Alternator charging switch

[Jarryr]

I've had my Vista 27HE for 3 years and love it. I have a long history with alternator charging of the coach batteries with my previous 1989 Itasca class C. It had a manual switch to turn on and off the solenoid linking the coach and chasis batteries. Through 2 alternator replacements I finally learned how to best use it.

Now back to the present. I finally found a faulty battery mode solenoid which has limited the alternator charging of my coach batteries in my Vista. I thought it was being managed by some smart controller or BIRD but find no evidence in the wiring diagrams for any management system in the unit.

I am strongly considering installing a manual switch for on an off operation of the alternator charging the coach battery (engaging the solenoid). What I have found through testing is the solenoid closes immediately when the ignition switch is in the run position. In other words the alternator will be charging all 3 batteries once the engine started.

Here is my question. I am concerned about overheating the alternator with charging at idle speed. I am also concerned about charging the coach batteries at alternator voltage (14.1-14.4) once they are at 100%. Am I over thinking this or are my concerns valid?

[wolfe10]

If the question is can you use a manual switch to select which batteries are charged by the alternator, the answer is OF COURSE.


You just have to insure that the alternator is always connected to some battery.


Common KISS wiring is alternator B+ and chassis battery to one lug of a marine ON-OFF switch and house bank to the other. Switch off and the chassis battery is charged. On and both banks are charged.

[Sgt B]

Originally Posted by wolfe10

If the question is can you use a manual switch to select which batteries are charged by the alternator, the answer is OF COURSE.


You just have to insure that the alternator is always connected to some battery.


Common KISS wiring is alternator B+ and chassis battery to one lug of a marine ON-OFF switch and house bank to the other. Switch off and the chassis battery is charged. On and both banks are charged.

Wolfe, you seem to know an awful lot about electricity, while I a fairly mechanical fellow, I am all thumbs when it comes to electricity. I own a 2018 Winne Forza 34T I bought used last Oct to downsize from a 40' Newmar. So, can I please ask a dumb Marine Grunt question? When driving, can I assume my alternator is charging both coach and chassis batteries? Or isn't that enough information for you to answer? LOL Every time I start my engine, I get a "low voltage" warning on my dash for several seconds. The engine starts fine, but I just worry about that warning. And, if I may, when plugged in to shore power at home are both sets of batteries charging then. I swear I should know a lot more about this stuff. Guess I am just too damn old to start learning a new "thing." LOL

[wolfe10]

Originally Posted by Sgt B

Wolfe, you seem to know an awful lot about electricity, while I a fairly mechanical fellow, I am all thumbs when it comes to electricity. I own a 2018 Winne Forza 34T I bought used last Oct to downsize from a 40' Newmar. So, can I please ask a dumb Marine Grunt question? When driving, can I assume my alternator is charging both coach and chassis batteries? Or isn't that enough information for you to answer? LOL Every time I start my engine, I get a "low voltage" warning on my dash for several seconds. The engine starts fine, but I just worry about that warning. And, if I may, when plugged in to shore power at home are both sets of batteries charging then. I swear I should know a lot more about this stuff. Guess I am just too damn old to start learning a new "thing." LOL

Short answer is YES, if everything is working as designed, both banks are charged by the alternator.


And, with a diesel engine with INTAKE MANIFOLD HEATER, it is common for the heater amp draw to exceed alternator output and trigger the light. This should only occur when the heater is activated which varies with temperature.

[twinboat]

Originally Posted by Sgt B

Wolfe, you seem to know an awful lot about electricity, while I a fairly mechanical fellow, I am all thumbs when it comes to electricity. I own a 2018 Winne Forza 34T I bought used last Oct to downsize from a 40' Newmar. So, can I please ask a dumb Marine Grunt question? When driving, can I assume my alternator is charging both coach and chassis batteries? Or isn't that enough information for you to answer? LOL Every time I start my engine, I get a "low voltage" warning on my dash for several seconds. The engine starts fine, but I just worry about that warning. And, if I may, when plugged in to shore power at home are both sets of batteries charging then. I swear I should know a lot more about this stuff. Guess I am just too damn old to start learning a new "thing." LOL

Your rig is a diesel and they have heater grids in the engine intakes that draw hundreds of amps at startup to minimize smoke. That heavy draw is what causing your Low Voltage light to light, normal.

[twinboat]

Originally Posted by Jarryr

I've had my Vista 27HE for 3 years and love it. I have a long history with alternator charging of the coach batteries with my previous 1989 Itasca class C. It had a manual switch to turn on and off the solenoid linking the coach and chasis batteries. Through 2 alternator replacements I finally learned how to best use it.



Now back to the present. I finally found a faulty battery mode solenoid which has limited the alternator charging of my coach batteries in my Vista. I thought it was being managed by some smart controller or BIRD but find no evidence in the wiring diagrams for any management system in the unit.



I am strongly considering installing a manual switch for on an off operation of the alternator charging the coach battery (engaging the solenoid). What I have found through testing is the solenoid closes immediately when the ignition switch is in the run position. In other words the alternator will be charging all 3 batteries once the engine started.



Here is my question. I am concerned about overheating the alternator with charging at idle speed. I am also concerned about charging the coach batteries at alternator voltage (14.1-14.4) once they are at 100%. Am I over thinking this or are my concerns valid?

Your overthinking it. The solenoid connects all the batteries together but your charging system can handle it. Your charged chassis battery is like a buffer.

An idling alternator will not output enough amps to overheat it. They need RPMs to get anywhere near full output.

[Sgt B]

Hey thanks guys, I really appreciate your replies, but what about on shore power, are both getting charged also

[Pillbox]

Semper Fi Jim,

Take a volt meter, unplug for shore power, no genny on. Check volts at the chassis and house batteries. Plug into shore power, check volts at house batteries, if higher, your charging the house batteries. Now check chassis batteries. If the volts are close to house batteries you are charging them also.
This infers you have a BIM or Bird type devise.
Unplug again, start vehicle, check all batteries again. Should be about the same.
All the while, you might here a clunck, about the same sound as salesman switch makes. That will be your solenoid engaging.

Low battery warning my also be 1 bad battery for your chassis.
This is assuming you have 2.
Disconnect both battery negative leads and check volts.

Terry

[wolfe10]

Yes, you need to verify with your digital voltmeter whether the chassis battery as well as house bank is charged from shore power/generator.


No "here is how they are all wired".

[Sgt B]

Originally Posted by Pillbox

Semper Fi Jim,

Take a volt meter, unplug for shore power, no genny on. Check volts at the chassis and house batteries. Plug into shore power, check volts at house batteries, if higher, your charging the house batteries. Now check chassis batteries. If the volts are close to house batteries you are charging them also.
This infers you have a BIM or Bird type devise.
Unplug again, start vehicle, check all batteries again. Should be about the same.
All the while, you might here a clunck, about the same sound as salesman switch makes. That will be your solenoid engaging.

Low battery warning my also be 1 bad battery for your chassis.
This is assuming you have 2.
Disconnect both battery negative leads and check volts.

Terry

LOL, come one Terry, you are talking to a dumb Grunt, a bird s something that has wings and flys?? LOL

[JChrisM]

To the extent that you have issues with the charging solenoid, you might consider a Renogy DC to DC Battery Charger.


It connects to the alternator circuit and controls the flow to the house batteries. It appears to prevent over charging of the batteries as well as preventing excess load on the alternator. Amazon has a description, including info from Renogy:



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


This may or may not be a good solution to your needs. I bought it for a similar issue, but traded to a different RV before I ever proceeded to installation. BTW, if anyone wants it, new in the box, I would sell it for $50 (about half). This is the 20 amp version.

[vsheetz]

I really don't think anything is needed. But if desired a switch can be inserted to interrupt the 12vdc IGN ON wire that activates the solenoid.

As for if the chassis battrry is charged when on shore power, check the chassis battery voltage with and without shore power active. If increases with shore power active - something is charging the chassis is battery.

[cbeierl]

Originally Posted by Jarryr

...
Now back to the present. I finally found a faulty battery mode solenoid which has limited the alternator charging of my coach batteries in my Vista. I thought it was being managed by some smart controller or BIRD but find no evidence in the wiring diagrams for any management system in the unit.
...

According to page 3 of the Chassis Electrical Box Assembly diagram for your coach you have a smart B(attery) I(solation) M(anager) which should be selectively connecting the battery banks together when either one is being charged so that all the batteries are properly charged.

I believe that this is the BIM in your coach: 00-10021-000-Battery-Isolation-Manager-RevF.pdf

[Mudfrog]

Originally Posted by Sgt B

LOL, come one Terry, you are talking to a dumb Grunt, a bird s something that has wings and flys?? LOL

It's always good to learn as much as you can about the rig. For this though, finding out if the chassis (starting) battery(s) is being charged on shore power is pretty easy. First, find the battery and take a voltage reading with the engine off and no shore or generator power. Then plug into shore power and take another voltage reading. The battery is being charged if voltage is higher.

On my older Itasca, the chassis battery does not get charged while on shore power.