From HKJ’s thermal images it looked like something in there got to 50c, you could attach the thermostat to that. Does the thermostat have built-in hysteresis? Doesn’t seem like it would help otherwise. I don’t think I understand what you are saying about the cavity. I see it, but what are you saying about it? Just that it’s a bad place to put the thermostat?
I have a BT-C3100 on order, but I have my doubts about whether I can tolerate the tiny fan at all. From what I can see, the stock fan can’t be achieving much. It generates almost no CFM to start with and it’s mostly directed at a solid surface a few mm away. Instead maybe a (slow) 92mm fan could do - it should fit nicely under the rest of the charger (144x100mm). I think Scythe makes good (thin/quiet) options for this, but they do not have a USA distributor anymore AFAIK. Slim 120’s are readily available, but that would would make the size of the charger’s footprint increase and preclude the option of a skirt that mostly just made the charger look thicker/taller… if you used a standard thickness (25mm) fan you’d hit 65mm tall before adding any plenum areas. The charger would be >80mm tall before you knew it, and at that point maybe it would have made more sense to put a (slow) 80mm fan at the back and relocate the DC-in jack. It’s common to use a baffle in PC PSUs ( see the last pic on that link, some baffles cover most of the fan). The same thing could be done with an 80mm fan at the back of the charger and a skirt/box/lift to make it taller.
It’s definitely a transformer. I don’t see the rectifier, but I suppose that it must be a DC transformer since it seems to bridge the physically isolated AC portion of the board over to the DC portion of the board.
EDIT:
In response to your clarification edit, transformers do not make AC turn into DC. Look up ‘rectifier’ for info on that.
I probably have 2 or 3 spare 300 watters laying around, they are a dime a dozen if you know where to get em (since I do computer repair as another one of my hobbies, I have quite a few of em…along with an assortment of 6-7 computers in pieces all over the house)
I used a 450 watter for my powersupply for my 70watt Yaesu FT-2900R 2M mobile station I was using as a base station for a while…then my coax went to crap…bleh
Thinking of whipping up a 4x USB board (that is stackable) from OSHPark to tie into the 5vdc output with the D+ and D- tied together thru a 130~ Ω resistor so that anything plugged into it will see it as a DCP (Dedicated Charging Port) and pull up to 1.5A from each port)
a 4” box fan pulled from an old Crown amp. I just let it run at half-quite speed when charging which cools the I4 just fine. It’s got enough power to cool three I4’s if needed.
If fan fails I could drop back with heat sink mod? :8) I like yours much better O-L!
The offer is much appreciated, but I don't even want to mess with all that stuff. I got too much to mess with now. The charger comes with a 110v plug in. It should work as is and with the heat, I think it would still feel hot to me, even on the power supply, or I would think the power supply was to hot...
My I4’s do not get hot! I do have Two new Fenix ARE-2 and they get very hot when charging 4 X 18650 3400mAh batteries. I got very similar temps as HKJ w/ the thrunite MCC4? I think that is the name…………anyway,that charger is identical to Fenix ARE-2 with only the labels[Fenix/Thrunite] being different.I measure it at 126F !
I keep mine plugged into my solar battery bank, Coming off the batteries is a 12 volt lead that I have a old computer fan rigged to. I just put it on the back of the charger to keep things cooler. Seems to work well for the charger & batteries. I do the same for my NiCd R/C batteries too. Guess I could cut a few holes in the top of the case to allow for better air flow. But, I haven’t had any issues to date.
It’s a shame to have such a nice hole and everything… My 2c is this: the AC side probably only has very few connections coming out of it going over to the rest of the circuit. I’d look to tap in there, but you may be forced to use a 12v fan.
There’s the physically isolated A/C side (or is it High Voltage side? whatever), then there’s the rest of the board. The transformer Cereal_killer was asking about joins the two, I’d check the two legs of the transformer that fall on that larger portion of the board. My suggestion is to check DC volts and AC volts to make sure it’s already rectified - I assume it should be DC in the 5-20v range. If it’s anywhere close to a fan voltage (4-15v or something) you can use a 5v or 12v fan.
Not as elegant solution as you were going for but maybe work something like a 110V Case Fan in underneath your i4 and use the top as an inlet or exhaust near your transformer.
Also I was able get a PC 12v case fan to spin up connected to the traces 2 of the three pins from the other side of the empty 12 volt connector on my i2 charger.
U1 and U2 between the + tabs on the battery side, 2 dual channel charge controller chips
That transformer might be a really big isolation transformer, it is between the AC and DC side on the board (that large routed out square area on the board)
I found a pretty in depth reivew of the board on laser pointer forums
Looing at the board from the top, the two coils on the right and the big fat capacitor, that is the DC conversion and filtering components, the big red transformer is a isolation transformer from the high side mains to the DC side
Here is a possible schematic of the Viper22A power control circuit
That makes a lot more sense than what I said. Clearly D1 cannot have the function I thought it did. I thought it was a full wave rectifier, but even if it is it can’t be feeding the transformer because transformers only work on AC. Good thing I don’t do this for a living
Ah, so it is. I thought it said D1 because of the angle of the pictures.
Anyway in that case I don’t get it. I get feeding AC through a transformer and then rectifying it (T2 and D4 in the diagram). Then you smooth it, C4. Then… SMPS happens, heh. I guess I need to read the Wikipedia page on SMPS.
I think the diagram you posted is the fanciest configuration ST has imagined for that chip. What we have with the i4 is probably more simple, I do not think that many components are present. It’s easier w/ the ones that just copy a circuit straight out of the datasheet
