burlmart
Baton Rouge
Senior Member
Joined: 03/28/2005
View Profile
 Offline
|
From experimenting with measuring the voltage and charging the newish house (coach) deep cycle battery and the 4-5 year old AC Delco engine (chassis) battery, I have discovered that the house and engine batteries are connected together.
* With the house battery terminal cables attached, both batteries have the same voltage.
** Both batteries charge with an external charger (house battery disconnect switch off), or likewise they both charge with shore power thru the onboard inverter/charger (house battery disconnect switched on).
*** Disconnecting the house battery cables and taking a voltage reading across them gives me the chassis battery voltage – they are alive.
Can this be so? If so, why did they put an emergency start toggle switch on the dash?
I looked thru the archives and see hints that some Rvs have a coach to chassis battery charging connection, but not much detail as to how this acts with the house battery disconnect switch or the emergency chassis start toggle switch.
Can someone help and explain what I am looking at?
2005 Trail Lite 213 B-Plus w/ 6.0 Chevy
|
YC 1
Yuba City Calif.
Senior Member
Joined: 01/11/2005
View Profile
Offline
|
On my Mh anytime there is voltage above a certain point either from the alternator running, shoreline power charging, or the solar panels putting out enough, there is a solenoid that is pulled in to charge all batteries. This same solenoid is my emergency start solenoid as well. The darn thing gets very hot and draws over an amp to stay energized. I replaced it once because there was a 1 volt drop across it. I took it apart and found the contacts very green and contaminated. I cleaned them and reassembled it for use in the future.
H/R Endeavor 2008
2007 Hummer H3 toad
Ranger Boat
|
carringb
Corvallis, OR
Senior Member
Joined: 07/28/2003
View Profile
Offline
|
The emergency start switch is probably a carry over from the Ford chassis, which isolates the house battery via the auxiliary batter circuit. Chevy does not have an auxiliary battery circuit, so unless an isolator is added after-market, they will be in parallel.
Bryan
2000 Ford E350 DRW Wagon (14-pass all captains chairs)
V10 w/ Banks PowerPack, Diablo Predator, 4.56 LS, 250,000+ miles
Had: Weekend Warrior 41' FSW
|
Gene in NE
Omaha
Senior Member
Joined: 09/15/2003
View Profile
Offline
|
burlmart wrote:From experimenting with measuring the voltage and charging the newish house (coach) deep cycle battery and the 4-5 year old AC Delco engine (chassis) battery, I have discovered that the house and engine batteries are connected together.
* With the house battery terminal cables attached, both batteries have the same voltage.
** Both batteries charge with an external charger (house battery disconnect switch off), or likewise they both charge with shore power thru the onboard inverter/charger (house battery disconnect switched on).
*** Disconnecting the house battery cables and taking a voltage reading across them gives me the chassis battery voltage – they are alive.
Can this be so? If so, why did they put an emergency start toggle switch on the dash?
...
Can someone help and explain what I am looking at? Wish we had a wiring diagram. We have the same RV manufacturer, similar size; but mine is 3 years older. I have not checked the voltage at each battery, but the operating scheme seems like the batteries are connected with an "isolator" that connects them together only when the engine is running. This to allow the engine alternator to charge the coach battery. I was under the impression that shore power would not charge the chassis battery - never checked. I once drained the coach battery by not setting the storage mode that disconnects the coach battery from the coach. I tried charging the coach battery by plugging in shore power. It did not charge the coach battery until I clicked the "use" mode. I know there are at least 2 if not 3 solenoids on mine. There are 2 right next to the coach battery and it sounds like one clicking right behind the wall of the "storage or use" mode switch.
You could have a faulty switch or solenoid or ?????
2002 Trail-Lite Model 211-S w/5.7 Chevy
Gene
|
burlmart
Baton Rouge
Senior Member
Joined: 03/28/2005
View Profile
Offline
|
Interesting posts...
The house battery isolator switch (a.k.a. house battery disconnect switch) is located just inside the RV house door near the step with a USE/STORE toggle switch (and a red LED light); toggled to USE, it causes a click sound near the house battery (solenoid, I guess). It seems to isolate right (it has never let the battery (batteries???) drain while switched to STORE at the storage shed, and all DC-powered things are unpowered.
And, when the RV is plugged in to shore power (AC house), the two batteries charge (their voltages go up) when the switch is toggled to USE; then, if toggled to STORE, the batteries' voltages drop down.
Curiously, the red LED light of the house battery isolator switch stays on regardless of the USE or STORE setting when plugged into AC shore, but when unplugged from AC, the LED is off when toggled to STORE, and it is on when the switch is toggled to USE.
The emergency start switch is located prominently to the left of the three cupholders atop the doghouse console between the two cab seats. I assume this console is put in by Chevy and then it would seem like R-Vision would have to decide whether or not to add in the emergency start toggle switch. It seems then that, like Gene said, there would be something like an isolator that this switch overrides.
|
|
|
tenbear
Northern Vermont, USA
Senior Member
Joined: 08/11/2004
View Profile
Good Sam RV Club
Offline
|
My Chevy has a solenoid that connects the coach battery to the chassis battery when the ignition is turned on, otherwise, they are not connected together. It looks like the solenoid was added by the MH manufacturer. When plugged in the two batteries are separate.
The battery disconnect switch disconnects the coach battery from the converter but it is still connected to several other things. The light on the disconnect switch is on anytime there is 12 volts in the coach circuits whether it is coming from the battery or from the converter.
2004/5 Four Winds Dutchman Express 28A, Chevy chassis
Subaru Impreza Outback
|
burlmart
Baton Rouge
Senior Member
Joined: 03/28/2005
View Profile
Offline
|
This morning, I put a charger on the engine battery, and found it did not change the house battery voltage, so there does seem to be some type of isolation after all – at least one-way. Reassuring.
Also today, unlike yesterday, I did not get a voltage reading across the house battery cables after detaching them from their battery terminals. Maybe all my probing inadvertently freed-up a 'stuck' solenoid...Maybe Quantum Effects!
For sure, when plugged in to AC shore power with the house battery isolator switch toggled to USE, both batteries are charging.
Still some things puzzle me, and may be very related:
1) Does higher house battery voltage automatically flow to the engine battery, and if so, what does the emergency start switch do? And will a bad chassis battery drain the house battery down.
2) When I charge the house battery with an external charger, why does it do so much quicker, naturally, and predictably if it is disconnected from the house cables? (Even though the battery isolator is set to STORE).
A separate question...When should I replace a 4-5 year old original AC Delco battery? It still seems fine, but usually reads 12.5 V whenever I check it.
|
markbrumbaugh
Spring, Texas
Senior Member
Joined: 09/01/2006
View Profile
Good Sam RV Club
Offline
|
You have a bad solenoid on the emergency start switch to put house power into the engine.
Patriot Guard, USA Ice Hockey Ref and Level 4 Coach, Reg Prof ChE
Hunting, Fishing, Lakehouse, Grandkids, Kids, Camping
Vulcan 900, Morphous
|
Harvey51
Alberta
Full Member
Joined: 12/11/2006
View Profile
Offline
|
I would keep the Delco battery for another year or two. 12.5 V is good, indicating 90% charged according to the chart at
http://www.ccis.com/home/mnemeth/12volt/12volt.htm
Shore power charging the engine battery could result in overcharging when you are parked for more than a few hours. Not good for the battery. I would be tempted to simply disconnect the emergency start wire rather than replacing the relay. If you can find it. You could always connect it again in an emergency.
2004 Adventurer (Canadian) 20 footer
|
burlmart
Baton Rouge
Senior Member
Joined: 03/28/2005
View Profile
Offline
|
Harvey, I will follow your advice on the Delco battery, thanks.
I am becoming convinced that my interest in metaphysics and Rving has led to a situation where Quantum effects are what I am measuring...different time-different phenomena. Day 3 seems to match day 1.
Today, with the house battery isolator toggle on STORE:
**1)initially both batteries settled into an equilibrium voltage of 12.61V house, 12.54 engine (this 0.05-0.07V difference was consistent throughout all subsequent readings)
**2)placing the external charger first on the house battery (at which point I happened to hear a click like a solenoid-maybe significant?), the voltage on the engine battery indicates it is charging as well
**3)placing the external charger nrxt on the engine battery, the voltage on the house battery indicates it is charging (unlike yesterday, when, starting with the charger on the engine, the house battery did not charge)
Turn on engine:
both batteries are getting well over 14 V alternator charge. Generator will not start with isolator toggled to STORE, but it does when set to USE.
With engine off, generator on:
genset charges both batteries with the isolator toggled to USE, and charges neither with it toggled to STORE. Same thing with genset off and on shore AC power.
Yesterday, I did not read a voltage across the house battery cables when disconnected from terminals, but I surely would have today, as I did 2 days ago.
Is everything above confirming what Markbrumbaugh says - that the emergency start solenoid is bad? FWIW, we have never even needed/used it.
I am not actually having any problems. I just never understood why a fully charged house battery does not maintain its 12.75V reading or its full charge for even 24 hours when hooked to house cables and isolator set to STORE. I bet if I put an on/off switch at the house battery positive terminal, the battery would keep its full charge for at least a couple weeks.
* This post was
edited 09/30/09 01:46pm by burlmart *
|
|
|
|
