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1999 Jeep Wrangler TJ
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Discussion Starter · #1 ·
Hey, all!

I have a new volt meter that I want to install. With my headlights dimming already but still wanting to install a third amp I want to see how bad I'm losing voltage.

My question: where do I install this thing? Specifically, what power wire do I tap into?

I've read "Tap into the power line for your sub amp to see the draw" but that feels like I wouldn't get accurate results for the whole system. I've read "Just any power wire that's only on when the key is turned." This seems more likely, but I don't think it matters that it's an "only on when key turned" because this meter has a remote turn on wire.

So... where to connect?
 

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Discussion Starter · #3 ·
Ideally the battery but any power wire will do.
Makes sense. Would probably need an in-line fuse as well if it's going that far.

Okay, so for now just any power wire would do, then when I get some longer wire run it to the battery.
 

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Discussion Starter · #5 ·
Literally any power wire in the car will do.
Could I just use the power wire feeding the head unit? It would be easy to t-tap that and roll.
 

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Discussion Starter · #7 ·
yep you can. lately when I put one in its to replace a 12v socket with a 2 USB and a volt meter combo dealio thinger. So I always end up using the power and ground to that.
You use the head unit's source for that?

I have one of those, just barely does not fit my defunct cigarette lighter socket 😒
 

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Discussion Starter · #9 ·
no the power to the cig socket. i remove the socket all together and that usually gives me the proper sized hole
Ohhhh, I'm tracking now. Tomorrow is project day so I might have to give that a go 😁.
 
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Although you can install it anywhere, be aware that the under-load readings will be different in different places due to resistances building up as you get further from the battery, causing voltage drops. The closer to the battery the more useful the results will be, assuming that battery voltage is what you are after. E.g. if you want to know amp voltage then put it on the amp.

Having said all that, if you just want the resting battery voltage then putting it in the cabin is probably acceptable. I have one permanently installed in the cabin for this purpose, but if I want load tests I just put a portable DMM on the terminals of the batt or amp.
 

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oscilloscope is best for measuring high speed voltage dips, ..... dmm is next best, the volt meter combo dealio thinger is good too.
but just keep in mind..... you could be getting lower voltages in reality, because the dmm & volt meter combo dealio thinger are slow to display results.
just fyi, still good to do it, but keep that in mind.
 

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Discussion Starter · #14 ·
Although you can install it anywhere, be aware that the under-load readings will be different in different places due to resistances building up as you get further from the battery, causing voltage drops. The closer to the battery the more useful the results will be, assuming that battery voltage is what you are after. E.g. if you want to know amp voltage then put it on the amp.

Having said all that, if you just want the resting battery voltage then putting it in the cabin is probably acceptable. I have one permanently installed in the cabin for this purpose, but if I want load tests I just put a portable DMM on the terminals of the batt or amp.
Ahhh, got it. I'd like to know how the voltage is working with the overall vehicle, so I'm going to guess battery is the best location. I have the wire, I'll just need an in line fuse to make it happen. Not like I don't already have a half dozen wires going through the firewall 😂

oscilloscope is best for measuring high speed voltage dips, ..... dmm is next best, the volt meter combo dealio thinger is good too.
but just keep in mind..... you could be getting lower voltages in reality, because the dmm & volt meter combo dealio thinger are slow to display results.
just fyi, still good to do it, but keep that in mind.
The one I have is one of those SMD high speed analog ones (I'm sure not as good as an o-scope, but I've read it's faster than a lot of the digital ones).
 

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Discussion Starter · #16 ·
Actually an analog meter is the next best thing to the oscilloscope for picking up quick dips in voltage , once upon a time all multi meters were analog , when digital became the normal the one thing they didn't do well compared to the analog meters was to show quick dips in voltage or current.
Awesome! I got it on discount, but I'm glad to hear I got the right product. It's pretty slick looking, can't wait to install it tomorrow.
 

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are you talking about the VM-1? that claims ~130mS response time, according to the website. good stuff, that's probably in the neighborhood of a good DMM. it would sample & update the display around 10x per second. is no bad.

I want to buy the D-Amore "VU-DIY kit" it looks like it has the function of all of those meters rolled into one, you just need to supply the LED's :)

The one I have is one of those SMD high speed analog ones (I'm sure not as good as an o-scope, but I've read it's faster than a lot of the digital ones).
Why do you reference adding a fuse? You do not need to fuse to connect the VM-1. That meter probably already has high impedance input, it will not draw any current. So no fuse needed for it. Just connect wires.

I have the wire, I'll just need an in line fuse to make it happen. Not like I don't already have a half dozen wires going through the firewall 😂
 

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Discussion Starter · #18 ·
are you talking about the VM-1? that claims ~130mS response time, according to the website. good stuff, that's probably in the neighborhood of a good DMM. it would sample & update the display around 10x per second. is no bad.

I want to buy the D-Amore "VU-DIY kit" it looks like it has the function of all of those meters rolled into one, you just need to supply the LED's :)



Why do you reference adding a fuse? You do not need to fuse to connect the VM-1. That meter probably already has high impedance input, it will not draw any current. So no fuse needed for it. Just connect wires.
Exactly! The reviews on it are solid, seemed like a good investment. I'm really curious to see how much current I'm drawing while I play, especially at highway speeds.

I put a fuse on anything if it's coming directly off the battery. If I splice it into an existing power wire (thinking on it, I bet I could just use my DSP's power line, or maybe do like JHeitt and just grab it from the cigarette lighter) then I won't. But directly from battery? Always.
 
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I want to buy the D-Amore "VU-DIY kit" it looks like it has the function of all of those meters rolled into one, you just need to supply the LED's :)
Oh thats a neat little board. I actually have a little VU meter kit i bought years ago that will go in the jetta when i ever get around to actually installing in the jetta.

bouncy needles
 

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What is the point?
(You already know you have a problem.)

You could end up chimping at the meter when you drive, and the lights dimming are already reacting fast enough to tell you.

A data logger running at say, 100 Hz, would be dandy.
 
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