Chassis Batteries

[Larry Dedrick]

Ed:
         Thanks again.
           I'm at the shop, where the alternator came from and the bench check did show a problem with the regulator, but I can't explain the detail the tech gave me because I will more than likely mess it up. I was cautioned to keep an eye on the ignition switch, due to it possibly presenting a problem some how in connection with the sense wire. Hopefully I understood this relationship correctly.
          A few weeks ago, I started the engine and it immediately died after about 3-5 seconds, so I turned the ignition off, and then back on and nothing happened to power the gauges and nothing to the starter, but by cycling the ignition a few times, I got power and the engine started fine and has repeatedly operated fine since then (so far). The reason I bring this up is, the shop cautioned me about these ignition switches. So, I am thinking about getting another ignition switch, but before I do that, I will check all connections to the ignition.

                         Larry D.

[Edward Buker]

Larry,

I noticed on my Marquis that from the factory my switch when it was vertical with the key in what was typically the off position, it was actually the accessory position that is normally to the left of vertical on some of the older GM switches if I remember right. That meant that in the crank position was more clockwise and off was where run would normally be. I had sometimes turned the engine off myself while starting it by coming back to the off position. See if that is possible in your case also. I do not know if my switch was just set up that way in error or if more coaches were like that. If it gives you trouble again there are two components that can be the likely causes. The ignition switch and the big solenoid at the bottom of the two copper strips in the electrical bay under the driver seat. Both have contacts that can wear out. If it continues to work O.K. do not worry about it. The connections to the ignition are probably fine given they are housed inside the coach and electrical bay. The ignition switch has a plug on the back and the solenoid has small wires on screw terminals that come from the switch. If you have the ignition on and do not get power again, leave it that way and take a meter and measure the small terminals on the solenoid. If you have 12V there then it is the solenoid, if you do not then it is the switch.

Later Ed

[Larry Dedrick]

Ed:
          The ignition key positions you mention sure rings a bell, never thought about that, but I will take notice. I already have purchased a continuous duty solenoid rated at 200 amps, they did not have the 85amp in stock. They had indicated that a higher amp would not matter, after I inquired about it. Hope that are correct. Plan on getting an ignition switch also.
           So, now I will put the alternator back on, and troubleshoot the sense wire. I may just take a long jumper from the chassis battery + terminal to the sense post on the alternator and then take a voltmeter to see what the alternator is putting out. If that brings the voltage to around 14 I will then start messing with the existing sense wire and see where the fault is. Does this sound reasonable?
           By the time I'm done and hopefully successful, it will be good knowledge toward any future problems, Thanks to All who responded.
           Also, the device that sits nearby the echo charger, with the echo charger fused leads going to, I believe is an isolator with three posts. This isolator then has Three battery size cables, one from each post going to two junction posts withe cables continuing to, one to the coach batteries and one to the chassis batteries. The junction post for the chassis batteries is where, I believe, the sense wire is routed to. The third cable from the isolator may be to the alternator, any thoughts on this? I will solve this when the rain stops.

[Edward Buker]

Larry,

The larger capacity solenoid will be fine, actually better. There is a diode on the small terminals of the original unit, just install that on the new one the same way as it is on the old one when you get around to changing that.

I would try and read the labels that Beaver put on the wires and I'm hoping that you labeled them or numbered them when you took them off. If the shop found a regulator issue then I would hook it up the way you unhooked it because it was working and charging just the voltage was off on the high side. I believe that the sense wire has the battery voltage on it all the time so try and not touch that one to ground. I'm not completely sure of that but I think so. Be careful not to run the alternator without all the wires on it, especially the larger red one. The alternator needs to see a load on it like charging the batteries or the voltage can go too high and take out some of the internal electronic components, most likely the diode pack. If you have questions as to which wire goes where look up the alternator that you have and most manufacturers have a wiring diagram and there may be a typical one in the schematics for Beaver coaches on the website here. That is the isolator that you are describing. The alternator feeds current that gets splits between the battery leads and current from the batteries is blocked from going back to the alternator and from flowing from one battery bank to the other through the isolator.

Later Ed

[Larry Dedrick]

Thanks much Ed:
                         Today, I hope to have this resolved, You and Steve have been a great help.

                              Larry D.

[Larry Dedrick]

Ed, Steve and others:

                      Alternator in and All is Well, (knocking on wood). Glad I didn't have to work on the sense cable, but was prepared to. I now know much more than I did earlier.

                   Thanks for the patience and help.                  Larry D

[Edward Buker]

Larry,

Glad you are up and running again. The voltage should  stay in the 13.8 to 14.4V range +/- when the batteries are charged up and you are cruising down the road. If you have headlights etc on and a high load it may run less until the heavy load is back off.....all normal.

Later Ed

[Larry Dedrick]

Gentlemen:      
                  Apparently I may have knocked on the wrong wood, because my issue may have returned.
                  This time, I started the engine, with the generator running, and two roof A/Cs operating when I noticed the Silverleaf alternator voltage indication was reading 15.7 volts. I turned off the A/Cs to see if that would have any influence on the voltage, and it did not. I then turned off the generator and still no change. I turned off the engine, and then restarted it and the voltage was in the 15.5 to 15.7 range.
                  Whats surprising me this this time, when I accelerate the engine to 1800 rpm the voltage drops to around 14.7 volts, this is opposite of what took place on my earlier post before I reinstalled the alternator.
                  I'm thinking of maybe just being patient with this and operate the coach and monitor the condition, as long as the voltage drops to the 14.6 range. Could this maybe be a sense wire situation as previously suggested. After reinstalling the Alternator a few weeks back I had checked the voltage with a voltmeter at the sense wire, and it was 12.2 at 1800 rpm, the alternator indicating 13.6 at the alternator, batteries showing 13.2 volts at the batteries.
                  So, any ideas will be appreciated and in the mean time I will operate and monitor my voltage.

                  Thanks in Advance:                Larry D

[Jeremy Parrett]

Larry,
I started my engine with the generator running and fried the inverter/charger !!  I won't do it again.

[Larry Dedrick]

Jeremy:
               That had to hurt. Is this a big no no? It's not what I do normally, but I just happened to have the gen running when I wanted to check my air line in the back of the coach with brakes and thus, started the engine.
               I will use caution from here on.
               Now if only my voltage would return to normal, we'll see.

             Thanks Jeremy

[Steve Huber Co-Admin]

Jeremy,
I'm not aware of any reason for not starting the engine with the geni running. Only thing that occurs to me is that you got a voltage spike from the batteries when they saw the engine alternator and that could only occur if the battery isolator is faulty.
Steve

[Edward Buker]

Larry,

There is a second alternator involved that is within the genset and that may confuse things a bit here. With the charger/inverter charging also we have a third voltage source involved.  Just run the main engine and the main alternator and take some measurements with a meter and the silverleaf.

Measure the voltage at the chassis battery + to ground and then measure the sense wire to a good ground. The voltage should be the same with the engine running. If it is not then check the connections on the sense wire to make sure they are clean and tight and not corroded. The sense wire should be on the battery side of the isolator or lead to the + battery wiring and not the terminal of the isolator that leads to the alternator. If it is wired correctly and the the sense terminal is clean see if you get 13.8 to about 14.4V. With no other complication of other charging systems involved see where the new alternator sets the voltage levels.

Later Ed

[Gerald Farris]

Jeremy,
There is no reason on your coach not to start the engine with your generator running. The electrical systems for the engine starting system and the inverter are totally isolated from each other, and the only connection that the generator has with the inverter is that it produces the 120 volt current that the inverter uses to charge the house batteries, not the chassis batteries that start the engine.

Gerald

[Edward Buker]

Gerald, Jeremy,

I have a situation with my coach that I am a bit wary of. If I crank the engine with the genset running it will kill the genset. I concluded that the DC voltage will drop low enough during engine cranking, that the protection circuits in the genset cause a shut down. Not all coaches have this issue.

While that should not be much of an issue electrically in general I could see a an issue with high current being pulled from the house charger during engine starting while the genset AC supply is being dropped to the charger at the same time in a manner that is not clean until the transfer switch trips open. In my case I have just an Echo Charger coupling the chassis and house batteries so there should not be a large current draw from the charger, with the Echo charger limiting the current to 15 amps. That may be tolerable.

If I had a Big Boy or some large current coupling of the house and chassis batteries I could see the potential for possible Xantrex damage occurring. While you would like to think the Xantrex and Magnum chargers have all kinds of protection circuits built in, you have to remember that they rely on voltage levels being normal and in spec to work properly. It is not possible to design protection circuits that work when abnormal voltage levels and waveforms are being supplied to the charger. I basically do not crank the engine with the genset running as a practice. If your coach does not have the genset shut down issue while cranking the main engine then I would not find a good reason to worry.

Later Ed

[Gerald Farris]

Ed,
The generator shut down issue when cranking the engine is related to only a voltage drop at the chassis batteries that is caused by a high amperage draw from the chassis batteries by the starter. There is no connection between the house batteries that are being charged by the inverter when the generator is running and the chassis batteries in your coach or Jeremy's coach other than the Echo Charger and it can not flow enough current to cause any consequences with the inverter. Therefore, I am under the opinion that there is no way that starting the engine can damage the inverter if the generator is running. Even if the generator dies when cranking the engine, there is no difference than just turning off the generator as far as the inverter is concerned.

The generator shut down issue when cranking the engine is caused by one of two things or a combination of the two. They are either your chassis battery bank does not have sufficient cold cranking amps because of lower capacity or aged batteries or your engine starter is drawing excessive amperage, and most likely it is the batteries. I have had the issue in the past when one of my chassis batteries was marginal, but I waited until I had to use the boost switch before I replaced the battery.

Gerald