The truth about "house battery" alternator charging

[Morich]

Maybe way too late in this discusion to mention but there can be a pretty simple way to get down to checking the solenoid. It depends on being able to reach the solenoid easy enough to make it worth doing, though.

The solenoid is pretty simple and easy to test if we are prety sure it is getting the signal.
If you have start battery power to one big lug and coach battery to the other, there is one quick way to test if the solenoid is closing and passing the current through.
Since you have two points with 12 volt battery on either side of the solenoid, it is pretty simple to touch something metal between one of those 12 volt point and the small connection from the dash!

On old cars that had the solenoid up on the firewall where it could be reached, it was pretty common to keep an old set of pliers handy to just short from one big lug to the other long enough to crank the engine! Arcing and sparks were common, so don't use your favorite, best pliers?

The only thing the LR wire coming from the dash does is put 12volts on that small lug it is attached to, so if we put the 12 volts there, we DO know it is there and if we don't see the same voltage reading on each of the big lugs while we have the 12 volts applied, there are only a couple things left to check.
When we put the strap on, we should hear and feel the solenoid jump as the contacts are closed. That tells us it moved! Duh!

So if the two big lugs are not reading the same voltage, the contacts are moving but not good enough to connect. Bad solenoid!

But before we jump too quickly, it "might" also be a bad ground, so make sure the body of the solenoid is screwed down good to the metal mount on the three wire style or that there is good ground on the FM wire if using the four wire type.
The four wire type is kind of double assurance there is ground as the wire should be ground and it is often tied to the mounting which is also ground.

[CJBROWN]

Originally Posted by Bob35A

Chris, can you post a detailed schematic of the battery to battery install and how it relates to the alternator and genset when it's running? Will it interfere with the onboard converter when the genset is running?

Thanks

I don't have a schematic, but here is what I did with my 2005 Sunrise/Voyage class A motorhome:

1. Built a 230A lifepo4 DIY battery from Eve prismatic cells. "Li - lithium" batteries have such low internal resistance that they will pull as much current as your alternator will deliver, which can overheat it especially at idle or low rpms. It's just a really great way to cook your expensive alternator. Most 12V converter chargers either don't have the right voltage output for charging Li, or don't ever terminate charging - which is bad for Li. These batteries have a different charging profile from lead-acid batteries.

2. The isolator/combiner solenoid discussed in this thread serves to connect the house circuit with the chassis/starting circuit when you start the engine. There's also a boost switch that manually does this, on the dash, should your starting battery go flat you can combine your house battery for starting. However when converting to Li you run the risk of burning up your alternator. So in my case I simply took it out.

3. In place of the isolator solenoid I installed a Victron Orion dc-to-dc charger. This is a battery charger that is activated with the engine key switch and supplies 18A at full current to the Li house battery from the starting battery - again, only when the engine is running. Since Li doesn't like cold or hot it got moved inside, so the space left in the battery tray under the steps got an additional starting battery in parallel, and its own solar panel and charge controller so it always stays fully charged. A 100W solar panel does a bangup job. In a worst case scenario a set of jumper cables could jump from house to starting. I don't really think that will ever be needed.

4. These units come with a Parallax 12V converter/charger - they are the worst piece of junk ever invented and will literally cook your house batteries. And no, they don't charge the starting batteries either. I replaced mine very early on with an IOTA IQ4 smart charger and a pair of 6V golf cart batteries. We got by with this for the past 17 years, works very well. But it's just not the right charging profile for Li, so it got replaced. For one thing, an equalize charge should never be applied to a Li battery - the voltage is too high.

5. A 12V converter/charger is generally plugged into a 110 outlet on a dedicated circuit - mine is combined with the 110V Norcold fridge burner. I replaced the IOTA with a 55A Powermax lithium converter charger, however the charge voltage in their lithium profile is too high for my battery, causing the BMS to shut down charging for cell over volt. So I installed a switched outlet for the Powermax, set it for fixed voltage charging - CV - and simply turn it on when I need it and turn it off when charging current reaches 5% of the battery capacity, in this case about 10-11A. It tapers current down as the battery reaches full charge. It is set to charge at 14.1V for a quick boost charge when plugged in or running the generator. It is normally left off - so far I have not had to use it, solar keeps the house battery fully charged.
I recommend a stand alone Li compatible battery charger in lieu of a converter/charger, like a MeanWell NPS750 or a Victron IP22 charger - something with a lithium compatible charging profile.

6. I have about 600W of solar panels and charge controllers, with two charge profiles - one for storage that maintains the battery at about 80%, and one for 'away' or traveling that peaks it to full charge each day. If we're driving the Orion DCtoDC charges it back up.

7. The generator 12V lead comes from the house battery on these units - don't ask me why, or the logic, because if your house battery goes flat that means you can't start your generator. I think that's a dumb idea in the first place. And surely now with the combiner solenoid removed I would be out of luck. Plus the generator starter probably draws too many amps to use the Li - it has a 120A BMS, or output current max. So I simply moved the wire from the house side to the chassis/starting side and it works perfectly. We also use the generator when driving for roof air, or any heavy AC loads, but the converter is switched so it doesn't automatically come on. I also installed a Xantrex 600W inverter with a couple of it's own outlets in the main salon, the outside radio box, and in the master state room. It's great for running a fan, charging electronics, the ebike batteries, etc.

I spent several months and a couple of thousand to update the electrics in this old coach, and gleaned a TON of information on Will Prowse's forum: diysolarforum.com

I would post some pics but this stupid forum doesn't allow photobucket images, which I have used for the past dozen years without incident. Oh well.

Good luck and let me know if you have any questions.

[creativepart]

Originally Posted by CJBROWN

I would post some pics but this stupid forum doesn't allow photobucket images, which I have used for the past dozen years without incident. Oh well.

A number of years ago Photobucket was sold to another company and they quit hosting images for use on forums for free. Users had to pay a membership fee for the first time to use this hosting service. Since most used the site because it was free only a very small number of people signed up for the paid service.

Over 1 billion + images all over the internet were orphaned by this change and instead of seeing the photo that had been linked a broken image icon and ad for photobucket was left in it's place.

So, yes, the forum doesn't support Photobucket any longer.

You simply need to ATTACH your images on your computer/phone/etc directly to your posts using the "Paper Clip" Icon shown in the Advanced Editor. It's super easy.

[BarryLS]

"Over 1 billion + images all over the internet were orphaned by this change and instead of seeing the photo that had been linked a broken image icon and ad for photobucket was left in it's place."

Mine among those. It really ticked off a lot of people, myself included. I'd never use photobucket for anything or send them a penny. Had they done it differently, not breaking all the original content, I would have considered them.

Quite a few websites began direct picture hosting as a result. Like this one.

And as you say, very easy to do. If your pic is only on photobucket, just download it to your PC and place it on here. You can erase it after.

[Morich]

The generator 12V lead comes from the house battery on these units - don't ask me why, or the logic, because if your house battery goes flat that means you can't start your generator. I think that's a dumb idea in the first place. And surely now with the combiner solenoid removed I would be out of luck.

This may be a case of missing some of the basics and that leads to the idea the design is totally wrong.
Step one of the basics is that we should always start the RV engine first to give the generator the best voltage levels for starting. So if we ignore the best paractice on starting the generator, the rest of what we see will also be skewed!

If we do step one right, the mode solenoid will have both the coach batteries and start batteries combined as well as the voltage from the engine alternator and that gives a much better chance of starting the generator. All electrical things work best when they have the best power to do their job.

The idea that it is dumb is simply based on not doing things the best way.

[CJBROWN]

Originally Posted by creativepart

A number of years ago Photobucket was sold to another company and they quit hosting images for use on forums for free. Users had to pay a membership fee for the first time to use this hosting service. Since most used the site because it was free only a very small number of people signed up for the paid service.

Over 1 billion + images all over the internet were orphaned by this change and instead of seeing the photo that had been linked a broken image icon and ad for photobucket was left in it's place.

So, yes, the forum doesn't support Photobucket any longer.

You simply need to ATTACH your images on your computer/phone/etc directly to your posts using the "Paper Clip" Icon shown in the Advanced Editor. It's super easy.

Ridiculous - this is on the user. This is the ONLY forum on the internet that blocks photobucket images. Total fail.
And no, I'm not making a special effort to post pics for this forum. It's just not worth it. YOU lose, not me.

[CJBROWN]

Originally Posted by Morich

This may be a case of missing some of the basics and that leads to the idea the design is totally wrong.
Step one of the basics is that we should always start the RV engine first to give the generator the best voltage levels for starting. So if we ignore the best paractice on starting the generator, the rest of what we see will also be skewed!

If we do step one right, the mode solenoid will have both the coach batteries and start batteries combined as well as the voltage from the engine alternator and that gives a much better chance of starting the generator. All electrical things work best when they have the best power to do their job.

The idea that it is dumb is simply based on not doing things the best way.

I took my solenoid out - you don't want to combine a lifepo4 house circuit with a FLA starting circuit. PERIOD.
The level of FUD here is astounding.

[creativepart]

Originally Posted by CJBROWN

Ridiculous - this is on the user. This is the ONLY forum on the internet that blocks photobucket images. Total fail.
And no, I'm not making a special effort to post pics for this forum. It's just not worth it. YOU lose, not me.

Totally untrue! I guess if I spoke like you do I'd say you are the "total fail." But I wouldn't do that. You simply don't know the impact of this action by Photobucket.

So perhaps you'll read this:

https://medium.com/@AxelUnlimited/ho...e-4a244bda6b7e

[Morich]

Originally Posted by CJBROWN

I took my solenoid out - you don't want to combine a lifepo4 house circuit with a FLA starting circuit. PERIOD.
The level of FUD here is astounding.

Obvious from the postings that this is one who doesn't want the truth on many things. Best to just ignore this sort!

All my Photobucket went dead and I stopped using them for anything as most other users I know.

[BarryLS]

I know of several websites and bloggers that reject anything photobucket. It is not just this place.

I wouldn't use them if they paid me. Cannot be trusted.

[Bob35A]

It's been a minute, but I wanted to do a follow-up question. the question is about the "Yellow wire LR", 12VDC coil power to the Mode Relay.

Every time I push the dash button it energizes the Mode Relay (Normal operation)

With the motor running: LR is not always energized

With the motor running and I push the boost button I can hear the relay pull in

With the motor running and I push the boost button I hear nothing because the relay is already energized.

Is there an energy management system that controls the "control voltage on LR?"

If my Batteries are fully charged will the system know that? and will it shut LR off while the engine is running?

Please keep in mind: Everything works: The relays are brand new and have been checked out, all of the connections are correct and tight, the batteries are brand new and are fully charged. All I'm looking for is the operation of the Yellow Wire LR and if it is controlled by an energy management control.

[creativepart]

I hope I don’t confuse things more, but since the momentary button on the dashboards only purpose is to combine house and chassis batteries for starting the RV’s engine (or starting the generator when the RVs engine isn’t running and you need to charge your batteries) why would you need to use that button when the RV’s engine is running?

I don’t think there is any energy management system but there is an ignition trigger on the BIM that tells the BIM that the engine has started. That’s what tells the solenoid to combine both house and chassis banks for alternator charging. Pushing the button on the dash when the engine is running would be redundant because the two banks are already combined.

Again, if I’ve missed the point please ignore me.

[Morich]

Originally Posted by Bob35A

It's been a minute, but I wanted to do a follow-up question. the question is about the "Yellow wire LR", 12VDC coil power to the Mode Relay.

Every time I push the dash button it energizes the Mode Relay (Normal operation)

With the motor running: LR is not always energized

With the motor running and I push the boost button I can hear the relay pull in

With the motor running and I push the boost button I hear nothing because the relay is already energized.

Is there an energy management system that controls the "control voltage on LR?"

If my Batteries are fully charged will the system know that? and will it shut LR off while the engine is running?

Please keep in mind: Everything works: The relays are brand new and have been checked out, all of the connections are correct and tight, the batteries are brand new and are fully charged. All I'm looking for is the operation of the Yellow Wire LR and if it is controlled by an energy management control.

No. LR is not controlled by any erergy management system. In fact the time frame of your RV had very little in the way of what we now call "energy management".
However it is somewhat more complex than many think as LR has two different sources of the battery power that moves the solenoid to connect start and coach batteries. As you've found, pushing the switch does give battery to operate the solenoid, but there is a different connection which also can feed LR and that feed comes from a point often called "ignition hot".
The name used by different chassis builders may vary but the basic idea is that there is a set of connections which are only hot when the ignition is "on"while there are other points which may be on full time.
Looking at drawings from Winnebago will not show this second connection very well as they usually do not go into showing the chassis portion on many things.
Type of info we would need to have the chassis drawings to see that connection but we know it is there because it works that way?

But there seems to be a bit of conflict in what your post is telling us? Maybe need to recheck the testing?

You say this:
With the motor running: LR is not always energized

With the motor running and I push the boost button I can hear the relay pull in

With the motor running and I push the boost button I hear nothing because the relay is already energized.

Is this what you actually meant as it seems to not say the same thing each time?? Typo, perhaps?

The idea is that the LR should always be hot and read 12Volts when the ignition is on, even short of actually starting the engine.

[Morich]

This is the drawing of that portion of your RV and we can get a look at how it works. But there are some things that are NOT shown and maybe a point that needs to be more clear?

Click this snip to get a better view.



First point is that they do not tell us directly that the "Isolated Stud" is the start battery connection. Like the computer world, "we just have to know that!"

Second is the way the FM wire is shown is not clear that it DOESN"T connect on the big lug with the start battery! Just poor graphics but if we look at the notes in the lower left, we see they show it is connected to the mounting screw!! This is a ground wire and on the three lug solenoid it lays on the screw connection to get ground from the frame/ body metal while on RV using four lug solenoids it it has a seperate small lug. They both use LR for battery and FM for ground for the coil in the solenoid to operate.

But this is where Winnebago often doesn't show the connection for LR as it is on the chassis group which is not in the part they consider "their job"!
To find the specific point, we would need to get the chassis drawings from Ford, Chevy, Workhorse?

A quick way to test this solenoid it by looking at the batteries with a meter.
Most of the time the coach and start batteries will read slightly different when not connected.
When we want to see if the solenoid works in both methods, we can read the voltage on the coach batteries and have somebody start the engine. We then should see the coach battery voltage jump high and moves as we rev the engine, showing we are getting voltage from the engine alternator to the start battery and on to the solenoid and winding up at the coach battery to charge them!

On testing the "boost" feature, we can check both batteries are a bit different voltage with engine not running and not pushing the button. Then when we do push the button, the voltages of both batteries will level and match very closely as they are connected together!

But do keep in mind that the switch is momentary and will not stay with them connected if we push the button and then go back to look at the meter!

[BarryLS]

Looks like Winnebago needs to hire an electrical engineer...

[Morich]

Originally Posted by BarryLS

Looks like Winnebago needs to hire an electrical engineer...

That may be why they no longer use this but it still works on the RV which are more than 25 years old!
The big difference is that this system was something we could fix with $20-30 worth of parts we could buy from the auto parts store and the new stuff is not
repairable short of several hundred dollars!

[BarryLS]

Originally Posted by Morich

That may be why they no longer use this but it still works on the RV which are more than 25 years old!
The big difference is that this system was something we could fix with $20-30 worth of parts we could buy from the auto parts store and the new stuff is not
repairable short of several hundred dollars!

Sorry, I was too brief
The actual design is fine, particularly as you say, for the time. It's the drawing itself, which looks a bit like my grandchildren's art work...
The solenoid and relay drawing are fine, the rest is poorly executed, even for 25 years ago. YMMV, and I'm off the topic.

The advice and analysis are excellent by the way.

[Bob35A]

That is a list of conditions I have experienced.

Test #1 with motor off, push dash switch: Relays energizes

Test #2 start motor: Relay energizes (but not every time)

Test #3 start motor: Relay doesn't energize until I push the dash switch, then it drops out when I release the switch.

This coach has a "Power Line Energy Management System". The Boost switch is a great test because it puts power directly to LR whether the motor is running of not, it's the motor running condition that has the difference. On my energy management display I can see the voltage applied to #1 the engine battery and #2 the house batteries. Sometimes with the motor running I don't see the alternator voltage applied to the house batteries, other times I do see the alternator voltage applied to the house batteries. My thought was the Energy Management System has control over LR with the motor running.

[Bob35A]

Read them as individual conditions and it makes sense.

If the boost switch is pushed and you don't hear a click, then the relay was already powered.

[Morich]

By what you are saying, I'm guessing it is actually what is called the "mode solenoid"? Relay and solenoid are often much the same, so I assume that is what is meant? Not confusing and speaking of the disconnect relay which is right next to what I'm calling the solenoid?

I think we are talking the same item and one thought on not hearing it click when you start the engine is due to what I might think is the engine starting noise keeping you from hearing the click?
Maybe hard to hear a small click when the big noise of starting is going on?

But this is an area that is semi-famous for going bad over time. One of the reasons I like to mention it so often is that it gets lots of wear and tear that cause arcing every time we start the engine!
The solenoid/ relay is just a metal shaft inside a coil that makes an electromagnet to pull that shaft in so that a metal item very much like a large washer is slapped against the two big studs on each side!
That click arcs each time as contact is made and the washer can get burned and pitted so that it can click but still not make contact. Since it is sometimes just kind of loose on the shaft, the washer can rotate slightly each time we hit the key and may move from a bad spot to good or change each time we hit the switch!
What I'm getting at is that hearing it click is a good first thing to prove it is moving but if the contacts are too burned, it may still be failing!
So if we look at the battery voltages and don't see them get near the same voltage, even when we hear the click, we need to consider it has bad contacts on the solenoid.


Nice thing to have a boost switch but it is not needed too often because it is just for giving the engine start battery a "boost" when it is too weak to crank the engine. Jump start without cables needed??
One way this can happen is if we leave the dash radio powered off the chassis battery, use it a lot while camped and run that battery down!
I've found teenagers are a hazard around radios, and may find turning the right switches in the right way is not their big thing!

Otherwise, if all is working right, it is pretty much automatic and the main thing is it lets us pump a little voltage back into the coach batteries that we often run low as we camp without hookups! If we drive long enough (several hours) we get to the next site with full batteries again.

On looking further, I do find mention of EMS but not what I was thinking of involving the battery charge function. There are several types of energy management designs as time has gone on, so I was confused when saying you had none!

They change names on things and I'm fully confused on the names at times. The latest version of battery management is called Battery Isolation Manager (BIM) and replaces the solenoid and partswith solid state with much of it built in a way we can't switch or repair.
What I'm finding on your Rv seems to be more involved with heat/ air and heat pumps at times!
https://www.winnebago.com/Files/File...ire_138913.pdf