Boondocking an Electric Heater

[Civilguy]

Originally Posted by Buggeee

This is a relative discussion, my batteries know full well that "the beatings will continue until morale improves."

I expect that others will step in and further clarify or correct my hazy recollection that coupling batteries in series is a good thing, but parallel arrangements apparently don't allow you to harvest the full goodness from all...

That comes from my past reading up on why 6V batteries are commonly used in golf carts and RVs, but I may be full of Schnapps...

[Civilguy]

Originally Posted by Civilguy

The Safe and Warm (TM) brand electric blanket is described as operating on low voltage.

Here's the scoop on the Safe and Warm brick; 1A 120VAC to 3.5A 18VDC. This unit serves one side of a King size blanket.

This seems very inefficient so you might want to keep the brick in the bottom of the sleeping bag and harvest that extra goodness.

Also, it seems I may have also seen 12 VDC blankets sold online at storefronts serving truckers - ?

[Buggeee]

Originally Posted by Civilguy

..other than neglecting to divide by the airspeed of an unladen swallow, everyone else has been covering the formulas real well already.

Is that an African or European swallow? All in now it seems. Glad to have you aboard the magic bus Civil Guy!

I love the hot rock from the campfire idea.

The connections are crimped, crimped hard, with a hand hydraulic connection crimper. I'm smiling when I think of how hard those little strands are smashed, may have oozed some bullion out that day. They are still in good shape so far, a bit dull looking but no oxidation build-up to worry about. I have been pondering bus bars but I like that vibration is not transfered through cable and that the battery posts don't get stressed like they might bouncing around as a bus-barred group.

[Raspy]

It turns out everyone has been missing the obvious! In the spirit of saving fuels, such as propane or gasoline, and using batteries to do the work, we've missed a major issue.

After driving all the way to the campground and charging the batteries all the way, Buggee should just hook up the batteries in reverse to the tow vehicle and run the alternator as a motor. That will spin the engine and drive the car home. No need to start the engine or waste a bunch of gas. And the electric heater can be on in the trailer to keep it warm on the way.

Well, shoot! If the alternator is spinning it will charge the batteries. So the batteries can charge up on the way home too, while running the alternator as the power plant.

Now, you won't need the engine at all next trip! Just let the batteries charge up as they power the car.

If this works out as well as it should, big batteries are just a waste. So the plan will be to find out how small the batteries can be. I'm betting a pair of triple A batteries will do the trick unless the trip involves two extra cups from the Keurig or an overnight stay with the heater on.

We may be on to something here!

[Civilguy]

Wow, that is mathmagical! And, no swallows required I trust.

[Buggeee]

At last, the elusive perpetual motion machine. Mankind can now rest.

My daily is a battery car most if the time (Chevy Volt) and I think it's the cat's meow. .

[War Eagle]

I believe you're describing the "Prius Principle", but in your example, the Prius would have to be going downhill all the time - a kind of never ending stairs situation like below (kind of).

[Raspy]

As we tear across the desert on this old locomotive, steam and smoke pouring rhythmically out of the stack, I ponder the physical speed limit these things encountered. Horsepower wasn't the problem.

Dust and bugs in the teeth as we yell eeeehawww! while hanging on for dear life. Coal being shoveled in relentlessly by a dutiful worker, the engineer pulling harder on the throttle, looking for just a bit more speed, a maniacal look on his face as he pushes the johnson to it's final notch. A glance at the pressure gauge reveals we are at relief pressure, minus just a bit. I'd tap on the gauge, but I'd loose my grip. A sweaty hand clenched to near agony, but I hardly notice. A roaring, pounding cadence from the 72" wheels. Nearing the top speed allowed by pure physics. Such mechanisms are impossible to balance with mere weights and eventually the immense tonnage literally begins to jump up and down hard enough to leave the track with each beat. The engineer leans out a bit and his hat flies off. A coyote scampers off the track as the monster approaches. Pulsing light is visible under the wheels as they jump, I wonder about the lax track maintenance.

She's racing full bore, all in, everything she can muster, toward an uncertain and spectacular end.

The laws of physics have been pushed to the limit. Wild speculation has carried us beyond that point and into the absurd. It's little kids with matches on a grand scale. Women cover their faces and scream, other just faint.

As we begin to swing through a wide corner and cross another gorge, the sage brush is just a blur. The wind stops all communication as our total effort is just to hang on. Wild eyes. Our lives flashing by amidst the smoke.

What we don't know is, there's been a problem. Ahead, rocks have come down and separated the rails.

This is where we are with this discussion.

[Civilguy]

I'm banking on the swallows to make it right, governor.

[Buggeee]

Originally Posted by Civilguy

I'm banking on the swallows to make it right, governor.

And they will. The fourth battery is on its way. When it arrives, I'm going to charge the whole mess to float stage, let it rest for a few hours or over night and then... then I'm going to flip the switch and start the countdown. Do not exit until the ride comes to a complete stop. Oh... Courage... don't fail me now.

Or... to more truly get a read on how it will behave in the field, flip the switch on the 10 minute timer and let that run out. Rest the bank for a bit, flip the 10 minute timer again... repeat until empty. I won't be driving it off the cliff in one fell swoop in the field, so maybe that's how I'll do it. Total the number of 10 minute episodes and see how the math is on that.

Anyway, I think its coming ground so I've got a week to plan the disaster.

[John in Michigan]

Whatever you do, don't test it in the house, the garage or the Playpac... Waaaaaaaaaaaaay out back, and don the safety gear. My neighbor friend (a retired electronic controls engineer) 1st tested his new "custom" LiFePo battery charging system in the backyard IN a charcoal grill

[Buggeee]

Don't worry John, I'm just going to overwork my batteries a bit, not melt them. I promise to leave the door open so you will be able to sleep at night. Very good advice by the way.

Ok so you have all come this far. You know what I'm working with if you have been paying any kind of attention. Help a fellow out here. Want to suggest some plausible test protocols or whatever? It takes a community to toast a battery bank you know.

So the goals (add or subtract even on these if you are willing) are as follows, what protocols would help accomplish them:

1. Find credible data that helps predict what I will experience on a three day trip. The focus is isolated to the relationship between the heater and the battery bank, so the coffee will be brewed in the house, not the egg, during the test.

2. Not destroy the bank or, hopefully, damage it in any significant way. Deep cycle is designed to be exhausted a certain number of times. I'm looking to spend an exhaustion cycle, not smelt lead into buckshot. If pulling 66 amps from the bank (meaning 16.5 amps per 100 amp hour battery) for longer than X period of time is likely to cause venting of these SLA batts let me know what you think the X is so I can design the test protocol, and actual usage, to stay under that time period before resting it for a bit. (((With SLA/valve regulated, once the vapor escapes the vents it cannot be added back into the system and that's a lifelong impairment. If you have flooded cells that take water, these are a bit different, they recycle vapor and gasses internally, unless they are really cooked hard by way overcharging or total abuse while discharging - then a valve lets some pop out safely, but its gone and water can not be added ever because... well, because they are "sealed.")))

3. Have some numbers written down that I can report back to you all that you would find interesting, or might be useful to someone stumbling on this thread. (There will be others, you all know this is the supreme siren call and plenty more ships will hit the rocks).

4. Have fun while dreaming of the apocalypse, and my whole family being saved by 30 gallons of fresh water and 400 amp hours of electricity.

As of now all I have thought of is as stated earlier. Flip the switch on the 10 minute timer and let that run out. Rest the bank for a bit, flip the 10 minute timer again... repeat until empty. Maybe I don't have to go to empty to get the data I need to establish a usage guide for the trip? Like measurements of resting states after 10 minute timer sessions, down to half capacity or something? This kind of stuff....

[Buggeee]

To be clear, I'm not looking to achieve anything more than Newton permits. I'm looking to see what I can achieve using what I have to work with, so I'll know what is available to me and how to best ration it on a three day trip.

[John in Michigan]

Well Buggeee (your name or the camper's name?), please sit down:

1. The "credible data" is the prediction of resting voltage values at beginning of the first day (fully charge the batteries at least 12 hours before this time) and then after the batteries have rested 12 hours after the last time the heater is run on the third day. Plan to run the heater long enough so that the batteries are discharged to the 50% level. Estimate many amp hours are in the batteries when fully charged. Estimate how many amp hours are in the batteries when 50% discharged. Document how long you will run the heater and many times to get the batteries down to 50%. All of that is the predicted "credible" data, aka, the test plan/test design.

2. With SLA batteries, damage shouldn't be a problem. Outgassing happens during charging, but of course you are using a good smart battery charger.

3. Record and report the actual / measured resting voltages at the start of day 1, 2 and 3, and 12 hours after then end of day 3. Also record the start time and for how long the heater is actually run each time it is run.

4. Good luck!

EDIT: I actually performed a test like this a couple of years ago to verify that my battery would allow us to do the boondocking that we wanted to do during a 5 day period. It was basically a "dry run".

[Buggeee]

I prefer to stand when accepting my paddling.

Buggeee is my internet moniker, and possibly an apt reflection of state of mind. It was originally derived from the intent to run my bug on electrons. I still have the electric forklift motor in my garage. Had a bunch of fun rebuilding the combustion motor though so it's burning dinosaur shellfish for now.

My camper's name is "Boondoggle" which most of you will deeply appreciate, no doubt.

Thank you for your input John.

[Buggeee]

If there's anything I've learned on these forums it's that people like pictures. You're a strange crew in this electric category, being readers and all.

I'm attaching some pictures of the heater, inverter and some of the other components I'm getting together in my system here. You'll have to pardon the mess as this is in a mock-up stage right now. Once its all functioning I'll go back and mount things, tighten up some runs etc.

[John in Michigan]

Wow! Looks like you have one of those laser thingies!!! Make sure to wear welders goggles!

[John in Michigan]

Buggeee, I just PM'd you...

[Buggeee]

Originally Posted by Jon Vermilye

If you prefer the Keurig type coffee maker, look of the motel version - this one draws 700 watts. It draws less current than the larger versions that keep the water hot.

You know what this is don't you? (picture attached)

Of course you do... It's Battery Coffee! Tastes even better than regular coffee. Must be the mathmagical essences tickling the olefactory senses.

Thank you so much for that tip Jon, I'll think of your generosity at many a camp.

[Buggeee]

I have attached pictures of some specs on the batteries in the event anyone knows how to read them. The graph of curves on characteristics at various discharge rates is probably of interest to this application. Each battery is a 12v 100ah and there are 4 of them in parallel.