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Onan 6.5 died, see sparks!

Posted: Tue Aug 07, 2018 10:22 pm
by paskyhawk
Hey Gang

My generator stopped running after about 10 minutes with a small load on it. When I went in the bilge and hit the start switch it turned over hard, did not start and I could see sparks in the end bell area of the generator. I assume there is some kind of failure in the brushes but I am more worried about seeing sparks. Is there enough ignition protection to stop that from igniting fumes. I understand the concept of cooling the hot gases from a explosion but I guess I lost my comfort level.

We mostly used the use the gen for the refrigerator a when underway. I will order a marine inverter/charger to be installed outside the bilge, has anyone used the shore/gen switch for a inverter after decommissioning the gen? I haven't looked a the wiring diagrams yet.

Thanks,
Rich
1979 f36 tri

Re: Onan 6.5 died, see sparks!

Posted: Tue Aug 07, 2018 11:20 pm
by captainmaniac
Ignition protection means no sparks. Sparks = NO Ignition protection!!! If you have enough fumes in the bilge, you are a gonner. Need to get it fixed or replacement solution. Don't even try to run it unless 100% positive of fully ventilated / guaranteed absolutely no fumes.

Re: Onan 6.5 died, see sparks!

Posted: Wed Aug 08, 2018 6:03 am
by paskyhawk
captainmaniac wrote:
Tue Aug 07, 2018 11:20 pm
Ignition protection means no sparks. Sparks = NO Ignition protection!!! If you have enough fumes in the bilge, you are a gonner. Need to get it fixed or replacement solution. Don't even try to run it unless 100% positive of fully ventilated / guaranteed absolutely no fumes.
Yes I agree, I'm not sure if there is screening in there that was supposed to cool an ignition of fumes but I don't like the failure mode and I think I'll decommission it or take it out. An inverter should be fine for what I need.

Rich

Re: Onan 6.5 died, see sparks!

Posted: Thu Aug 09, 2018 7:39 am
by paskyhawk
Any thoughts on using the shore gen switch for an inverter. Is it two hot legs coming from the gen (split phase?) or one?

Re: Onan 6.5 died, see sparks!

Posted: Wed Aug 15, 2018 4:59 pm
by Jimmy
Your sparks more than likely came from the generator side of your unit. No ignition protection there. That girl is what generates your raw regulated power to your system. There are windings, capacitors, and a rectifier that all are capable of little bolts of lightning ( which is why you should ALWAYS keep the blower on before during and after she is purring along. There are quite a few spade wire connectors that eventually fail due to fatigue from vibration. Had to replace quite a few on mine and others. When those fail, your power will take the path of least resistance and arc from a broken wire rather than keep your beer cold. Remove the cowling and ask a short skinny friend with good eyes ( small dark area) to check all your connections back there, and when he finds the bad one, give him one of your cold beers. Those gennies are pretty robust, regular maintenance and inspections and they will be safe and trouble free.

Ditto on no fumes. Not even a fart.... just sayin.

Re: Onan 6.5 died, see sparks!

Posted: Fri Aug 17, 2018 10:30 pm
by paskyhawk
Jimmy wrote:
Wed Aug 15, 2018 4:59 pm
Your sparks more than likely came from the generator side of your unit. No ignition protection there. That girl is what generates your raw regulated power to your system. There are windings, capacitors, and a rectifier that all are capable of little bolts of lightning ( which is why you should ALWAYS keep the blower on before during and after she is purring along. There are quite a few spade wire connectors that eventually fail due to fatigue from vibration. Had to replace quite a few on mine and others. When those fail, your power will take the path of least resistance and arc from a broken wire rather than keep your beer cold. Remove the cowling and ask a short skinny friend with good eyes ( small dark area) to check all your connections back there, and when he finds the bad one, give him one of your cold beers. Those gennies are pretty robust, regular maintenance and inspections and they will be safe and trouble free.

Ditto on no fumes. Not even a fart.... just sayin.
Thanks, it looked like the sparks came from the brushes of the rotor. I'm guessing they wore out, admittedly I have never checked them. I don't trust the unit that much, had it quit for no reason and didn't like the exhaust and noise. I disconnected it and I'll leave it in place for someone else to revive someday.

I did pull the muffler out (for a very short cable run) and put two battery boxes w/105ah deep cycle batteries in series, an ignition protected marine circuit breaker and battery box venting out the old gen. exhaust. In the cabinet next to the cabin main panel I am installing a 5K-24v inverter/charger and putting the inverter 115v into the generator side of the existing shore/gen switch. 24 volts to keep the cable sizes reasonable.

Initial test show the inverter will handle about as much as the old generator. The only warning I received from the inverter was the split second inrush of the air conditioner starting, an audio warning from the unit that it would shut down if that peek load lasted for more than 30 seconds. I mainly want to keep the fridge going and the inverter says that's only drawing 260 watts running which should last for our trips.

Sorry no pics yet, I'll put them up soon.

Thanks,
Rich

Rich

Re: Onan 6.5 died, see sparks!

Posted: Mon Aug 20, 2018 9:09 am
by P-Dogg
paskyhawk wrote:
Fri Aug 17, 2018 10:30 pm
I mainly want to keep the fridge going and the inverter says that's only drawing 260 watts running which should last for our trips.
So 7 hours max away from shore power, fridge being only AC load? How are you recharging the batteries? Lead acid i presume?

Re: Onan 6.5 died, see sparks!

Posted: Mon Aug 20, 2018 3:13 pm
by paskyhawk
P-Dogg wrote:
Mon Aug 20, 2018 9:09 am
paskyhawk wrote:
Fri Aug 17, 2018 10:30 pm
I mainly want to keep the fridge going and the inverter says that's only drawing 260 watts running which should last for our trips.
So 7 hours max away from shore power, fridge being only AC load? How are you recharging the batteries? Lead acid i presume?
Yes, I could by additional batteries, but that's enough for us right now. The unit automatically recharges when on shore power. Lead acid vented.