MATTOO wrote: Great subject. I think I have my own problems around this, still investigating hence my interest. A couple of things I've noticed in posts. Checking current between battery pos terminal to hull. Not sure that is helpful to determine leaks with battery isolator switch off. If you think that through it's not a necessary valid test. Krow points to using the bus bar, from the positive to well what should be the neg bus bar with isolator switch off. Now that makes sense to me and is the test I would do. I have had a boat that completely isolated the engine from the pod. Somewhat expensive. Though I did it at the time for harmonics. bigfishbob. Was there a particular reason for a teardrop shaped anode or just a recommendation to use an anode. Another question that has occurred to me is some of my tech requires grounding, this is different to a negative grounding. So is this grounding in an alloy boat to the hull of a seperate form of grounding. |
Kandrew wrote: Yep this is right the battery switch should completely isolate the battery, so things don’t sound right. Can you see if any electrical works or if the starter with the battery switch off. If you want you can PM me your number and I’ll give you a call. |
Alan L wrote:
It makes perfect sense to me that I would get battery voltage by going from battery + to hull. As Krow states. The battery + is looking for an earth to ground to. The hull is a large block of metal. Perfect earth. Isolating sw on or off should not make any difference here? But I will check tomorrow at a +Ve bus connector and hull with isolating sw off. Should be zero - or mV. I think the trick is not to get a connection between your hull and the engine earth system. This will operate while the + circuit is live throughout the boat - isolating sw On. I installed 3 teardrop anodes in the hull about 8 yrs ago - worried about corrosion. Yes - some of the stainless bolts have frozen to the hull. But then I have stainless bolts all over the boat - incl the motor mounts. Dunno how you avoid them. Regards Alan |
Alan L wrote: I have no electrics when my isolating sw is off. My isolating sw disconnects the + side of the feed ONLY. The earth cycle goes straight to the battery. So there is a continuous + feed (on) or not (off). The -ve wire in my system goes nowhere near my isolating sw. Direct from the motor to the battery. You only need to break one leg of the cycle? Regards Alan |
Alan L wrote: Yep - agree. Either or. In my case it is the +ve that is broken. Will post some results tomorrow. Altho the boat is dry right now - windy. It should be worse mV reading in the briny - the transom is partly submerged. Will do both when I can - hopefully in a few days. Salt water is a great conductor. That is part of the issue. Pure water is a poor conductor. That is why fresh water is not so bad. Not perfect - but better than salt. Deionised water, in theory is a very poor conductor. I will do both tests over the next few days - depending when I can drop the boat in. Regards Alan |
krow wrote: Bigfishbob keep an eye on that anode as the bolts may cause corrosion to the hull. I had this issue. |
MATTOO wrote: Great subject. I think I have my own problems around this, still investigating hence my interest. A couple of things I've noticed in posts. Checking current between battery pos terminal to hull. Not sure that is helpful to determine leaks with battery isolator switch off. If you think that through it's not a necessary valid test. Krow points to using the bus bar, from the positive to well what should be the neg bus bar with isolator switch off. Now that makes sense to me and is the test I would do. I have had a boat that completely isolated the engine from the pod. Somewhat expensive. Though I did it at the time for harmonics. bigfishbob. Was there a particular reason for a teardrop shaped anode or just a recommendation to use an anode. Another question that has occurred to me is some of my tech requires grounding, this is different to a negative grounding. So is this grounding in an alloy boat to the hull of a seperate form of grounding. |
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