DC Fan OK With > 13.8 volts?

[HRTKD]

I'm planning to add air flow to my battery and inverter compartments. I've been poking around on the CoolerGuys website and ran up against a 13.8 volt limit on most of their fans - at least in the sizes I need. Some fans are listed as just 12 volt with no range.

I asked them about the upper limit and they said the fan will run at higher voltages but the lifespan of the fan will be reduced.

I don't expect the fans to run much. I'll set the range at which they come on. Should I use this type of fan or find something that can handle voltage up to around 14.4 volts.

 

[DThames]

I can't give a good answer but I have seen a few fans with built in temp dependent speed control. The speed control manages the volts to the motor to slow it and speed it up. In your situation, unless the fan is "hot" it would be running at a slower speed....lower voltage. That might be a feature to look for and to test .

 

[Lt.Dan]

I think it will be fine. The fan will spin marginally faster due to the higher voltage, but not much

 

[rin67630]

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Rated for up to 15V, i suppose running for a short ime at 15.5V during equalization (where you really need the fans to get rid of explosive gases) will not kill them.

 

[HRTKD]

I can't give a good answer but I have seen a few fans with built in temp dependent speed control. The speed control manages the volts to the motor to slow it and speed it up. In your situation, unless the fan is "hot" it would be running at a slower speed....lower voltage. That might be a feature to look for and to test .

The fans I'm looking at are single speed. I plan to control the fan with the relay on my Cerbo GX, so I don't have proportional control on the speed. I get on or off. I didn't like the temperature ranges of a couple of the fans I looked at that had internal temperature sensors. I think the fan would have been on a lot more than I wanted it to be. I would rather have control over the range at which it operates.

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Rated for up to 15V, i suppose running for a short ime at 15.5V during equalization (where you really need the fans to get rid of explosive gases) will not kill them.

The fans with voltage ratings higher than 13.8 are a lot more expensive. They aren't very common either. I'm using LiFePO4 cells, so venting of gases isn't a requirement. I just need to keep the battery and inverter compartments from getting hot.

 

[Horsefly]

Hey Jim, do you have a link to one of the fans you are looking at? I really don't think it will be an issue. In reality, you probably are never going to be much above 14V, right?

I would expect most of the 12V fans you might find are intended for 12V lead acid, in which case the charge voltage will probably be higher than that of LFP.

 

[DThames]

Maybe this?

 

[HRTKD]

Hey Jim, do you have a link to one of the fans you are looking at? I really don't think it will be an issue. In reality, you probably are never going to be much above 14V, right?

I would expect most of the 12V fans you might find are intended for 12V lead acid, in which case the charge voltage will probably be higher than that of LFP.

The typical voltage level I see is under 14 volts. But if I've drawn down the state of charge far enough, the charge voltage is going to exceed 14.0 volts.

120 mm fan rated to 13.8v: https://www.coolerguys.com/collections/120mm-fans/products/coolerguys-120mm-12v-low-speed-fan
70 mm fan with just a 12v rating: https://www.coolerguys.com/collecti...speed-dual-ball-bearing-12-volt-fan-r127010bh

I need both sizes.

 

[mikefitz]

Put a few silicon diodes in series, drop 0.6 v per diode. Using a bridge rectifier pack will give a drop of 1.2 volts, supply to the AC inputs, load to + and -.

Mike

 

[rcrracer]

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Use filters. Probably need auto start. Others sure to know much more about fans.

 

[Horsefly]

The typical voltage level I see is under 14 volts. But if I've drawn down the state of charge far enough, the charge voltage is going to exceed 14.0 volts.

120 mm fan rated to 13.8v: https://www.coolerguys.com/collections/120mm-fans/products/coolerguys-120mm-12v-low-speed-fan
70 mm fan with just a 12v rating: https://www.coolerguys.com/collecti...speed-dual-ball-bearing-12-volt-fan-r127010bh

I need both sizes.

Well, I still have to believe they would mostly be OK, but you could always get some cheap buck-boost converters. I didn't really search, but here's a pack of 10 for $16: https://www.amazon.com/Zixtec-LM2596-Converter-Module-1-25V-30V/dp/B07VVXF7YX

These should work for your situation, but the input voltage needs to be 1.5V above the output voltage, so you'd probably want fans that can operate just a bit lower than 12V. These converters are rated for 3A, and the fans you linked to pull less than an amp.

 

[HRTKD]

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Use filters. Probably need auto start. Others sure to know much more about fans.

I looked there earlier today. The fans with the 8 to 19.5v range aren't don't come in the sizes I need. The 12v fans, which do fit, often range up to 13.8v and way down to as little as 4 volts. The 24v fans do have a range, but not low enough.

 

[HRTKD]

Well, I still have to believe they would mostly be OK,

And that's kind of where I'm headed. In almost two years of operations, my LiFePO4 battery bank hasn't needed any additional air flow. But now that I put in the Multiplus 12/3000 (upgrade from a 1000 watt inverter) I'll be making use of the batteries more and more. Plus, the inverter and battery compartment are almost the same compartment and the inverter does bring up the temperature there. Better safe than sorry.

 

[rmaddy]

You could always put a 12V DC voltage regulator between your bus bars and 12V fuse box. Get one that can input 10V-15V and output exactly 12V (or some reasonable value you choose). The trick might be finding one that supports your needed amperage.

The following is just an example of what I mean. I have no experience with this specific item:

https://www.amazon.com/Cllena-Automatic-Converter-Regulator-Waterproof/dp/B08KZRZNCQ

 

[Horsefly]

And that's kind of where I'm headed. In almost two years of operations, my LiFePO4 battery bank hasn't needed any additional air flow. But now that I put in the Multiplus 12/3000 (upgrade from a 1000 watt inverter) I'll be making use of the batteries more and more. Plus, the inverter and battery compartment are almost the same compartment and the inverter does bring up the temperature there. Better safe than sorry.

An update for you @HRTKD. I posted a question on a random 120mm 12V fan on Amazon. I got several answers including one that said he had four of these fans running in his RV, where he knows the voltages get up over 14V on the alternator. Another said he had some of them hooked up directly to a 24V solar panel (???) and it has been running for months.

Anyway, I think you should be fine running these from your LFP batteries.

 

[HRTKD]

An update for you @HRTKD. I posted a question on a random 120mm 12V fan on Amazon. I got several answers including one that said he had four of these fans running in his RV, where he knows the voltages get up over 14V on the alternator. Another said he had some of them hooked up directly to a 24V solar panel (???) and it has been running for months.

Anyway, I think you should be fine running these from your LFP batteries.

Great! Thanks for doing that. I'm all set to put in an order, but I'm heading to Wyoming next week for a fishing trip. Having a package arrive while my wife is there to intercept it is something I try to avoid.