Ok so I have bought all Keeppower protected cells: set of sanyo, set of panasonic.
TOTAL CRAP!
Protection circuit trips at 3.5V per cell under load!!! WTF. Protected packs will run down to 3V per cell before tripping. I thought I had a bad circuit on one of my panasonics but now find THEY ARE ALL LIKE THIS. And authentic keeppower (well posted that way on amazon). Not sure wtf, using them in a fenix case for my bike lights. I reset protection on the one cell that trips each time and after reset they are just under 4V (3.96 ish) static. Load starts at 3A, gets to about 2A/3.5V per cell (7V on pack) and thats it, registers 2.5v on the meter, reset, dmm says 3.96V on each cell. I dont expect 3.0 on the cells before trip but they can go lower than that without damage, 3.25 seems to be where batteries start to say enough. I dont wlays need that low but come one, 2.5-2.6A for like 35-40 mins on 2600mah cells… should be able to get 50-55 safely I thought (unless these suck compared to LI-poly batteries).
Also these are balanced across my BC-6 on balance mode, then I switch to charge mode just to see if one is off from the other. All good to go.
SO what gives, tripping that soon you dont get alot of your capacity, its flat out wasted. ffs 3.7 is optimal on most cells, discharge is 5A+ but I dont get this. Im going to do some checking on the fenix case but I run unprotected in it just fine (just dont drop run long enough to get to 3V per cell under load anyway).
Any thoughts from you guys on this, getting peeved at spending money on cells to “be safe” that cant handle 2-2.5A draw for long before protection hits. And Ive been all over the graphs on the cells, should run fine.
Weird… I’ve got Keeppowers, generic protection, and Evva in 14500/18650/26650 never had them trip that high. Typically I don’t use them down to the trip, but when they do it’s always ~3v.
Have you tried the cells in other flashlights to check if the cells are the issue?
Maybe order a matched set from a trusted/confirmed source. Amazon has been known to pull items from mixed bins; they may have received some counterfeits that got mixed in.
Well I know the Panasonic set was real, I ripped the protection off it to salvage the cell lol. But prior to that at full charge it was tripping anything over 2A draw.
Going to be peeved if I have another bad protection circuit.
Ok so update, I decided to check my balance charger, think balancing in series the protection circuits are screwing with things as well. I let the balance run but they weren’t fully charged. Put the cells on individually and charger would still push .4A charging…
The voltage cutoff is high but I think that the fact they only took 672 mah of capacity back on balance mode means that charger is getting confused. So charging solo now then ill test again.
I’m also going to run them through my EEx2 since qlite I put in it pulls just over 3A to start
Thnx for the ideas on cells, how hard is it to just set the protection at 3v and be done lol.
But I think I’m going to run protected cells in flashlights, use my unprotected Panasonics for my bike lights so I know I’m not going to get some random stupidly early cut off.
I found a post not long ago and copied it here somewhere about protection levels.
Short answer, there’s no single setting — it’s an interaction with how much you draw from the battery because that can cause even a momentary voltage sag — and click, it’s protected you — while a lesser draw will not sag below the cutoff and run much longer.
But if the cutoff is set very low, to avoid a brief sag, then the user is going to drain the battery way low, perhaps too low, when using a lower draw flashlight
The conclusion seemed to be that deciding where a protection cutoff should be means deciding what amount of current draw is going to be required.
Of course the people making the cells expect some average draw.
Does anyone know if high-current-draw cells generally come with different (lower voltage cutoff) protection settings?
2-3A is a fairly light load for 18650 cells, this means that as long as the cell is not worn down, it will deliver all its energy before the protection trips.
But if you check the voltage after the protection has reset it will be well above 3 volt, it might even be above 3.6 volt.
In the above curve you can see loaded and unloaded voltage, the cells is basically empty when it hits 3.6 volt unloaded.
This depends on the actual cell chemistry, more tests here: http://lygte-info.dk/info/BatteryChargePercent%20UK.html
That fenix case is what mine were in. Tested both Panasonic and Sanyo keep power cells. Both trip at 3.5v (7 volts in 2s in the fenix case or 3.5 in a flashlight). 2-2.5Amps should be a light load but they only use half the capacity. I got some factor protected samsungs and no issues. I can drop them down to 3.25v under load and not trip (comes back up to 3.7-3.8 no load) so much happier now lol. Probably going to just rip the cells out of the keep power ones so I can actually use the BRAND NEW cells.
Only point of protected is for sons flashlight and his helmet light. I know to pay attention to the light and know when its time to shut down before damage. My son wont.