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Topic: Electrical/alternator problem (Read 1793 times) previous topic - next topic

Re: Electrical/alternator problem

Reply #25 –
The DW and I spent 3 hours taking our U225's alternator out this afternoon. The job was complicated by a previous owner rounding off the heads on the pivot bolt and nut. I finally just hammered one size smaller impact socket onto the nut and put the air impact tool on it... spun it off faster than I thought it would.

The alternator is a Heyr and there were only three wires connected to the unit; a negative wire (black), a positive out put wire (big thick red) and the red wire from the isolator. However, examination of the Hehr troubleshooting documentation it appears that the alternator was wired correctly enough to run (even though the battery sense was jumpered to the field excite (where the ignition wire was connected). Both of these have to have +12vdc in order to run.

Off to the electrical shop tomorrow for a bench test.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Electrical/alternator problem

Reply #26 –
You might take a look at this:

Alternator alternatives

I've been very pleased with the performance of this retrofit.  Newer alternatives have better/larger bearings per Leece Neville. 

Chuck
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Electrical/alternator problem

Reply #27 –
Quote from: Chuck Pearson –
You might take a look at this:

Alternator alternatives

I've been very pleased with the performance of this retrofit.  Newer alternatives have better/larger bearings per Leece Neville. 

Chuck

Chuck... thanks for the link. The Hehr that was on our U225 is kind of cool in that it has all the contacts for various configurations right on the unit. Just jumper across to change it. No drilling into the regulator.

I found that someone had jumpered the battery sense to the field excite (which comes from the ignition contact at the isolator). Info from Hehr says that both of these have to have +12vdc "at all times" when the alternator is running. I am not at all convinced that this was a good idea but maybe it works...

Since the alternator only had three wires connected (one to the negative, one to the postiive and one from the sense to the isolator) I don't actually know where the original "battery sense" wire from the batteries is. I'll have to look at the harness more closely.

The alternator was dead when we put it on the test rack. I explained to the tech how it was wired and he said he understood that configuration so that was ok. We're sending it to Spokane to see what needs to be done. It's either the regulator or the diodes. Bearings seem ok.

When I get it back I think I'll eliminate the strap between the battery sense and the field excite and wire up a real battery sense instead. I wonder if turning the ignition off (which cuts off the 12vdc battery sense) hasn't caused the field to collapse too quickly and blown the diodes.

Or maybe it's heat.

I'll keep everyone posted. These seem to be on-going problems and a newer, more heat-resistant, unit might be the answer.

Thanks again for your info. :)

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Electrical/alternator problem

Reply #28 –
Craig, That 4th wire should be to an IGNITION ON source. Mine  is wired to the hot wire at the rear engine start panel.  If you go there be sure that the hot wire to the alternator is well clear of any heat source or  other point where it can ground.n Don't ask how I know that.  Its embarrassing. :-(
Gary B

Re: Electrical/alternator problem

Reply #29 –
Quote from: Gary Bouland –
Craig, That 4th wire should be to an IGNITION ON source. Mine  is wired to the hot wire at the rear engine start panel.  If you go there be sure that the hot wire to the alternator is well clear of any heat source or  other point where it can ground.n Don't ask how I know that.  Its embarrassing. :-(
Gary B

Gary, thanks. I understand about the "don't ask me how I know" stuff. Theoretically, the fourth wire is connected to an ignition on source... but it's from the isolator. When the ignition is turned on both of those contacts are hot... however they are both from the isolator.

I don't understand why a battery sense voltage couldn't be from the same source as the ignition voltage... but a constant voltage to the battery sense might be important if it keeps the field from suddenly collapsing and blowing the diodes. Since the ignition on voltage stops as soon as you turn the ignition off, then there is no voltage to the battery sense when the alternator is slowing.

This may make no difference at all. But the Hehr technical documentation specifically says that the jumper to the field excite (which is where the ignition on voltage goes from the isolator) should be removed and a wire from the battery (a battery sense voltage) connected to that post. 12vdc is 12vdc no matter what route it takes to the alternator but sometimes the removal of that voltage can cause problems.

Solar panels are lots easier. :P

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Electrical/alternator problem

Reply #30 –
Whooooops.Sorry Craig, I was referring to a Leece Neville, I had to replace my Hehr Powerline and then I had to rewire it.  I should have read post closer.
Gary B

Re: Electrical/alternator problem

Reply #31 –
Craig, I'm not up on the Hehr alternator but unless it's self excited I expect jumpering voltage sense to excite will make it drain current when the engine as off as the alternator is always excited.  You might want to check on this.  Jumpering will work on almost any alternator but they've been known to be battery drainers. 

Chuck
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Electrical/alternator problem

Reply #32 –
Quote from: Chuck Pearson –
Craig, I'm not up on the Hehr alternator but unless it's self excited I expect jumpering voltage sense to excite will make it drain current when the engine as off as the alternator is always excited.  You might want to check on this.  Jumpering will work on almost any alternator but they've been known to be battery drainers. 

Chuck

Chuck... the jumper is from the hot ignition connection to the battery sense connection. Since the ignition connection only comes on with the key there is no drain. But the documentation says to *not* jumper those two and, instead, sense the battery voltage direction. This would, of course, mean that there would always be +12vdc on that connection (which is, I think, the way the FT coaches come from the factory).

Since we know that the previous owner was having alternator problems I wonder what caused mine to fail and whether it was that jumper.

And Gary... the Hehr is supposed to be wired up exactly like a Leece Neville. At least according to the documentation I found on the 'net.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Electrical/alternator problem

Reply #33 –
Chuck, The original Hehr apparently was factory wired but when I put the Leece on I had to add a wire.  There are so many variations on these coaches that its really hard to apply a one size fits all fix.
Gary B

Re: Electrical/alternator problem

Reply #34 –
Quote from: Gary Bouland –
Chuck, The original Hehr apparently was factory wired but when I put the Leece on I had to add a wire.  There are so many variations on these coaches that its really hard to apply a one size fits all fix.
Gary B

Gary, you got that right.  And when it comes to alternators the selection is immense also, some models are superseded several times with tech notes for changes to each revision.  Really, after thinking about it, it seems like they need not one but two sense circuits, one for each battery bank.  I have a hard time thinking that charging a battery bank should kill a 160 amp alternator but I can see it being a problem if you're sensing coach batteries and charging house batteries (boost switch on.)  At that point you've got an unbalanced load with the alternator in the mix, sensing a hybrid voltage.  There's also the problem of gel/agm/wet cell batteries, different styles in the two banks each with different charge profiles. 

I can see charging a gel battery bank putting a hurt on the alternator.
 
Chuck
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Electrical/alternator problem

Reply #35 –
Quote from: Chuck Pearson –
I can see charging a gel battery bank putting a hurt on the alternator.

Your remarks make perfect sense. Many of us have two different types of batteries between the coach and chassis units. We've upgraded the shore power circuits in order to protect our batteries but have forgotten that we should probably do the same thing to our engine-driven charging systems as well; especially when we can drive 12 to 16 hours a day occasionally (well, some of us).

Right now I'm wondering whether it might be a good idea to have a way of turning the engine-driven alternator off while driving in sunshine with roof-mounted solar panels (and the boost switch on). My MPPT controller for the solar panels is vastly more sophisticated than the regulator for the alternator. This would help control heat buildup in the alternator and also protect the battery bank.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Electrical/alternator problem

Reply #36 –
Craig, Some one here has done just that by adding a switch to take the alternator out of the circuit when desired.  I can't find the post right now but do a search on alternators and maybe it will pop up.
Gary B

Re: Electrical/alternator problem

Reply #37 –
Chuck,

You're always charging both coach and chassis battery banks with the alternator through the isolator.  Starting the engine with deeply discharged coach batteries is an easy way to overload a 160 amp alternator.  To make matters worse, turn on the boost switch to compensate for deeply discharged chassis batteries, and you have a recipe for alternator failure on engine start-up.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R
 

Re: Electrical/alternator problem

Reply #38 –
Quote from: amos.harrison –
Chuck,

You're always charging both coach and chassis battery banks with the alternator through the isolator.  Starting the engine with deeply discharged coach batteries is an easy way to overload a 160 amp alternator.  To make matters worse, turn on the boost switch to compensate for deeply discharged chassis batteries, and you have a recipe for alternator failure on engine start-up.

One reason many FT owners run the generator (boost switch on) for 30 minutes before starting the engine after they've been boondocking for a few days.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."