When is a fan inside a DIY power station required?

[AF_Bob]

Newbie here. For those who built their Power Station, can someone please tell me what criteria is used to know whether a box fan is required? I'm installing 2 100-Amp Li Time Mini batteries in series (24V), connected to a Giandel 24VDC to 110VAC 2,000 watt pure sine wave inverter. I'll be using a Victron MPPT 100|15A solar charge controller connected to 4 100-Watt Ecoflow Mono solar panels in series (68.1V nominal at 5.9A).

Since the inverter has its own fan and the BMS is inside the LIFEPO4 battery (I think it's mounted vertically inside the Mini Li Time battery case at one end), do I need to install a fan at all? If so, do I need more than one fan? The case is a RIGID 2.0 25" all-terrain rolling cart but the inside dimensions are really more like 19" wide, 12" deep/front-to-back, and 14" tall. I'm actually hoping everything will fit. Worst case, I'll get a smaller box that fits on top for the inverter.

Any help would be greatly appreciated. I've already learned a great deal from reading posts on this website regarding pre-charging of the inverter capacitors. I plan on using a cut-off switch to ensure 0 current from the batteries when the power station is off and rather than zap the inverter with 24+ volts (2,560 WH capacity from the batteries), I plan on using a momentary push-button near the cut-off switch to supply 24V to the inverter through a 30 Ohm, 25 watt resistor for a few seconds before I turn on the switch.

 

[Rednecktek]

The thing is that the air inside tge box is going to get warm making it harder to dissipate heat which adds more heat making it harder to dissipate heat and the evil cycle begins.

At the very least you need some sort of vent holes to allow the hot air out, but a temp controlled fan would work better. I personally prefer the Noctua IP67 fans and a basic thermostat. They're quiet, move a good amount of air, and weather resistant.

 

[AF_Bob]

The thing is that the air inside tge box is going to get warm making it harder to dissipate heat which adds more heat making it harder to dissipate heat and the evil cycle begins.

At the very least you need some sort of vent holes to allow the hot air out, but a temp controlled fan would work better. I personally prefer the Noctua IP67 fans and a basic thermostat. They're quiet, move a good amount of air, and weather resistant.

Thank you, Solar Wizard! If I mount the fan on the side of the box. Should the fan blow air OUT of the box while the vent holes suck the air in? Or should the fan suck the outside air in and blow the air across the components and out of the vent holes?

 

[Rednecktek]

Physics is going to make the final decision, but I prefer to have the active air over the hottest parts, so along the vanes of the inverter would be best.

 

[Brucey]

If going with a single fan I would have it exhausting out of the box. You'd need an intake vent assuming the box is otherwise sealed, I've seen some designs where there is an intake and exhaust fan on opposite sides of the box.

 

[Brucey]

 

[AF_Bob]

Physics is going to make the final decision, but I prefer to have the active air over the hottest parts, so along the vanes of the inverter would be best.

Thank you very much.

 

[AF_Bob]

If going with a single fan I would have it exhausting out of the box. You'd need an intake vent assuming the box is otherwise sealed, I've seen some designs where there is an intake and exhaust fan on opposite sides of the box.

Thank you Brucey. I tried google to find an answer before posting, but you'd be amazed at what I found: “It turns out there is no single answer to this modest question. when air is pushed in by a fan at the front-end, dust will accumulate to some extent on the screen and blades. The result is decreased airflow ranging from a few percent for some dust on the blade edges, to a double-digit if the screen gets clogged. In contrast, if the fan is at the exhaust port and is pulling air through, dust will be more likely to accumulate on internal components and will not impede airflow at the intake ports. But as with most design issues, there’s a tradeoff: that same dust may settle on the components which need cooling and forming an insulating blanket around them.”
I think I'll do what you and Solar Wizzard said and either try to mount the fan to exhaust the air...but put the vent holes in line with the inverter on one end of the box and the fan at the other end of the box so airflow from outside will flow across the heat sink of the inverter...or just install 2 fans (one blowing outside air in and one blowing it out) and put both in line with the inverter.