I noticed the tiny fridge in my small but mighty Camplite 11FDB had less than ideal distribution of "cold" in the compartment. I could have food near the back get really cold or even get ice crystals while other food near the door was moderately cold. The way such issues are usually remedied is to add a battery-powered fridge fan accessory of the type sold at places like Campers World. Those battery ones are relatively bulky compared to my tiny fridge & I don't like buying batteries. So what I did was install a 12v fridge fan system purchased on-line from >> [a href="http://rvcoolingunit.com/Dometic-Evaporator-Fan-Greater-inside-Cooling-Deluxe-Model-P2428153.aspx"]RV Cooling Unit Warehouse[/a] <<. They are a company dedicated to helping rv owners have better performance from their rv fridges. If you are having any fridge problems they are a great resource as they sell competitively-priced replacement parts & controllers, as well as various accessories. My understanding is most of their customers install the parts themselves so they provide DIY instructions. Visiting their site you will learn how to make your rv fridge more efficient.
[a href="http://rvcoolingunit.com/Dometic-Evaporator-Fan-Greater-inside-Cooling-Deluxe-Model-P2428153.aspx"]
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(http://s22.postimg.org/be7dhvqk1/fridge_fans.jpg)
That's a nice tip, I have one of the battery ones you mention and I hate buying batteries so I may copy you. Thanks
[font size="3"]PEI,
Any idea how much DC current the fans pull? No specs on the web site. And are both fans necessary? I'm thinking of main battery life in dry camping situations. I currently have the little blue battery cube unit and it really seems to help.
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Quote from: @charliem" timestamp="1434334352" source="/post/12318/thread[font size="3"]PEI,
Any idea how much DC current the fans pull? No specs on the web site. And are both fans necessary? I'm thinking of main battery life in dry camping situations. I currently have the little blue battery cube unit and it really seems to help.
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It looks like they put 2 computer fans in an aluminum housing and a switch. The computer fan I'm looking at is 0.21A ... found another in my stash of spare parts.... 0.56A. Pretty much a mousefart.
Tomorrow morning before work I'll turn on the fan. I'll then review the amount of amp-hours used 12 hrs later as monitored by my battery monitor. From that info I should be able to advise how much juice the sexy fans absorb. Keep tuned kids!
PEIslander: Could you post some pictures or a careful description of how you ran the wire out of the interior of the fridge and where you connected to 12V?
the fans arent just like computer fans...they are computer fans. looks like they are modifying a premade hard drive cooler by adding a switch and the clamps. pretty good idea.
here is one that uses 50mm fans (but they make then with different sizes...your appears to use 80mm fans). notice the aluminum housing is identical
[img style="" style="max-width:100%;" src="http://images10.newegg.com/NeweggImage/productimage/A6UM_130679225933696608vxBgeBk0ga.jpg"]
http://www.newegg.com/Product/Product.aspx?Item=9SIA6UM2KD2448&cm_re=hard_drive_cooler-_-9SIA6UM2KD2448-_-Product
Quote from: @tlbones" timestamp="1434409824" source="/post/12346/threadIt looks like they put 2 computer fans in an aluminum housing and a switch. The computer fan I'm looking at is 0.21A ... found another in my stash of spare parts.... 0.56A. Pretty much a mousefart.
[font size="3"]When you're dry camping a 1/2 Amp constant load (12 AH/day) is not insignificant.[/font]
[quote timestamp="1434417196" author="@peislander" source="/post/12353/thread"]Tomorrow morning before work I'll turn on the fan. I'll then review the amount of amp-hours used 12 hrs later as monitored by my battery monitor. From that info I should be able to advise how much juice the sexy fans absorb. Keep tuned kids![/quote][font size="3"]What type of battery monitor and can you isolate the fan load from other loads such as propane alarm, fridge electronics, electric gas valves, etc.? Can you measure the fan current directly?[/font]
It is just anecdotal but I think my daily Ah draw with the trailer sitting idle is about 1/2 Ah per day. That would relate to the draw from the propane alarm, and my battery monitor. I typically have the fridge turned off and I have no tank monitoring system. I say anecdotal because I've never made any effort to get a accurate grasp on that usage.
If I account for that 1/2 Ah it appears the fridge fan system uses 6.9 Ah per day. I'd say that is not an insignificant amount if you were boondocking for more than a couple of days. Of course you can still use the fan when on shore power. My battery monitor is a Victron Energy BMV-600S. Earlier I had a posting that included info on that monitor. You can find it >> [a href="http://livinlite.proboards.com/thread/1077/added-dc-inverter-battery-monitor"]here[/a] <<.
tlbones --- I will try and take some pics showing how I powered up the fans. In the pic above you can see the wire leaving the compartment. Just above the fins there was an existing hole associated with what I think is the fridge's thermostat sensor --- you can just see the edge of a metallic tube just below where the wire goes out.
[quote source="/post/12403/thread" timestamp="1434496473" author="@peislander"]It is just anecdotal but I think my daily Ah draw with the trailer sitting idle is about 1/2 Ah per day. That would relate to the draw from the propane alarm, and my battery monitor. I typically have the fridge turned off and I have no tank monitoring system. I say anecdotal because I've never made any effort to get a accurate grasp on that usage.
If I account for that 1/2 Ah it appears the fridge fan system uses 6.9 Ah per day. I'd say that is not an insignificant amount if you were boondocking for more than a couple of days. Of course you can still use the fan when on shore power. My battery monitor is a Victron Energy BMV-600S. Earlier I had a posting that included info on that monitor. You can find it >> [a href="http://livinlite.proboards.com/thread/1077/added-dc-inverter-battery-monitor"]here[/a] <<.
tlbones --- I will try and take some pics showing how I powered up the fans. In the pic above you can see the wire leaving the compartment. Just above the fins there was an existing hole associated with what I think is the fridge's thermostat sensor --- you can just see the edge of a metallic tube just below where the wire goes out.[/quote]6.9 Ah per day is a fair chunk, when I'm boondocking I use no more than 20 Ah per day and that includes the fridge on propane, Water heater, and lights as needed.
[quote timestamp="1434496473" author="@peislander" source="/post/12403/thread"]It is just anecdotal but I think my daily Ah draw with the trailer sitting idle is about 1/2 Ah per day.
[/quote][font size="3"]The 1/2 AH/day seem light. When I measured my 21RBS with only the propane detector and fridge keep alive electronics (fridge off) I read 90mA. Admittedly this was with a clamp on Ammeter so not perfectly accurate, but that multiplies out to 2+ AH/day. I'm also assuming LL used the same propane detector.
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Charliem -- what do you mean by "fridge keep alive"? I just checked and my 24-hour usage was 0.4 Ah. From what I can tell that usage is only the propane detector & the Victron Energy Monitor. Are you saying the 3-way fridge would use 12v dc even if turned completely off --- mine is off. I do have a SureSine Inverter but it is switched so my understanding is when off it uses no power.
I agree that in all likelihood we have the same detector. We may not have the same fridge. In the small but mighty Camplite 11FDB they use a small but not so mighty fridge -- just 2.5 cu.ft. with no freezer compartment.
[font size="3"]OK PEI,
You asked for it so here comes some Geek speak (engineer talk). Most electronic devices that have a momentary push button (push and release) switch to turn it on/off have a small amount of circuitry that is powered all the time. It's function is to monitor for that button push and power up the device. A good example is a modern television controlled by a remote control. There is a small circuit in the TV, consuming some power, which constantly awaits the push button signal from the remote. When the signal is detected the monitoring circuit turns on the rest of the TV. Sometimes, to prevent accidental operation, the button has to be held for a few seconds, but the principle is the same. [/font][font size="3"]If your fridge is like mine, although not so mighty, it has a touch button to turn it on or off. [/font][font size="3"]The alternative control, those that are totally off when they're off, are toggle switches like light switches, pull chain lamp switches, and rotary knob switches that click on and off. There are such things as toggle push button switches, but they also click on and off. The amount of power drawn by these monitoring circuits is small, but it adds up when you're dry camping or running off grid on solar. To further muddy the water there are "instant on" devices that come to life very quickly after pushing the button, and they consume considerable power when in standby, but most of those went away with the demise of the vacuum tube.
So all of that said, if your measurement of 0.4 AH/day is accurate the current draw would have to be 16.67 mA (0.4/24 = 0.0167A). This seems very low from what I've read about the propane detectors. As I said I'm a bit skeptical about my clamp on ammeter at very low currents so I'll go out and measure it with a true digital multimeter and report back shortly. Something I've been meaning to do anyway for my own curiosity.
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My LP detector draws much than yours. Right around .3A IIRC.
[font size="3"]PEIslander,
And the number is.....................On the 21RBS with everything "off" the residual current as measured with a good DVM is 0.19 Amps. This includes the fridge keep alive current (fridge off) the propane detector, the radio keep alive current with the clock display off, and one usb charger I have hardwired in but nothing connected to it. Most of that current is the propane detector though some current goes to the radio, the fridge, and the usb charger. Turning the radio clock display on increases the current to 0.25A. So at 0.19A the battery usage is 4.56AH/day, not at all insignificant if dry camping. For perspective, in ten days this is half the capacity of the typical 86AH Group 24 "Marine" battery supplied with our campers. Whoofit thinks his propane detector draws 0.3A so I'm suspicious of your low reported currents. Do you have a digital multimeter to check against?
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I'm going measure mine across the fuse tomorrow. I suspect the calibration sequence it goes through on power-up uses more juice.
Regarding that residual current -- I have no radio, television, money counter, card shuffler or charger. I do have a cassette toilet that monitors the tank level with some form of float switch. The grey & fresh tanks have no monitoring. The Victron Energy Monitor uses 4mA when the backlight is off & it is not in an alarm state. I have it set up so the backlight only comes on when using the display. It is not in an alarm state. The resolution of the monitor when measuring current between 0 & 10A is +/- 0.01A.
Sorry I don't have a digital multimeter.
I just went and looked at the Victron Energy Monitor. It indicates it has been 4.1 days since I had 100% charge and that in those 4.1 days it consumed 5.2Ah. That consumption includes the 12-hour test I did running the fridge fan and 4 or 5 minutes of running one of my Fantastic-vent ceiling fans a few days ago & a minute or so of testing my LED cabin lighting (StarLights Brilliant Lights -- one fixture with dimmer & night light modules). I also confirmed the operation of the 300W inverter for a minute or so using a transistor radio with a 110v power adapter. I also confirmed the operation of the water pump but it just ran for several seconds. The 12-hour fridge fan test consumed 3.45Ah. Subtracting that 3.45Ah from the 5.2Ah I'm left with 1.75Ah being used in the four days -- and that includes the testing of the fan, pump, inverter, lights, and fiddling with the energy monitor. ---- I did not confirm the propane detector is operational.
[quote source="/post/12461/thread" timestamp="1434587448" author="@whoofit"]I'm going measure mine across the fuse tomorrow. I suspect the calibration sequence it goes through on power-up uses more juice.[/quote][font size="3"]I watched the current during the 10 minute power up. It toggled between 0.19 and 0.21. After the green light came on continuously it read 0.19. I didn't think of the calibration routine. That may be what I was seeing. We're awaiting your report.
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[font size="3"]PEIslander,
Something still doesn't ring true. That would mean you were seeing about 17.8 mA for the 4 days. Everything I've read about propane detectors suggests something in the 100+ milliamp range depending on type and manufacturer. Does your propane detector have a green light that stays on all the time, two test/mute buttons, and a red light that come on for test or alarm?
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In addition to this fascinating conversation about how much current the fan draws, a more interesting issue for me is how it is wired to DC. It would be much preferable for me if it was wired in to the fridge's circuit so it only came on when the fridge was on. If it is wired to the DC supply to the Fridge then it will run continuously as long as the batteries are connected and have juice.
We often camp overnight and I don't bother cooling down the fridge in that case. We just take a small cooler for food and drinks for that single day.
So could you describe exactly where you picked up power and if wired into the DC supply is there a place where you can safely pick up power that is switched by the fridge.
David
[font size="3"]David,
I agree the preferable connection would be to a point switched by the fridge on/off function, but that will depend on the particular fridge. The CL11, CL16, CL21 all have different fridges. Best bet is to look at your particular fridge schematic and try to find the proper point. Failing that, the switch mounted on the fan assembly can be used.
I also question the need for two fans. I use just one of the little blue cube fans in a 7 cu. ft. fridge and believe it make a noticeable difference. Maybe the best solution would be to replace the supplied switch with a single pole three position on-off-on switch. This switch plus a diode would allow one fan for dry camping and both for max cooling on shore power.
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[quote source="/post/12472/thread" timestamp="1434633010" author="@david"]It would be much preferable for me if it was wired in to the fridge's circuit so it only came on when the fridge was on. If it is wired to the DC supply to the Fridge then it will run continuously as long as the batteries are connected and have juice.[/quote]The fan is switched so it comes on only when you turn it on. When you use it is therefore optional. You could for instance just use it when running the fridge on propane or shore power.
[quote source="/post/12477/thread" timestamp="1434645848" author="@peislander"][quote source="/post/12472/thread" timestamp="1434633010" author="@david"]It would be much preferable for me if it was wired in to the fridge's circuit so it only came on when the fridge was on. If it is wired to the DC supply to the Fridge then it will run continuously as long as the batteries are connected and have juice.[/quote]The fan is switched so it comes on only when you turn it on. When you use it is therefore optional. You could for instance just use it when running the fridge on propane or shore power.[/quote]My brainstorm was a rheostat to dial down the fan speed (and amps needed) or some sort of timer that would turn the fans on and off every so often...say for 1 minute every 4 to still circulate the air but use only 1/4 the run-time/amp-hours? I don't know how expensive or possible either of these ideas would be....
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[/p][p]Todd,
This is an elementary drawing of the repeat interval timer that you were suggesting in your post. This is old school relay logic, but it's very effective in terms of reliability and only uses two components, and does not require an external trigger as SW1 is the trigger. Yes, there are more sophisticated applications available but may cost more and may be more complicated to apply? I haven't priced any of these components and now days you may be able to get a, Chinese made, dedicated repeat interval timer for less than the price of the two relays? Keep in mind that the relay holding coils also require current to operate. You need to do a study to determine the current draw of the holding coils verses the fan motor. And, you may find that this is not a worthwhile project and that a small fan running full time may work just as well. I still use the little blue cube fan with a D battery.[/p][p]
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(https://c1.staticflickr.com/1/427/18948900341_3031471e05_k.jpg)
(https://flic.kr/p/uSs4Ui)001 (https://flic.kr/p/uSs4Ui) by james M (https://www.flickr.com/photos/132834048@N05/), on Flickr
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[quote source="/post/12508/thread" timestamp="1434739036" author="@james"][p]
[/p][p]Todd,
This is an elementary drawing of the repeat interval timer that you were suggesting in your post. This is old school relay logic, but it's very effective in terms of reliability and only uses two components, and does not require an external trigger as SW1 is the trigger. Yes, there are more sophisticated applications available but may cost more and may be more complicated to apply? I haven't priced any of these components and now days you may be able to get a, Chinese made, dedicated repeat interval timer for less than the price of the two relays? Keep in mind that the relay holding coils also require current to operate. You need to do a study to determine the current draw of the holding coils verses the fan motor. And, you may find that this is not a worthwhile project and that a small fan running full time may work just as well. I still use the little blue cube fan with a D battery.[/p][p]
[/p][p][a href="https://flic.kr/p/uSs4Ui"]
(https://c1.staticflickr.com/1/427/18948900341_3031471e05_k.jpg)
The blue fan will run for a very long time, I used one all last summer and didn't have to change the batteries until the fall.
The electrical stuff is pretty interesting (really), but I'll raise a question about thermodynamics. These are small refrigerators. I'll hazard a guess that a very small fan would help the natural convection and improve the eveness of temperature inside as well as improve the efficiency a bit. However, at some point there is overkill and the fans themselves will be adding excessive heat. As well, I wonder if there is such a thing as too much air circulation that may add excessively to the conduction of heat to the interior. Bottom line is that I think (but I don't know) that a very small fan inside would be useful but not any more than that. On the outside, however, I can imagine a larger fan helping a lot to move air through the coils. The refrigerator in my 16 does not have a fan in the outside compartment and I think I'll add one that comes on when things get hot.
[quote timestamp="1434849146" author="@sandroad" source="/post/12525/thread"]The electrical stuff is pretty interesting (really), but I'll raise a question about thermodynamics. These are small refrigerators. I'll hazard a guess that a very small fan would help the natural convection and improve the eveness of temperature inside as well as improve the efficiency a bit. However, at some point there is overkill and the fans themselves will be adding excessive heat. As well, I wonder if there is such a thing as too much air circulation that may add excessively to the conduction of heat to the interior. Bottom line is that I think (but I don't know) that a very small fan inside would be useful but not any more than that. On the outside, however, I can imagine a larger fan helping a lot to move air through the coils. The refrigerator in my 16 does not have a fan in the outside compartment and I think I'll add one that comes on when things get hot. [/quote]
(http://www.findtheneedle.co.uk/images/companydescription/135414.jpg)So this fan is out of the question?
[quote source="/post/12525/thread" timestamp="1434849146" author="@sandroad"]The electrical stuff is pretty interesting (really), but I'll raise a question about thermodynamics. These are small refrigerators. I'll hazard a guess that a very small fan would help the natural convection and improve the eveness of temperature inside as well as improve the efficiency a bit. However, at some point there is overkill and the fans themselves will be adding excessive heat. As well, I wonder if there is such a thing as too much air circulation that may add excessively to the conduction of heat to the interior. Bottom line is that I think (but I don't know) that a very small fan inside would be useful but not any more than that. On the outside, however, I can imagine a larger fan helping a lot to move air through the coils. The refrigerator in my 16 does not have a fan in the outside compartment and I think I'll add one that comes on when things get hot. [/quote][font size="3"]Merlin,
You're correct, there is a point of overkill. I think the twin fans are overkill. The best info I can find on the twin fan 3.5" HD coolers is 10.5 CFM and 0.12A at 12 VDC. I think a single fan would suffice. At 5.25 CFM it would move all the air in a 5 cu.ft. fridge around each minute. I use the blue cube battery powered fan in my 21RBS and it seems to be effective and it moves a whole lot less air than 5 CFM. I put batteries in it last summer, before a month+ trip, and the batteries are still good. I think a slightly bigger fan may help somewhat, but it's not high up on my todo list.
My 7 cu.ft. fridge does have outside fans controlled by a thermostat. I hear them come on frequently on hot days, particularly when the fridge is facing the sun. It probably would be a worthwhile addition to your fridge, but you should include the thermostat for noise and power considerations.
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