This Forum is supported by C&C 27 owners like you whose membership in the C&C 27 Association makes possible this Forum and the accompanying site. Thank you, members, for your continuing commitment.
You are not logged in.
Pages: 1
C. David Sandford, in Ontario Sailor advises use the switch for proper battery operation.
The article advises not to use the Both switch. What is the electrical engineering principle to support that instruction?
Why is it better to use Battery #1 alone and Battery #2 alone?
Aloha
Last edited by (2010-03-13 02:50:29)
Offline
A lot of boat electronics info is changing, so take this with a grain of salt. Ont. Sailor's writer advises switching to battery 1, a cranking battery, to get the engine going and leaving it there as long as you are under way. This battery is recharged by running the engine. At the mooring, you cut over to 2, the house bank of deep-cycle batteries, used only for lights, etc. This bank is only recharged by plugging in to shore power (which is fine if you spend a lot of time hooked up on shore, questionable otherwise).
Why the rigid separation? As I understand it, when a discharged battery is connected directly to a charged battery, the two will equalize, leaving you with two half-discharged batteries. Ideally, the battery banks should be separated not only by a switch, but also by a battery isolator, which prevents current flowing between them if you should switch to "both", deliberately or inadvertently.
It's not clear what the writer means by "isolator", but there are options. The traditional, simple diode ones unfortunately reduce the alternator voltage to the battery by a small but significant percentage, so your batteries re-charge at a glacial rate unless you fit additional voltage controllers to your alternator. New, more sophisticated isolators sense the voltage from the alternator and on both batteries, diverting power where it's needed while preventing unseemly dumping of the charge from one battery to another. They are surprisingly reasonably priced.
I have an inexpensive battery combiner that performs part of this task admirably, but I've written about this elsewhere (search "combiner" in the Message box on the search page).
There's interesting information about batteries on the West Marine site, but you may find that some of their advice is overkill for the way many of us use our boats.
http://www.westmarine.com/webapp/wcs/stores/servlet/westadvisor/10001/-1/10001/Battery-Combiners-Relays.htm
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
Offline
David Weatherston explained the function of the new "sophisticated isolator" technology. My interpretation suggests the following.
Discontinue my old practice of starting the engine with the BOTH SWITCH.
I will use the Number 1 Switch to start the engine to exit the harbour- to recharge Battery 1. I will use the Number 2 Switch to start the engine to re-enter the harbour- to recharge Battery 2.
Would that be prudent for the casual sailor?
Last edited by (2010-03-13 07:25:58)
Offline
I wouldn't do it that way if I were you. Neither battery is going to be fully recharged by the process of entering or leaving harbour unless you've got some distance to go and you're able to go at a speed that lets the alternator put out its rated amperage. With your scheme, what you'll probably end up (when least convenient, naturally) is two rather depleted batteries.
The advice I've always read is to have a starting battery for starting and a house battery for (housing?) and don't mix the two unless the starting battery fails you. Test them from time to time through the season to monitor their charge state and top them up when necessary.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
Last edited by (2010-03-13 08:44:26)
David Weatherston
Towser, Toronto
C&C 27 Mk IV
Offline
Back in the dark days when electrics were primitive and all C&C's were essentially brand new, I was trained that you switched to battery 1 (the starter battery) to start the engine, switched to "Both" while the engine was running (so that both batteries would charge) and then switched to battery 2 (the house battery) when the engine was stopped and you were sailing. This was supposed to guarantee that the starter battery would always have sufficient power to start the engine for propulsion and charging. Unfortunately, in whatever excitement was happening around the start line, people would tend to forget to switch from "Both" to battery 2, meaning that both batteries would be getting drained for the radio, instruments, nav lights, etc. On one memorable overnight race, one of our club boats had to use a cell phone to call the clubhouse and request that someone transport a battery out to them because they had remained on the "Both" setting all night long while they played the stereo at significant amplification. They no longer had enough juice to even make a call on the VHF.
For the last several years, my practice has been to simply switch to battery 1 on odd-numbered days and to battery 2 on even-numbered days. This balances the charge-discharge cycles between the two batteries, ensuring that both of them have as long a lifetime as possible. The batteries are identical Series 27 Deep-Cycle units and have no problem starting the Atomic 4. I no longer have to worry about both batteries getting drained out or about maintaining distinct house and starter batteries. As a system, I am quite happy with this approach and my 6-year old batteries are still going strong. If I were more of a cruiser and wanted to maintain a larger bank of house batteries, then I might opt for one of the dual-circuit switches with a built-in isolator, but my current system has the advantage of being simple and of guaranteeing that I always have a starter battery in reserve. This provided real peace of mind for the 3 days non-stop sailing on the Lake Ontario 300 last summer.
Marcus from Carriden
Mk III, Hull #847
Oakville, Ontario
Marcus Opitz,
Formerly from Carriden, Mk III, Hull #847,
now skippering "Everdina," a 1975 Ontario 32
Offline
A group 27 spins my little Yanmar admirably so I no longer make a distinction between starting and house batteries.
One thing that might be worth consideration, especially since much of the fleet will be returning to the water soon, is to remove and throughly check your main battery switch. When I purchased Wind Horse, I found that the switch "leaked" a lot of current in the off position. Replacing the switch added a lot to battery life.
Mike M
SV Wind Horse
#375
Galveston, Tx
Mike M
SV Wind Horse
#375
Galveston, Tx
Offline
Pages: 1