I noticed that with the topping off also and it don’t really bother me. I was more concerned with the cells maybe catching fire or anything like that. New charger for me so I wasn’t sure what was going on.
Thanks for the info Pete7874. Just so I am understanding this correctly (I doubt I am), what exactly does “top off” mean? Is it have anything to do with getting cells up to the 4.2V then terminating charge?
Top-off means charging with very low current for several hours after the main charging cycle has finished. Top-off is sometimes used for NiMH cells. It’s never used for Li-Ion cells, as far as I know.
Oh ok. Makes sense now. So does the D4 have that top off? When I use the D4 to charge my NiMH cells it seems to take ages. My Tenergy chargers take even longer, but the cells get very hot. Different type of charger. Seems like an over night charger just for NiMH/NiCD cells. Also says li ion and lifepo (wrong spelling) but I don’t trust it at all for my li ion cells.
What I mean is that the part where 4.2 volts has been met until it says 100% seems long. Sometimes it reaches 4.2 volts and says it has about 10% to go if I remember correctly. From that point on could take hours still to complete. Again , the readings are sporadic sometimes I think. Tried the usual rotating the cell , putting pressure on the slide terminal , switching slots . Switching slots gives wide reading swings. All new cells from good vendor . All with protection.
That’s just normal CC/CV charging algorithm for Li-Ion cells.
First phase is CC (constant current). During this phase, the current stays fixed while voltage rises, up to about 4.2V.
Second phase is CV (constant voltage). During this phase, voltage stays at about 4.2V while current slowly reduces, up until current drops to almost nothing.
If you are talking to me I have the C4-12 and it doesnt take hours (maybe an hour sometimes half hour, hour and a half). Not usually over 2 hours, but mine is also weird and buggy so i dont trust it at all. I am gonna buy another off amazon. Hopefully i just got a bad one :person_facepalming:
It is possible for the CV phase to take in excess of an hour, depending on the condition of the cell and its IR. The charts in HKJ’s review illustrate that.
Think of filling up your car’s gas-tank, but giving the cashier, say, 10bux (less than a fill-up).
When it first starts, up until maybe 9.70, it’ll go full-tilt, as fast as it can fill it.
When it hits that 9.70 or so, it slows down to the slow-fill mode, so it doesn’t try shutting off, missing the cutoff, and dumping more gas than the 10bux will buy. Then, when it finally hits 10.00 on slow-fill, it stops.
The fast-fill is the equivalent of CC mode, that whatever the charging current’s set at, it goes for that full amount. That lasts up until maybe 90–95 of the charge.
When it switches to CV mode (“10bux”), it holds that amount as its reference, and slooooowly fills so that nothing comes “sloshing out”.
Some cells, depending how much is still “in the tank”, it’ll get through CC mode in an hour or so, but keep trickling it in, in CV mode, for possibly even longer than the CC phase.
If I don’t want a stuffed-full cell, I’ll pull it when the charging current starts tapering off, as it switched from CC to CV, and is already mostly-full.
Or, I can wait and wait and let it fill the cell right up to the spout.
I only used this charger a few times.
Perhaps I overlooked a setting but for my use, 26650 cells, it’s a shame the charging current can’t be permanently set at 3A.
It always seems to start in automatic/smart mode