C34 Electrical Systems
Just a couple of comments on the previous few posts.
1. Battery combiners are wired between the battery banks, NOT "between the alternator/regulator and the battery banks."
They essentially take the place of the 1-2-B switch. The description below is from the West Marine Advisor at:
http://www.westmarine.com/webapp/wcs/stores/servlet/WestAdvisorDisplayView?advisor=464-465.htm *******************************************
How do I charge both banks simultaneously?
By isolating starting and house banks, you face a challenge trying to charge them from a single source like single-output chargers or alternators. If you violate the "separation" of the two banks, you face the probability of two dead batteries due to "operator brain-fade". That's why we are great believers in the West Marine Battery Combiner and Heart Pathmaker, Balmar Dual Output Alternators, and to a lesser degree, battery isolators. These products sense the voltage of the battery banks and connect the batteries together whenever one battery's voltage is elevated. Both banks charge simultaneously and remain combined until the voltage drops, whereupon they are disconnected from one another. It's much like having a very attentive engineer flip your battery parallel switch on and off at exactly the right moment. The result is maximum charging performance for two banks, and complete isolation of the two banks to ensure that you can start your engine.
Do I have to scrap my present switch?
While you don't have to, we strongly recommend the use of simple-to-understand OFF-ON switches. Shoot, even your brother-in-law can probably figure out how to operate an OFF-ON switch, but might be completely baffled by a OFF-1-BOTH-2 switch. Alternatively, you can use your current battery switch, plus a second OFF-ON switch, but we think it becomes complicated to understand what each switch combination accomplishes. As an added benefit, the fact that the battery switches are seldom, if ever, operated while underway greatly reduces the chances of damaging your alternator by accidentally opening its output circuit.
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Battery isolators take up voltage, and shouldn't have to be used since they are way old technology. You could use the switch or a combiner FOR A SINGLE SOURCE OF CHARGING INPUT. But remember, it's ONLY because of "brain fade" in forgetting to switch the 1-2-B switch!!! If you can remeber to do that, you don't need a combiner or an echo charger! Islators are crazy: I ripped the iolators out of our boat when I first bought it. They drop between 0.6 to 1.0 volts. Why ever consider them?
I personally disagree with West's idea of the battery switches. I discussed this in the earlier referenced post with Kyle Ewing. If you can remember to switch the battery switch, why spend the money for extra switches? However, if you're redoing everything, it's not a bad idea for simplicity or if you're "switch-challenged." (more brain fade...) On our engine kill lever, I have a little Dymo label says; "2" - it reminds me to switch the battery switch if I start on our start battery #1. Once the engine is off, just use the house battery.
2. Reference to Calder's comments on paralleling batteries: Yes, he did say that. However, you need to take it in context because he also goes on to talk about large house banks, the complete text of which I've posted on this board at least twice. (Search on Calder, you should be able to find it.) Sure, a cell can go bad, which is what started this thread in the first place, but even Calder's answer is just take that battery out of the system. How can you ever build a large house bank without paralleling batteries? Also, two 6V batteries in series could have the same problem, or more than one battery in any bank, for that matter. The idea is to maintain your batteries with a reliable charging system.
3. "...discusses charging with a single alternator output and even two alternators but he doesn't cover much about how to add an AC charger in the circuit."
Ron, think of it this way: The charger and the alternator SHOULD NOT BE ON TOGETHER - ever. You don't add it INTO the circuit between the alternator and the bank, it is a separate source. Then the concept is simpler.
The shorepower charger, whether multiple or single outlet, charges the batteries when you're plugged in. The alternator charges when you're running the engine.
I think I understand your concern which is: "What happens when I use a multiple output shorepower charger IF I have installed a combiner to split the charge from the alternator? Won't the combiner combine when the multiple shorepower charger is on? Will this harm the system?" You could install a shutoff switch on the combiner for when you are using the shorepower charger, but this adds complexity and another switch, which is what you are trying the AVOID in the first place! BTW, the combiner literature does cover this and includes the idea for the switch.
Go back to my discussion above.
You have two choices: use only one output from the charger to the house bank, wire the alternator to the house bank, too, and use the combiner or get an Echo Charger. The advantage of the echo charger over the combiner is that you won't overcharge your starting battery. One of our electrical guru's was recently cruising in the Abacos and found that the combiner overcharged his start battery when motoring for enough time to replenish his house bank. That's why the echo charger is better, since the start bank is almost always full.
4. "Many do not motor nearly long enough to fully charge the their battery banks so most of the work is done at dock side by the AC charger. For these folks a good charger is well worth the extra expense."
That's correct. IF you still have the original internally regulated OEM alternator and you don't have an external regulator for your alternator. We've also discussed this in great length. Do a find on alternators, regulators, etc. Also, Calder explains this in detail in his book. Automotive regulation just doesn't work for boats, which is why many of us are still so disappointed that boat manufacturers continue to produce electrical systems that are prone to immediate failure right out of the box. Geez, two lousy small batteries, with plasma screen TVs, refrigeration, lights galore. It boggles the mind, and makes these discussions necessary. Welcome, but necessary. This is a fascinating topic.
Just to summarize: as we've said before ONLY YOU can determine how you plan to use your boat. If you're plugged into marinas (your choice) much of this "how do I charge with my alternator?" is absolutely meaningless to you. However, if you like to be out and away from it all for extended periods, AND you don't want to use the 1-2-B switch to manually parallel your charging from single sources like alternators and solar, then you get involved in combiners and echo chargers. It CAN all be done manually, too, don't forget.
Last, but NOT least, IN ANY EVENT, get a darned good charger, which, in our (C34) combined experience, is the Statpower Xantrex 20 or 40, or a Trace or Heart combined inverter charger. If you don't you'll end up spending $$ on replacing batteries. Why not keep the batteries and get an instant return on investment with a quality three stage charger. This applies to any kind of use of the boat.
Stu
PS Ron, a representative wiring diagram is on the Projects page:
http://kindred-spirit.net/upgrades/wirediagram.html It has a combined inverter charger with a combiner. You'll not that the alternator and the charger are wired to the house bank. If you sketch it out for your boat, it may help you figure this out.
