Bentoolong 94 #1 Posted September 22, 2021 (edited) I am considering rewiring my C-120. I am looking at the attached wiring diagram and I'm wondering why the fuse is only protecting the accessory circuit. It seems like the lights are the least critical of all circuits. Would it be better to put the fuse between the battery and the solenoid and the ammeter or in my case (I'm eliminating the ammeter) between the solenoid and the "Battery" post on the ignition switch. I've never measured the amperage when starting or running a tractor but it seems like the fuse would protect more wiring/components. Your thoughts? 1977 B and C-Series OM Wiring Color.pdf Edited September 22, 2021 by Bentoolong Practice Share this post Link to post Share on other sites
ebinmaine 67,598 #2 Posted September 22, 2021 A fuse in every circuit wouldn't be overkill. I too eliminate all ammeters from my tractors. The have a place in this world 🌍. Just not on my equipment. I wired my Cinnamon Horse C160 with 2 fuses. One is a maxi fuse for the battery. The other I believe I used a 20 or 25 amp ATC in the battery to ignition switch wire. I can get pics later today or tomorrow. Share this post Link to post Share on other sites
Bentoolong 94 #3 Posted September 22, 2021 Thanks Eric, Yes, I've always wondered how valuable an ammeter is. So you can tell that something is drawing a little power. Normal right. A voltmeter that has a 12V marking can tell you at least that your charging system is working and maybe the relative health of the battery. and the ammeter is not fused in the original wiring. Speaking of... The reason I need to rewire is that most of the wire had melted the insulation. I'm not sure what calamity may have caused this amount of failure but I suspect there was more than one cause. It may have had an ammeter fail and that may have contributed to the carnage. I do know that the stator has good output but I'm not sure about the voltage regulator. Is there a way to bench test it or is it just a matter of hooking it up to the stator and checking the DC output from the regulator? Share this post Link to post Share on other sites
ebinmaine 67,598 #4 Posted September 22, 2021 6 minutes ago, Bentoolong said: ammeter @squonk Mike can give a good explanation for the ups and downs of an ammeter. 6 minutes ago, Bentoolong said: Is there a way to bench test it or is it just a matter of hooking it up to the stator and checking the DC output from the regulator? I don't know of a way to bench test a VR myself. I do it the way you describe... Share this post Link to post Share on other sites
squonk 41,151 #5 Posted September 22, 2021 Lots of guys don't like ammeters. I am not one of them. Yes they can fail. But most voltmeters you buy are as accurate as a weather forecast. Looks like 14 Volts. Well is it or is it 13? is it 12? I went round and round with a garage we sold a rebuilt alternator to. They kept saying the new ones were bad. Well Why? Well the voltmeter reads only 12 volts running. Funny my multimeter at the battery reads 14.3! I have yet to see an accurate voltmeter on a tractor. Maybe if you cut loose with some cash on a top of the line SW one but who's gonna do that! Ammeters on bounce all over when the battery is charged and little current is flowing. But when it's discharging or charging it will tell you which way the current is flowing. A volt meter won't tell you something has happened to the charging system until it drops enough for you to notice. An ammeter on a fully charged battery will show discharge as soon as say the stator failed and something is drawing current. This is my opinion only. All the voltmeter guys flame away 2 Share this post Link to post Share on other sites
ebinmaine 67,598 #6 Posted September 22, 2021 10 minutes ago, squonk said: All the voltmeter guys flame away I like gauges. A lot of gauges. Like an 80s Pete with a dashboard full of em. TBH my only issue with an ammeter is the concern of a meltdown. I've had them short straight through.... Then melt a wire, luckily. Can an ammeter be reliably isolated or maybe fused so a direct short can't happen? Share this post Link to post Share on other sites
squonk 41,151 #7 Posted September 22, 2021 You can fuse anything. Just put a fuse in large enough to handle the maximum amount of current (starter draw) expected under normal conditions and matched to wire size and length of circuit. If you have a starter draw of say 60 amps a 80 A fuse will be sufficient. A 6 foot long #6 wire is rated at 100 amps https://jascoautomotive.com/automotive-wire-amperage-capacity-chart/ 1 1 Share this post Link to post Share on other sites
ebinmaine 67,598 #8 Posted September 23, 2021 On 9/22/2021 at 5:33 PM, squonk said: You can fuse anything. Just put a fuse in large enough to handle the maximum amount of current (starter draw) expected under normal conditions and matched to wire size and length of circuit. If you have a starter draw of say 60 amps a 80 A fuse will be sufficient. A 6 foot long #6 wire is rated at 100 amps https://jascoautomotive.com/automotive-wire-amperage-capacity-chart/ So if I want to leave the ammeter and fuse it... And it reads ((30A??))... Then I should be a fair amount more electrically safe if I install a 30 amp fuse in that wire.... That could be a possibility for Colossus in particular. @Bentoolong I have only one fuse in my C-160. It's the 867 that 2. The C160 fuse is in the wire from battery to ignition switch. It is 15 amp at this time. Share this post Link to post Share on other sites
squonk 41,151 #9 Posted September 23, 2021 You want to fuse it higher. Everything goes through the ammeter. If your starter draws say 60 amps and you put a 30 amp fuse in it you may blow the fuse when you try to start it. The ammeter may be marked 30 amps but it can handle more. The wiring itself should be able 100 amps. Try a 60 amp fuse and if it blows out in an 80 Share this post Link to post Share on other sites
ebinmaine 67,598 #10 Posted September 23, 2021 6 minutes ago, squonk said: You want to fuse it higher. Everything goes through the ammeter. If your starter draws say 60 amps and you put a 30 amp fuse in it you may blow the fuse when you try to start it. The ammeter may be marked 30 amps but it can handle more. The wiring itself should be able 100 amps. Try a 60 amp fuse and if it blows out in an 80 What size is the O. E. Wire? I'm not looking at a schematic but I thought the ammeter measured everything - except - the starter draw? Largest cables (on a Wheelhorse at least) go direct from battery to starter. Please correct me if I'm mistooken... Share this post Link to post Share on other sites
squonk 41,151 #11 Posted September 24, 2021 Your correct. I was thinking about some bigger machinery I've run into. I would wire the ammeter with #10 and use a 30A fuse. You would use the bigger fuse if you wanted to protect the wiring on a non solenoid equipped tractor 1 Share this post Link to post Share on other sites
