I also installed an EC and it was my understanding from previous posts from Maine Sail as well as the EC manual that unless all charging sources-including the Alt are led to the House Bank, the EC will not charge properly. I don't want to misrepresent what MS has said on this topic, so perhaps he can clarify...Just wanted to thank everyone on this thread, it helped solve a wiring issue on my boat. The boat is a 2006, sometime in 2008 a Generator and a 4D House battery were added. I could not figure out what position on the switch was house no matter which battery I disconnected 12 volt side had power. After digging into the issue I figured out that the yard wired the start battery to the common post on the 1/2/B switch, still not sure of everything they did. They also wired the battery charger is such a way that all 3 banks on the charger were charging the batteries, boiled the starting battery, a flooded group 27. Replaced the starting/reserve with AGM 31, the 4D is testing good so far. Wired the shore charger to just charge the 4D, no charger on the reserve, I have an echo charger and battery monitor arriving tomorrow to take care of the starter/reserve and monitor the house. I will not run the AO to the house battery but let it flow via the cable from the engine starter, I am the only one who touches the switch and have enough sense to not go to OFF when the engine is running plus I can charge the starter/reserve if needed. I may run the AO to the house in the future; I have to see how this setup works. Great learning experience. The Echo and the Mon. was just handed to me, arrived a day early.
Here's what he said:I also installed an EC and it was my understanding from previous posts from Maine Sail as well as the EC manual that unless all charging sources-including the Alt are led to the House Bank, the EC will not charge properly. I don't want to misrepresent what MS has said on this topic, so perhaps he can clarify...
The paragraph #5 that you quoted simply was explaining the deficiencies of the Dual Circuit switch, and not those of the simple 1-2-B or the 1-2-B plus separate reserve bank switches, both of which allow either/or switching of the two banks. You might want to consider going back and rereading the whole concept.This is the only thing that concerns me about wiring the alt directly to the positive post of the house bank. In the event of a shorted cell in the house bank it appears we have lost the ability to charge the other bank. I don't see anyway to keep the start battery up enough to keep the refer cold and nav systems on line for several days to get back to civilization. I would hate to lose the meat in the freezer ($) or the ice cream (not a lot of investment but a scoop of ice cream on a hot afternoon makes me feel like one of the rich guys). What would you suggest as the simplest or least expensive way to deal with this? Possibly a 3 way switch on the alt + lead?
Ideally the alternator & other sources would be wired to a positive charge bus bar and there would be a battery compartment ON/OFF switch to isolate the battery from the charge bus. You can then pull the house bank fuse and use combine to direct alt current to the start but an additional ON/OFF and charge bus is the best course of action.First, Thanks Maine Sail for your time and expertise on these forums. Yours' is always the voice of reason and sound consideration of your experience.
With the alt + wired directly to the house +........
'#5 With a bank failure, such as an internal short, it forces the user to use the "BOTH/COMBINE" feature and combine a good bank with a failed bank. This can leave a boater dead in the water as it did for one of my customers as recently as last summer. That customer has since switched back to a 1/2/BOTH/OFF with a second ON/OFF for engine start isolation. It is more complicated, as he has two switches to turn ON & OFF, but he has more comfort in knowing he has redundancy and full isolation without the need for using the "BOTH/COMBINE" feature, the same feature that left him dead in the water.. While these failures are rare they can & do happen. Short of re-wiring the system, when a battery dies, you have no way to isolate a bad bank."
This is the only thing that concerns me about wiring the alt directly to the positive post of the house bank. In the event of a shorted cell in the house bank it appears we have lost the ability to charge the other bank. I don't see anyway to keep the start battery up enough to keep the refer cold and nav systems on line for several days to get back to civilization. I would hate to lose the meat in the freezer ($) or the ice cream (not a lot of investment but a scoop of ice cream on a hot afternoon makes me feel like one of the rich guys). What would you suggest as the simplest or least expensive way to deal with this? Possibly a 3 way switch on the alt + lead?
If that fuse blows, YOU NEEDED IT TO !!!!!I have a question about the cable going from the alternator directly to the house bank. If that cable is fused and the fuse blows while the alternator is charging, wouldn't that blow the diodes in the alternator, just like if a selector switch gets turned Off? Is anyone aware if that has occurred?
Thanks
And when they work, they sometimes only work once. No one ever knows it is blown so if they do it a second time pop goes the alt... I have seen alts with Zap Stops with blown diodes...FWIW, Balmar sells a "transient spike protector" that may save your alternator diodes if the fuse blows. It's basically a sacrificial diode that runs between the positive and negative terminals of your alternator and costs about $20.
I'm slow to get back here but thanks. Running it to the positive "battery direct buss" will be easy and cheap.Ideally the alt would be wired to a positive buss bar. You can then pull the house bank fuse and use combine to direct alt current to the start..... There are many was to handle that situation but the situation is rare enough that removing the house bank fuse is one that will work. You need to isolate the bank anyway to figure out which battery is the shorted one.......
Great thread.If that fuse blows, YOU NEEDED IT TO !!!!!
If the alt output shorted to ground, without the fuse, you would also damage the alt and likely start a fire because the batteries are now feeding the short......
A properly sized fuse for an alternator will be at least 150% of its output rating...
The fuse for an alt wire ALWAYS goes at the battery end of the wire, preferably within 7" of the positive battery post....
Any properly installed direct wired high output alternator should already have wire that can easily handle a fuse at 150% of the alts output rating.. Key words there are "properly installed"... If not properly installed then you would use max ampacity tables and may need to use the 150% rule if necessary...Great thread.
Question: shouldn't the properly size fuse for an alternator be the right size to protect the wire? I know this may be nit picking; maybe sized for the wire, or 150% alternator rating, whichever is lower?
Thanks,
jv
"Breaking a thread" is called "hijacking" it - to change the subject. That's a no-no. Novice, post your own question and start your own new thread. That's a yes-yes.Sorry to the break the thread...help a total novice...