Hi,
I think the C4 EVO is an interesting charger.
But the fan seems to be very loud, if it´s the same fan and fan controlling like the old C4.
EVO-users, what do you think about the fan, OK or to noisy?
I have a Opus BT-C3100 with fan so I´m not a fan of a fan 
Strange thing is, the N8 have no fan but can only charge all cells with same current?
First impressions with the C4 Evo
With 4x AA charging @1A it stays quiet, the fan started only at the switch-on-moment
While discharging the fan is noisy and annoying.
Because of the compact design the AA-cells get warm at the charging-end, it exceeds over 45° (measured with an Infrared Thermometer)
The good selection of charging speeds is very nice, especially for low capacity cells.
Nice display, overall good handling. If you are use the same settings for every Slot you have to select the settings for the first cell and if you don´t press buttons in the first 4-5 seconds it uses your selection for every Slot. It also remembers your last setting after powered off and again on, but dunno how long.
If you use diffrent setting (Charge/discharge, diffrent current etc.) you have to do some button actions. Skyrc is IMHO better in this, at least for my usecases, it remembers the settings for every Slot (if not powered off)
The difference between charged/discharged capacity is a bit high for my feeling.
The charged capacity looks also a bit high in most cases (compared with my other chargers)
The biggest negative point so far is the stop of charging after some mAh, in my tests it stopped with one cell at 74mAh. First I thought oh no, a 2nd VC4SL?
No!
After re-inserting the problematic cells it loaded correctly till the cell is full, worked with every cell. With the VC4SL the next charging ended again to early.
Testing going on
Further experiences:
The stopping of charging before the cell is full happens way to often. Dunno why, I tried different Power Supplies, different cables, should also not be a temperature problem. I had one cell which stopped 2x the charging, others stopped one time.
But the stop itself prevents me calling this an reliable charger.
BTW, charging 4x AA with 1A leads to much heat. The cells are hot a short time before charging ended. Never heard the fan working in this case; dunno if it help much, it seems the fan works only at discharging if the charger itself getting hot.
A bit confusing is: If the charger is in Automatic Mode at chemistry and you want to select other task than charging most of the modes are not available. If you select manually the chemistry the modes appear (think also if the charger recognized the chemistry)
I like the modes, the many supportet chemistries, the good selection of charging/discharging currents and the nice display. The handling is good, but there´s still room of improvement. It remembers the last action you made, if you insert a new cell it will start with the last setting. If you make different tasks in every slot it´s getting annoying, Skyrc make it better because the Skyrc remembers (if not powered off) the settings for every slot.
Conclusion at the moment: Nice features, good looking, but not unproblematic. IMHO too expensive for the what it´s offers.
First thing i’d do if i had that charger would be to remove the stock fan, 3d print this ISDT C4 charger upgrade body for Noctua NF-A4 fan by PeterMakesThings - Thingiverse and use a much better fan.
I think about it if the warranty is over 
I typically don’t stress warranties on $50 items. Even so, if the charger did have a defect and crapped out, it would still be covered by the warranty if you put the back of the case back on with the stock fan. Consumer protection laws in the US don’t allow companies to void your warranty for something completely unrelated to the point of failure. Companies might claim it would void it, but that’s just to scare you away.
I guess it´s not that easy. Is something overheatet the manufacturer say it would be happen while you changed something like the fan. It´s on you to prove the opposite. I think in germany it´s a bit different than in USA, consumers have more rights there.
And here it cost 70$
But like I said, I hear the fan only if I discharge 3 or more cells with 1A every cell
At charge I can use 4 cells with 1A each and the fan gets not activated because the charger electronic is cooler than at discharge. The cells aren´t cooled
What a pity.
I was also interested in this charger but I don´t like chargers which stops charging much to early and have a noisy fan
Interesting, I found some old NiMH with ~0,13V, while some other chargers don´t recognize these cells the C4 EVO show this voltage and start charging