Cheapest (and easiest) way to run a Maxxair Fan?

[quincytrout]

I’m about to get a used FWC Eagle, and am hoping to install a maxxair fan in the vent hole that already exists. I travel pretty minimal, that’s the only thing I will be running overnight, and likely not during the day. I am trying to decide between installing another battery and an isolater switch, or a really small solar setup. The Maxxair manual says it needs 12V/5A at a minimum, but the draws that people have reported from trimetrics meters at low fan speeds are way lower than 5a (see pic attached). I also don’t know anything about power/currents so I could be misunderstanding this.

Long story short, does anyone have recommendations for a cheap and easy power set up? It’s currently 94 degrees and raining down in the red river gorge and I leave in a week, I wanna set myself up for a little bit of comfort!

 

[Pilat]

It just means that in order for the fan to operate at it's maximum, it needs a minimum of a 12/5A (60W) power supply. That means that the power supply needs to be able to supply at a minimum 5A @ 12V (60W).

If the power supply couldn't deliver that, the fan would either blow fuses (if installed), or it could set the wire (or plug) on fire.

So, if you give it a 5A fuse, and the plug and wiring is up to delivering that on full blast, you're good to go. Remember that fuses are there to protect the wiring from melting/going up in flames. Not to protect the fan.

I would trust the people who have actually measured how much it draws at various settings. Notice how it says 4.7A on full tilt? That is what the wiring should be able to supply at a minimum (more, ecause if there's corrosion, there will be higher resistance). At lower speeds, it will draw less.

 

[quincytrout]

It just means that in order for the fan to operate at it's maximum, it needs a minimum of a 12/5A (60W) power supply. That means that the power supply needs to be able to supply at a minimum 5A @ 12V (60W).

If the power supply couldn't deliver that, the fan would either blow fuses (if installed), or it could set the wire (or plug) on fire.

So, if you give it a 5A fuse, and the plug and wiring is up to delivering that on full blast, you're good to go. Remember that fuses are there to protect the wiring from melting/going up in flames. Not to protect the fan.

I would trust the people who have actually measured how much it draws at various settings. Notice how it says 4.7A on full tilt? That is what the wiring should be able to supply at a minimum (more, ecause if there's corrosion, there will be higher resistance). At lower speeds, it will draw less.

That’s super helpful. So, My buddy has a solar panel + battery that will output at 12V/4a, would I be able to run the fan on a lower setting off this setup?

 

[Pilat]

Yes, you will - at least in theory, and if everything is perfect. But it kind of depends on what the plug is rated at. The fan will try to pull 5A at the higher settings which could blow fuses in the battery pack and if nothing present, it could melt the plug and/or wire, starting a fire.
The fan can also pull much more than the rated output if a fault occurs (say, a loose wire, corrosion, etc.).

Also, depending on the size of battery, it could be depleted in short order (at full tilt you'd be using 60w).

In any case, if it actually delivers 4A at 12V (and not at, say, 5 or 9V), you should be able to run it safely at the "7" setting. The "8" is running it a tad too close to the max of the battery pack and its wiring/plug.

Make sure the voltage of the battery pack is actually 12v and not 5 or 9V, and make double sure it is rated as you say. Also make sure it is big enough in the Ah department.
Seriously, you should spring for a big battery that can support the drain throughout the night/day, and use the correct sized wiring and plugs. That way you won't have a fire or fuses blown because someone accidently turns the fan up too high.

Another thing: You will likely burn out the wires or plug if you draw too much on that battery pack and its wiring. Especially if there is just a little bit of corrosion in the wires/wire plugs, or t has been bent sharply, causing breaks in the fibres. That means that your 12v "4A" wiring could suddenly be "2A" due to resistance. That's not good if trying to pull more amperage through them (i.e. FIRE!).

Better to oversize the plug and wiring slightly, so it can take, say, 8A, use tinned wire (helps against corrosion), and crimp the wires with a good wire crimper.

Again, I'd only do what you suggest in a short-term emergency. I wouldn't rely on it, and I certainly wouldn't call it "good".

 

[john61ct]

I am trying to decide between installing another battery and an isolater switch, or a really small solar setup

Why would this be an either-or choice?

Putting in more energy **storage** at such a small scale has little to do with the need to increase energy **inputs**.

The key is matching the sources' inputs rates, in Ah per 24hrs, so that exceeds your load devices' consumption, by a comfortable margin.

Storage just gives you a buffer, to accommodate variability.

Actually measure your Ah/day usage with the MaxxAir in hot weather using an Ah meter, aka totalizer, coulometer.

Without solar your only input is your alternator while driving?

So then the question is, are you driving four hours a day or one? Once a week or every day?

Are you living off grid for weeks or just camping 1-2 days at a time?

Without such details, question is like "how long is a piece of string?"

 

[quincytrout]

Why would this be an either-or choice?

Putting in more energy **storage** at such a small scale has little to do with the need to increase energy **inputs**.

The key is matching the sources' inputs rates, in Ah per 24hrs, so that exceeds your load devices' consumption, by a comfortable margin.

Storage just gives you a buffer, to accommodate variability.

Actually measure your Ah/day usage with the MaxxAir in hot weather using an Ah meter, aka totalizer, coulometer.

Without solar your only input is your alternator while driving?

So then the question is, are you driving four hours a day or one? Once a week or every day?

Are you living off grid for weeks or just camping 1-2 days at a time?

Without such details, question is like "how long is a piece of string?"

Thanks for the info about matching input rates. It’s currently an either/or because of financial and time constraints- I will be putting a lot more time and thought into my long term set up, so I was mainly just asking if there was a “shortcut” for the short term. (I can’t measure the ah/day usage if I haven’t found a way to power it!)
But Pilats response above has convinced me to not shortcut this, and at the very least get a dual battery and isolater set up before I leave, with the option of adding solar to the system later.

 

[john61ct]

Yes, preventing the Starter battery from getting drained and leaving you stranded is Job One.

Install an Ah counter with the fan and start logging consumption to get a ballpark for peak Ah/day.

You may find yourself being able to downsize the House bank later if you want to, but too much is better than not enough.

Plus you'll likely add more loads anyway, e.g. lights, running/charging screen gadgets, maybe even a fridge - but that's a much bigger consumer.

The best plan for solar, if roof space is limited, is "as many watts as you can fit"

 

[quincytrout]

Yes, preventing the Starter battery from getting drained and leaving you stranded is Job One.

Install an Ah counter with the fan and start logging consumption to get a ballpark for peak Ah/day.

You may find yourself being able to downsize the House bank later if you want to, but too much is better than not enough.

Plus you'll likely add more loads anyway, e.g. lights, running/charging screen gadgets, maybe even a fridge - but that's a much bigger consumer.

The best plan for solar, if roof space is limited, is "as many watts as you can fit"

I will definently invest in one of those with the fan, I would definently like to know where I’m at in terms of usage and capacity from the get-go. Would something like this do the trick?

Programmable Digital AH meter. Ideal for battery monitoring: Other Products: Amazon.com: Tools & Home Improvement

Programmable Digital AH meter. Ideal for battery monitoring: Other Products: Amazon.com: Tools & Home Improvement

www.amazon.com

 

[john61ct]

No shunt?

Mixed reviews, I'd say keep looking.

This is a good vendor, and inline style

Powerwerx Watt Meter, DC Inline Power Analyzer, 45A Continuous, 12 Gauge, Powerpole Connectors

Measuring capacity up to 60V and 100A. 12 gauge wire with Powerpole connectors. Bright blue backlit LCD display. Measures 8 electrical parameters: Amps, Volts, Watts, Amp-hours, Watt-hours, Peak Amps, Minimum Volts (Sag), Peak Watts. No configuration, works automatically!

powerwerx.com

 

[brice]

Unless i am missing something in your post, you need another battery either way, because the solar setup will have to store the energy somewhere. So the question is, do you want to charge the battery with solar or your truck? A simple switched battery isolator should be way cheaper than a solar setup. Wiring the fan to the battery with an inline fuse and the proper sized wire should be a fairly small expense relative to the camper, fan, and battery.

 

[Pilat]

I'm glad to hear you will do it properly, Quincy! That puts me at ease. I thought long after if I had given bad advice that might endanger you. But as you will now do this properly, I can relax about that part, lol.

 

[john61ct]

Doing it right, is the opposite of cheapest and easiest.

But yes it is easy to spend a grand on monitoring / control gear for a bank only worth $500

Each owner needs to find their own balance.

 

[quincytrout]

Thank you both for all your help. I've found a place in town that can help me with the battery and isolater install, however, they told me that if i don't use the exact same battery as the one i currently have (toyota true start), they can't guarantee that the system will work properly. Does that sound right?

 

[Pilat]

Nonsense. It may need to be the same chemistry with that set up (i.e. not mixing battery types (when charging both or combining them) - i.e. AGM + Lead-acid, or Agm + Lithium), but they're talking nonsense otherwise. You don't want a starter battery as your house battery. And it doesn't need to be the same size Ah-wise (i.e. you probably want a bigger capacity battery for your house than you need as your starter battery).

But, in any case, it may even be that it is easier (and cheaper) to swap the starter battery to match the type you use as your house battery.

 

[quincytrout]

Nonsense. It may need to be the same chemistry with that set up (i.e. not mixing battery types (when charging both or combining them) - i.e. AGM + Lead-acid, or Agm + Lithium), but they're talking nonsense otherwise. You don't want a starter battery as your house battery. And it doesn't need to be the same size Ah-wise (i.e. you probably want a bigger capacity battery for your house than you need as your starter battery).

But, in any case, it may even be that it is easier (and cheaper) to swap the starter battery to match the type you use as your house battery.

Yeah that's what I thought, I think it must just be their standard disclaimer. I was definently not planning on using a starter battery as my house battery.