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Discussion Starter #21
So this is my 12 volt system I have in my shed. This is what i'm wanting to directly connect to with my DW charger (not my pickup).
Looks like a science experiment but theres some method there. Oh, my inverter is 410W.



 

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Discussion Starter #22
24V DC is very unlikely to hurt you. There's is not sufficient voltage drive a lethal current through your skin. I say very unlikely because there are situations, like if you punctured your skin on a hot wire, or were soaked in salt water or something, but you would generally not be in harms way with that system sort of the batteries exploding from the current draw.
I've always been told current kills, not voltage. However, i guess the assumption behind such statement is that the voltage is significant enough to push the lethal amperage.
Whereas a 12/24v system does not?

This would explain how touching the leads on a battery does nothing but I wouldnt dare do that with a 120v circuit.. again>:)
 

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I've always been told current kills, not voltage. However, i guess the assumption behind such statement is that the voltage is significant enough to push the lethal amperage.
Whereas a 12/24v system does not?

This would explain how touching the leads on a battery does nothing but I wouldnt dare do that with a 120v circuit.. again>:)
Correct; 24 VDC is not sufficient to cause electrical breakdown of human tissue of any significant thickness. In other words, the resistance of your tissue is effectively infinite with 24V across it, hence no current flows.

I've heard people say the "current kills, not voltage" thing as well. It is one of the silliest and least useful over-simplifications in existence. People who can't comprehend Ohm's Law should not work around electricity, period.

Regarding 120 VAC, remember that AC voltages are specified by their RMS value, and the peak amplitude of a sine wave is about 1.4 times this quantity. So what we call 120 VAC has a peak voltage of about 170 volts to ground.

More practically, you should have absolutely no issues running your Dewalt charger off that system. Is your barn solar powered?
 

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Discussion Starter #24
Correct; 24 VDC is not sufficient to cause electrical breakdown of human tissue of any significant thickness. In other words, the resistance of your tissue is effectively infinite with 24V across it, hence no current flows.

I've heard people say the "current kills, not voltage" thing as well. It is one of the silliest and least useful over-simplifications in existence. People who can't comprehend Ohm's Law should not work around electricity, period.

Regarding 120 VAC, remember that AC voltages are specified by their RMS value, and the peak amplitude of a sine wave is about 1.4 times this quantity. So what we call 120 VAC has a peak voltage of about 170 volts to ground.

More practically, you should have absolutely no issues running your Dewalt charger off that system. Is your barn solar powered?
Barn is completely solar. 3 -100watt panels, a MPPT controller (capable of handling 5 panels) and 4 - 115Ah, 6v golf cart batteries in series-parallel give me my 12v system.
You could argue i fall into the OHMs camp of people that shouldnt touch electricity. But I wanted power in my shed and to learn more about electricity/wiring/etc. Building this accomplished both.
 

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Barn is completely solar. 3 -100watt panels, a MPPT controller (capable of handling 5 panels) and 4 - 115Ah, 6v golf cart batteries in series-parallel give me my 12v system.
You could argue i fall into the OHMs camp of people that shouldnt touch electricity. But I wanted power in my shed and to learn more about electricity/wiring/etc. Building this accomplished both.
Very cool project. I wasn't implying that you didn't or couldn't understand Ohm's Law. But there are plenty of folks out there who don't hesitate to offer electrical advice despite being completely ignorant of the basic facts. Regarding car and truck batteries, I can't count how many times I've heard some moron say something to the effect of, "the voltage is good, but it doesn't provide enough amperage." Facepalm.
 

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So this is my 12 volt system I have in my shed. This is what i'm wanting to directly connect to with my DW charger (not my pickup).
Looks like a science experiment but theres some method there. Oh, my inverter is 410W.




I see fuses so your already a step ahead of 95% of the work ive had to fix in my time. Fuses save lives people.... use them.



I've always been told current kills, not voltage. However, i guess the assumption behind such statement is that the voltage is significant enough to push the lethal amperage.
Whereas a 12/24v system does not?

This would explain how touching the leads on a battery does nothing but I wouldnt dare do that with a 120v circuit.. again>:)
Correct, it is the current through your heart that kills you, but you need sufficient voltage to drive that current through your highly resistive body. This is also why tazers dont kill you, sufficient voltage but limited current. Your skin dry has several thousand ohms of resistance which requires significant voltage to drive current through.



Very cool project. I wasn't implying that you didn't or couldn't understand Ohm's Law. But there are plenty of folks out there who don't hesitate to offer electrical advice despite being completely ignorant of the basic facts. Regarding car and truck batteries, I can't count how many times I've heard some moron say something to the effect of, "the voltage is good, but it doesn't provide enough amperage." Facepalm.

i just died a little more inside.... thanks for that. >:)
 

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Correct, it is the current through your heart that kills you, but you need sufficient voltage to drive that current through your highly resistive body. This is also why tazers dont kill you, sufficient voltage but limited current. Your skin dry has several thousand ohms of resistance which requires significant voltage to drive current through.
Well, not exactly. The reason a tazer doesn't (usually) kill people is that the current path doesn't (usually) go through the heart or other vital organs, since both the positive and negative electrodes are shot out of the tazer and land relatively near each other on the skin. It can probably cause a thermal burn, though. However, if one of the electrodes was on a person's back and the other on his chest, I suspect it would very likely be fatal.

i just died a little more inside.... thanks for that. >:)
;)
 

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Well, not exactly. The reason a tazer doesn't (usually) kill people is that the current path doesn't (usually) go through the heart or other vital organs, since both the positive and negative electrodes are shot out of the tazer and land relatively near each other on the skin. It can probably cause a thermal burn, though. However, if one of the electrodes was on a person's back and the other on his chest, I suspect it would very likely be fatal.



;)


hum.... i was always under the impression that the tazer was current limited to under 6ma so that even a non optimal shot would not be, in most cases, lethal and the scathing pain came from the high voltage shock like touching a van de graaff generator... a really really painful van de graaff generator....
 

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hum.... i was always under the impression that the tazer was current limited to under 6ma so that even a non optimal shot would not be, in most cases, lethal and the scathing pain came from the high voltage shock like touching a van de graaff generator... a really really painful van de graaff generator....
I'm having a hard time finding reliable info on this, but it seems to me that there must be something that regulates the voltage such that the current never exceeds some threshold, as you stated. But I am pretty damn sure that if you applied thousands of volts across a person's heart it's going to kill them. Now, even without some kind of voltage regulation, a taser probably still wouldn't electrocute you as long as the electrodes were pretty close to each other on the skin. But thermal burns would be nearly a certainty.

On the topic of things that suck, I have never been tased, but I have been OC sprayed and hit with CS gas. I can say without a doubt that being sprayed with concentrated OC was the most painful thing I have ever experienced.
 

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Discussion Starter #31
Jd, you like your AIMS inverter? I'm a little ways from investing in one but I've been told to look at Xantrex(?) but have always seen AIMS out there too in the realm of pure sine waves.

Pure sines are more expensive but when is it not necessary? When is modified okay?

btw, i've looked at your 3kW inverter install thread multiple times since joining here. Nice write up and nice layout of the wires/outlets/etc.
 

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Jd, you like your AIMS inverter? I'm a little ways from investing in one but I've been told to look at Xantrex(?) but have always seen AIMS out there too in the realm of pure sine waves.

Pure sines are more expensive but when is it not necessary? When is modified okay?

btw, i've looked at your 3kW inverter install thread multiple times since joining here. Nice write up and nice layout of the wires/outlets/etc.
It's given me no issues thus far, although it has a hell of a time with my 15k BTU/hr air conditioner due, I believe, to the crappy power factor of the compressor (I'm currently working on a solution to this and if it's effective I'll post an update in my inverter thread). But it can certainly put out the specified wattage without breaking a sweat.

Everyone will tell you that there are "certain types of equipment" that work better on pure sine. I believe that inductive loads like motors and compressors (things with power factors less than unity) will function better on pure sine, but the only device that I can say certainly will not work on anything other than pure sine is my Keurig. There's a little induction motor inside that pumps the water, and I think its power factor is so low that modified sine AC just can't get it turning. It works flawlessly with the AIMS, though.

I would say if it's a one-time build and the cost difference isn't huge, just get the pure sine to be safe. But if you really want to save money and you're only using tools and equipment that are tolerant of noisy waveforms then modified sine is probably going to work.
 

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I'm having a hard time finding reliable info on this, but it seems to me that there must be something that regulates the voltage such that the current never exceeds some threshold, as you stated. But I am pretty damn sure that if you applied thousands of volts across a person's heart it's going to kill them. Now, even without some kind of voltage regulation, a taser probably still wouldn't electrocute you as long as the electrodes were pretty close to each other on the skin. But thermal burns would be nearly a certainty.

On the topic of things that suck, I have never been tased, but I have been OC sprayed and hit with CS gas. I can say without a doubt that being sprayed with concentrated OC was the most painful thing I have ever experienced.
ive never experienced any of those things and if all goes well, i dont plan to :grin2:


Though.... i did disassemble a disposable camera as a kid and boy.... that flash capacitor will light you up! My arm tingled for a full week after that.
 

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ive never experienced any of those things and if all goes well, i dont plan to :grin2:


Though.... i did disassemble a disposable camera as a kid and boy.... that flash capacitor will light you up! My arm tingled for a full week after that.
Oh yeah?

[[cracks another beer]]

Did I ever tell you about the time I was struck by lightning?
 

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Splurge for $10, order and install one of these....it'll kick it 500% on start up.
https://www.supco.com/web/supco_live/products/SPP6.html
Thank me later. :howdy
Thanks, I'll check it out. What's weird is that the inverter has absolutely no issue starting the compressor, but the amount of current in the circuit -- and the load on the truck's charging system -- is way higher than what one would expect from an air conditioner drawing ~1500 watts (I can pull 3kw off the inverter for purely resistive loads without the thing skipping a beat). In fact, unless I set elevated idle, the truck's charging system will drop all the way down to about 10.5 volts, at which point the inverter's safety cutoff kicks in and the load is disconnected. So I think it has to do with the power factor of the crappy trailer AC unit being much less than unity, which is supported by the fact that my current meter shows about 25 amps flowing in the main panel when it should really be more like 15 (which is what it shows with the same load when connected to the power grid). This is consistent with the circuit carrying the full apparent power because the inverter is unable to dissipate the reactive power except as heat, which is exacerbating the matter.

I ordered a crappy Chinese power factor correction capacitor so I'll see if that has any effect; if not (or if it burns down my truck and I happen to survive) I'll definitely give the hard start device a look.
 

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Discussion Starter #37
It's given me no issues thus far, although it has a hell of a time with my 15k BTU/hr air conditioner due, I believe, to the crappy power factor of the compressor (I'm currently working on a solution to this and if it's effective I'll post an update in my inverter thread). But it can certainly put out the specified wattage without breaking a sweat.

Everyone will tell you that there are "certain types of equipment" that work better on pure sine. I believe that inductive loads like motors and compressors (things with power factors less than unity) will function better on pure sine, but the only device that I can say certainly will not work on anything other than pure sine is my Keurig. There's a little induction motor inside that pumps the water, and I think its power factor is so low that modified sine AC just can't get it turning. It works flawlessly with the AIMS, though.

I would say if it's a one-time build and the cost difference isn't huge, just get the pure sine to be safe. But if you really want to save money and you're only using tools and equipment that are tolerant of noisy waveforms then modified sine is probably going to work.
Why the inverter and charger model, not just the inverter?
 

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Why the inverter and charger model, not just the inverter?
Originally I thought I could use a low instantaneous power generator (say, 1.6 kw or so) hooked up to the power inlet while I ran my camper off the output side, thus allowing me to instantaneously draw up to 3 kw or so (by drawing down the truck's batteries over a short time interval), and then having the generator recharge the batteries as the demand dropped below the generator's max output. But I'm not sure it works that way; I think when there's power supplied it does a straight pass-through, so if you tried what I just described you'd overload the generator and trip its breaker. Oh well.

Anyway, when I get a new camper I'm going to rip the 12V power supply out of it and replace it with an inverter-charger similar to the one I have in my truck, so having some familiarization isn't a bad thing.

Regarding the Dewalt charger, just as I suspected, the current draw is very low. 0.5A at 120 VAC is 60 watts, or 5 amps at 12 VDC. You could run two of these at the same time off a 150-watt cigarette lighter inverter.

 

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Or just plug it into the 120v plug that's already in the truck!

Pretty sure I said that already
 

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