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, att...@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.