Voltmeter

[mark in ny 27]

I'm rewiring a c125 that has no safety switches or anything. Where would be the best place to pull the positive for the voltmeter? Also I have a electric fuel pump and made a previous tractors voltmeter needle jump around maybe a better route to pick. My engine is from a unregulated charging 1986 312. 

[ebinmaine 67,452]

Read below...

 

Edited January 2, 2021 by ebinmaine

[pfrederi 17,734]

5 minutes ago, ebinmaine said:

I'd go right off battery positive

If you did that the voltmeter would show 12 volts all the time and run down the battery

 

I would run the volt meter off the ACC or I terminal

Edited January 2, 2021 by pfrederi

[Handy Don 12,216]

19 minutes ago, mark in ny said:

I'm rewiring a c125 that has no safety switches or anything. Where would be the best place to pull the positive for the voltmeter? Also I have a electric fuel pump and made a previous tractors voltmeter needle jump around maybe a better route to pick. My engine is from a unregulated charging 1986 312. 

Without a regulator, there will always be some fluctuation in the voltage even though the battery is acting like a capacitor to damp it out somewhat. If your meter is very sensitive it'll bounce but most analog meters have at least a little bit of mechanical damping. Agree with @ebinmaine and @pfrederi--direct through Accessory terminal is the best bet.

Edited January 2, 2021 by Handy Don

[Ed Kennell 38,157]

I agree with Paul on this one.    I wouldn't want anything powered up with the ignition switch off.      I would use the   "I" (ignition post on the switch).   That would also indicate the switch is seeing battery voltage and the voltage is getting to the coil.   

[ebinmaine 67,452]

1 hour ago, pfrederi said:

run the volt meter off the ACC or I terminal

Nevermind my earlier post. Obviously needed more coffee. 

 

I run all mine off I terminal on the ignition switch. 

[Ed Kennell 38,157]

No worry Eric....we are all allowed one or two each day.

[ebinmaine 67,452]

3 minutes ago, Ed Kennell said:

No worry Eric....we are all allowed one or two each day.

 

 

"Pre-coffee Eric"  has been known to be challenged....

 

[mark in ny 27]

Awesome thanks guys

[WheelHorseNut 222]

Hey guys -- how do you tap into the I terminal?  Do you use something like this:

1 in 2 out splice connector

 

Or something like this:

Ideal 3 port push in connector

 

There was another type similar to the Ideal -- I can't find it but I've used them before...  I have a mess of the simple taps that pierce the wire and you use a female blade end on it, but I am leery to use them here...

 

Any thoughts?  How have you guys done it?

Thanks!

Edited October 16, 2023 by WheelHorseNut

[ebinmaine 67,452]

12 minutes ago, WheelHorseNut said:

simple taps that pierce the wire and you use a female blade end on it, but I am leery to use them here...

 

Sounds like what you are talking about are 3M Scotch locks or similar.

 

IMHO... You should gather up every single one of those that you have.  Immediately throw them all into the trash. Live happily ever after.

 

 

 

When I want to join two wires into a branch I normally do it one of two ways.

1. If the wires are being connected onto a stud type terminal like a bolt, I make two individual wires individual terminals and I put them on that way.

2. If that's not a possibility, or I am trying to neaten up a wiring harness, I will take a butt connector from the next size up and feed the wires, two into one end and one in the other.  

I use appropriately sized heat shrink wrap to protect that terminal.

 

 

Another option would be to simply strip the wires and solder them all together followed by heat shrinking that connection as well.

 

The connectors that you posted above are a perfectly good option for indoor usage. Any place that the humidity level is going to change like it does on a vehicle, I don't use those.

 

 

[WheelHorseNut 222]

2 minutes ago, ebinmaine said:

 

Sounds like what you are talking about are 3M Scotch locks or similar.

 

IMHO... You should gather up every single one of those that you have.  Immediately throw them all into the trash. Live happily ever after.

 

 

 

When I want to join two wires into a branch I normally do it one of two ways.

1. If the wires are being connected onto a stud type terminal like a bolt, I make two individual wires individual terminals and I put them on that way.

2. If that's not a possibility, or I am trying to neaten up a wiring harness, I will take a butt connector from the next size up and feed the wires, two into one end and one in the other.  

I use appropriately sized heat shrink wrap to protect that terminal.

 

 

Another option would be to simply strip the wires and solder them all together followed by heat shrinking that connection as well.

 

The connectors that you posted above are a perfectly good option for indoor usage. Any place that the humidity level is going to change like it does on a vehicle, I don't use those.

 

 

 

Haha -- noted.  Yeah, I think they are Scotch locks, actually.  I got them a long time ago when I was building my 12 volt electrical supply box.

 

Solder is probably the best for this application with the vibration and such...I do have larger butt connectors, though... and marine grade shrink wrap -- definitely the easiest way...  I appreciate the input.  I will definitely use one of those methods tomorrow when my temporary voltmeter arrives. 

[ebinmaine 67,452]

1 minute ago, WheelHorseNut said:

Solder

 

 

Just as a point of information here. You definitely want to do your own research and not take my word for this.

 

I've read good and bad about soldering wires on boating and off-road forums.

 

My thought process would be the same as yours where the vibration might warrant a good strong soldered connection...

 

But I've read multiple times that the vibration can actually cause a breaking point right where the solder stops.

 

 

[WheelHorseNut 222]

1 minute ago, ebinmaine said:

 

 

Just as a point of information here. You definitely want to do your own research and not take my word for this.

 

I've read good and bad about soldering wires on boating and off-road forums.

 

My thought process would be the same as yours where the vibration might warrant a good strong soldered connection...

 

But I've read multiple times that the vibration can actually cause a breaking point right where the solder stops.

 

 

Hmm, never thought about it like that -- good point.  I'll definitely take that into consideration.  Thanks again!

[Handy Don 12,216]

11 minutes ago, ebinmaine said:

cause a breaking point right where the solder stops.

Indeed. Counteract this with shrink wrap to spread out the bend so there isn’t a single flex point. Nothing wrong with a second layer over the first one, either.

On my trailer wiring, I use those solder/shrink connectors and then shrink wrap on top and then “liquid electrical tape” to make sure I have good seals.

If you have the room and are really meticulous, wire clamps and looms can help too. It is important not to put tension on wiring connections.