A Burner Analogy For Understanding Electricity

[fresh]

Thanks FJ, I think my fan's case might be too small to use bolts without getting in the of the connector. I will try it though!!! I bought collapsible insulated silver dryer duct for the hose. Hope that works!!! Last year I used the collapsible hose from my portable a/c unit at work. THe boss has not seen how dustie it is...

[Captain Goddammit]

Last year I used the collapsible hose from my portable a/c unit at work. THe boss has not seen how dustie it is...

Well that's unfortunate. I guess you have to be FIGJAM to be dustay

[gyre]

Touch anything to your tongue.
Just don't run the path across anything valuable, like your heart or head.
This is why you may keep one hand behind you while working near voltage.

I really hate the water analogies.

Horsepower wins arguments.
Torque wins races.

You know what's like electricity?
Electricity.

[Zumaria]

Thank you Captain Goddamn it for breaking me out of my fear-paralysis!! What a little gem this thread is

I have been losing my mind trying to figure out all of this and thinking that I get it but not really for sure and it's been making me fear paralyzed lol

I feel much better now, but was still wondering if you could check my math just to make sure.

1. I have solar panels that produce 45 watts of energy. (still confused on how that's measured...per day, per hour...anyway I digress)
2. I would like to use a fan which is 1.6 amps and 12 volts.
3. 1.6 amps x 12 Volts (1.6 x 12=) equals 19.2 watts. If my solar panels are producing 45 watts, this should be no problem, right?
4. Now I'm a little stuck. I know I need to build up a reserve in a battery. If I have a battery that is 12V and has 35AH, at full charge, it could run the above fan for ...2 hours?

Figjam, what if my sink is draining and has the faucet on?

Thank you everyone!

[FIGJAM]

Your pump and fan will use close to 2 amps per hour.

You don't want to drain the battery below 50% if you want it to last a number of years.

So you can use the cooler for 8 hours without a recharge before the battery is down to 50% charge.

[Captain Goddammit]

It appears you are confusing amp-hours and watts. Watts is volts x amps. It's the combination of how fast you're pedaling and how hard you're pedaling that equals the amount of work being done (watts).

Ah, amp-hours, is simply how many hours the battery can make how many amps. The volts are always 12, since its a 12 volt battery.

If it's a 50ah battery then theoretically it can put out 50 amps (at 12 volts - you already know that part, it's a 12-volt battery) for one hour. Or, 5 amps for 10 hours. If your load is 10 amps, you get 5 hour's worth.

But you can't really use all that power from a battery. Discharging below about halfway is bad for the battery, which doesn't really matter because it's usually too weak to make your appliance work at that point anyway.
So you need to estimate very conservatively. Give yourself twice the battery capacity the numbers say you need.

I'll quibble just slightly with FIGJAM over saying the pump and fan will draw 2 amps per hour; they draw 2 amps, at all times. What he means is they will use 2 amp-hours per hour.

[FIGJAM]

Eggsalad.

I wordeded it awkwardly.

[SnowBlind]

1. I have solar panels that produce 45 watts of energy. (still confused on how that's measured...per day, per hour...anyway I digress)

It's 45 Watts. Not per hour, or per day, just 45 Watts. Think about a Stereo system that produces 120 decibels. That's not 120 decibels per hour, or per day, its simply 120 decibels. Watts is like that.

(More technically, a Watt is defined as Joule per second, so it's already got the 'time' component baked in. So your panel produces 45 Joules of energy every second (when it is on maximum output).)

I would like to use a fan which is 1.6 amps and 12 volts.
...
If I have a battery that is 12V and has 35AH, at full charge, it could run the above fan for ...2 hours?

Since they are both 12V you can compare them directly. So, 1.6 amps for an hour is 1.6 AH. You got 35 AH, so you could run it for 35/1.6=21.9 hours. Theoretically. As others have pointed out, depending on the battery, you don't want to discharge it completely. If it's a lead acid you shouldn't discharge it more than 50%, so lets figure 10 hours.

Also, all this math assumes ideal behaviour. In reality, everything has losses.

[Just_Joe]

Now that you have an idea of how many amp hours you need for you cooler per day, you need to figure the amps needed for other stuff. Add all your needed amps up and then double that number to determine the size (ah) battery you need. You then need to size your solar array to "refill" all the amps used by your battery in a day. The panel you have will refill a max of 2-3 amps per hour for six hours (12-18 amp hours) of good sun if you reposition it a couple of times during the day.

[Zumaria]

Damn! So...close but not at all? lol

Thank you everyone for the insight! I recently came into possession of an 85 AH deep cycle battery. I'm going to begin field testing...

[rideincircles]

Bumping up this thread since its highly valuable. I assume the 1.5 watt solar panel I have is almost worthless for accomplishing much. I will probably hook it up, but don't expect much out on the playa.

I still am sorting through what battery to get and whether or not to bring a larger solar panel. Was thinking maybe 10 watts if i did.

Continuing into the discussion of batteries. I read that AH can be calculated from RC (reserve capacity) by using (RC x25)/60 but wasn't sure if that was correct.

For instance, the Costco Interstate deep cycle 27DC battery lists 600 CCA and 160 RC. If that calculation is correct than it has 160 x 25 = 4000/60 = 67 AH.

So far most of the batteries I have found in stores are marine style starting batteries with 175 RC being the biggest I have found at Oreillys for $90. I would probably use the battery for my boat next year which has a 225 hp v6 later, my optima died and the boat is sitting around until I can get it tuned up.

I only will need it for the 12v pump and Endless Breeze fan swamp cooler I have for the week as of now. I would like to avoid charging it.

I remember reading somewhere to hook it up to the car for a while to level the battery loads and then running the engine so the alternator can charge it. Please update anything incorrect and I can edit it if I am totally off base.

[FIGJAM]

Everything in that post was spot on!!!

You should be able to run the cooler for a total of 18 hours before the battery is down to 50% and should be charged.

At 5 hours a day, that's almost 4 days.

[rideincircles]

Noted.

I went by Academy and checked out their batteries during lunch and they have a Exide 31DCMST battery with 205 RC and 115 ah listed for $110. This seems to be the largest size I have found looking around, but still have a few more places to check for a better price.

The 205 RC x25 = 5125/60 = 85.41 which does not jive with the 115 ah listed. Any reason for the discrepancy? Which one is the one I need to worry about on the playa?

Also, When I pulled up some info on a Superstart 31DC this is what I found (not the same battery as listed above).

Polarity: Left Positive
20 Amp Hour Rate (Ah): 105Ah
Battery Type: Deep Cycle
Reserve Capacity (min): 210 Minute
Reserve Capacity At 23 Amps (min): 225 Minute
Reserve Capacity At 25 Amps (min): 185 Minute
Electrolyte Composition: Acid

http://www.oreillyauto.com/site/c/detai ... &ppt=C0327

I assume some of that factors into the discrepancy. Just not sure how that all computes. It seems that we are using the 25amp equation.

[Roundabout]

I assume the 1.5 watt solar panel I have is almost worthless for accomplishing much. I will probably hook it up, but don't expect much out on the playa.

I still am sorting through what battery to get and whether or not to bring a larger solar panel. Was thinking maybe 10 watts if i did.

Don't bother with any solar panel that is less than 50 watts, preferably 100 watts. Search the internet machine for very reasonable pricing. Most solar panels bought from a store shelf are outdated technology and overpriced. YMMV

[lucky420]

bump because i really need to read all of this, just not right now

[mooserider]

I assume the 1.5 watt solar panel I have is almost worthless for accomplishing much. I will probably hook it up, but don't expect much out on the playa.

I still am sorting through what battery to get and whether or not to bring a larger solar panel. Was thinking maybe 10 watts if i did.

Don't bother with any solar panel that is less than 50 watts, preferably 100 watts. Search the internet machine for very reasonable pricing. Most solar panels bought from a store shelf are outdated technology and overpriced. YMMV

Indeed. Your solar panel needs to have at least at least twice the output of your total electrical load, since it will only generate power during the daytime, so it needs to produce enough electricity not only to carry the day-time load, but simultaneously recharge the batteries for the night-time load.

[FIGJAM]

"20 Amp Hour Rate (Ah): 105Ah"

That right there is all you need to know.

Contact cosco and wallymart for something comparable at the cheapest price.

[some seeing eye]

These threads are what is best about ePlaya. Smart and experienced burners providing good advice.

I'm more the water analogy camp, but it neglects that water can go at different speeds, while electricity has relatively constant speed. But I would throw this in:


Also I would encourage burners to buy when they can American made solar panels - cells made here and panels assembled here, not Chinese cells with final assembly here.

From a wholesale supplier, even for one panel, you should pay $1 to no more than $1.50 per Watt, even American made. One full size panel with today's technology is going to be 300Watts +-.

I always suggest that considering for the first time, new and experienced solar enthusiasts visit the Alternative Energy Zone on playa. They would especially be useful if you are going to purchase your first solar panels, batteries or controllers for the 2016 burn; want to understand Amps, Volts, Watts, AWG, inverters and charge controllers; and how to be economical in your solar adventures.

The time I visited they were serving solar oven baked chocolate chip cookies!

On a sad note I do not believe BM solar pioneers Snow Koan Solar are participating this year. We wish the best to the founder looking down upon us from the sun itself.

[jfeaz]

Hey, great thread. I'm starting to get a feel for this.

I'm tasked with lighting an art project this year and I'm trying to figure out the math. I'm looking at strip LED lighting, 20 meters worth, purchased as four 5-meter strips with 300 LEDs each.

The product is advertised as a 12V DC system that runs at 5 "working amps". Based on what I've learned here, that means that I'm looking at 12v x 5a = 60 watts.

Say I want to have this piece lit for 84 hours total. Let's pretend recharging isn't a thing and I wanted to run the whole thing off pre-charged 100ah 12V batteries (I don't but I'm dumb and trying to understand the math).

So a 100ah battery can run the lights for 5 hours, right, since 100ah = 20a x 5 hours? So I would need 17 of those to keep it going without recharging (just pretending the batteries don't suck below 50%)


Confusingly, the light strips also say the LEDs are 0.24w each, which I don't understand because if you multiply that by 300 lights, it comes out to 72 watts, not 60. What am I missing?

[Captain Goddammit]

Your calculations seem good, the rated specs probably aren't 100% accurate.