I put two 2400mAh Turnigy’s into JetBeam BA20 and left it running on high mode in order to discharge batteries before putting them into slow break-in charge mode in C9000.
When I pulled out the batteries, flashlight was giving out something between 3 lumens and 7 lumens.
One of the cellls showed slightly below 0.9V, while the other showed 0.1V, WTF?!
So I re-tested voltage on this cell after every couple of minutes, it started to increase, the higher the voltage was, the faster it increased.
Now its back to ~0.9V level for empty NiMh.
What could have been wrong and should I pay special attention to this particular cell in the future regarding its capacity and self discharge rates?
my ecig uses stacked rcr123a, and it always has one further discharged than the other when i swap cells. i cant remember exactly right now, but i think its the one closest to the tailcap that is usually lower.
I did that in the PA40, it was like moonlight mode after I left it on high all night.
I put them in the C9000 and did a break in cycle and one of them come out about 200mAh less than it used it be, but it still works fine now. I don’t even know which one it is as I think it returned to normal after a few more uses.
Since then I just learnt to charge them before they run flat and not to leave any on if I’m not using them.
Multiple battery setups do not draw current evenly through all batteries. There will always be a difference in discharge. Depends on the internal resistance of each battery and the fact that one is being drawn from the lighting source and the other is being drawn through the first battery. It will never be equal. The only way to do it would be to discharge in a controlled environment like a charger with a discharge feature.
I was told mine would damaged and wont be any good, so I’m not sure if I was lucky it come back to life or I didn’t do as much damage as others had done.
I recently had one AA NiMh battery (out of a 2AA battery device) check at something like 0.1v while the other was "normal" (+/-1.0v). The battery wouldn't charge in my "smart" charger, but did charge up in a cheap dumb "timer-based" charger. I haven't used it since, but I am watching its voltage and it's been holding steady with 3 others I charged at the same time.
Why not just discharge them with the C9000 instead? As others have said, running cells flat in series carries a risk of reverse charging one, which can do permanent damage.
Like Didge said, you could have used the discharge mode in the C9000. Set it to a 500mA discharge rate.
Anyway, the break in mode already performs a full discharge and charge in a controlled rate.
Point being - I have plenty of NiMh’s to break in and only ONE C9000, I cant spend weeks of breaking in batteries with its 40+ hour break-in mode.
Thats why I discharge batteries in flashlights and charge them up in break-in mode with C9000, that saves time considerably ;)!
Only thing I missed is the fact that in multi cell lights not all cells will be drained equally, so I will resort to single cell lights and keep on discharging them that way ;)!
Only one battery mis-treated and only once, so its not like Im about to ruin all of my batteries, they will be perfectly fine as long as I keep on using single cell lights and keep an eye on voltage :D!
The C9000’s break-in mode always start in charge mode, regardless the cells are fully-charged or discharged. I don’t think you shorten the break-in mode’s cycle by doing a full discharge.
You put in your battery in C9000, select BREAK-IN, then you have to MANUALLY enter battery’s rated capacity in mAh, after its done C9000 will begin charging your battery for 16h non-stop at 0.1C, after its done charging it will stop at REST for couple of hours, after that it will discharge batteries at 0.2C and then stop again for some time and after rest will start charging at 0.1C for 16h again.
I believe its important to put empty batteries into C9000 if you want to do BREAK-IN mode.
Once its done charging at 0.1C for 16h, I remove those batteries and place fresh batch of empty batteries into C9000 and do 16h BREAK-IN charge with them, meanwhile recently removed batteries for the sake of time economy are being discharged down to 0.9V with flashlights.
I find it perfectly sensible, except for this one case when one of the batteries was over-discharged in multi cell light :D!
My regime for doing break-ins on the C9000 is as follows:
1. Discharge at 1A (takes 2hrs max with my Eneloops)
2. Break in - 16h charge, 1h rest, discharge @ 0.2C - (takes around 5hrs)
3. Read cell capacities during the next 1hr rest, then remove cells and repeat.
This whole cycle normally takes around 24 hours, which means I can get through 28 cells in a week if I time it right.
I charge up the cells again using a seperate charger, a Maha 801D, which can do 8 cells at a time, rather than doing the extra break-in charge on the C900, which takes another 17hr including the rest.
Yeah, didge, Ive been wondering whether I could simply omit the 2nd break-in charge and simply charge the batteries up at normal rate and charge into them mAh’s that are close to rated capacity of said battery instead of doing 2nd break-in charge where it shows to pump in around 50%(first and second break-in modes charge the same amount of mAh’s into battery, they charge battery at the same charge rate for the same period of time) more than battery’s rated capacity.
I understand that part of that charge is being lost in the form of heat, so its not exactly 3.6-3.8A pumped into 2.4A battery, but still, it looks like with charging battery for longer it somehow forms the battery’s internals to be able to acquire its rated capacity instead of 100-200mAh’s less than advertised as it happen to be the case pretty often with NiMh’s?
Wouldnt omitting 2nd break-in charge not-fully-form-the-battery, or harm its health?
And btw, while were at it, does any of you know dumb charger that charges at slow rates and NEVER stops charging and doesnt overheat batteries, ie, charges AA’s at 200-250mA and AAA’s at 80-100mA?
It would become some sort of poor-mans/ultra budget C9000 wanabe for breaking in cells lol.
I asked the same question the other day here:
No takers so far :)!
Now that made me wonder, if one copies(as in - remembers or writes down the charge/discharge sequences etc) all the protocols from manuals of C9000(except for safety options such as voltage/temperature issues that cheap chargers are not likely to be good at), then perhaps such charger, that never stops charging and does so at charge rate that is approximately around 0.1C of common AAA and AA battery capacities, could become budget resolution for those, who cant/dont want to spend their money on C9000?
Only drawback would be checking battery temps and voltages manually once in a while to ensure that the charger isnt destroying those cells.