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Re: (ET) Power disconnect? Shunt cable?



Back in the day I had an ammeter problem (running to the red) under very light load with my E12.  No loss of power, no unusual battery drain.  Thought this was a resistance issue but did not where to look except to trace the ammeter back to pwr disconnect....at this point my limited electronics knowledge took over.  Someone, probably Harold, led me to look at the shunt from disconnect to pto contactor.  The HO manual page 4-16 says 'shunt MS-1 is a 20" length of 6 AWG cable.  Mine was 19" or maybe a bit less.  Replaced it with a 20" and ammeter works normally.

Think an oddity in the HO manual is on page 4-16 where it says that cable from disconnect to pto is 18.5" of 6AWG.  Someone will have to explain this for me.

Cheers, Jack


On Jul 6, 2015, at 10:52 PM, jlantonucci comcast net wrote:

My restored 150 performs the same way with the exception of the wires getting hot.  I always assumed it was the batteries.
------ Original message------
From: Chris Tromley
Date: Sun, Jul 5, 2015 4:50 PM
To: Elec-trak Mail List;
Subject:(ET) Power disconnect? Shunt cable?
Hi All,

For my EGT 150 (similar to ET 15M), "normal" has always included performance that feels OK for mowing the first 1/4 acre.  Then it gets slower up inclines and I notice the micro-switches sometimes have a delayed effect, like voltage sag prevents the relays from pulling in.  The ammeter ("load" meter) starts dipping into the red at this point.  I thought it was just the nature of the beast.  Since last season sometimes I could smell that something electrical was too hot.  It seemed to come from somewhere in the front, but I couldn't pin it down better than that.  (Not the toaster - it's fine.)

Recently it's become worse.  It turns out the big cable from the main power disconnect to one of the big contactors (PTO?) is getting stinking hot.  I've removed the access panel below the dash now, and when things start slowing down that cable is too hot to touch for more than a second.  It's at the point where I have to park it and let it cool twice to get everything mowed (3/4 acre).  The insulation is hard and cracked at that end, and the wire is corroded.  The ammeter wire on the same terminal is also pretty well cooked.

Is the power disconnect switch a known failure point, as in still functioning but increasing its resistance?  Should its resistance be measurable?  Or did years of corrosion raise the resistance at that end of the cable?  If the fuse wire just normally runs hot, has anyone replaced the whole shebang with a breaker that would run cooler?  What parts would be needed?

I remember reading that the cables are on the small side to limit current, but I'm inclined to put something in there that's beefier and install a proper shunt for the ammeter.  Any reason why I shouldn't, and what short of shunt would I need to work with the ammeter?

Any other ideas?

Chris
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