Volt Meter Idea

[Coltf1991]

Holy Chit. Sonic, Yurtle and John. My brain is going into lock down mode. This is badass. Whether you guys are arguing or not this is some cool chit. I love reading technical information. Its crazy how things work.

Thanks for the info guys

Keep it coming

[yurtle]

Originally Posted by Coltf1991

Holy Chit. Sonic, Yurtle and John. My brain is going into lock down mode. This is badass. Whether you guys are arguing or not this is some cool chit. I love reading technical information. Its crazy how things work.

Thanks for the info guys

Keep it coming

It's just interesting how something as simple as electricity quickly becomes a chemistry experiment, with all the dissimilar metals, moisture, acids, fumes, etc.

Don't know if I'm right, just trying to apply stuff I learned from work. I have no formal training at electricity, but i can make stuff spark and blow up.

BTW, I got my wheels turning for the first time in over a month! I still have my roof off, since I'm pulling in three new circuits for my Alltrax Ex-Ray. Until I get those wrapped up, I'll have to be satisfied that my new AXE4855 and battery lugs work, even if only on jack stands.

One think JohnnyB mentioned that I'm giving serious consideration to are the ring terminals I have to use for my voltage signals. EZ-GO uses a small ring terminal from the B- connection on the controller to the solenoid. I used four on my last setup and had no problems. I've decided to hold off on installing these until I can research beefier ring terminals. I'll have a lot more amps now than before. One option is to install the Ex-Ray's temperature sensor on a lug that has a ring terminal and watch it for a month.

[Coltf1991]

I rest my case

[sonicj]

Originally Posted by yurtle

I'll look it up. I do know that the stock cables I removed appeared to be plated, though not with silver. The previous owner replaced several bad cables and used copper lugs. They were all green and deeply corroded when I bought the buggy, even though they were newer, but the old stock ones are still shiny.

What we use at work are high amperage plated lugs bolted with plated bolts to copper plated bus bars. Often, this switchgear is located in condensing environments - which don't always have internal space heaters installed or wired up - and with medium voltage, corona often occurs. Corona can create nitric acid and ozone, both of which are quite hostile.

Here's one for you to look up, "corona".

I'm not saying any of this occurs in a buggy, but if silver plating can hold up to the hostile environment at work, I would hope it would be fine in a buggy.
If not, I'll simply tin them.

It all comes down to proper maintenance. Bare copper should never turn green, though brown is normal. If it does, someone hasn't done their job of properly cleaning and protecting them. Technically, we shouldn't need to heat-shrink a soldered connection, but it's a good idea. I was planning on coating mine with liquid electrical tape, to seal them, then heat-shrink for cosmetic purposes. Then I found a heat-shrink tubing that has a built in gooey substance that completely seals them from the inside - something lots of other heat-shrink tubing fails to do.

All of the above is just my philosophy of the day, and subject to change, based on new ideas, corrections by other posters, or me finding new and wondrous stuff in a box I've long forgotten about - like my Weidmullers, to get back on topic.

yea, green is a result of improper process. speaking of which..., i found a prime example of just last night. *see photos 1 & 2. found this on the x-former primary inside a delta-q quiq charger. bummer!

soldered or crimped, the heat shrink is necessary to avoid wicking of moisture by the fine strands of Cu. if it were solid core, we could get away with no shrink.... btw, have you seen a cross section of a proper crimp? its a gas tight connection!

corona is a neat phenomena! i haven't made any of my own (intentionally) yet. are you subscribed to photonicinduction's channel? good stuff right there!

Originally Posted by yurtle

Interesting. "This article does not cite any references or sources", but I'll follow up. It's surprising that all metal-clad switchgear at work uses silver plated bus bars, if this is a problem. Perhaps it all goes back to maintenance and inspection, along with thermal infrared scans.

yea, that why i linked the google search and not the wikipedia page. a number of papers on the subject though...

allbright uses silver plated contacts and bus bars on their high current contactors to prevent welding. maybe in your industry its necessary to prevent the fusing of connections during surges?

the last photo shows the exposed copper bars on my contactor. i use a light coat of no-ox-id a special on all of my connections. wipes on with a rag, won't wash off easily, resists chemicals & moisture, it even smells delicious! its the bees knees imo!
-sj

[sonicj]

Originally Posted by Coltf1991

Holy Chit. Sonic, Yurtle and John. My brain is going into lock down mode. This is badass. Whether you guys are arguing or not this is some cool chit. I love reading technical information. Its crazy how things work.

Thanks for the info guys

Keep it coming

no arguing here... just the free-flowing exchange of thoughts and ideas without the typical heckling from the "in-crowd."
-sj

[Coltf1991]

I hear ya! Information is good. A little over my head, but hey I'm a learning youngster.

[yurtle]

Originally Posted by JohnnieB

Right now I working on a way to mount an Ammeter shunt (75 mV @ 500A) so it doesn't wiggle or put weight on the battery terminal while not blocking air flow through it. I had it all figured out and was getting ready to do some cutting, than I discovered the plastic I was making the bracket out of, was conductive. Now I've got to search through my stash of "might be useful someday" stuff some more.

Any update on your ammeter and shunt? I'd be interested in monitoring amperage. Are you going to use a digital or analog meter, or merely have a place to hook up a DMM?

[JohnnieB]

Originally Posted by yurtle

Any update on your ammeter and shunt? I'd be interested in monitoring amperage. Are you going to use a digital or analog meter, or merely have a place to hook up a DMM?

No progress. The garage isn't heated and these old bones don't work too well in the cold.

This is what I have: http://rover.ebay.com/rover/1/711-53...item3cab3b6e14
wizardket helped my find it - Thanks Wiz.

I screwed up when I ordered it and didn't get a Digital panel meter that runs on 36V, but it's low power so a zener diode and a resistor, or a 3-terminal voltage regulator is all that is needed to feed it from the key-switch.

The shunt itself is about the size of a pack of cigarettes. Only 75mV @ 500A, so it'll be about the same impact as adding a foot of 2Ga copper, which leads me to an interesting thought.

If you can accurately determine the resistance of your high current cables, you can use it for a ammeter shunt. Even if you couldn't set up a DVM to read directly in Amps, a simple cheat sheet would take care of that and for comparisons, just higher and lower voltage readings will probably suffice.

Actually, for comparison purposes, you really don't need to know the number of Amps, so just measuring voltage drop across the same cable would work. Probably one of the longer cables to get higher voltage readings. (One foot of 2Ga would be about 15mv/100A, 2ft would be 30mV/100A, etc.)

Gotta break out the old slip-stick and do some calculations, but I just might be able to monitor Field current and Armature current (PDS system) without investing in more shunts.

[yurtle]

Originally Posted by JohnnieB

No progress. The garage isn't heated and these old bones don't work too well in the cold.

This is what I have: http://rover.ebay.com/rover/1/711-53...item3cab3b6e14
wizardket helped my find it - Thanks Wiz.

I screwed up when I ordered it and didn't get a Digital panel meter that runs on 36V, but it's low power so a zener diode and a resistor, or a 3-terminal voltage regulator is all that is needed to feed it from the key-switch.

The shunt itself is about the size of a pack of cigarettes. Only 75mV @ 500A, so it'll be about the same impact as adding a foot of 2Ga copper, which leads me to an interesting thought.

If you can accurately determine the resistance of your high current cables, you can use it for a ammeter shunt. Even if you couldn't set up a DVM to read directly in Amps, a simple cheat sheet would take care of that and for comparisons, just higher and lower voltage readings will probably suffice.

Actually, for comparison purposes, you really don't need to know the number of Amps, so just measuring voltage drop across the same cable would work. Probably one of the longer cables to get higher voltage readings. (One foot of 2Ga would be about 15mv/100A, 2ft would be 30mV/100A, etc.)

Gotta break out the old slip-stick and do some calculations, but I just might be able to monitor Field current and Armature current (PDS system) without investing in more shunts.

I like it!

I've used cheap (Chinese) eBay digital meters in the past, and have been surprised at how accurate they are.

Given that this is pulsed (chopped) DC, is there a chance that a CT can be used in lieu of a shunt?

Nixies would be kewl, but it's not gonna happen.

[JohnnieB]

Originally Posted by yurtle

1. I've used cheap (Chinese) eBay digital meters in the past, and have been surprised at how accurate they are.

2. Given that this is pulsed (chopped) DC, is there a chance that a CT can be used in lieu of a shunt?

3. Nixies would be kewl, but it's not gonna happen.

1. I am amazed at how accurate they are. It wasn't all that long ago I was paying 5-10 grand for meters that weren't any more accurate than one we can get for 10-50 bucks these days.

Along the same line. Have you ever had the pleasure of using a differential voltmeter?
I can now get voltage measurements almost instantly that it used to take several minutes to get, if the test equipment was warmed up and stabilized.

2. Send me a couple and I'll let you know.
There might be some linearity issues, and it'll probably not read if the PMW reaches 100% Duty Cycle, but other than that, they should work.

However, why use them? The shunts already exist. We've just been calling them cables.
That was the Eureka moment I had today.

My ammeter shunt is basically a 0.00015 ohm resistor and 2Ga cable is .0001563 ohms per foot. (4Ga = 0.0002485 and 6Ga =0.0003951)
Without amplification, you'd need a 5 digit meter or better to read under about 10A with a 1 ft length of 2Ga, but at 100A you'll read 15 millivolts.

3. Brings back memories.......