Voltmeter only reads when engine is off

[RED-Z06 2,138]

Ive tried for 2 hours to wrap my brain around this.  I bought a pretty nice analog gauge, 8v-16v, 3 wires...blue us common ground, its hooked right to the battery.  Red is 12v switched from any 12v source.  Orange is 12v for the backlight.  The backlight is tied into the light switch and it works.  The red i tied into the coil 12v+.  Key on..gauge reads 12.5v.  Turn key to start, gauge cuts off.  I moved the red feed wire to the + side of the battery, hot all the time...it does the exact same thing.  While the engine runs, at any speed, the gauge refuses to display anything.  If i stall the engine, it suddenly works.

 

It makes 0 sense.

[squonk 39,020]

How are you connecting the ground wire to the battery? Almost sounds like you losing something with maybe vibration. Or possibly the gauge itself is being effected by vibration.

[RED-Z06 2,138]

15 minutes ago, squonk said:

How are you connecting the ground wire to the battery? Almost sounds like you losing something with maybe vibration. Or possibly the gauge itself is being effected by vibration.

Ring terminal on the hot and ground, tried holding the gauge and mounting it.  I put a 2nd identical gauge on and its the same result.  Tried them on 5 other engines with mixed results, seems it dislikes the charging system pulses, it worked fine on the 702 with a starter gen, but was 50/50 on an onan.

 

Ill send them back, try something else, its very disappointing 

[Handy Don 10,660]

4 minutes ago, RED-Z06 said:

Ring terminal on the hot and ground, tried holding the gauge and mounting it.  I put a 2nd identical gauge on and its the same result.  Tried them on 5 other engines with mixed results, seems it dislikes the charging system pulses, it worked fine on the 702 with a starter gen, but was 50/50 on an onan.

 

Ill send them back, try something else, its very disappointing 

Digital gauges can be tricked by the charging wave form. If you have a spare condenser laying around, try connecting that to the red (V-in) line and ground to see if that moderates the pulsing enough to remove the gauge’s confusion?

Edited February 4 by Handy Don

[squonk 39,020]

13 minutes ago, RED-Z06 said:

Ring terminal on the hot and ground, tried holding the gauge and mounting it.  I put a 2nd identical gauge on and its the same result.  Tried them on 5 other engines with mixed results, seems it dislikes the charging system pulses, it worked fine on the 702 with a starter gen, but was 50/50 on an onan.

 

Ill send them back, try something else, its very disappointing 

I figured this was on your 702. If I new otherwise I would have mentioned the charging system. 

[RED-Z06 2,138]

Tried a capacitor, no change.  Unplugged the regulator..no change.  

 

Gotta be the points ignition.

 

Ill send them back, just wont work for this application 

[Handy Don 10,660]

6 minutes ago, RED-Z06 said:

Tried a capacitor, no change.  Unplugged the regulator..no change.  

 

The only other option would be to put the capacitor inline with V-in to dampen the response time. It’d have to be a very small capacitor, though, since the voltmeter’s draw will be miniscule.

Send back!

[RED-Z06 2,138]

8 minutes ago, Handy Don said:

The only other option would be to put the capacitor inline with V-in to dampen the response time. It’d have to be a very small capacitor, though, since the voltmeter’s draw will be miniscule.

Send back!

The gauge i ordered for the 416 is a SunPro, only one i could find with the needle on top, if it works on thes others too then i guess ill order more, just really wanted white face gauges for the 702 and C100.

[Handy Don 10,660]

2 minutes ago, RED-Z06 said:

The gauge i ordered for the 416 is a SunPro, only one i could find with the needle on top,

A couple years back I put one of these in the 310-8 for the same reason, much easier to read looking down at it. Somehow the glass got broken on the original meter.

[RED-Z06 2,138]

7 minutes ago, Handy Don said:

A couple years back I put one of these in the 310-8 for the same reason, much easier to read looking down at it. Somehow the glass got broken on the original meter.

Mine works but the needle goes past the stop when you turn it off so you have to hit it a few times to knock it loose...its just annoying because for years that tractor had charging issues and ive resolved them but i like to keep an eye on the voltage.

[RED-Z06 2,138]

I found a guy on the bay selling a box of new in box, discontinued Sunpro analog volt gauges, these should be the old pre-computer models, it was cheap enough to buy the box of 4 to try.

[Handy Don 10,660]

11 hours ago, RED-Z06 said:

these should be the old pre-computer models

Let us know! 😉

[RED-Z06 2,138]

The other gauge i had ordered prior for the 416 came in, i tried it on the 702 and it functioned fine, installed it on the C100 and its fine.  I can see why the other one wouldn't work, look how dirty the signal is especially at idle.

 

I was pleasantly surprised this gauge was extremely shallow, if the other ones are too deep for the 702 then this one will get moved to it, wiring is all the same in back.

 

702 has the steering shaft right behind the gauge mount.

 

[squonk 39,020]

The Kohler stator charging systems are archaic at best. Add in the vibration and you have gauges jumping all over the place.

[RED-Z06 2,138]

39 minutes ago, squonk said:

The Kohler stator charging systems are archaic at best. Add in the vibration and you have gauges jumping all over the place.

That and the coil load at low rpm...points close, big load, points open..0 load.  

[RED-Z06 2,138]

The new gauges came in, surprisingly they fit just tight enough to clear the steering shaft without mods.  Wired it in and it works great.

[RED-Z06 2,138]

Looks good at night too.