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upgraded charging fuse?

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upgraded charging fuse?

Postby 38racing » Wed May 09, 2018 11:24 pm

last summer I upgraded friend's ariens with briggs 28 series and electric clutch to 10 amp regulated from dual circuit 3/5 unregulated. first time out this year he ran for short time and now no crank. A quick check and battery to solenoid will turn it over. I'm going to check it over tomorrow maybe but in preparing I've printed the schematic. 7.5 amp fuse so what's the chance I'll find a blown fuse? I don't recall upping the fuse when I changed charging system. looking at schematic it would likely stay running with blown fuse since stator output is direct to keyswitch and although no drain on battery it would not get recharged. hoping it's that simple as his safety switches are questionable. he showed me what appeared to be a reverse overide switch but at first glance I've found nothing in the manual about seeting it and nothing in the schematic.
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Re: upgraded charging fuse?

Postby bobodu » Thu May 10, 2018 5:05 am

Neighbor had a charge issue. Well known local dealer sold her a new battery. I replaced the faulty regulator...then it blew fuses..turned out someone put in a 7.5 when the manual called for a 20.
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Re: upgraded charging fuse?

Postby KE4AVB » Thu May 10, 2018 6:26 am

Double check your wiring diagram. you probably find two fuses.

Fairly good chance if it has a 7.5 amp fuse in the main circuit. 7.5 amp is usually the protection fuse use in the electric clutch circuit in case the PTO draws more than 7 amps. These electric clutch can normally draw about 3-5 amps.

The system fuse is not the stator output rating but is the electrical load at start up plus 25-50 % overrating. Typically most mowers will have a 15 amp fuse through a few have 20 amp or larger. This is even on mower with the basic 3 amp stators. You got remember you got the stater solenoid, fuel solenoid, plus any additional loads pulling current through that fuse at startup.

Typically stators are not fused and only limited by their ability to generate voltage and current at the desired design levels.

Now if you do the correct fuse[s] in place then do a current draw test on both at start up and while running with the electric PTO engaged. I have seen electric PTOs to partially short and draw excessive current. I had them draw over 15 amps and still operated though it was causing a battery discharge.

Hopefully I didn't confuse the issue.
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Re: upgraded charging fuse?

Postby 38racing » Fri May 11, 2018 9:27 am

blown fuse. replaced with15. started right up. 2nd fuse is for lights on this one. I checked non engine running amp draw on pto last year. not excessive .
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Re: upgraded charging fuse?

Postby 38racing » Tue Aug 28, 2018 8:08 pm

I've got this mower back in my yard again. It's got a low battery and cranking is slow once again even back to full charge. There is another thread about this somwhere. It is electric pto and that's why I upgraded stator and regulator. It's charging whole running. I've check valves multiple times. It's not the stop/start type of cranking. Just most times slow. This time I was going to replace the starter but have done some voltage drops. On negative side Solenoid has separate ground. It tested ok . ok to starter ground as well. I'm getting 1.6 voltage drop at the small terminal of solenoid. So I'm heading back to the keyswitch which of course doesn't have the tabs labelled. Been awhile but i thought that I has used the jd relay setup before and it didn't fix it. Anyway going to go find s tab now.
Quick update - only 3 of usual of 5 tabs are used plus there is the 6 th tab outside the connector
Last edited by 38racing on Tue Aug 28, 2018 9:17 pm, edited 1 time in total.
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Re: upgraded charging fuse?

Postby 38racing » Tue Aug 28, 2018 9:16 pm

So this is strange. May need to go look at schematic. If I check resistance from s tab in connector I get zero ohms with PTO off and brake out. If I put PTO on I lose the path. That led me to suspect that brake switch has been overridden. But when I put connector on back on kswitch to check voltage drop at s tab it won't crank unless I put brake on. That voltage drop is 1 volt. So continuing at kswitch I get this interesting result. I'm using an auto ranging meter. I have one lead on b tab. In run I have continuity to the 6th tab. If I touch second lead to b tab I see continuity as expected since both leads on same tab. When I move 2nd lead to s tab I see infinity as expected. When I turn key to start the meter doesn't change. Just sits at infinity. Doesn't even give a megaohm value . I put connector back on and turn key to start and get my slow crank. Also interesting is what is on tab 1? Switch is mounted to plastic. How is magneto killed. Relays I bet.Getting late. Going inside to look at schematic and start fresh in the morning.
Update again: I better do some reading. Keyswitch is way different
to quote:
The ignition switch incorporates a number of functions,
although not all functions are used on all equipment.
The switch has three positions: OFF, RUN, and a
momentary contact START position. Use an ohmmeter
to check the continuity of the switch in each position.
OFF Position - Should be continuity between contacts
G and M. These connections ground the engine
magneto and stop the engine in the OFF position.
RUN Position - Should be continuity between contacts
B and A. These connections supply power to the rest of
the wiring harness. Connections G and M open to each
other.
START Position - Hold switch in START position while
testing. There should be continuity between contacts
S1 and S2. These connections apply power to close
the solenoid contacts and operate the starter motor.
In addition to the above test, place the switch in the run
position and check between each contact and ground
(metal case) to be sure no terminals are grounded. If
the switch is operating properly, there will be no
continuity between contacts other that those described
endquote

A is what I call 6th terminal. B is as I had it. S1 is what I called S and S2 is the single tab of the 5 set. So needs closer look for testing. But there are no wires on G an M!
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Re: upgraded charging fuse?

Postby KE4AVB » Wed Aug 29, 2018 10:53 am

Just using the fuel solenoid for shut down. JD switch setup. Lots place for bad connections and bad contacts as the starter safety circuit is a live circuit running the brake/clutch, PTO switch, and even possibly the seat switch.

You said the starter is engaging but is dragging then not the solenoid trigger circuit but is a bad starter or bad connection in the main starter feed lines. This includes ground return path and the internals of the starter relay (solenoid).
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Re: upgraded charging fuse?

Postby 38racing » Wed Aug 29, 2018 12:48 pm

Actually grounds magneto through a relay. Family matter this morning so no progress. Going to recheck voltage drop at starter lug and solenoid small. If it's positive I might set up the relay to see if i can get it to zero. Goes through 4 switches or if no drop at starter I will change it.
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Re: upgraded charging fuse?

Postby 38racing » Wed Aug 29, 2018 7:54 pm

Testing today still had 1.6 drop on small solenoid . Even on cable end of wire on solenoid large output drop was below .3. and .7 at starter terminal.I decided to pull starter. I found quite a bit of play in the top bushing. First two replacement candidates also had some play. Third oneoff an old 11hp on a craftsman left at our church scrap is on it now. Drop on it is .4. Currently cranking fine but a did have battery charging while doing replacement. Voltage on battery was dropping with all my test cranks. While I have it I'm going to add the relay and see if I get less voltage drop to the small solenoid tab. Currently battery ground cable is to engine block at shroud. I'm going to add second ground to chassis.
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Re: upgraded charging fuse?

Postby 38racing » Thu Aug 30, 2018 7:41 am

Darn. I had it in my mind that voltage drop should be max .3 but in fact manual said .1 and had an example where it was .3. I'll see what I have after the relay addition. Might need a new solenoid. Cables on positive side are both new.
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