Run Fan Without Solar

[thezenvan]

I'm planning to install the Maxxair 5100K that I ordered soon but won't be hooking up solar yet. What are some good ways of being able to run the fan without solar for the time being?

I was thinking about running it off the van battery (Nissan NV2500) but not sure if that would damage the battery. Any suggestions?

Thanks

 

[AbuelaLoca]

I can't actually answer this, but did a quick search on google and found this:

http://www.fiberglassrv.com/forums/...ir-fan-for-7-hrs-off-my-rv-battery-42516.html

From the little I've read, it looks like the fans don't draw too much on the batteries... YMMV

 

[John61CT]

Maxx Air is very efficient for the CFM, but at top setting will draw a fair bit, likely enough you'd find your Starter flat once in a while.

And Starters aren't designed for that (deep cycling) so you'll need to replace it sooner.

If all that's OK, carry a jump start power pack.

Otherwise get a second House bank, ideally a quality one designed for deep-cycling, as cheap as $180, and one of the many combining/isolating solutions, as cheap as $50.

Shore power or a little gennie can get you recharged, doesn't **have** to be solar.

 

[Trebor English]

This is what I did.  It worked for me.  Your mileage may vary.  

Step 1:  I started with a cigarette lighter inverter for my electric shaver and a usb charger for my phone.  I calculated the battery capacity.  It said on it the reserve capacity in minutes at 25 amps.  Convert minutes to hours by dividing minutes by 60.  Multiply the 25 amps by the hours to get amp hours.  The 50 percent guide is for thick plated deep cycle batteries.  For starter batteries 5% to 10% are a better limit.  I used a $5 Harbor Freight multimeter to measure the amps used by each device and manually kept track of amp hours used.

Step 2:  I got a rubbermaid tub, battery, inverter, cigarette lighter socket, battery charger, alternator connection wire with manual switching.  I installed a battery disconnect switch for the van battery because the vehicle computers were unpleasant.  Opening or closing a door flashed the headlights and then there was a one amp load for 30 minutes.

Step 3: The van battery got to the end of the warranty period and started discharging even when disconnected.  I may have hastened its death using it as a house battery but the 5 percent limit allowed the battery to get to the end of the wartanty period.  I replaced it with the biggest deep cycle battery that would fit in the original location.  I got a group size 24 75 amp hour flooded cheap trolling motor battery.  It was $20 cheaper than another starter battery.  I have never needed a jump start.  I carry jumper cables but have only used them for other people's flat batteries.

Step 4:  I gave away the battery box.  A friend needed it and I had a big battery under the hood.  I recalculated how much I could use figuring 25% max discharge to be sure to be able to start the engine.  I installed the Harbor Freight 400/800 inverter and the MaxxAir fan.  It only uses .1 amps on low.

Step 5:  I added a 100 watt solar panel using a cheap $20 PWM controller.  I still have the one battery.  Now I use a netbook computer and crank up the MaxxFan and I can stay put without driving until I run out of water to drink.

 

[tx2sturgis]

It wont damage the battery unless its left on high overnight, then you might find your starting battery is fully depleted, and wont start the van. Not good, and this WILL damage the battery if done a few times.

You could add a second battery, or you could add a mechanical wind-up timer switch to shut off the fan after a few hours, and, running on low, this will preserve your battery.

 

[Spaceman Spiff]

I have a MaxxAir 5100K.  This is what my Trimetric reports:

On setting:

1.  = 0.2 amps
2.  = 0.4A
3.  = 0.6A
4.  = 0.9A
5.  = 1.2A
6.  = 1.6A
7.  = 2.2A
8.  = 2.8A
9.  = 3.5A
10.  = 4.7A

all numbers for exhaust.  Intake should be the same

 -- Spiff

 

[SternWake]

Got to love actual data.

As far as damaging lead acid batteries, well they are less than happy anytime they are less than fully charged, so any device drawing them down is less than ideal. The lower they are drawn and the longer they remain there the less happy they will be, and thus lose capacity faster

But they wear out anyway. It is just a matter of time.

Carry a jumper pack and keep yourself comfortable.
Its not like a starting battery is 1000$

 

[John61CT]

I have a MaxxAir 5100K.  This is what my Trimetric reports

Wow, great data, thanks!

 

[tx2sturgis]

On setting:

1.  = 0.2 amps
2.  = 0.4A
3.  = 0.6A
4.  = 0.9A
5.  = 1.2A
6.  = 1.6A
7.  = 2.2A
8.  = 2.8A
9.  = 3.5A
10.  = 4.7A

Spiff, a few years ago I converted my base model 3 speed Fantastic Fan from the simple resistor network it came with, to an off-the-shelf PWM variable speed controller.

I didnt like all the wasted energy (and heat) being consumed by the resistors, I don't remember the exact current on low, but it was about an amp or maybe a bit more.

With the PWM motor speed controller, I could vary the speed down to really low, and the current draw was somewhere around .5 amps IIRC.

Plus it gave me variable speeds, which was nice.

The only problem in my case was that the PWM board had no RFI shielding and my on-board ham radios tended to interfere with it when transmitting, and the reverse was also true: The PWM board spit out EM interference up and down the VHF and UHF bands, and my antenna is pretty close to it, so it was able to actually desense the receiver when operating.

Normally, I'm not using both at the same time, but it was aggravating until I figured things out.

I wonder if the MaxxAir electronics are shielded from all of this? Might be worth me looking into.

 

[Gideon33w]

Keep in mind, lead acid batteries can fail in only 30 cycles if you draw them deeply. Starting a car on a starter lead acid battery only draws them down 2-5%. This is what they are designed for. Drawing deeper than this regularly will severely shorten the batteries lifespan. The difference between a deep cell battery and a starting battery is self explanatory. Starting batteries are designed to flow big current for short periods and deep cell batteries are designed for prolonged small draw (sounds like a fan doesn't it?). Here's a good article: https://www.solar-electric.com/learning-center/batteries-and-charging/deep-cycle-battery-faq.html

All that said, the average size auto battery provides 45ah and running 0.2a (Maxxair on lowest setting) for 8h is only a 3.5% draw. So, running the fan (and nothing else) for 8h followed by starting the vehicle is still within the realm of what the battery is designed for. Worst case scenario is that after running the fan all night and starting in the morning you will have drawn down the battery 8.5%.

I say go for it. Just add a digital voltage gauge so you can monitor your battery voltage.

12V Battery voltage guide: 12.7V = 100%, 12.5V = 90% (these are optimal), 12.4V = 80%, 12.3V = 70%, 12.2V = 60% (these numbers are ok but you're pushing it), 12.1V is 50%, 12V is 40%, 11.75 V is 30% (this is bad and your battery is over-stressed) 11.6V = 20%, 11.3V = 10%, 10.5-11V is dead (battery is in serious trouble or has failed)

Do note that lead acid batteries tend to float a bit high after receiving a heavy charge so you wont get 100% accurate readings until the battery has sat for a little after shutting down the vehicle.

 

[Trebor English]

I wonder if the MaxxAir electronics are shielded from all of this? Might be worth me looking into.

With my MaxxAir 10 speed PWM controller  AM and SSB radio are useless.  FM gets desensed and that doesn't work either but it's not so noisy.