Quote:
Originally Posted by LIforrelaxin
Boat Guy 64,
I want to thank you for putting the information out there. The truth is always good to know. I am glad to know that the proper investigation was completed, and the true root cause was found. As an electrical engineer, I am dam disappointed that the wiring on the boat, even has the possibility of being miswired like that. Hopefully Cobalt has since redesigned there wiring for a dual battery set-up.
I hope that your friend has continued to boat as well and that this Mishap hasn't discouraged him away from boating. This indeed could have happened to any of us.
Accidents happen folks....Even in a Colbalt.....
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As a general rule I thought the bilge pump was supposed to be wired to one of the batteries, no switch (other than the float) involved. I suppose you could wire to both batteries via an "isolator" (aka diodes) but I've yet to see that done. I don't
know what happened in this case but let me suggest a few possibilities.
First lets assume a leak of some kind is filling the bilge and engine compartment. Seems to the case given what we've heard. Now lets say the pump is wired to one of the batteries and the boat is switched to, and running off, the other battery. So why doesn't the bilge pump "work" ? Well perhaps it did and that batttery ran until it was dead. Now the water comes in unabated and the boat goes down. The pump won't run until the battery switch is set to "both". Why ? What's happening is the voltage is now being sent from the good battery through the switch to the terminal of the bad battery. While the bad battery loads the circuit down, the good is strong enough to run the pump. Alternately the connection between the clamp and the (bilge pump) battery terminal could have been corroded or even disconnected. The end result is the same, the pump wouldn't run until the switch was set to "both".
As for proper operation of the switch ... as OCD said it depends. I run off 1 battery one day and then the other the next day, cycling so as to charge both. If I'm making a long run I'll switch to "both" to charge both batteries but I try to remember to switch back to "off" (or just 1 battery) when I'm done so I can't kill/drain both batteries while on the hook or at the dock. Really the best thing to do is get an automatic charging relay (ACR) and let it do the switching. The ACR disconnects the secondary batt when the engine is off. When the engine is on and the voltage is "high", a relay connects the secondary battery so it get's charged as well. If you run all your "accessories" off the secondary battery then the ACR will prevent you from draining the main, starting battery whilst listening to tunes at the sandbar.
What this thread has reminded me to do is to get a bilge pump alert that let's me know if the pump is on, or has been on in my absence. And ideally for how long. And mebbe I should make a relay circuit to switch the pump(s) from battery #1 to battery #2 if #1 ever goes dead for some reason. Might as well give the pump(s) every opportunity to save the boat ... if needed.