Replace an amp meter with a volt meter???

[Doubletrouble 10]

Is it possible to do this? I'd rather keep an eye on voltage than amps. I have a '79 c-111 I'd like to do this on since I checked the voltage today and at idle it was about 14 volts but it went real high at full throttle.

[smoreau 658]

Yes you can. the two wires for the amp meter need to be tied together, and the power for the volt meter needs to be connected to key on power and the ground needs to be connected to the battery ground :dunno:

[Doubletrouble 10]

OK, Thanks! I think the amp meter is working but it dont seem to move much. The battery in the tractor wont hold a charge so I thought the amp meter would read a little higher.

[WheelHorseSteve 56]

OK, Thanks! I think the amp meter is working but it dont seem to move much. The battery in the tractor wont hold a charge so I thought the amp meter would read a little higher.

What is the purpose of the ammeter, anyway? To show that the charging system is producing a charge? I tend to agree... it would be nice to know how many volts are sitting in that battery when I go to start it. If they go down over time it could be a charging system issue or that the battery is just old and isn't holding as much of a charge. Ideally you'd have both but I'd prefer the voltmeter.

Am I missing something there? :dunno:

[Doubletrouble 10]

I never really understood the amp meter myself. My grandpa's old tractors on his farm always had them and I didnt get it then either. lol I would rather see the condition of the battery and charging system by a volt meter.

[305 380]

a properly wired ammeter shows current flow in and out of the battery , not necessarily what the charging system is putting out

for example: fully charged battery with a system draw of 20 amps ( lights , ignition , etc) and a charging system putting out 20 amps would show 0 on the gauge. same situation , but the charging system stops working the gauge would read -20 amps

i do prefer voltmeters myself

[JamesBe1 84]

The ammeter on my D-180 is bad. I was just going to replace it with another one till I saw this thread. I admit, I find the idea of a voltmeter a lot more useful.

A cluster gage that shows both current and volts would be the best of both worlds.

I'll have to hunt around the interwebs to see what I can find.

In the mean time, does anyone have a link for the preferred voltmeter?

[JamesBe1 84]

I replaced my bad ammeter with a sunpro voltmeter today. Wasn't bad at all. At least it matches the sunpro oil pressure gage that I installed a while back.

FYI, I butt spliced the ammeter wires together to complete that circuit, and ran new wires for the voltmeter. I tapped off of the accessory connector of the key switch for the positive, and ran the negative back to the battery about ten inches away. Works nice. The needle shakes a little bit at certain RPM's, but all in all worth the effort.

I think seeing the voltage is a lot more useful than seeing the current draw.

[WheelHorse_of_course 99]

Ideally one should be able to monitor voltage as well as current. The combination tells more than either alone!

[JamesBe1 84]

Ideally one should be able to monitor voltage as well as current. The combination tells more than either alone!

That would be ideal. I'd love to find a 2" dual gage with voltage and current. I'm sure that we are not the only people to think of it. Odd that nobody offers any.

After looking around, there is this, but it is over $120.00

http://www.aircraftspruce.com/catalog/inpages/a60-001r.php

[wheeledhorseman 579]

Having both on a tractor is probably overkill I think James as well as overpriced if you're looking for both in one unit.

Ammeters and votmeters both give you some idea of what's going on but on balance a voltmeter offers a better 'at a glance' overview which is probably why automobile manufacturers have standardised on them when fitted.

Just my opinion.

Andy

[JamesBe1 84]

Having both on a tractor is probably overkill I think James as well as overpriced if you're looking for both in one unit.

Ammeters and votmeters both give you some idea of what's going on but on balance a voltmeter offers a better 'at a glance' overview which is probably why automobile manufacturers have standardised on them when fitted.

Just my opinion.

Andy

I couldn't agree more Andy. I have switched to a voltmeter on my tractor. The idea of having both is more of a 'want to have' instead of a 'need to have'. It would be cool, but unless sunpro starts making a $20 one, I'll be more than happy with the voltmeter.

[dkopp 1]

What about finding a way to hook up a bi-color LED to show charge discharge status. Have it show red for discharge and green for charging. i agree that some of the old guages didn't show charge and discharging conditions very well, but a bi-color LED would be easy to see and tell which state the charging system is in.

[JamesBe1 84]

What about finding a way to hook up a bi-color LED to show charge discharge status. Have it show red for discharge and green for charging. i agree that some of the old guages didn't show charge and discharging conditions very well, but a bi-color LED would be easy to see and tell which state the charging system is in.

An interesting a simple solution! It might be doable if one could figure out the forward and reverse biasing of the led. I'm a little rusty on my electronics.

How about a digital display of bi-color led's to display the voltage by their arrangement (typical led display) that changes color from charge to discharge?

Drop in a 555 timer and you can have it flash if something reaches a critical value. Cool but much more costly.

I kinda like your idea since it is simpler and more cost effective.

[dkopp 1]

Been thinking about this one all day. Probably the best way to do this is to use a current sensing amplifier along with the LED to allow for any variations in current and voltage levels. Would be more than just a LED and resistor, but should be very robust and fairly simple. The circuit would have to sense bi-polar currents and switch between a high and low output of sorts. I'm thinking a Schmitt trigger might work well for this application.

[JamesBe1 84]

Been thinking about this one all day. Probably the best way to do this is to use a current sensing amplifier along with the LED to allow for any variations in current and voltage levels. Would be more than just a LED and resistor, but should be very robust and fairly simple. The circuit would have to sense bi-polar currents and switch between a high and low output of sorts. I'm thinking a Schmitt trigger might work well for this application.

Your good. I gave up after I realized that the circuit had to sense bi-polar currents.

[Save Old Iron 1,568]

Don't give up - there are other ways - more interesting, surprisingly inexpensive ways. Hint, hint

http://www.sparkfun.com/products/10643

http://www.sparkfun.com/products/8882

http://www.sparkfun.com/products/710

[Save Old Iron 1,568]

or how about an "energy balance" readout. If you crank the engine for 10 seconds at 50 amps, you draw 500 amp seconds from your bank. The monitoring circuit sees this. Then you charge back the 500 amp seconds at a controlled 5 amps (for 100 seconds). You put back 500 amp seconds charge back into the battery - plus a little for lead acid coulombic inefficiencies, etc. The monitoring circuit shows you a charge account balance.

Get it? - CHARGE ACCOUNT - I crack myself up !!

I should charge entertainment tax!

[JamesBe1 84]

Don't give up - there are other ways - more interesting, surprisingly inexpensive ways. Hint, hint

http://www.sparkfun.com/products/8882

http://www.sparkfun.com/products/710

Now that's a cool sensor for only $10. I'm impressed.

or how about and "energy balance" readout. If you crank the engine for 10 seconds at 50 amps, you draw 500 amp seconds from your bank. The monitoring circuit sees this. Then you charge back the 500 amp seconds at a controlled 5 amps (for 100 seconds). You put back 500 amp seconds charge back into the battery - plus a little for lead acid coulombic inefficiencies, etc. The monitoring circuit shows you a charge account balance.

Get it? - CHARGE ACCOUNT - I crack myself up !!

I should charge entertainment tax!

Wonderful idea, but I think it kinda jumps the shark.

[dkopp 1]

Don't give up - there are other ways - more interesting, surprisingly inexpensive ways. Hint, hint

http://www.sparkfun.com/products/10643

http://www.sparkfun.com/products/8882

http://www.sparkfun.com/products/710

Good hunting there SOI! I thought about going the shunt resister route at first but was not sure of the exact voltages and current levels that the LED would be seeing in a parallel arragnement. All would be OK at current levels in the normal regions, but the circuit would not be reliable at midpoint, or right near zero amps. An op-amp would have to be used in that situation to allow the small currents to be measured and output to a suitable device.