My nephew has been working on an organic farm for the last month or so. He's living in a tent. Not like camping tent but more of a heavy canvas say 15x10 with a 10x10 porch. Not quite Harry Potter style but nice. Anyway he has running water but no electric. He current system is the charge a 18ah battery/inverter system in a box at the barn then walk 200 yards to his tent. He charges his cell phone and runs a fan. He has a light but doesn't use it much because it kills the battery. The phone and fan kill the battery by 7am the next morning. The fan and light are 115v and I didn't ask but pretty sure the phone charger is also. I know he's loosing at least 30% efficiency there. My thought was first replace everything with 12v. 120mm computer fan, 12v strip leds like I use for our hurricane setup, and a 12v phone charger. Next I'd like to set up a solar battery charger. He doesn't get enough sun at his tent but there's a spot about 50 yards away. I figure two 36ah lawn mower batteries would allow him to swap while one charges. That'll also give him a lot more headroom to run things. My math says a 100watt system should be enough. First am I right on that and second is there anything out there y'all would recommend?
You will want deep cycle batteries, normal car batteries don't do well in this situation. While I abhor them for a bigger system, a marine battery is a semi deep cell and would work for his tiny amount of usage. Remember too 36ah battery means he has 18ah to use since you really don't wanna take flooded cell batteries beyond 50 percent.
Depending on how much sun he gets a 100w panel would do wonderful for what he's using
DC is a good idea in his situation too, no need to convert it to AC if you can run everything off DC.
100W panels are less than 100 bucks on Amazon too
Also for panels, stay away from amorphous panels like HF sells, they literally don't work well in direct sunlight
Sirocco 12v fan is where he should head if he's planning on staying like this for a while.
Editied to add specs
Specifications:
Weight1.25KgMax. CFM185Input Power12/24 V Auto SensingFan Speed Settings3 (Speed 1 @ 0.12A | Speed 2 @ 0.22A | Speed 3 @ 0.35A)Current Draw on Low0.06 Amps. Current Draw on High0.35 Amps. Dimensions89(L) x 241(W) x 304(H)mm
These get used on boats etc for a reason. They're a little spendy, but damn good
What is the power consumption of the fan? A phone & LED light should an almost negligible amount of power.
It might be easier to add more capacity to the battery and re-size the fan than to deal with solar. If you add solar to the system but no more battery capactiy, isn't it still going to be drained every night?
Ok did some math. Assuming a total 12v system we're looking at:
1 ah for for fan so 8ah running all night
Phone is 4000 ma battery so 4a to charge
Lights depend on how long of a strip but I'm thinking 1a per hour and maybe 3 hours a night for 3ah total.
That adds up to 15ah of usage per night.
Would it be better to run 12v power that 50 yards so that it's a more perm install? Then I could run two batteries and supply him for the evening.
In reply to Stampie :
That's up to you, even a $80 marine battery would likely run his setup for 3 or so nights and 100w solar would charge it pretty fast.
Is there no sun whatsoever closer?
In reply to Antihero (Forum Supporter) :
Yeah his tent is a in a legacy location I'm assuming for the shade. Would be a PITA to relocate everything.
I use a 5v USB fan when camping. It will run for several nights on a 30k mAh battery bank. That battery will also charge my phone 4-5 times. USB LED lighting should be extremely low load as well. For charging, there is an assortment of USB solar panels on the market. A couple of batteries would let him use one while the other is charging.
My fan is like this. They are available at Walmart or Amazon.
Solar panels are usually foldable and compact. This particular one is 28 watts and they are available up to 100. How secure is the area he would set up the solar panel. They would be fairly easy to steal.
Personally I'd look into bigger (deep cycle) batteries and a cart or dolly to move them. If you have a spot to charge them from an outlet, I'd avoid the headache of the solar panel a little closer (I actually wouldn't, but I'm dumb). I'd put the extra money into a second battery instead and swap them out every day or two.
Edit: Maybe old golf cart/hover-round batteries? Gotta be some floating around down there.
Sorry I had no relevent info, still subbed for actual info.
You guys are totally overthinking this. My wife and I use a rooftop tent to camp. We have 2 phones, a laptop, a fan, flashlights, and tent lights that we use on an Amazon purchased battery. All devices/ lights are usb vagaries and the battery gets us 2 days worth of charge after a 3 hour plug in. (There is a solar panel option and car cigarette lighter charging option but we haven't needed them yet). Pi's to follow...
How long is he going to be there? Like should this be a very long term solution, or one to just get by for the summer?
First, IMHO, I think the change to all 12V stuff if the best thing to do- there are a TON of options for that which take barely any power. And if this is longish- that even goes for fridges- there are some good and inexpensive 12V fridges that also take barely any power.
In terms of batteries- for a short term solution, lead acid or AGM are good choices, but if this goes really long, LiFePO4 batteries are getting pretty cheap. Even better- they can be fully used in terms of voltage rage, where as the lead ones can only be used half way.
How far are you talking from where there's good sun to the tent? Since panels output higher voltage than the batteries- you can do a long run of wire from the panel to the charge controller.
And oversize the system as much as you can afford- especially for the battery- there will be days where charging will be a challenge.
I use this site as some good reference- https://diysolarforum.com/ and there are some plans for smaller systems.
In reply to alfadriver :
To add onto Alfadriver's mentioning of LiFePO4s, how long will he be out there? With how fast sulfation occurs on lead-acids that are used that much, those lithium phosphates could save him money very quickly. They deal with winter temps better, too.
I agree that changing everything to 12V is needed; like you said, going DC to AC kills efficiency quickly and there's lots of 12 volt camping supplies out there. Deep cycle batteries (if he stays lead) are also needed too, this kind of thing sulfates car batteries quickly. Solar panels have largely consolidated plugs and terminals nowadays and their rapid progression means old ones get replaced all the time (or B stock is sold for cheaper prices) so I would argue that he should buy some secondhand panels that test fine, build a small rig locally to hold them and run it's AC cables to the inverter/controller combo inside. Amazon has cheap-chip controllers like this everywhere, but be sure to read the Amperage they can take and check reviews to see what modifications people have done to them.
You're pretty close on the wattage, but he also should invest into a "dump load" just in case he generates too much power so he doesn't boil/explode his battery. Something as simple as a heating element in a tank of clean water will be great for that.
Since eventually we're going to add solar to the van, I've been following this guy on YouTube. He has some great vids comparing budget solar options vs. the higher dollar ones, and often he concludes the cheaper one is the better value overall.
Also, there are some cheap used panels available out there(which he also has vids on). So don't be put off by sticker-shock when you start looking at components.
In reply to GIRTHQUAKE :
A decent deep cycle lead flooded cell will last for many many years before sulfation. Mine are used every day and last about 8 years at a time.
You aren't wrong about cold temps but really the only thing you need to worry about is freezing and that will only happen if the battery is really low on charge. Lead acid batteries that are charged can do pretty much anything besides Antarctica.
Plus a marine battery is very cheap, he might be able to do this whole thing for $150-200.
Sorry busy day at work. I read the responses at lunch but wanted to sit down at home to answer. Time wise this system is at least going to last a year. He was told that if he stayed a year they would look at building him a cob house. Now that might still not have power so most likely this system would be transferred over. As far as home rolling a lithium battery I'm just not comfortable with that. Having almost lost a Challenge car to an over charged lithium battery I'm not willing to risk that with my nephew. I would be more inclined to home roll a deep cycle battery but I'm also more than willing to pay a little extra to get an all in one system.
Pete Gossett (Forum Supporter) said:
Since eventually we're going to add solar to the van, I've been following this guy on YouTube. He has some great vids comparing budget solar options vs. the higher dollar ones, and often he concludes the cheaper one is the better value overall.
Also, there are some cheap used panels available out there(which he also has vids on). So don't be put off by sticker-shock when you start looking at components.
FWIW, Will's forum page is the one I posted- https://diysolarforum.com/
Stampie said:
Sorry busy day at work. I read the responses at lunch but wanted to sit down at home to answer. Time wise this system is at least going to last a year. He was told that if he stayed a year they would look at building him a cob house. Now that might still not have power so most likely this system would be transferred over. As far as home rolling a lithium battery I'm just not comfortable with that. Having almost lost a Challenge car to an over charged lithium battery I'm not willing to risk that with my nephew. I would be more inclined to home roll a deep cycle battery but I'm also more than willing to pay a little extra to get an all in one system.
Li-ion batteries, absolutely. But LiFePO4 batteries don't have a fire risk. It's one reason they are more expensive than the normal Li-ion batteries.
BTW, GIRTHQUAKe suggested that they are more robust to temps- somewhat. But you can't charge them below 34 F. One great suggestion was to use a RV tank heater mat- they keep a water tank above freezing, and that's it.
For what your nephew is doing, for now, all he would need is a battery, a solar charge controller, and solar panels. A battery management system would be a great add. But that's it- charge controllers do output control, too.
We're basically talking about a very simple RV setup like the one in my Westy. I've got a 100W panel and about 100 Ah of battery (I forget exactly what) with a controller. Voila. As long as the fan isn't some sort of monster, that would be enough to run some LED lights and a phone charger for a few days. Set up the panel in the sun, aim it properly and run wires to the tent. Voila. Most charge controllers can be set to cut the battery power once the battery is discharged to a certain point in order to protect it.
Dunno just how penny pinching we're being, but take this and add a marine battery and you're basically done: https://www.amazon.com/WEIZE-Starter-Efficiency-Monocrystalline-Applications/dp/B08LH7PL4N/
I'd actually be tempted to splurge a little and spend another $21 to get Renogy. That's who made my panels and they've been around for a while.
https://www.amazon.com/Renogy-Monocrystalline-Negative-Controller-Connectors/dp/B00BFCNFRM
In reply to alfadriver :
OK I'll look into the LiFePO4 batteries. How are they if totally drained? I love my nephew but he's the type that would just run them all the way down.
In reply to Keith Tanner :
That's pretty much what I'm looking for.
In reply to Keith Tanner :
One thing to follow up (again) on Keith's post- run the highest voltage thing on the long wires. In this case, it should be the solar panel- well above the battery voltage system.
Which also brings up the obvious- make sure you have enough wire to run from the panel to where ever you need it. Wire is cheap, as I've found on Amazon.
Placement of the panel is really important, too. It has to face the sun at the correct angle and be in direct sunlight. Even a little bit of shadow on the panel will kill the efficiency - they're kinda weird. Best to keep it clean if he's flirting with the limits of the system.
If you set the controller up properly, it should protect the battery from nephew abuse. It'll just cut the supply when things get too low. Since space isn't an issue here, I'd definitely price out a bunch of marine battery versus the lithium chemistry with the same total useable capacity.
In reply to alfadriver :
Ok that makes sense. Might be able to actually make it so he's not carrying around batteries all the time.
