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used 18650 in series and parallel - opinions.
Simen:
I've received all the parts; mishandled a piece of 4 mm plywood, and put it all together. :P
And the innards;
Everything performs just as i hoped. ;) The voltages out from the usb ports are reasonable stable; at around 5.17V unloaded, and it drops to around 5.13V with 1A load. (I haven't testet with larger loads yet.)
The battery graph/display should be calibrated for 2S LiCo cells, with 100% at 4.20V, and 0% at 2.95V.
I've adjusted the charger to 8.32V (4.16V/cell), and a constant-current of 3.0A, and i've set the charge-light to switch from red to green at 200mA draw, indicating end-of-charge.
I'm using Anderson PowerPole connectors for connecting a charge-source, since i already use them on my many smaller (10-100W) loose solar-panels.
dnix71:
Simen if you drop the voltage from 4.16 to 4.0 you will get many more cycle out of the cells. At 4.16 and above lithium metal begins to plate out inside the cells and that is what reduces their life.
I have dozens of 14500 lithium iron phosphate cells. I use them in microphones that came with AA NiMH or alkaline cells. One lithium and one dummy cell. The real capacity is about 400 to 600mah for a 14500 cell. They can be destroyed by overcharging, but I have never seen one burn even though the plastic label melted off and the cell got hot enough to set paper on fire. Those were installed in a cordless drill in place of the original NiCads. I had to buy a special charger from eBay for about $10 to charge the pack correctly, but that works perfectly and the cells stay charged for months sitting in the tool cabinet.
I am only guessing, but an 18650 would probably hold 1000 mah in real life, no matter what some eBay seller say.
I wish there was some way to hold eBay executives personally accountable for allowing blatant liars to sell batteries with fake capacities.
Simen:
--- Quote ---I am only guessing, but an 18650 would probably hold 1000 mah in real life, no matter what some eBay seller say.
--- End quote ---
If this is your experience - stay off ebay! :D
I've never experienced a Lithium cell that has not been close to, or at, specified capacity - But then, i get them from 'respectable' laptop brands... :)
LiFePO4 cells are an another world, when it comes to safety... LiCo etc. have a runaway temp. at 140 Deg.C. ,while LiFe are around 260 Deg.C.; much safer.
BTW: How did you manage to get LiFe cells that hot?!?! Did you charge them at 4.2V?!
They should be charged at 3.65V max...
Bruce S:
Simen;
I agree, all of the 18650s I've re-purposed from laptop batt-packs, they are either dead or pretty close to their rated levels.
I'm looking at a battery balance setup ($110USD) so I can actually test to batteries before assembling the packs.
I helped a friend swap out one of the modules in his Hybrid Camry, the unit he bought worked so well for find the bad module and testing my packs I'm ordering my own.
I don't have enough of the 145xx to say, but the ones out in my solar lights last a long time.
PS>>> I order any batteries I have to have from aliexpress. I'm in no real hurry so them taking 7-10 days is no big deal
dnix71:
Simen I burned up some 14500 LIFePO4 cells by using an unregulated charger iintended for NiCads. They took a remarkable amount of abuse before failing.
I am very choosy about buying rechargable cells of eBay. There is a Battery Store in town again. I can get almost anything there but the price is high. NiMH cells are also overrated on eBay. I stick with Duracell brand and have not been disappointed yet.
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