Does alternator charge house batteries

[cbeierl]

Just to add to Morich's post immediately above the Front End Wiring Installation diagram for your 2011 Via does confirm on page 5 (View DA) that the Battery Boost switch does have the 'standard' wires LS, LR and KE connected to it. Looking in the Wiring Identification Guide shows that these are:

LR / 14 YEL BATTERY MODE SWITCH (AUX START SWITCH) BATTERY MODE SOLENOID (AUX START SOLENOID)

LS / 12 YEL OVERCURRENT PROTECTION 20A BREAKER TYPICAL,COACH FEED GENERAL PURPOSE(BATTERY MODE, RADIO POWER,BATTERY CONDITION

KE / 14 YEL RUN ONLY POWER SOURCE GENERAL PURPOSE(RELAY TRIGGER, REAR AUTO HTR,DRL,MONITOR,ETC

At rest the Battery Boost switch connects KE to LR, triggering the solenoid to join the two battery banks whenever the engine is running. When depressed the Battery Boost switch connects LS to LR, triggering the solenoid as long as the switch is depressed.

[NeilV]

Originally Posted by Romer1

Checked today, generator running charges house batteries, engine running does not

Note that the house batteries will charge once the engine battery is fully charged so there may be a few minutes of delay after the engine is started before you may notice the house batteries getting charging voltage readings.

The converter did not as an OEM provision charge the engine batteries but just the house batteries back when our coaches were built.

That's how it works on my 2001 Adventure 35U on the F53 Chassis.

[mikf]

Originally Posted by NeilV

Note that the house batteries will charge once the engine battery is fully charged so there may be a few minutes of delay after the engine is started before you may notice the house batteries getting charging voltage readings.

The converter did not as an OEM provision charge the engine batteries but just the house batteries back when our coaches were built.

That's how it works on my 2001 Adventure 35U on the F53 Chassis.

Same as mine. I thought that I had a problem until I figured out what was happening. How it works I have no idea. I have a 2002 Adventure 35u.

[davismills]

Originally Posted by Romer1

2000 Suncruiser 35U, does anyone know if the engine alternator charges my house batteries while driving?

This will sound crazy, but check and see if your start/boost switch has a 3-way position. Winnebago installed such on mine.

Toggle up to get a boost to start with a release returning the switch to the center position.

Toggle hard down to return to house charging position.

When I first bought my Winnebago Sightseer, I had a bad ground and couldn't start after a gas stop. Toggle up got me running again and the switch returned to the center position. For over a year, I found no charging to the house batteries while traveling.

By accident, I clicked the switch down to the "mysterious" down position, and charging resumed.

This was probably a factory fluke, but it's worth checking out on your coach.

[Geosman]

Thank you for the insightful information on the charging circuit wiring. I'm overloaded with Geothermal installations and radiant heat projects at the moment but will...hopefully have some time to focus on the RV control system here in the next two weeks and will respond with my findings/solutions so that others may also benefit.

[Geosman]

You may have saved the day...and yes, I failed to pull the battery disconnect cable near the MB floor fixture to the right of the accelerator while the RV was in storage for several months of non use...the Chassis battery died in storage. I tried the boost switch to no avail and had to use my car and jumper cables to get the MB running. At the same time, the house batteries were charged and getting power from the land line connection.
So it is still a curiosity as to what happened but this is a good start. I will try the possible 3 way to see if it might solve the issue ....as well as the insightful wiring diagrams to trace out the problem.

[Morich]

One of the things I notice most about electrical discussions is how they often get way off course on some of the simple things and we wind up speaking all kinds of high tech when all many of us need is the basics----without trying to remember lots of terms.

So often we think of charging a battery as some high tech thing that involves lots of high tech principles and equipment when all most of us need to know is how it works!

Charging and water are often used as examples of how it works and since most of us have experience with water and we can see it, comparing the two may help to clear some confusion.

If we have two buckets, one with 12 inches of water, connected by a small pipe with a valve to the second which has 6 inches of water in it, we can see that the water will flow from number one to number two if we open the valve between them.

How fast that water flows between them is only limited by how much water will flow through the pipe between them and how much difference there is between the water levels in the two buckets. The water will flow from the full bucket to the less full bucket.

If we look at the same thing, only call them batteries instead of buckets and a solenoid instead of a valve, we get the same thing.
When we set the valve (solenoid) to let current flow the power will flow from the battery (bucket?) with the most to the one with less. Whether it flows from the start battery to the coach batteries or the other way, depends on which is higher voltage (more full?) and how fast is will flow depends on the DIFFERENCE in the two levels.
If we add a hose running into bucket ! it is the same as when we add an alternator running adding to battery 1.

If we ignore all the tiny differences that the high tech talk wants to bring in like temperature and weird stuff the electrical flow will act very much like the water flow and we can see that the amount of flow will slow as the two containers get nearer the same level. Remember the flow depend on the difference, so as the difference gets less the flow also gets less. No high tech control mechanism involved, just works that way is enough for most of us to know!

If we have a coach battery run down and an engine battery (with alternator running) the current flows to the coach battery when the solenoid connects them together!
But if we have a run down start battery and we connect it to the coach battery with solenoid, the current may flow the other direction!
How fast and how much current flow, depends on the DIFFERENCE in the levels.
No high tech controls needed! If has a high current flow when there is a big difference and low current flow when they get closer to the same levels. Whether we want to push a dash switch to help the start battery or let the automatic operation connect the batteries to get a small amount of charge put back in the coach batteries, we don't need to know about any high tech involved as all we want to do is connect the two and it takes it from there!


The solenoid is just a valve controlled by electrical controls and opens/closes the path between the tow buckets/batteries.

DISCLAIMER:
This is an obvious simple explanation and if we did want to go into lots of high tech stuff we could make it terribly complex but since few of us are trying to engineer or build from scratch, this may help to clear some confusion.

[Romer1]

Just to let everybody know, it was a bad relay.

[Morich]

Originally Posted by Romer1

Just to let everybody know, it was a bad relay.

In your case, are you saying you changed the battery disconnect relay or only using the terms loosely and mean you changed the solenoid?
I can fully agree that the solenoid is a relay but others who might not know, could be confused.

[Romer1]

Replaced with this:


MaySpare Max 200A Trombetta Continuous Solenoid Relay 3 Terminal Heavy Duty Winch Marine 24106 SPST Solenoid 12VDC

[Morich]

Originally Posted by Romer1

Replaced with this:


MaySpare Max 200A Trombetta Continuous Solenoid Relay 3 Terminal Heavy Duty Winch Marine 24106 SPST Solenoid 12VDC

Okay, looks like what I would see and agree needed. One of the follies we can get into is the names of various things like solenoids and relays. Exactly where they split into each group is pretty vague in my mind as they are both electrically operated "switches" and when to call it a relay or solenoid is still an open area to me!
So the one on the left in the drawing that connects the two battery strings together is the one and what we call it is no big thing.

Thanks for the reply!!

[Geosman]

Success! Using the generic Winnebago diagrams I was able to test and replace the left solenoid that links the chassis charging system with the coach batteries. It was not an easy task. The panel on this VIA 25Q is in a cubby bay just behind the stairwell. It literally takes a circus contortionist to work in this location...My rotator cuff will attest to that! Obtaining a Trombetta replacement would take too long for the turn-a-round I needed to get back on the road. I found a Granger / White Rogers continuous duty DC Power Solenoid that is dong just fine. WR Model 70-902. ( Granger item # 56JF13). It is interesting that White Rogers prefers the solenoid be mounted cap down; which is opposite to the position of the previous Trombetta solenoid.
I tested the Tombetta with the coach battery disconnected and with engine running I had 13.4 volts on the chassis side but only 11.2 on the coach side...pretty much a case of bad contacts by my observation. The solenoid would open and close as I broke and remade the coil post connection so it was "working mechanically" but not passing good voltage across the contacts to charge the coach batteries.
With the new WR solenoid, I measure the same 13.4 to 13.6 volts on each side of the new solenoid and can now read 13.4 volts on the coach monitor which tells me the problem is solved.
Interesting side bar to this discussion....my problem started after winter boondocking when the propane heater continued to run the coach batteries down. My fuel tank was below 1/4 so the generator was of no use. I ran the engine to help add charge to the coach batteries. I just have to wonder if the amperage/current passing from chassis to coach across the old Trombetta contacts was too much and they were heat stressed. I've seen AC compressors do this with old contactors and suspect it could be a source of RV/Trombetta failures?
Does anyone out there have a good feeling for the amperage that might pass between a fully charged battery along with running alternator when connected to a nearly dead battery? I just gotta wonder if it turned the old Trombetta into a mini DC arc welder and cooked the contacts?

[Phil G.]

It's VERY EASY - whenever the engine is running - to conveniently monitor to make sure the alternator is charging the engine battery and the coach battery(ies):

Plug an inexpensive voltmeter like this - https://www.amazon.com/INNOVA-3721-B...00EVWDU0&psc=1
into a cigarette lighter receptacle on the dash so it can be seen when driving.

Then use velcro to mount another inexpensive voltmeter on the dash and - using it's 6 ft. cord with a cigarette lighter plug on the end - plug it into a cigarette lighter receptacle back behind the cab in a forward area of the coach somewhere right behind the cab. Here's a link to this kind of voltmeter - https://www.tac-comm.com/VoltMinder.html

The first voltmeter always shows the voltage of the engine's 12V system (hence the starting battery). The second voltmeter always shows the voltage of the coach's 12V system (hence it's batteries).

Both voltmeters should always read almost the same whenever the alternator's output voltage is getting to the coach battery bank ... if the voltage on the coach voltmeter is lower than the engine voltmeter ... then "something" is wrong and the coach batteries will not be getting charged by the alternator. The usual cause of this is a failure of the solenoid that connects the engine 12V system to the coach 12V system whenever the engine is running.

I'm on the 3rd interconnect solenoid in 15 years of owning our motorhome..

[imnprsd]

When you think of charging you are asking if the alternator has the "Potential" to charge the battery... or the other way around, which is not good.

Since the alternator is connected to the engine battery, and since the maximum a 12V FLA battery can hold is 12.8V -12.9V; anytime you have an alternator putting out more than 13.0V you will have the "Potential" for electron charges to move from a position of higher potential to a lower one.

I also have a couple of these in my RV. One by the drivers seat and one in my bedroom so I can look at it when I go to bed.

[url]https://www.amazon.com/Jebsens-Charger-Battery-Monitor-Voltage/dp/B01N00I4TM/ref=pd_sbs_2/131-9482363-8451252?pd_rd_w=OtfZh&pf_rd_p=a5925d26-9630-40f3-a011-d858608ac88b&pf_rd_r=CP3FFCGNBG1QZEQJ9Y6X&pd_rd_r= 63d1383a-9fe4-4fc3-afac-330c3d5ca66f&pd_rd_wg=1aC0M&pd_rd_i=B01N00I4TM&psc =1[/url

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In your alternator there is a Voltage Regulator and full bridge rectifier. This device tanks alternating current (hence the reason we call it an Alternator) and it turns it into DC current, typically limited to 14.8V.

The reason why you will see your Voltmeter vary between 14.8V and 12.9V has to do with your engine battery's internal resistance. I.e., as your battery fills up it push back on the incoming charge. That is to say your battery's internal resistance increases.

In general, anytime your alternator is putting out 13.0V or more, you will be receiving a small charge current. Typically in the 1-2A range. And when your engine battery is low on voltage, your alternator output can be as high as 80A, but typically it varies between 1-40A. And as your engine battery fills up you will see 10A-15A nominally.

Engine batteries are typically not your primary objective when it comes to your alternator charge concerns. I.e., when our House Batteries are connected in parallel with our engine batteries, then some alternator current will flow to the house batteries, which is desirable.

However, you really need to use a VSR or a Battery Isolator to better protect your charging circuit to FLA batteries.

And if you have LiFeO4 house batteries you will want to use a DC-DC converter, which is "smarter" than the VSR/Battery Isolator; and will also take into account any charging amps coming from you solar panels, if you have any.

[Elkman]

A battery isolation manager will prevent the coach batteries from drawing current from the chassis battery. There are ones for use with lithium-phosphate batteries so if planning to make the upgrade then go with something like this which is sold by Battleborn and others:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1