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Old 07-15-2017, 07:31 PM   #1
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Isolators versus continuous duty solenoids

I always wondered why we see Solenoids instead of Isolators in some of the classics.
So I did a little digging and became to realize that a "continuous" duty solenoid seems to be the better way to go, since it only connects the batteries for charging with the terminal S activated by ignition on. So no voltage loss when dormant.
The important thing to note is that not any starter solenoid will work and probably burn out in short order, it has to be a a continuous duty solenoid like this one:
http://www.auto-parts-world.com/bwd-...s603-18970418/
Probably not news for most of you. Am i missing anything?
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Old 07-16-2017, 05:44 AM   #2
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Quote:
Originally Posted by PeterH-Airstreamer View Post
I always wondered why we see Solenoids instead of Isolators in some of the classics.
So I did a little digging and became to realize that a "continuous" duty solenoid seems to be the better way to go, since it only connects the batteries for charging with the terminal S activated by ignition on. So no voltage loss when dormant.
The important thing to note is that not any starter solenoid will work and probably burn out in short order, it has to be a a continuous duty solenoid like this one:
http://www.auto-parts-world.com/bwd-...s603-18970418/
Probably not news for most of you. Am i missing anything?
Peter, I came to the same conclusion a while back and decided not to use one of those "blue" solid state battery isolators. Instead I'm going to be installing a
Blue Sea 7622 ACR (Automatic Charging Relay).

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Every review I read about it was good so I figured I'd give it a try.

Brad
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Old 07-16-2017, 09:30 AM   #3
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Holy MSRP Batman!
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Old 07-16-2017, 09:52 AM   #4
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Holy MSRP Batman!
Well, I didn't pay quite MSRP
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Old 07-16-2017, 10:03 AM   #5
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Brad, I like what I read about it, but I don't think it solves one problem I had with the 310 and EFI:
If I would start the generator after starting the 454, the drag on the entire 12V system was sometimes so much that it would kill the more sensitive power requirement of the EFI module and its sensors to the point of the engine stalling. The only way around it was to start the generator first and then the fuel injected engine. I don't see a way around this with any of the systems mentioned above, do you?
Edit: It does the below, can that be applied to the reverse situation, like cranking a generator?
Start Isolation (SI): can be configured for temporary isolation of House loads from Engine circuit during engine cranking to protect sensitive electronics
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Old 07-16-2017, 10:21 AM   #6
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Brad, I like what I read about it, but I don't think it solves one problem I had with the 310 and EFI:
If I would start the generator after starting the 454, the drag on the entire 12V system was sometimes so much that it would kill the more sensitive power requirement of the EFI module and its sensors to the point of the engine stalling. The only way around it was to start the generator first and then the fuel injected engine. I don't see a way around this with any of the systems mentioned above, do you?
Which battery are you starting the generator from, coach or starting? I always have the generator powered from the coach battery.

What size battery cable is running from the battery compartment to the generator? Same for the ground, where is it grounded and what size is the ground, it should be the same size as the +12 feed and preferably #2 gauge or larger.

Since your's is an aftermarket EFI I'm wondering if the EFI is grounded properly. Mine insisted that the ground for the EFI system be made at the back of the head.

Also, the engine ground needs to run from the back of the head to the frame AND from the back of the head to the body. In other words the engine has two ground cables.

Where are you feeding the +12 to the EFI system and how large are the wires? You're obviously experiencing a voltage drop of some kind that is affecting the EFI components.

What it really sounds like to me is either undersized wiring for the EFI or poor grounding.

Brad
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Old 07-16-2017, 10:52 AM   #7
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Holy MSRP Batman!

The price answers your question in the first post.
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Old 07-16-2017, 10:57 AM   #8
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Which battery are you starting the generator from, coach or starting? I always have the generator powered from the coach battery.

What size battery cable is running from the battery compartment to the generator? Same for the ground, where is it grounded and what size is the ground, it should be the same size as the +12 feed and preferably #2 gauge or larger.

Since your's is an aftermarket EFI I'm wondering if the EFI is grounded properly. Mine insisted that the ground for the EFI system be made at the back of the head.

Also, the engine ground needs to run from the back of the head to the frame AND from the back of the head to the body. In other words the engine has two ground cables.

Where are you feeding the +12 to the EFI system and how large are the wires? You're obviously experiencing a voltage drop of some kind that is affecting the EFI components.

What it really sounds like to me is either undersized wiring for the EFI or poor grounding.

Brad
Generator is started by the coach batteries, but I see voltage drops in the engine 12V system when cranking the generator.
I would definitely put some fault of this to the factory undersize wire running all the way from the front left (batt compartment) to the rear right (generator).
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Old 07-16-2017, 11:08 AM   #9
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Originally Posted by PeterH-Airstreamer View Post
Generator is started by the coach batteries, but I see voltage drops in the engine 12V system when cranking the generator.
I would definitely put some fault of this to the factory undersize wire running all the way from the front left (batt compartment) to the rear right (generator).
If the coach and starting batteries are not connected together then the only point in common is the grounding system.

This is the cable I'm using for the generator feed on my Argosy. Obviously the distance is abut 10 feet less than your 310!

You might consider using 1/0 to run that distance with a 1/0 ground cable as well.
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Old 07-16-2017, 12:48 PM   #10
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Quote:
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...
What it really sounds like to me is either undersized wiring for the EFI or poor grounding.

Brad
Brad, I really think you are on to something with the poor grounding. The only time the batteries are connected momentarily is during starting of the engine via a relay at the battery box. After that they separated at the Isolator. I wrongly assumed that starting the generator would draw more current via the Isolator to the point of voltage drop on the engine side. My bad. Thanks for your input.
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Old 07-16-2017, 01:07 PM   #11
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So I'm reading along here. My generator starts off my chassis battery. I thought the theory behind that set up is that you don't want the charging mechanism for a battery to also start off that same battery, or you're outa luck should you run that battery down to a point where it won't start the genny. So say you're boondocking and you accidently run your coach batteries down, the only way to charge them is running your genny...but it won't start cause it's starts off the coach batteries (that have been run down).

I have disconnect switches on both sides. So if we are stopped for several days in one spot I try to make a habit of switching the chassis battery off so I know I'll have juice to start the genny should I need it.

So I'm just wondering why both you fellers have your genny start off the coach side? How did they come wired from the factory? What's the theory behind having the genny start off the coach side......you two know wayyyyyyyyyyyyy more than I about this stuff

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Old 07-16-2017, 01:48 PM   #12
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So I'm just wondering why both you fellers have your genny start off the coach side? How did they come wired from the factory? What's the theory behind having the genny start off the coach side......you two know wayyyyyyyyyyyyy more than I about this stuff

Mike
One guess from the vehicle warranty side, not responsible for any other wiring/systems added by the RV side.

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Old 07-16-2017, 01:51 PM   #13
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....you two know wayyyyyyyyyyyyy more than I about this stuff

Mike
Mike, you are the one with all the On-The-Job training, so we have to rely on your first hand field experience.
BTW, i just figured out that my 310 generator was connected to the Motor Battery, which is causing all the voltage drop issues during firing up the generator
Besides the above voltage drop issue, which is a problem if your EFI wants a min of 9Volts to operate, the idea is to always reserve the chassis battery to start your Motor.
Ok, like you said, you are out boon docking and your coach batteries are getting low, so you want to start the generator. Damn thing cranks but doesn't start all the way to running down the engine battery. Bam, you are stuck.
If your generator would have been connected to the coach batteries, which are dead now, you can always start your engine and charge the coach batteries via the isolator, until you can start the generator.
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Old 07-16-2017, 02:42 PM   #14
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Mike, you are the one with all the On-The-Job training, so we have to rely on your first hand field experience.
BTW, i just figured out that my 310 generator was connected to the Motor Battery, which is causing all the voltage drop issues during firing up the generator
Besides the above voltage drop issue, which is a problem if your EFI wants a min of 9Volts to operate, the idea is to always reserve the chassis battery to start your Motor.
Ok, like you said, you are out boon docking and your coach batteries are getting low, so you want to start the generator. Damn thing cranks but doesn't start all the way to running down the engine battery. Bam, you are stuck.
If your generator would have been connected to the coach batteries, which are dead now, you can always start your engine and charge the coach batteries via the isolator, until you can start the generator.
What Peter said

Primary concern is being able to get home, secondary concern is being comfortabe
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Old 07-16-2017, 08:14 PM   #15
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BTW, i just figured out that my 310 generator was connected to the Motor Battery, which is causing all the voltage drop issues during firing up the generator
Besides the above voltage drop issue, which is a problem if your EFI wants a min of 9Volts to operate, the idea is to always reserve the chassis battery to start your Motor.
Peter,

I think the battery cable running from the battery to the generator is way under sized. For the generator to pull the starting battery below 9 volts while trying to start means the generator starter is working too hard due to low voltage. That's hard on the starter motor.

I would suggest up sizing that cable by 2. If it's 4 gauge right take it to 2 gauge. If its 2 gauge take it to 1/0.

Brad
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Old 07-16-2017, 08:20 PM   #16
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I'm a little confused here. My gen set starts from the chassis battery. This is the same battery that starts my Isuzu diesel. While cranking the little generator the battery hardly knows it is there. I would start by finding out why your generator is drawing so much current.

As to the isolator I like the kiss principle. I just replaced my isolator after 35 years. It has worked just fine and the idea of adding more wiring to use a solenoid is not worth the gain. The small residual loss from the isolator is not an issue, I just drive the coach more often. That thing Brad bought is just too far above my pay grade. Makes my head hurt just thinking about it.

I don't know maybe I'm just getting lazy in my old age. No, I've been pretty lazy all along.
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Old 07-17-2017, 07:27 AM   #17
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I'm a little confused here. My gen set starts from the chassis battery. This is the same battery that starts my Isuzu diesel. While cranking the little generator the battery hardly knows it is there. I would start by finding out why your generator is drawing so much current.

As to the isolator I like the kiss principle. I just replaced my isolator after 35 years. It has worked just fine and the idea of adding more wiring to use a solenoid is not worth the gain. The small residual loss from the isolator is not an issue, I just drive the coach more often. That thing Brad bought is just too far above my pay grade. Makes my head hurt just thinking about it.

I don't know maybe I'm just getting lazy in my old age. No, I've been pretty lazy all along.
Dan, I think the key issue Peter is/was suffering is when trying to start the generator the voltage drops to 9v or less, at least momentarily anyway. I don't think there are any sensitive electrical components on a diesel (are there any electrical components?!). You wouldn't notice that on your diesel rig but Peter is on his 454 EFI. It's possible his generator starter is failing but it's just as likely the battery power feed is undersized. It's amazing how much voltage drop you get with DC on long runs.

The Blue Sea ACR is nothing more than a relay with some smarts built into so it knows which side is charging and keeps them separated when the voltages don't match or fall within a certain range. It's bad juju to have to batteries with miss matched voltage levels being charged from one charging source.

Lazy? You? Tell me something I might believe....!

Brad
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Old 07-17-2017, 11:00 AM   #18
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Brad I don't think I have actually put a meter on the battery while cranking the gen set but I would not expect it to drop that much. I agree long runs and poor connections are a problem and I would look there first.

The Isuzu has no electronics, even the fuel shut off is mechanical. If the battery drops that much cranking the little gen set how would it ever have a high enough voltage while cranking the 454 to ever fire the EFI to start the engine? I'm not sure where the batteries are on Peters coach but on my coach I believe the batteries might actually be closer to the gen set than the Isuzu. Just kind of thinking out loud.

I agree there are endless discussions about the proper or best method to charge batteries but as I said the simple isolator has worked just fine charging the 2 house batteries along side the single chassis battery for the last 35 years. And that mixes deep cycle and starting batteries.

You may not believe I'm lazy but you are redesigning and rebuilding 2 coaches and mowing acreage and taking care of a donkey and other farm stock while holding down a full time job. I'm just trying to keep my coach somewhat useable and cut enough firewood to keep the house warm through the winter. Big difference my friend. Makes me tired just thinking about. I think I need a beer and then a nap.
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Old 07-17-2017, 04:59 PM   #19
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The Isuzu has no electronics, even the fuel shut off is mechanical. If the battery drops that much cranking the little gen set how would it ever have a high enough voltage while cranking the 454 to ever fire the EFI to start the engine? I'm not sure where the batteries are on Peters coach but on my coach I believe the batteries might actually be closer to the gen set than the Isuzu. Just kind of thinking out loud.
..
Dan, good point on why cranking the big 454 doesn't rob all the voltage to disable the EFI, but it doesn't. One reason is the solenoid by the battery compartment combines all three batteries during starting
The battery compartment is the first compartment in the front on the drivers side, real close to the starter with big fat cables. The generator is on the opposite site in the rear with marginal, I would say #4 cables and only gets cranked by 1 chassis battery.
I value these discussions, despite the little gremlins that fall out of the cracks, like in my case the undersized cables and the stupid fact on my part, that the generator is started by the chassis battery alone.
Just imagine going down road at 68 mph with the fine EFI running at full blast when one decides to push the Generator start button on the dash
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Old 07-17-2017, 08:27 PM   #20
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I understand what you are saying Peter but a 454 in a car starts with one battery. A pickup with a tow package might have 2 batteries but I have no clue if the are tied together or isolated. Back to your coach if your 454 is running and presumably the alternator is putting out a minimum of 60 amps or probably 90 or more amps, the chance of the little gen set dropping voltage enough to kill the EFI just doesn't make sense to my feeble mind. I've seen riding lawn mowers with more HP than the gen set start with a small lawn mower size battery. You might set a normal starting battery outside the gen set and wire it directly to see what happens. It just seems the problem is somewhere to the rear of the coach behind the batteries.
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