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Voltage drop in secondary starting circuit

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Re: Voltage drop in secondary starting circuit

Postby bgsengine » Mon Aug 06, 2018 4:24 pm

Mr Mower Man wrote:
bgsengine wrote:
do a ground side voltage drop between the solenoid housing and B- , may find a bad ground connection somewhere?


So exactly how do I do this? You'll have to spell it out for me.


Same way you do a voltage drop on the + side... Perhaps review the briggs training? if I recall,they did have details on how to voltage drop the ground side too.

Meter on volts scale,one lead on the Solenoid ground side (if it is 2-pole primary,if there's just 1 primary,then solenoid body is the ground path) and one lead on the B- post , crank engine and observe voltage reading. a perfect connection will give 0 volts , anything above 0.1v or so and you have a ground resistance. Repeat test by moving the test lead from solenoid ground to the next point at which the ground goes to- Wire connector,or in the case of body grounded solenoid, to starter body or engine block (trace the ground path of the solenoid) until you show below 0.1v - once you find a spot that does that you have isolated the resistance between the 2 points that show the voltage difference.

It's basic electronics theory dealing with Ohms law.
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Re: Voltage drop in secondary starting circuit

Postby Mr Mower Man » Mon Aug 06, 2018 4:33 pm

38racing wrote:
Mr Mower Man wrote:
bgsengine wrote:
do a ground side voltage drop between the solenoid housing and B- , may find a bad ground connection somewhere?


So exactly how do I do this? You'll have to spell it out for me.

Go to section 17.35 of this
http://web.ncf.ca/da229/smallengine/mtd ... ical-2.pdf

Thanks! Good stuff here! Makes a lot of sense. It goes well with a 1/2 hour Youtube video I just watched about voltage drop. (If I'm allowed to paste links to online content on here, I'll post a link to the video). I think I now have some more (and better) testing to do. I'll let you guys know how it turns out. And please keep the good ideas coming!
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Re: Voltage drop in secondary starting circuit

Postby Mr Mower Man » Mon Aug 06, 2018 8:15 pm

OK, so I did the voltage drop test on the ground side, and it tested fine. I got a minimal voltage reading from the solenoid housing to the negative battery terminal (.01-.02). So the problem is on the positive side.

I was doing voltage drop testing at multiple points along the "trigger" circuit, expecting to find one point where there was a big jump. No such luck. At the solenoid, the end of the circuit, the voltage drop from the positive side of the battery was 5 volts (during the times when the starter didn't engage). But as I worked my way upstream, testing on both sides of each switch and connector (main wire harness connection, brake switch, both neutral switches, PTO switch, ignition switch, hot wire from the battery at various points), the voltage drop reading became consistently and steadily lower at each successive test point as I got closer to the battery. Anywhere from .2-.5 volts difference from point to point. That is NOT what I expected to find, and I have no explanation for it. It's like the overall resistance of the whole circuit is too much, and there's no single culprit. Does this thing need a new wire harness, or what? What happened to this thing?

I thought I was understanding what I was reading and learning about voltage drop testing, but this has me wondering what I'm doing wrong.
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Re: Voltage drop in secondary starting circuit

Postby bgsengine » Mon Aug 06, 2018 8:40 pm

Sounds like you are doing things right, and I sort of suspect, since it is a kawasaki, it just may be one of those that needs a relay to control the relay - See KE4's post #3 in this thread

To sort of verify that, see if you can wrap a heavier gauge (12 or 14 gauge) wire around the solenoid primary terminal and have it long enough to reach B+ directly - then when you can duplicate the issue, touch that jumper to the B+ post and see if it kicks in If it does, then it may just be the circuit has too much resistance (as the JD problem was) , but if it does not, then it may be the solenoid itself having an issue (I had once like that once, but it was a separate solenoid from starter, intermittently would not kick in.. finally replaced it, and out of curiosity I tore apart the old solenoid, found some wear spots that the moving contact was able to tip sideways just enough it was hanging just before it made full contact with both secondary terminals.. one side had a lot of arcing damage from that hang up until it got bad enough it just wouldnt kick in at all, except when the movable contact plate slammed straight in and made full contact)
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Re: Voltage drop in secondary starting circuit

Postby Mr Mower Man » Tue Aug 07, 2018 10:12 am

KE4AVB wrote:This was problem on some JDs where the fix is to wire inline a relay as there was too much voltage drop in the trigger circuit which was causing starting problems. The additional relay being of lower current needs to engage feed power right at the starter solenoid to the trigger side.

OK, so it's looking like I may need to do something like this to fix this issue. Where do I get the correct relay, and exactly where should I wire it in (if I really do have to go that route)?
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Re: Voltage drop in secondary starting circuit

Postby KE4AVB » Tue Aug 07, 2018 10:22 am

Just about any auto part store or small small shop should have the relay. You can use use those starter solenoids (relays) that use on the non solenoid shift starters.
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Re: Voltage drop in secondary starting circuit

Postby Mr Mower Man » Tue Aug 07, 2018 2:56 pm

Thanks for the diagram! I have a couple relays like that. I should be able to use one of them. A 4-pole starter solenoid would work too, like you said. But they take up more room, so I think I'll try to use one of those small relays. So I won't do anything with the center terminal (87a)?
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Re: Voltage drop in secondary starting circuit

Postby 38racing » Tue Aug 07, 2018 6:47 pm

When activated 30 and 87 are connected. When not activated 87a and 30 are connected. I put my battery to 30 and wire to solenoid on 87 but it will work as shown.
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Re: Voltage drop in secondary starting circuit

Postby KE4AVB » Tue Aug 07, 2018 7:06 pm

Setup as drawn just prevents 87a and 30 from being hot when the relay is at rest so no way for the circuit to be operational at rest unless the contacts of 87 and 30 fuse together. If 30 is wired to the battery then 87 is hot at rest and could accidentally cause problems. All the relay is SPDT switch that is electrically switched instead of manually switch.
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Re: Voltage drop in secondary starting circuit

Postby 38racing » Wed Aug 08, 2018 8:22 am

KE4AVB wrote:Setup as drawn just prevents 87a and 30 from being hot when the relay is at rest so no way for the circuit to be operational at rest unless the contacts of 87 and 30 fuse together. If 30 is wired to the battery then 87 is hot at rest and could accidentally cause problems. All the relay is SPDT switch that is electrically switched instead of manually switch.

Thanks. I'll keep that in mind.
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