if I had bought it before the other chargers I have I wouldn't need or own any of them. If you really get into flashlights and battery charging you might as well spend the money on the best now and be done with it.

If you decide to buy one I will direct you to a distributor here in the US who will handle any warranty issues immediately and will give you an as good or better price than you can get on the China sites. $80 plus what ever the actual USPS shipping is from Ca. It will arrive in 2 to 5 days depending on where you live instead of the 3-4 weeks or more from China with basically no warranty. I got mine to my door for $85. He also sells the Opus if you decide to go that route.

All of the above is my opinion and I have no connection with SkyRc, Opus or the above seller. I just appreciate fine electronics and enjoy helping others do the same. Link to the factory MC3000 manual: http://www.skyrc.com/index.php?route=product/product/download&download_id=168

 

[Ag76]

The Opus is a great charger and I wouldn't ever get rid of mine but unfortunately it will not auto discharge to storage voltage so you would have to manually monitor it and pull them. However it would be significant a step up from the VC4. Right now as far as I can tell the MC3000 is the only non hobby charger that has an actual storage mode that will discharge to the proper voltage unattended. You can also use the discharge mode and set whatever cut off voltage you want and it will do it unattended as well.

The MC3000 is the most versatile advanced charger/analyzer out there IMO. Yes it is more complicated, expensive and has a greater learning curve than the other chargers but it does so much more! It will be the last charger you ever buy for cylindrical cell battery's. Don't sell your self short on being able to operate it. If you like computers and gadgets, have a little patience and are willing to sit down with the manual and practice you can master it in no time. You have this forum for help and there are lots of Youtube videos. The manual details every mode and setting and a forum member has made a nice cheat sheet for us.

I suggest you download the manual and study it first to get an idea of what it will do. Watch the videos (search SkyRC MC3000 on youtube) and remember it will be easy when you have it to practice on. It does have a "dummy mode" that operates as easy as say the Opus and other less advanced chargers to get you started. As you study up on it you will find comments about teething problems found on the early models but they have been corrected on the latest production ones. I love mine and if I had bought it before the other chargers I have I wouldn't need or own any of them. If you really get into flashlights and battery charging you might as well spend the money on the best now and be done with it.

If you decide to buy one I will direct you to a distributor here in the US who will handle any warranty issues immediately and will give you an as good or better price than you can get on the China sites. $80 plus what ever the actual USPS shipping is from Ca. It will arrive in 2 to 5 days depending on where you live instead of the 3-4 weeks or more from China with basically no warranty. I got mine to my door for $85. He also sells the Opus if you decide to go that route.

All of the above is my opinion and I have no connection with SkyRc, Opus or the above seller. I just appreciate fine electronics and enjoy helping others do the same. Link to the factory MC3000 manual: http://www.skyrc.com/index.php?route=product/product/download&download_id=168

I had ruled out the SkyRC, but you've given me enough good information to make me think I should reconsider. I'll definitely look at the manual to see what's involved. I would also appreciate knowing the U.S. based seller you recommend for either the SkyRC or Opus. You've given me some good options to consider, and I appreciate the help.

 

[Torchmee]

I had ruled out the SkyRC, but you've given me enough good information to make me think I should reconsider. I'll definitely look at the manual to see what's involved. I would also appreciate knowing the U.S. based seller you recommend for either the SkyRC or Opus. You've given me some good options to consider, and I appreciate the help.

I sent you a forum private message, check it.

 

[Ag76]

I sent you a forum private message, check it.

Got it, thanks.

 

[Gauss163]

If you want to do it right for long term storage charge or discharge them to 3.6 - 3.7v and store in a cool place, the fridge being an option if the wife will allow it. This will give you max storage life. If they are going to be used in a week or two leave them fully charged. Of course be sure your DMM is reasonably accurate. Some of the top end chargers have a storage mode to adjust the voltage for you.

Be aware that 3.6-3.7V is far too low for some chemistries (can be below 10% SOC). Generally a good storage voltage is in the range 35-50% SOC, depending on length of storage, ambient temperature, etc. See HKJs charts for Voltage vs SOC for some common chemistries.

 

[hmjgriffon]

Be aware that 3.6-3.7V is far too low for some chemistries (can be below 10% SOC). Generally a good storage voltage is in the range 35-50% SOC, depending on length of storage, ambient temperature, etc. See HKJs charts for Voltage vs SOC for some common chemistries.

So if you wanted to store batteries for an emergency SHTF type scenario, those should be non rechargeable?

 

[photonhoer]

The Opus is a great charger and I wouldn't ever get rid of mine … If you decide to buy one I will direct you to a distributor here in the US who will handle any warranty issues immediately and will give you an as good or better price than you can get on the China sites. $80 plus what ever the actual USPS shipping is from Ca. It will arrive in 2 to 5 days depending on where you live instead of the 3-4 weeks or more from China with basically no warranty. I got mine to my door for $85. He also sells the Opus if you decide to go that route.

Torchmee Is your referral offer still valid? I'd like to get one of the SkyRC MC3000 chargers. John

 

[sll]

I've tried various searches with little luck so I thought I would ask. I'll be sure and note the responses this time.
1- Seems like in one post someone mentioned a charged 18650 should hold a charge for at least a week before starting to drop. Is this right?
2- Why I ask is I have a ~5 month old Fenix 3500 which charges to ~4.2v +/- but drops to 4.15v after 2 days. I charged it back up the first time I noticed but this time I'm going to keep watching it. Is that rate of voltage drop high? Suggestions?
3- Will the battery continue to operate and what kind of service time would I expect?
4- How do you determine when a battery is at the of life?
5- Any additional information is once again greatly appreciated!
Thanks!

 

[ven]

I've tried various searches with little luck so I thought I would ask. I'll be sure and note the responses this time.
1- Seems like in one post someone mentioned a charged 18650 should hold a charge for at least a week before starting to drop. Is this right?

**Pretty much, but the initial termination voltage will drop slightly and settle.
2- Why I ask is I have a ~5 month old Fenix 3500 which charges to ~4.2v +/- but drops to 4.15v after 2 days. I charged it back up the first time I noticed but this time I'm going to keep watching it. Is that rate of voltage drop high? Suggestions?

**Not too sure how measured and if measured with same MM(multi meter/charger). Chargers spec tend to be + or - 0.05v, which is 4.15v to 4.25v. After charging, the voltage will drop slightly. For example, fresh off the charger at 4.2v, can settle to 4.18v.
3- Will the battery continue to operate and what kind of service time would I expect?
**After the initial drop is important, does it stay around 4.15v or continue to drop at the same rate. If the latter then yes the battery is tired.
4- How do you determine when a battery is at the of life?
**Usually when the voltage does not hold after settling , so once the V gets near 4.1v after charging(presuming the charging initial V is 4.2v ) then for me, the cell is past its best. At 4.1v, you still have roughly 90% charge................plenty use in the cell providing it does not continue to drop.
5- Any additional information is once again greatly appreciated!
Thanks!

^ answered above my thoughts in between Q's

**Would not be over concerned at this stage, if your going to store the cell, aim more for around 3.7 or 3.8v(if months rather than weeks). Other than that, dont get too hung up. Lots of my cells get used/charged daily so it will take a while for me to actually see Voltage drop. To try and explain better, i will use a work cell which is a samsung 30Q. Now this is around 4.2v terminated, measure after coming off the opus bt c100 it shows 4.18v. This cell goes straight into a 6p ready fro the next day. Its gets used the following day for X amount of time(variable). Back on charger and may read anywhere from 3.6v to 4.0v............repeat! So not too easy in that respect, if the term V off the charger is lower i will notice. Obviously i will notice if the cell does not last me my typical use or the V is very low when put back on charge to top off. So i dont get too hung up on the cell V, i take note and until something obvious................gets used. I do take note of the IR reading(internal resistance), this also has not really changed. I do take this with a pinch of salt.

The Fenix cell will either be a sanyo GA inside or an LG. Both good cells, at 5m of age it should be fine(use dependent but would have to have many discharge/charge cycles in that time to effect). Measure the V after a couple of days, then a week, then 2 weeks to get a rough idea. I would have thought it wont drop much if anything lower than 4.15v. Just make sure what your measuring on is the same device for consistency. Other than that, use and enjoy

 

[sll]

Thanks for the detailed reply. I have made notes so I don't have to keep asking. The battery was at 4.14v yesterday and is 4.12v this morning. I use the same DVM and the other batteries typically settle at 4.17-4.19 after several day days. I do notice the XTAR VP2 charger will occasionally stop at 4.18v to 4.19v. Sometimes I'll put the batteries back into the charger to get them up to 4.2. Is this "topping off" the batteries [1] Really that necessary since they are at 98-99% capacity? and more importantly [2] Is this detrimental to the batteries?
Thanks again!

 

[terjee]

The topping matters too little that I'd care, both in terms of how much more energy you can fill, and also in terms of negative effect. I wouldn't bother to do it.

If you absolutely need as much juice as you can get into the battery, you can charge at a slower rate.

The faster you charge btw, the faster the voltage will drop after charging. You could perhaps see something like charging at 2A dropping from 4.2 to 4.17, and charging at 0.5A dropping from 4.2A to 4.19V. It doesn't matter too much though.

Not charging too fast (such as a weak battery at 2A or more) would not be good for the battery. I stay at less than 1A for an 18650, unless I know it'll be comfortable taking more. VTC-series for example, I'll charge at 2A.

If you want a quick an easy way to keep an eye on the health of a battery, then a charger showing internal resistance can be a good way to go about it. I can't recall if the Opus does that (I don't think so, but I could be wrong). Depending on your level of interest and how much you'd be willing to spend, the MC3000 or SC4 could be something to consider (the latter will default to charge at 2A though).

Analyzing the available capacity by doing a charge/discharge cycle, is also useful in determining battery health.

 

[sll]

I charged the questionable battery and one other at 0.5A today and the both had 4.20 V an hour after coming off the charger. Previously I had been charging at 1.0A but maybe I'll cut back to the 0.5A. Any problems with that?

The questionable battery was at 4.10V before charging it today and I plan to monitor it for voltage drop. Is the consensus if I charge it one day before use that it should still have >90% capacity and function fine for the one day?

Thanks

 

[hkusp9]

The topping matters too little that I'd care, both in terms of how much more energy you can fill, and also in terms of negative effect. I wouldn't bother to do it.

If you absolutely need as much juice as you can get into the battery, you can charge at a slower rate.

The faster you charge btw, the faster the voltage will drop after charging. You could perhaps see something like charging at 2A dropping from 4.2 to 4.17, and charging at 0.5A dropping from 4.2A to 4.19V. It doesn't matter too much though.

Not charging too fast (such as a weak battery at 2A or more) would not be good for the battery. I stay at less than 1A for an 18650, unless I know it'll be comfortable taking more. VTC-series for example, I'll charge at 2A.

If you want a quick an easy way to keep an eye on the health of a battery, then a charger showing internal resistance can be a good way to go about it. I can't recall if the Opus does that (I don't think so, but I could be wrong). Depending on your level of interest and how much you'd be willing to spend, the MC3000 or SC4 could be something to consider (the latter will default to charge at 2A though).

Analyzing the available capacity by doing a charge/discharge cycle, is also useful in determining battery health.

whats the typical resistance for an unprotected 3500 mah 18650 LG battery and how close do they need to be to each other to be "matched"?

 

[dragosios]

Should in the tens of miliohoms range.
You should select the most closest ones in your batch. Of course, financial constrains will limit your choice, also cells age more or less the same if they are used and not used the same.

 

[terjee]

One bit of trouble is that if you're matching up cells, you'd need to check both internal resistance and capacity.
Most people just build packs from cells purchased together without added checks.