Chassis Batteries

[Dennis Crawford]

Folks,

I am still fighting the dead chassis batteries in my '05 Monterey.  The coach is quite a distance away, having the 3M mask replaced.  Anyway, the batteries were removed today, and taken to Interstate.  They tested fine, but definitely needed a charge.  I just cannot figure out where the drain is occurring.  I was thinking a loose ground, but she starts right up with the boost switch.  I was also thinking that since the batteries really died after the first week, they never had a chance to fully charge.  And the other thing I am thinking about is the continuous duty solenoid up in the electrical bay.  I have had issues with those things not engaging.  I am wondering if the one I have in there now is not disengaging.  All these words for just one question.  If you use the boost switch to start it, I am assuming that just sends positive power to the starting batteries and the chassis battery ground is used.  Any help will be appreciated.  If it warms up here in sunny Florida, I should be able to get my coach back next Monday.

Dennis

[Gerald Farris]

Dennis,
When you use the "boost switch", you are combining the positive terminals for both of your battery banks, and as such, this leaves the ground circuits for both battery banks still active. So either ground circuit, or both ground circuits are used to complete the circuit.

Gerald  

[Edward Buker]

Dennis,

My assumption is you have a Cat engine with a CPU. That unit stays powered and draws enough current to kill starting batteries in a few days. The only way to avoid that is to remove the + or ground terminals from the starting battery bank. If you have a chassis battery bank power switch it will cut power to other chassis items in the coach but the CPU power bypasses that switch and remains powered in the off position. If your coach stays plugged in and you have a way to keep the banks tied together, or an echo charger, you will avoid the discharge problem. If you do not have a way of leaving the coach plugged in you will need to remove a battery lead or rewire the CPU power feed so it goes through the chassis battery switch.

A loose ground may keep you from starting without the boost switch but it would not likely cause the batteries to be dead. The ground would have to be so loose that it would not pass a few amps of charging current. That kind of looseness would be very visible.

later Ed