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BopMan · 10-02-2014, 11:48 AM

Quote:

Originally Posted by wb7auk

As Myron stated if the battery boost relay was closed already and there was no power
or very little at the chassis battery the majority of power was taken from the house
batteries and a bad connecting at the tie point for the relay and chassis battery was
bad drawing several hundred amp's would cause failure.
I do not believe the alt had anything to do with the failure.

Based on what I've read here I need to contact Camping World and have them check all the solenoids. I hope you're right about the alternator... they don't give them away. I might also look into replacing the isolator with something like a "Big Boy" solenoid. I don't know if that's a better approach but it seems more safe.

Thanks again.

BopMan · 10-02-2014, 12:04 PM

Quote:

Originally Posted by nothermark

It's not just corrosion and loose terminals. All wiring has resistances built in. The general approach is to make them small enough so as not to be a problem. A good example is the tables that specify what wire gauge for a given length and load extension cord. If you are trying to pull a couple of hundred amps for a starter or inverter very small resistances can become a big issue. The formula is V= IR so for a 200 A current at .01 ohms you have a 2 V sag. One reason the lights dim when one hits the starter.

FWIW I was curious about the starter current so I did a bit of looking. I underestimated what you probably pull. Typical 8 cyl diesel is ~ 650 A according to this source:

http://www.linnbenton.edu/auto/fall/...start_test.pdf

The few hundredths of an ohm is a typical number for the small losses in any circuit but the lowest are in high current low voltage designs. With that in mind you could be easily losing several volts in the wiring. As I recall there are also similar numbers inside the batteries. I do not have a good source right now to quote.

Bottom line is that there are a lot of little resistances that have to be accounted for in high current low voltage systems. Most of the time they do not matter to the user but this was not one of those times. Checking each connection after starting by feel or IR temp gun might show some interesting results. All those losses show up as heat. ;-)

"not one of those time"... You got that right. I feel lucky more damage wasn't done.

Great information! I know CW will be replacing some parts and hopefully all the connections will be removed and reconnected. I'll check with them and see if they have an IR temp gun or something else to determine heat.

Looking at the picture of the damage it appears some of the cable shielding/casing is damaged. Would you know if all that heat inside the cabinet could damage the actual high current low voltage cables?

wb7auk · 10-02-2014, 01:05 PM

The 2 most important items to have, a good volt/ohm meter and a infrared thermometer gun.

BopMan · 10-02-2014, 02:02 PM

Quote:

Originally Posted by wb7auk

The 2 most important items to have, a good volt/ohm meter and a infrared thermometer gun.

I have the meter but do cheap infrared thermometer work okay?

wb7auk · 10-02-2014, 03:19 PM

Quote:

Originally Posted by BopMan

I have the meter but do cheap infrared thermometer work okay?

Even the cheap infrared thermometers are close to real temp's , what
you are looking for is a difference in temp's in this case.

YC1 · 10-02-2014, 06:48 PM

No way the alternator would have caused this issue. With the wiring cleaned up and a new isolator installed CW surely would check the input and output voltages. I would not toss out the design and install a big boy. Just not necessary and could lead to other issues if you are not a real techie.

YC1 · 10-02-2014, 06:50 PM

Quote:

Originally Posted by BopMan

I didn't use the battery boost to start the rig the day the isolated failed. What's strange is I need both cutoff switches on for the motor to turn. I would think only the chassis cutoff would need to be on to supply enough power to start the rig. That's the reason I want to test the boost solenoid to ensure it's not engaged all the time. I did a 50amp stress test on the chassis battery and it passed.

Thanks for your input.

There is always a chance the system is setup to automatically pull the aux start solenoid in when the key is turned. Only a voltmeter test would tell for sure.

YC1 · 10-02-2014, 06:52 PM

Quote:

Originally Posted by mel s

YC1
A solid "state isolator", (like the OP's Cole Hersee 48160 200AMP model), uses/needs no solenoid.
Mel
'96 Safari

That is purely to keep the banks separated, the solenoid bypasses the output of the isolator. It merely shorts the two outputs together.

BopMan · 10-02-2014, 07:08 PM

Quote:

Originally Posted by YC1

There is always a chance the system is setup to automatically pull the aux start solenoid in when the key is turned. Only a voltmeter test would tell for sure.

I'll check the setup when I get the rig back from CW. I'm still puzzled by having to have both cutoff switches on... I don't remember if this was the case before this issue occurred.

wb7auk · 10-03-2014, 05:07 AM

Quote:

Originally Posted by BopMan

I'll check the setup when I get the rig back from CW. I'm still puzzled by having to have both cutoff switches on... I don't remember if this was the case before this issue occurred.

When you turned on the chassis cutoff switch that put power to the the
chassis controls but did not have the voltage and current to start the
engine for what ever reason. When you turned on the house batteries that
provided power thru the battery boost relay to start the engine however
the connections and wiring system of the boost system was not designed to
be the soul source to start the engine and failure happened.

Still unanswered is why you did not have the voltage and current from the chassis battery in the first place.
I would be sure to check the chassis battery connection at the battery.

wb7auk · 10-03-2014, 07:15 AM

If these were used more often a lot of problems would go away.

http://www.amazon.com/POWER-BUSS-AMP...rhf_gw_p_img_1

BopMan · 10-03-2014, 07:45 AM

Quote:

Originally Posted by wb7auk

When you turned on the chassis cutoff switch that put power to the the
chassis controls but did not have the voltage and current to start the
engine for what ever reason. When you turned on the house batteries that
provided power thru the battery boost relay to start the engine however
the connections and wiring system of the boost system was not designed to
be the soul source to start the engine and failure happened.

Still unanswered is why you did not have the voltage and current from the chassis battery in the first place.
I would be sure to check the chassis battery connection at the battery.

The cutoff switch issue could of been there prior to the isolator melt down but I don't know. The only time I turn the cutoff switches off is when I take the batteries out for winter storage. I did remove the chassis battery connection when I did the stress test and they both looked good with no corrosion. I always put dielectric grease on all battery connections.

I have to admit I don't check the battery connections enough and I've never checked the connections to the isolator. Now that I see what can happen I'll be checking these connectors on a regular basis.

Quote:

Originally Posted by wb7auk

If these were used more often a lot of problems would go away.

Amazon.com - POWER BUSS BAR 400 AMPS MADE IN U.S.A. - Bar Tables

Sure looks like something I need to look at... Thanks Art

traveler999 · 10-03-2014, 06:37 PM

I'm not sure why all discussion about starting current. The only current that goes through the Isolator is from the Alternator to each of the batteries and any load on the batteries. The isolator is there to make sure the batteries are isolated from each other and the batteries do not feed back into the alternator. Because the burnt post on the isolator is the domestic side I would suspect a high current appliance was being used and the connection at the post that burnt had some resistance. It doesn't take much resistance at a 100 amps to create a lot of heat.