/\ Thanks for the links…. 
I have contacted Henry 3 times since August 25,2017…about every 10 days after the initial email… NO REPLY
I am baffled why all of the sudden he does not respond. We exchanged dozens of emails in April and May of 2017. He was very efficient and prompt,no more!
Did something happen to him? Did he get another job?,If so,someone in the company probably would have responded.
Hmmm… that does seem strange. That has been a bit over 3 weeks. … possibly he is taking vacation / time off.
I am trying to replace fans.
I have a couple of questions.
The fans I am looking at take about 0.45 W at 12 VDC. It is one of the Sunons in a link above. It is much quieter that many others. 16 dbm, 3 CFM.
How much power is available from the 12VDC feed going to the OEM fan?
Second is kind of an idea around the same fan. There is a version of it that uses a third wire for speed control. Using that version I could just tie the fan to raw DC, and use the controller. The question in that scenario is what does the output of the fan driver in the charger look like. Is it PWM, or just a variable DC output being dropped by the resistor that is in series. If I can use a third wire for a low power control signal, it eliminates worrying about the power available from the original driver.
Great test and great idea to replace the fan!
According to HKJ it can take up to 2W[POST 1].
My Delta is rated @ 1.44W and has been working fine since its installation last spring.
Regarding your other questions,I do not know,HKJ and some others may know.
Thanks :+1:
Just sent them another[and my FINAL] email. First[4th overall] one since September 10,2017.
The fact that so far they have not responded after promising me a FREE sample of the NEW AND IMPROVED Opus is very bothersome.
After 9 weeks and 4 emails I finally got a response from Henry. 
sales@opus-instrument.com
5:33 AM (8 hours ago)
to me
Hi, Robert
Thanks for your interests with our new item development.
we have some delay due to manpower reason. Our firmware engineer resigned so we need to find new engineers to complete the project.
we are not clear when the new design can be released. I will update you once there is result available.
regards
henry
/\ … Excellent… glad he finally responded. :+1:
I found a quality 5v fan for replacement. Any reason why a 12v fan was used for replacement?
The stock fan is 12vdc.
I thought so too until I read the OP and found this below.
Stock[ADDA] fan- 5v/0.13a/0.65W
Delta fan- 12V/0.12A/1.44W
Yep…. The 5V fans had a resistor wired in line to knock the 12V power supplied down to 5V.
The 12V ‘replacement fans’ were just wired straight with no resistor.
Thanks. I will have to look at this video below again as he replaced the stock fan with a 5v fan but I missed the part where
the resistor was in the wire when he cut and spliced the connector.
In one of the Opus chargers, I installed a 12vdc fan salvaged from a PC power supply. I drilled several holes at the bottom half of the charger, spliced off a connector from another Opus charger, then installed the connector in place of the stock connector (which is still connected to the stock 12vdc fan but no longer connected to the pcb as shown).
The new fan now sucks through the numerous holes, drawing ambient air through the cells and down the 4 rails and the pcb below, and much quieter now, making the cells just warm enough to trigger the charger’s temp. termination requirement.
The new fan still kicks in automatically as required by the sensors.
And yes, the stock fan is 12vdc, left untouched.
Below shows the original connector I got from my other Opus is connected to the new fan, then connected to the original male terminal, leaving the Original fan and connector untouched. So in effect the bigger fan is still controlled by the charger automatically.
Btw, those long rectangular raised strips, surrounded by my drilled holes, are also open on its side (air can pass through too), just cannot be seen from this photo angle.
Lastly, this mod is just for fun, (and an improvement with regards to noise and cooling), but actually, the stock fan is enough for the cooling needs of this charger.
tatasal, that's a nice little setup you got going there, I like it. I have a lot of spare pc fans so you've given me a good idea thanks.
@ tatasal……
I remember seeing those pictures of your ‘Opus Fan Mod’ somewhere before!! That is one sweet mod too…… :+1:
Nice job!!
Thanks…but l forgot where l posted it so l had to take new photos again haha. 
Your welcome. I can’t remember either, but I do remember seeing it somewhere. It was such a cool mod it was unforgettable. :+1: …