BAC Forum
General Boards => Technical Support => Topic started by: steve zannella on March 01, 2015, 07:09:46 PM
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About 4 years ago I changed my chassis and coach batteries and noticed after the battery replacement that my back up camera a weldex 7057c, $280, didn't work. At the time I didn't associate the battery change to the camera demise until recently when I changed the batteries again and guess what the camera died again.
When I changed the batteries shore power was not connected, the inverter was set of off, both battery disconnect switches were off, the solar panels were covered and I disconnected and reconnected the hot battery leads first. I did notice arching when reattaching the ground cable on the coach batteries.
At this time I'll disconnect the camera before I do anything unless someone knows what went wrong.
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Steve-
I can't speak to the camera issue, but as to a safety issue whenever I deal with battery connections on any chassis-grounded configuration, my rule of thumb is remove the grounded cable first and put it back last. You said you disconnected the positive cables first.
As long as the battery is connected to the chassis, it leaves open the chance of accidentally short circuiting with a tool from positive post to surrounding chassis metal - it's essentially equal to laying a crescent wrench between the two posts. With the ground disconnected, electrons have no pathway back to the negative side if your wrench or a screwdriver handle touches anything while working the positive cable.
Even with switches and solar off, there can still be something on line, such as drivetrain ECM's, that isn't subject to the switches. So there can still be a slight arcing, but I'd expect it most likely with the chassis batteries. It sounds like you covered all the bases prior to, so I'm not sure what would be bypassing the coach main switch to the battery bank unless it's some aftermarket add-on. Is the camera routed properly through a circuit breaker and terminal buss in the electrical bay?
Joel
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Joel,
I should add the chassis batteries were connected with the main switch off when I changed the coach batteries and there are several wires connected to the positive terminal of the chassis batteries. The coach batteries only have 1 power wire connected to the positive terminal.
I also determined the camera power is somehow connected to the alladin system because when the alladin is powered down the camera also powers off either by relay or direct connect to the alladin system. If there was a power surge it must have come from the alladin system or its relay.
I'm wondering if I could install two diodes before the camera protecting the pos and neg wires.