Bounder: Chassis and house battery question

[classic60]

Greetings,
I am considering replacing the original AC Delco chassis battery on my 03 36S Bounder as I figure it's probably time after almost 8 years of use. While doing some routine maintainance on my house batteries, (adding water, cleaning terminals, etc) I disconnected the postive wire from the battery bank. Since my house battery bank consists of 2 Trojan 6 volt batteries connected in series, I figured I was going to temporarily lose 12 volt power to all the things that run off 12 volts in the house. I was surprised that in fact all of my interior lights, vent fan, etc. continued to run even with the bank disconnected. (shore power not connected)

Since I believe that the chassis and coach batteries have to be tied in some how, or else my converter/charger would not be able to charge both house and chassis, I wondered if in the absence of juice from the house battery bank, my house lights were running off the chassis battery.

In light of this, I was wondering if the system is designed so that the chassis battery provides additional "capacity" to my house bank, however slight it may be.

Additionally, if this is the case in fact, it would appear to me that replacing the original chassis starting battery with a deep cycle battery would give me additional battery capacity when I'm dry camping.

However, it doesn't make sense to me that this would work as I could run down both the house and chassis batteries leaving me with no way to start the coach.

What am I missing here? why would my house lights continue to work even when the bank was disconnected?

Any input would be appreciated. Thanks in advance.

[Johnnyd111]

Quote:

Originally Posted by classic60 Greetings, I am considering replacing the original AC Delco chassis battery on my 03 36S Bounder as I figure it's probably time after almost 8 years of use. While doing some routine maintainance on my house batteries, (adding water, cleaning terminals, etc) I disconnected the postive wire from the battery bank. Since my house battery bank consists of 2 Trojan 6 volt batteries connected in series, I figured I was going to temporarily lose 12 volt power to all the things that run off 12 volts in the house. I was surprised that in fact all of my interior lights, vent fan, etc. continued to run even with the bank disconnected. (shore power not connected) Since I believe that the chassis and coach batteries have to be tied in some how, or else my converter/charger would not be able to charge both house and chassis, I wondered if in the absence of juice from the house battery bank, my house lights were running off the chassis battery. In light of this, I was wondering if the system is designed so that the chassis battery provides additional "capacity" to my house bank, however slight it may be. Additionally, if this is the case in fact, it would appear to me that replacing the original chassis starting battery with a deep cycle battery would give me additional battery capacity when I'm dry camping. However, it doesn't make sense to me that this would work as I could run down both the house and chassis batteries leaving me with no way to start the coach. What am I missing here? why would my house lights continue to work even when the bank was disconnected? Any input would be appreciated. Thanks in advance.

Phew.. a lot to take in... yes, it was running off the chassis batt.

Do not replace the chassis battery with a deep cycle, they generally can not produce the cranking amps needed to start a vehicle.

while plugged into shore power, you may be charging both batteries through your converter.charger (assuming its a converter/charger)

also just a thought, your 12volt lighting may run as well with your chassis battery, but you may find that accessories do not.

[bluepill]

Various methods are used to "Bridge" the two banks under different conditions.

A solinoid is often actuated for emergency use of the house batteries to crank the engine if the chassis batteries can't do it alone.

The two battery banks have to be bridged for charging by the alternator - sometimes by solinoid, sometimes by isolator diodes.

The converter/charger may pass through some of the charging current to the chassis bank with a Trik-L-Start device.



Sounds like something is staying connected when it shouldn't. Because they are mechanical and subject to contact burning and sticking, the solinoid(s) would be my prime suspect.

[loulong]

Your Bounder uses a solenoid in the BCC to connect the chassis battery and the house batteries together in any one of the three following conditions:

When shore power, or generator power, energizes the converter/charger (and at least 13.2 volts is detected), the BCC will direct the Aux Start/Charge solenoid to pick thus connecting the batteries to charge the chassis battery as well as the house.

When the engine alternator reaches more than 13.2 volts, the BCC will again pick the solenoid to charge both batteries.

When the Aux Start switch is pushed (and held) the solenoid will pick, connecting the batteries to assist in starting the engine.

BTW - if you have low or dead house batteries, using the Aux Start will allow the generator to start and can be used to recharge the batteries via the converter.

I suspect the solenoid has "welded" it's internal contacts together, appearing to be energized all the time. The solenoid is easily and cheaply replaced.

Print this document http://dl.dropbox.com/u/15918372/BCC%20Package.pdf for instructions and diagrams to assist in diagnosis and repair.

[Gary RVRoamer]

I agree with Lou - your crossover solenoid is stuck "on", connecting the house and chassis systems. This is not by design - it is problem if you ever run without shore power on or the engine running. The chassis battery will be depleted at the same rate as the house battery and after a while you can't start the engine.

[classic60]

Thanks for the information and trouble shooting guide. Gonna have to look into this further as I believe that's it's probably related to problems with my battery disconnects as well.