Should be fairly easy for the guy that designed it, or for you possibly…
After reading the posts after mine, I would say that electronics is not an exact science at all, since almost every time I see a group of "electronics guys" huddled around something, there's ten different solutions, from ten different people and they all have a reason why the other guys solution doesn't work, but they never state the actual complete solution.
Guys, don't get me wrong, I love y'all to death, but you could confuse the pope about what a catholic is.
The easiest way to mod it looks like to use a small, low current 12V fan.
The output of the 12V DC input jack appears to be OR’ed (combined) with the output of the wall power AC input power supply (9V) using diodes D7 (the one standing on end next to the DC input jack) and D? (big one laying down next to the red transformer). Try a 12V fan connected to the top of diode D7 (+) and ground (-). You can pick up ground on the DC input jack.
When running the charger off the AC input, the fan should have around 8.5V on it.
Sort of; after closing circuit the bimetal needs to get to ~30°C to reset. I gave up on these after the seller sent me some 40°C NC sold as NO. The cavity is a good place for a switch, and with an adjustable thermostat it shouldn’t be a terrible place for a sensor.
It’s running at 12V so it is a bit noisy, but seems to draw a lot of heat out. More annoying is the way it behaves when the charger is just around 40°C threshold and generating only a little heat (say charging a couple of eneloops). I have the charger on the floor so it isn’t as noisy as it could be on a desk.
you could connect the fan to a separate small AC/DC ( 9v to 12v) DC power supply, even one recycled from an old cordless phone or charger for any old appliance that used 9 to 12 volts DC. ( though you would have 2 power cords to plug in.
I only use the fan on the days that have garage 95F @ 200%(?) humidity in New Orleans. 4” DC (variable speed) box fan free but would cost more than i4. My i4 does not always run hot so, like I said, fan runs on hot days or back to back charging. My iCharger has built in fan but still use 4” fan especially doing back to back discharge to storage voltage.
I've been charging 4 of these 25R batteries now, for over an hour. Cool as a Cucumber, as they say. Room temperature, for the charger and the batteries. That fan really works. Of course, it's really loud too! Sounds like a dentist's drill.
Awesome… I think they are all loud with fans from what Ive read. Seems to be the status quo. PC fans are quiet, but they are considerably larger, while the CPU fan I can hear kick in as its smaller and must spin a lot faster to get the air flowing.
This is my comment as well. I actually have no idea how long the 5v fan will last, but considering it was not a fancy one to start with I wouldn’t push it. If you own two of those fans you could double up. Two 5v fans in series would see 4.5v each off of that (apparently) 9v source.
Just a thought — I recall that some NiMH chargers detect the temperature change of the cells as one way to identify state of charge (I have some older chargers with covers that say to keep the cover closed during charging or else it won’t warm up enough to stop the charging). I have no idea if cooling changes anything about how the i4 charger detects charge state —- I guess checking the voltage will tell you.
is like that but uses delta voltage change to stop charging. Using heat is kind of scary? My iCharger comes with thermo couple, for safety monitoring, to stop at user settable setting.
