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Olddawgsrule ![]() Senior Member ![]() Joined: 20 Sep 2017 Location: New Hampshire Online Status: Offline Posts: 1014 |
![]() Posted: 22 Apr 2018 at 7:06am |
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Update on the 'coil' style unit. It came in 'marked' AC only. It will not even read DC voltage never mind Wattage.
It's going back.
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Tars Tarkas ![]() Senior Member ![]() ![]() Joined: 14 Jan 2013 Location: Near Nashville Online Status: Offline Posts: 1452 |
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The specs on the Amazon site plainly state that this is for AC only. I agree, the title of the page is deceiving though. In this case, apparently "DC" means "Digital Current", as in digital current reader, as opposed to an analog current reader, I suppose. If you needed a reason to send it back that's good enough. That's a dam stupid title. Really stupid or intentionally deceptive.
I'm curious about the pics you posted though. You have this thing sitting on your battery and it appears to be reading 12.something volts. TT |
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Olddawgsrule ![]() Senior Member ![]() Joined: 20 Sep 2017 Location: New Hampshire Online Status: Offline Posts: 1014 |
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It's sitting in a test spot to see if it works. Final home will be inside Lily. Top left is battery voltage as it sits. Top right is amperage draw 'real time'. Lower left is Wattage 'real time'. Lower right is cumulative. Want to know what you sed in day/weekend/week? Mounted on the battery to the right is the 'shunt' I refer to. 4 wires to the unit. 2 for battery voltage, 2 for amperage/wattage that run through the 'shunt'. |
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Olddawgsrule ![]() Senior Member ![]() Joined: 20 Sep 2017 Location: New Hampshire Online Status: Offline Posts: 1014 |
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18hr test. Looks about right.
228ma average (240ma if you wish to use the 12v baseline, I used standing voltage at 12.7) ![]() |
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DavMar ![]() Senior Member ![]() ![]() Joined: 04 Aug 2017 Location: Lexington, NC Online Status: Offline Posts: 592 |
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Okay Oldawgsrule help this poor soul out because now you have me completely confused! First I thought you said this unit picked up the voltage by induction using a coil which means it has to be sensing AC and I assumed, maybe stupidly, that it rectified this induced voltage to DC for your reading. Now you say it uses a shunt to read the DC voltage and current? Since I really can't make out heads or tails from your photo, sorry maybe its my faulty eyes, how about drawing out a schematic of what you did for your test set up take a photo of that then post it, hmmm? It would also be helpful if you can show how and where you plan on using this meter in your Pod if you decided to use it. On a topic completely off subject how do you like your 2017 SR5 is it a 4x4? Thanks! |
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Dave & Marlene J with Zoey the
wonder dog. 2017 Rpod 180 2016 Toyota Tacoma SR5 4x4 Lexington, NC |
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Olddawgsrule ![]() Senior Member ![]() Joined: 20 Sep 2017 Location: New Hampshire Online Status: Offline Posts: 1014 |
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Okay, Let's simplify this. I bought a unit that I thought stated it could read DC current through a coil unit. Hopes were that technology had come along and it could. It can not.. We're not there yet (or at least marketing has not). Confusion came in as others stated it can't happen, yet I was willing to give it a go, at my expense and see where it lands. I do know that there are ways, just not this unit or for anyone to buy. Now, the unit that does work involves what is called a 'shunt'. http://en.wikipedia.org/wiki/Shunt_(electrical) Basically, well a fuse of types, that allows current to pass through. by connecting to, with a meter allows you to read current/amperage/wattage running through. I say fuse of sorts cause it will blow is over amperage, just like a fuse. One end of the Shunt connects to the negative terminal of the battery. The other end is where you connect you supply cable. Sounds like a fuse now, doesn't it.. The meter has two connections, before and after the shunt. Small wires because not much is passing through it but, and important, it passes through it. This gives it a 'real' reading. When you look at the picture and see that black thing with two silver ends, that's the Shunt (or fuse of sorts). The nuts are the connections in and out on both ends. The two little screws you see are where the meter hooks in. The meter also has two more wires that connect to the positive and negative terminals to give real time voltage. So 4 wires in all and a shunt. It's not a scary thing to do and if you need, well worth the few minutes to hook up. Ask away if you have more questions or I did not explain well enough. Always willing to assist s fellow Rpod'er. |
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Olddawgsrule ![]() Senior Member ![]() Joined: 20 Sep 2017 Location: New Hampshire Online Status: Offline Posts: 1014 |
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Did a 4hr run on the battery using the frig.
I have 375 watts used. At voltage shown, 7.62 amps per hour/ 94 watts per hour. Or 30amps used. The onboard station says full charge (after 1/2hr rest), but I know it's not. Ya, it's important to know and why I'm going through all this. I do wish to have power while boon docking and 'know' what I have left. Ya, I'm weird like this.. LOL
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GlueGuy ![]() Senior Member ![]() ![]() Joined: 15 May 2017 Location: N. California Online Status: Offline Posts: 2702 |
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A shunt is just a wire, or wire-like thing that has a known resistance, AKA "voltage drop". All shunts are designed to provide a known value for a given range of current. If you have a meter that is matched to the shunt, it will give a direct reading of the current. From the current, you can calculate the voltage and power. Good old Ohm's law.
Shunts that carry a lot of current can be pretty darn hefty, or else they might melt, and provide the "fuse" function you mentioned. |
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bp
2017 R-Pod 179 Hood River 2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost |
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DavMar ![]() Senior Member ![]() ![]() Joined: 04 Aug 2017 Location: Lexington, NC Online Status: Offline Posts: 592 |
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I'm more then familiar with with what a shunt is and good ole Ohm's law since I spent my working days in electronics. What I couldn't see or understand was how this device that Oldawgsrule installed was wired, the shunt, and that he first said that this meter used a coil to sense voltage which means it had to be induced voltage aka AC. So thanks to his explanation and his newest photo I better understand what he's up to doing with this device. So is the plan to leave the shunt outside by the battery and run the wiring into the Pod and mount the meter somewhere inside?
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Dave & Marlene J with Zoey the
wonder dog. 2017 Rpod 180 2016 Toyota Tacoma SR5 4x4 Lexington, NC |
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GlueGuy ![]() Senior Member ![]() ![]() Joined: 15 May 2017 Location: N. California Online Status: Offline Posts: 2702 |
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bp
2017 R-Pod 179 Hood River 2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost |
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