I use 4 cell balancing and protection circuits, cost a couple of $ more but well worth it, I use holders because of limited availability of cells with straps, but rest assured they are held down (discarded PCB)'s, I on purpose did not get into technical details I was only trying to share reliable sources, based on disappointing past experiences. Bert Kehren In a message dated 1/22/2017 10:00:45 A.M. Eastern Standard Time, attila@kinali.ch writes: Hoi Bert, On Sat, 21 Jan 2017 08:08:22 -0500 Bert Kehren via time-nuts <time-nuts@febo.com> wrote: > purchased _2x Samsung 35E 3500mAh 10A 18650 High Drain Rechargeable Battery > INR18650-35E_ > (http://www.ebay.com/itm/112173495496?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT) for two reason 10 A load and good price. These > cells have no protection, which I want, since I will for our applications > stack 4 with a 4 cell controller and in two application also parallel cells > for a total of 8. I have now completed my tests and concentrate my > battery work on using these cells. > After having tested 26650 cells with disappointing results my focus is on > 18650. I am sure there will be 26650 cells available, but right now our > focus is on 18650. > I have no connection in any way with these two sources, but think it may > be helpful for those that look for batteris and do not want to go through > the process I went through. Some small remarks: 18650 is by far the most common form factor of Li-Ion batteries on the market. This is IMHO the better choice than the 26650 if you want to be able to replace them in 10-20 years. If you stack Li-* batteries, you will need to have a controller that monitors each cell individually while charging or has some other means of ensuring that none of the cells are overcharged (or rather that they are charged the same amount). This kind of circuit is called balancer. A protection circuit does _not_ replace a balancer. The protection circuit is only to protect against catastrophic failure. Ie it is still possible to overcharge a battery even if it has a protection circuit. You also do not know what the protection circuit does to protect the cell. There are a lot of chips out there, that simply open a switch and thus disconnect the cell. In this case, the protection circuit of one cell will disconnect the whole stack and break charging. A lot of the multi-cell Li-Ion charger chips have integrated cell protection circuitry. Ie if you use one of them, you will not need an additional protection circuit. But be aware, the regulation for battery protection circuit states that the circuit has to be wired fix onto the battery in a way that this connection cannot be broken (without breaking the housing of the battery pack). The reason for this is, i think, pretty obvious. I would recommend that you solder each cell indidividually into your circuit instead of using some kind of holder. Or if you are using a holder, make it such that there is no chance any of the cells can be accidentally short circuited. Attila Kinali -- Malek's Law: Any simple idea will be worded in the most complicated way. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

Well worth mentioning that you have found a reputable vendor. I may give them a try. A while back, I bought a dozen 18650 inexpensive(<$5 each) cells from 3 vendors picked at semi-random on eBay (4 from each) for evaluation and I tested each one of them with a data logger. The best one had about half the advertised capacity, the others went down from there. Important to observe that none of the set I bought were even remotely matched, a crucial consideration if you are going to put them in series (a balancer will only ensure your pack is no better than the worst cell in the pack). Many of the 18650 cells you find on eBay (and maybe other places) are actually coming from old laptop battery packs that normally should have been discarded/recycled. In my anticipated application, I only needed one cell (to be followed by a small boost converter), so the issue of balance and matched set was not important, but simply I needed the capacity and none were remotely satisfactory. I ended up using cell phone booster packs, since I needed 5V anyway. On Sun, Jan 22, 2017 at 9:44 AM, Bert Kehren via time-nuts < time-nuts@febo.com> wrote: > I use 4 cell balancing and protection circuits, cost a couple of $ more but > well worth it, I use holders because of limited availability of cells > with straps, but rest assured they are held down (discarded PCB)'s, > I on purpose did not get into technical details I was only trying to share > reliable sources, based on disappointing past experiences. > Bert Kehren > > > In a message dated 1/22/2017 10:00:45 A.M. Eastern Standard Time, > attila@kinali.ch writes: > > Hoi Bert, > > On Sat, 21 Jan 2017 08:08:22 -0500 > Bert Kehren via time-nuts <time-nuts@febo.com> wrote: > > > purchased _2x Samsung 35E 3500mAh 10A 18650 High Drain Rechargeable > Battery > > INR18650-35E_ > > > (http://www.ebay.com/itm/112173495496?_trksid=p2060353. > m2749.l2649&ssPageName=STRK:MEBIDX:IT) for two reason 10 A load and > good price. These > > cells have no protection, which I want, since I will for our > applications > > stack 4 with a 4 cell controller and in two application also parallel > cells > > for a total of 8. I have now completed my tests and concentrate my > > battery work on using these cells. > > After having tested 26650 cells with disappointing results my focus is > on > > 18650. I am sure there will be 26650 cells available, but right now our > > focus is on 18650. > > I have no connection in any way with these two sources, but think it > may > > be helpful for those that look for batteris and do not want to go > through > > the process I went through. > > > Some small remarks: 18650 is by far the most common form factor > of Li-Ion batteries on the market. This is IMHO the better choice > than the 26650 if you want to be able to replace them in 10-20 years. > > If you stack Li-* batteries, you will need to have a controller that > monitors each cell individually while charging or has some other means > of ensuring that none of the cells are overcharged (or rather that they > are charged the same amount). This kind of circuit is called balancer. > A protection circuit does _not_ replace a balancer. The protection circuit > is only to protect against catastrophic failure. Ie it is still possible > to overcharge a battery even if it has a protection circuit. You also do > not know what the protection circuit does to protect the cell. There are > a lot of chips out there, that simply open a switch and thus disconnect > the cell. In this case, the protection circuit of one cell will disconnect > the whole stack and break charging. > > A lot of the multi-cell Li-Ion charger chips have integrated cell > protection > circuitry. Ie if you use one of them, you will not need an additional > protection circuit. But be aware, the regulation for battery protection > circuit states that the circuit has to be wired fix onto the battery > in a way that this connection cannot be broken (without breaking the > housing of the battery pack). The reason for this is, i think, pretty > obvious. I would recommend that you solder each cell indidividually > into your circuit instead of using some kind of holder. Or if you are > using a holder, make it such that there is no chance any of the cells > can be accidentally short circuited. > > Attila Kinali > -- > Malek's Law: > Any simple idea will be worded in the most complicated way. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. >

Recovered cells aren't only sold through ebay parts adverts - they're also used for production. I recently bought a few cell phone boosters which consist of an 18650, a charge circuit and a voltage booster to 5V. They were low cost and nicely made with an extruded aluminium case and they worked very well in my application. But on taking one apart, it was apparent that they'd used a recovered cell. I've no complaints given the price, but be aware that the cell phone packs may not be new either. On Sun, Jan 22, 2017 at 4:48 PM, Didier Juges <shalimr9@gmail.com> wrote: > Well worth mentioning that you have found a reputable vendor. I may give > them a try. > > A while back, I bought a dozen 18650 inexpensive(<$5 each) cells from 3 > vendors picked at semi-random on eBay (4 from each) for evaluation and I > tested each one of them with a data logger. > The best one had about half the advertised capacity, the others went down > from there. Important to observe that none of the set I bought were even > remotely matched, a crucial consideration if you are going to put them in > series (a balancer will only ensure your pack is no better than the worst > cell in the pack). > Many of the 18650 cells you find on eBay (and maybe other places) are > actually coming from old laptop battery packs that normally should have > been discarded/recycled. > > In my anticipated application, I only needed one cell (to be followed by a > small boost converter), so the issue of balance and matched set was not > important, but simply I needed the capacity and none were remotely > satisfactory. I ended up using cell phone booster packs, since I needed 5V > anyway. > > > On Sun, Jan 22, 2017 at 9:44 AM, Bert Kehren via time-nuts < > time-nuts@febo.com> wrote: > > > I use 4 cell balancing and protection circuits, cost a couple of $ more > but > > well worth it, I use holders because of limited availability of cells > > with straps, but rest assured they are held down (discarded PCB)'s, > > I on purpose did not get into technical details I was only trying to > share > > reliable sources, based on disappointing past experiences. > > Bert Kehren > > > > > > In a message dated 1/22/2017 10:00:45 A.M. Eastern Standard Time, > > attila@kinali.ch writes: > > > > Hoi Bert, > > > > On Sat, 21 Jan 2017 08:08:22 -0500 > > Bert Kehren via time-nuts <time-nuts@febo.com> wrote: > > > > > purchased _2x Samsung 35E 3500mAh 10A 18650 High Drain Rechargeable > > Battery > > > INR18650-35E_ > > > > > (http://www.ebay.com/itm/112173495496?_trksid=p2060353. > > m2749.l2649&ssPageName=STRK:MEBIDX:IT) for two reason 10 A load and > > good price. These > > > cells have no protection, which I want, since I will for our > > applications > > > stack 4 with a 4 cell controller and in two application also parallel > > cells > > > for a total of 8. I have now completed my tests and concentrate my > > > battery work on using these cells. > > > After having tested 26650 cells with disappointing results my focus > is > > on > > > 18650. I am sure there will be 26650 cells available, but right now > our > > > focus is on 18650. > > > I have no connection in any way with these two sources, but think it > > may > > > be helpful for those that look for batteris and do not want to go > > through > > > the process I went through. > > > > > > Some small remarks: 18650 is by far the most common form factor > > of Li-Ion batteries on the market. This is IMHO the better choice > > than the 26650 if you want to be able to replace them in 10-20 years. > > > > If you stack Li-* batteries, you will need to have a controller that > > monitors each cell individually while charging or has some other means > > of ensuring that none of the cells are overcharged (or rather that they > > are charged the same amount). This kind of circuit is called balancer. > > A protection circuit does _not_ replace a balancer. The protection > circuit > > is only to protect against catastrophic failure. Ie it is still possible > > to overcharge a battery even if it has a protection circuit. You also do > > not know what the protection circuit does to protect the cell. There are > > a lot of chips out there, that simply open a switch and thus disconnect > > the cell. In this case, the protection circuit of one cell will > disconnect > > the whole stack and break charging. > > > > A lot of the multi-cell Li-Ion charger chips have integrated cell > > protection > > circuitry. Ie if you use one of them, you will not need an additional > > protection circuit. But be aware, the regulation for battery protection > > circuit states that the circuit has to be wired fix onto the battery > > in a way that this connection cannot be broken (without breaking the > > housing of the battery pack). The reason for this is, i think, pretty > > obvious. I would recommend that you solder each cell indidividually > > into your circuit instead of using some kind of holder. Or if you are > > using a holder, make it such that there is no chance any of the cells > > can be accidentally short circuited. > > > > Attila Kinali > > -- > > Malek's Law: > > Any simple idea will be worded in the most complicated way. > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > mailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. >

One of my hats is working with a recycler to help them best utilize their input stream of recycled electronics. To that end, I take a lot of things apart, looking for failure mechanisms. This allows me to discover common problems, and to suggest which items are economical to repair, and which aren't. In the course of that activity, I have observed a lot of failed lithium battery packs. The most common failure is due to the pack being allowed to discharge too deeply. The protection electronics is happy to disconnect individual cells when they have reached a safe lowest voltage, which is good, but it doesn't do a very good job of protecting cells that are then left for weeks, months, or years in that discharged state. Eventually the cells self discharge (fueled by the protection circuitry's monitoring circuits) to a point where the protection circuitry won't allow them to be charged anymore. If you catch the packs quickly enough, you can bypass the protection circuitry, and pump some charge directly into the cells to restore function. If you wait too long before restoring the cell, they will often get hot, swell up, catch fire, and sometimes explode. They will also do this if you physically abuse the cells by denting them, heating them too hot, or bending them too far. You have been warned! Once you have a cell that functions properly, but maybe at a reduced capacity, it will continue to work reliably, and will continue to slowly lose capacity, just as a new cell would. -Chuck Harris Adrian Godwin wrote: > Recovered cells aren't only sold through ebay parts adverts - they're also > used for production. I recently bought a few cell phone boosters which > consist of an 18650, a charge circuit and a voltage booster to 5V. > > They were low cost and nicely made with an extruded aluminium case and they > worked very well in my application. But on taking one apart, it was > apparent that they'd used a recovered cell. > > I've no complaints given the price, but be aware that the cell phone packs > may not be new either. > > > On Sun, Jan 22, 2017 at 4:48 PM, Didier Juges <shalimr9@gmail.com> wrote: > >> Well worth mentioning that you have found a reputable vendor. I may give >> them a try. >> >> A while back, I bought a dozen 18650 inexpensive(<$5 each) cells from 3 >> vendors picked at semi-random on eBay (4 from each) for evaluation and I >> tested each one of them with a data logger. >> The best one had about half the advertised capacity, the others went down >> from there. Important to observe that none of the set I bought were even >> remotely matched, a crucial consideration if you are going to put them in >> series (a balancer will only ensure your pack is no better than the worst >> cell in the pack). >> Many of the 18650 cells you find on eBay (and maybe other places) are >> actually coming from old laptop battery packs that normally should have >> been discarded/recycled. >> >> In my anticipated application, I only needed one cell (to be followed by a >> small boost converter), so the issue of balance and matched set was not >> important, but simply I needed the capacity and none were remotely >> satisfactory. I ended up using cell phone booster packs, since I needed 5V >> anyway. >> >> >> On Sun, Jan 22, 2017 at 9:44 AM, Bert Kehren via time-nuts < >> time-nuts@febo.com> wrote: >> >>> I use 4 cell balancing and protection circuits, cost a couple of $ more >> but >>> well worth it, I use holders because of limited availability of cells >>> with straps, but rest assured they are held down (discarded PCB)'s, >>> I on purpose did not get into technical details I was only trying to >> share >>> reliable sources, based on disappointing past experiences. >>> Bert Kehren >>> >>> >>> In a message dated 1/22/2017 10:00:45 A.M. Eastern Standard Time, >>> attila@kinali.ch writes: >>> >>> Hoi Bert, >>> >>> On Sat, 21 Jan 2017 08:08:22 -0500 >>> Bert Kehren via time-nuts <time-nuts@febo.com> wrote: >>> >>>> purchased _2x Samsung 35E 3500mAh 10A 18650 High Drain Rechargeable >>> Battery >>>> INR18650-35E_ >>>> >>> (http://www.ebay.com/itm/112173495496?_trksid=p2060353. >>> m2749.l2649&ssPageName=STRK:MEBIDX:IT) for two reason 10 A load and >>> good price. These >>>> cells have no protection, which I want, since I will for our >>> applications >>>> stack 4 with a 4 cell controller and in two application also parallel >>> cells >>>> for a total of 8. I have now completed my tests and concentrate my >>>> battery work on using these cells. >>>> After having tested 26650 cells with disappointing results my focus >> is >>> on >>>> 18650. I am sure there will be 26650 cells available, but right now >> our >>>> focus is on 18650. >>>> I have no connection in any way with these two sources, but think it >>> may >>>> be helpful for those that look for batteris and do not want to go >>> through >>>> the process I went through. >>> >>> >>> Some small remarks: 18650 is by far the most common form factor >>> of Li-Ion batteries on the market. This is IMHO the better choice >>> than the 26650 if you want to be able to replace them in 10-20 years. >>> >>> If you stack Li-* batteries, you will need to have a controller that >>> monitors each cell individually while charging or has some other means >>> of ensuring that none of the cells are overcharged (or rather that they >>> are charged the same amount). This kind of circuit is called balancer. >>> A protection circuit does _not_ replace a balancer. The protection >> circuit >>> is only to protect against catastrophic failure. Ie it is still possible >>> to overcharge a battery even if it has a protection circuit. You also do >>> not know what the protection circuit does to protect the cell. There are >>> a lot of chips out there, that simply open a switch and thus disconnect >>> the cell. In this case, the protection circuit of one cell will >> disconnect >>> the whole stack and break charging. >>> >>> A lot of the multi-cell Li-Ion charger chips have integrated cell >>> protection >>> circuitry. Ie if you use one of them, you will not need an additional >>> protection circuit. But be aware, the regulation for battery protection >>> circuit states that the circuit has to be wired fix onto the battery >>> in a way that this connection cannot be broken (without breaking the >>> housing of the battery pack). The reason for this is, i think, pretty >>> obvious. I would recommend that you solder each cell indidividually >>> into your circuit instead of using some kind of holder. Or if you are >>> using a holder, make it such that there is no chance any of the cells >>> can be accidentally short circuited. >>> >>> Attila Kinali >>> -- >>> Malek's Law: >>> Any simple idea will be worded in the most complicated way. >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ >>> mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/time-nuts >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >

I'm using Lithium batteries too. Button for everything. For stationary lab bench use where AC mains is available and all I want is back up our the lead/acid gel cells work fine. They are cheap, large and heavy and will take abuse and don't normally catch fire. For the mobile devices that I like to build nothing beats Lithium batteries. I've been using the kind sold for use on remote controlled drone aircraft. They have incredible power density and low cost. Their biggest down side (an advantage to me) is their lack of consumer appropriate packaging. The cells are only shrink wrapped and are easy to damage. I change them with a programable "balanced" charger that is commonly used by hobbyists. I have found that YES you can start a fire from carelessly handing Lithium batteries. You do have to understand how to use them and keep them packaged such that they remain safe even if they fail or (more likely) you make some mistake. I keep them in fire proof glass fiber/silicone envelopes then inside a tightly close steel "ammo box". When in use they are installed in the mobil device I built in a metal compartment (I use those old fashion Japanese lunch boxes, they are like Tupperware but made completely of metal) Get these batteries at any of the Hobby supply outlets (NOT eBay, lots of fakes there.) Here is just one example of the last set I bought https://hobbyking.com/en_us/zippy-flightmax-4000mah-4s1p-20c.html On Sun, Jan 22, 2017 at 9:13 AM, Adrian Godwin <artgodwin@gmail.com> wrote: > Recovered cells aren't only sold through ebay parts adverts - they're also > used for production. I recently bought a few cell phone boosters which > consist of an 18650, a charge circuit and a voltage booster to 5V. > > They were low cost and nicely made with an extruded aluminium case and they > worked very well in my application. But on taking one apart, it was > apparent that they'd used a recovered cell. > > I've no complaints given the price, but be aware that the cell phone packs > may not be new either. > > > On Sun, Jan 22, 2017 at 4:48 PM, Didier Juges <shalimr9@gmail.com> wrote: > > > Well worth mentioning that you have found a reputable vendor. I may give > > them a try. > > > > A while back, I bought a dozen 18650 inexpensive(<$5 each) cells from 3 > > vendors picked at semi-random on eBay (4 from each) for evaluation and I > > tested each one of them with a data logger. > > The best one had about half the advertised capacity, the others went down > > from there. Important to observe that none of the set I bought were even > > remotely matched, a crucial consideration if you are going to put them in > > series (a balancer will only ensure your pack is no better than the worst > > cell in the pack). > > Many of the 18650 cells you find on eBay (and maybe other places) are > > actually coming from old laptop battery packs that normally should have > > been discarded/recycled. > > > > In my anticipated application, I only needed one cell (to be followed by > a > > small boost converter), so the issue of balance and matched set was not > > important, but simply I needed the capacity and none were remotely > > satisfactory. I ended up using cell phone booster packs, since I needed > 5V > > anyway. > > > > > > On Sun, Jan 22, 2017 at 9:44 AM, Bert Kehren via time-nuts < > > time-nuts@febo.com> wrote: > > > > > I use 4 cell balancing and protection circuits, cost a couple of $ more > > but > > > well worth it, I use holders because of limited availability of cells > > > with straps, but rest assured they are held down (discarded PCB)'s, > > > I on purpose did not get into technical details I was only trying to > > share > > > reliable sources, based on disappointing past experiences. > > > Bert Kehren > > > > > > > > > In a message dated 1/22/2017 10:00:45 A.M. Eastern Standard Time, > > > attila@kinali.ch writes: > > > > > > Hoi Bert, > > > > > > On Sat, 21 Jan 2017 08:08:22 -0500 > > > Bert Kehren via time-nuts <time-nuts@febo.com> wrote: > > > > > > > purchased _2x Samsung 35E 3500mAh 10A 18650 High Drain > Rechargeable > > > Battery > > > > INR18650-35E_ > > > > > > > (http://www.ebay.com/itm/112173495496?_trksid=p2060353. > > > m2749.l2649&ssPageName=STRK:MEBIDX:IT) for two reason 10 A load and > > > good price. These > > > > cells have no protection, which I want, since I will for our > > > applications > > > > stack 4 with a 4 cell controller and in two application also > parallel > > > cells > > > > for a total of 8. I have now completed my tests and concentrate > my > > > > battery work on using these cells. > > > > After having tested 26650 cells with disappointing results my focus > > is > > > on > > > > 18650. I am sure there will be 26650 cells available, but right now > > our > > > > focus is on 18650. > > > > I have no connection in any way with these two sources, but think > it > > > may > > > > be helpful for those that look for batteris and do not want to go > > > through > > > > the process I went through. > > > > > > > > > Some small remarks: 18650 is by far the most common form factor > > > of Li-Ion batteries on the market. This is IMHO the better choice > > > than the 26650 if you want to be able to replace them in 10-20 years. > > > > > > If you stack Li-* batteries, you will need to have a controller that > > > monitors each cell individually while charging or has some other means > > > of ensuring that none of the cells are overcharged (or rather that > they > > > are charged the same amount). This kind of circuit is called balancer. > > > A protection circuit does _not_ replace a balancer. The protection > > circuit > > > is only to protect against catastrophic failure. Ie it is still > possible > > > to overcharge a battery even if it has a protection circuit. You also > do > > > not know what the protection circuit does to protect the cell. There > are > > > a lot of chips out there, that simply open a switch and thus > disconnect > > > the cell. In this case, the protection circuit of one cell will > > disconnect > > > the whole stack and break charging. > > > > > > A lot of the multi-cell Li-Ion charger chips have integrated cell > > > protection > > > circuitry. Ie if you use one of them, you will not need an additional > > > protection circuit. But be aware, the regulation for battery > protection > > > circuit states that the circuit has to be wired fix onto the battery > > > in a way that this connection cannot be broken (without breaking the > > > housing of the battery pack). The reason for this is, i think, pretty > > > obvious. I would recommend that you solder each cell indidividually > > > into your circuit instead of using some kind of holder. Or if you are > > > using a holder, make it such that there is no chance any of the cells > > > can be accidentally short circuited. > > > > > > Attila Kinali > > > -- > > > Malek's Law: > > > Any simple idea will be worded in the most complicated way. > > > _______________________________________________ > > > time-nuts mailing list -- time-nuts@febo.com > > > To unsubscribe, go to > > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > > > _______________________________________________ > > > time-nuts mailing list -- time-nuts@febo.com > > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > > mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > mailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California

In the days prior to my recent retirement, when I was directing research at a large VA Medical Center, one of our projects used inordinate quantities of 18650 Li-ion batteries. We found in short order that buying from Amazon or eBay was penny wise and pound foolish. Rather than flogging the internet for deals, trying to save a few bucks, just buy Panasonic, Duracell, Sanyo, Samsung Sony or LG directly from an authorized dealer. As Chris pointed out, ammo boxes work are excellent for storage. We found the manufacturer''s packaging perfectly adequate. They aren't bombs, guys. Use sensible precautions and get on with it. On Sunday, January 22, 2017, Chris Albertson <albertson.chris@gmail.com <javascript:_e(%7B%7D,'cvml','albertson.chris@gmail.com');>> wrote: > I'm using Lithium batteries too. Button for everything. For stationary > lab bench use where AC mains is available and all I want is back up our the > lead/acid gel cells work fine. They are cheap, large and heavy and will > take abuse and don't normally catch fire. > > For the mobile devices that I like to build nothing beats Lithium > batteries. I've been using the kind sold for use on remote controlled > drone aircraft. They have incredible power density and low cost. Their > biggest down side (an advantage to me) is their lack of consumer > appropriate packaging. The cells are only shrink wrapped and are easy to > damage. I change them with a programable "balanced" charger that is > commonly used by hobbyists. > > I have found that YES you can start a fire from carelessly handing Lithium > batteries. You do have to understand how to use them and keep them > packaged such that they remain safe even if they fail or (more likely) you > make some mistake. I keep them in fire proof glass fiber/silicone > envelopes then inside a tightly close steel "ammo box". When in use > they are installed in the mobil device I built in a metal compartment (I > use those old fashion Japanese lunch boxes, they are like Tupperware but > made completely of metal) > > Get these batteries at any of the Hobby supply outlets (NOT eBay, lots of > fakes there.) > Here is just one example of the last set I bought > https://hobbyking.com/en_us/zippy-flightmax-4000mah-4s1p-20c.html > > > > On Sun, Jan 22, 2017 at 9:13 AM, Adrian Godwin <artgodwin@gmail.com> > wrote: > > > Recovered cells aren't only sold through ebay parts adverts - they're > also > > used for production. I recently bought a few cell phone boosters which > > consist of an 18650, a charge circuit and a voltage booster to 5V. > > > > They were low cost and nicely made with an extruded aluminium case and > they > > worked very well in my application. But on taking one apart, it was > > apparent that they'd used a recovered cell. > > > > I've no complaints given the price, but be aware that the cell phone > packs > > may not be new either. > > > > > > On Sun, Jan 22, 2017 at 4:48 PM, Didier Juges <shalimr9@gmail.com> > wrote: > > > > > Well worth mentioning that you have found a reputable vendor. I may > give > > > them a try. > > > > > > A while back, I bought a dozen 18650 inexpensive(<$5 each) cells from 3 > > > vendors picked at semi-random on eBay (4 from each) for evaluation and > I > > > tested each one of them with a data logger. > > > The best one had about half the advertised capacity, the others went > down > > > from there. Important to observe that none of the set I bought were > even > > > remotely matched, a crucial consideration if you are going to put them > in > > > series (a balancer will only ensure your pack is no better than the > worst > > > cell in the pack). > > > Many of the 18650 cells you find on eBay (and maybe other places) are > > > actually coming from old laptop battery packs that normally should have > > > been discarded/recycled. > > > > > > In my anticipated application, I only needed one cell (to be followed > by > > a > > > small boost converter), so the issue of balance and matched set was not > > > important, but simply I needed the capacity and none were remotely > > > satisfactory. I ended up using cell phone booster packs, since I needed > > 5V > > > anyway. > > > > > > > > > On Sun, Jan 22, 2017 at 9:44 AM, Bert Kehren via time-nuts < > > > time-nuts@febo.com> wrote: > > > > > > > I use 4 cell balancing and protection circuits, cost a couple of $ > more > > > but > > > > well worth it, I use holders because of limited availability of > cells > > > > with straps, but rest assured they are held down (discarded PCB)'s, > > > > I on purpose did not get into technical details I was only trying to > > > share > > > > reliable sources, based on disappointing past experiences. > > > > Bert Kehren > > > > > > > > > > > > In a message dated 1/22/2017 10:00:45 A.M. Eastern Standard Time, > > > > attila@kinali.ch writes: > > > > > > > > Hoi Bert, > > > > > > > > On Sat, 21 Jan 2017 08:08:22 -0500 > > > > Bert Kehren via time-nuts <time-nuts@febo.com> wrote: > > > > > > > > > purchased _2x Samsung 35E 3500mAh 10A 18650 High Drain > > Rechargeable > > > > Battery > > > > > INR18650-35E_ > > > > > > > > > (http://www.ebay.com/itm/112173495496?_trksid=p2060353. > > > > m2749.l2649&ssPageName=STRK:MEBIDX:IT) for two reason 10 A load > and > > > > good price. These > > > > > cells have no protection, which I want, since I will for our > > > > applications > > > > > stack 4 with a 4 cell controller and in two application also > > parallel > > > > cells > > > > > for a total of 8. I have now completed my tests and concentrate > > my > > > > > battery work on using these cells. > > > > > After having tested 26650 cells with disappointing results my > focus > > > is > > > > on > > > > > 18650. I am sure there will be 26650 cells available, but right > now > > > our > > > > > focus is on 18650. > > > > > I have no connection in any way with these two sources, but think > > it > > > > may > > > > > be helpful for those that look for batteris and do not want to go > > > > through > > > > > the process I went through. > > > > > > > > > > > > Some small remarks: 18650 is by far the most common form factor > > > > of Li-Ion batteries on the market. This is IMHO the better choice > > > > than the 26650 if you want to be able to replace them in 10-20 > years. > > > > > > > > If you stack Li-* batteries, you will need to have a controller that > > > > monitors each cell individually while charging or has some other > means > > > > of ensuring that none of the cells are overcharged (or rather that > > they > > > > are charged the same amount). This kind of circuit is called > balancer. > > > > A protection circuit does _not_ replace a balancer. The protection > > > circuit > > > > is only to protect against catastrophic failure. Ie it is still > > possible > > > > to overcharge a battery even if it has a protection circuit. You > also > > do > > > > not know what the protection circuit does to protect the cell. There > > are > > > > a lot of chips out there, that simply open a switch and thus > > disconnect > > > > the cell. In this case, the protection circuit of one cell will > > > disconnect > > > > the whole stack and break charging. > > > > > > > > A lot of the multi-cell Li-Ion charger chips have integrated cell > > > > protection > > > > circuitry. Ie if you use one of them, you will not need an > additional > > > > protection circuit. But be aware, the regulation for battery > > protection > > > > circuit states that the circuit has to be wired fix onto the battery > > > > in a way that this connection cannot be broken (without breaking the > > > > housing of the battery pack). The reason for this is, i think, > pretty > > > > obvious. I would recommend that you solder each cell indidividually > > > > into your circuit instead of using some kind of holder. Or if you > are > > > > using a holder, make it such that there is no chance any of the > cells > > > > can be accidentally short circuited. > > > > > > > > Attila Kinali > > > > -- > > > > Malek's Law: > > > > Any simple idea will be worded in the most complicated way. > > > > _______________________________________________ > > > > time-nuts mailing list -- time-nuts@febo.com > > > > To unsubscribe, go to > > > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > > and follow the instructions there. > > > > > > > > _______________________________________________ > > > > time-nuts mailing list -- time-nuts@febo.com > > > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > > > mailman/listinfo/time-nuts > > > > and follow the instructions there. > > > > > > > _______________________________________________ > > > time-nuts mailing list -- time-nuts@febo.com > > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > > mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > mailman/listinfo/time-nuts > > and follow the instructions there. > > > > > > -- > > Chris Albertson > Redondo Beach, California > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. > -- If you gaze long into an abyss, your coffee will get cold.