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This is basically an alternator question. I have the typical battery switch OFF, 1, BOTH, 2. This is a mechanical switch designed to make contact with the BOTH position while still making contact with Bat 1 or Bat 2. So the question is will the alternator be damaged if I switch from Bat 1 to BOTH and then to Bat 2?? The alternator will always see a battery when doing this but there may be change in voltage from one battery to the other and also when in the BOTH position. I called Balmar and could not get a straight ans....they recommended a dual batter isolator. I still want to know if the alternator will be damaged and if so why? Thanks for your help
I can't see how it would be damaged. All modern battery switches are make-before-break switches. As long as you don't pass the off position while switching, go for it. If you want to be sure, turn on a light with the engine off, then slowly rotate the switch and see when the light goes out.
DO NOT DO THIS. You may only switch from 1 battery bank to the other or both if the switch has alternator field disconnect. You will burn out your alternator with even a momentary break in connection from your batteries.
As SteveInMD noted: If it's a modern switch: It should be make-before-break. Problem is: Switch contacts wear. Also, as Steve noted: If you accidentally go past "1," to "OFF,": *poof*. I accidentally did that the other day, but we were not motoring, so all that happened was we lost our instuments and so-on. My recommendation is: Don't switch the switch whilst motoring.
Switch from "OFF" to "ON" and the starter battery's connected to the starting system--the house bank to the rest. The echo charger will ensure both get charged, regardless of switch position.
Ebs..
the OP made a -good question. I am curious about it too
I've had the red wire coming out of my alternator disconnected once, with the engine runing, for over 1 hour, when I realized the batteries were not charging.
I looked around and found the wire disconnected at the alternator.
Nothing was damaged..the bateries, or alternator.
I have on other occasions, maybe once or twice, switched from Bat 1 to Bat 2 with the engine runing and nothing happened..
was I lucky? or is my engine good?
So one should not have any thing that charges the bateries when selectin 1, 2 or both??
I never did that in my whole life an nothing ever hapened.
I've done this on maybe 25 different boats over many years and never once have I damaged an alternator. I rarely do it any more since I always run on both batteries all of the time now.
I also run on both allways. I only have 2 75amp car batteries, (one for the engine one for the house)..allways used car batteries, they're lighter and cheap. And if damaged before the warranty of 2 years expire, I take them to the supermarket where I bought them and get a new one.
I have a 25 amp for the VHF (in europe the VHF needs a separate battery by law), and a 50 amp for the anchor windlass in the front.
One day we forgot the lights on and left, and when we returned we had no battery to start the engine.
So I brought the windlass bat and started the engine..then charged the 2 main ones...
I'm just quoting from West Marine and from my alternators manual. It may not happen but a momentary break between batteries and alternator will burnout your alternator and you cannot be sure when swithing between batteries that you will not disconnect the alternator from the batteries. The field must have a charge in order to excite the field. So Gui it's possible that you could run the alternator and because the field was not excited your alternator did not burn out. There are proper switches which allow you to switch while the engine is running, Semi pointed out one. But they are far more expensive and it's just bad practice to switch unless you have one of these switches. Murphy's law.
You may disagree, but that doesn't change the fact that if you remove the battery while the alternator is running, the sudden surge can, and quite frequently will, damage or destroy the alternator. This is why they make switches with field disconnect circuits.
Steve, maybe Captain Ron's law applies - if it's going to happen it's going to happen out there. If there is a possibility of frying your alternator - that's bad practice.
It's the engine that needs to be off, Alex, not the rest of the stuff on the boat. Even then, again: As long as you have a make-before-break switch that is in proper condition and you don't accidentally hit "OFF," it shouldn't be a problem. My point is: Why take the chance? Is there some good reason for switching between "1," "BOTH" and "2" while the engine is running? None I can think of.
I tend to start on "BOTH" and then switch to "1" or "2" after the sails are up and the engine's off. That way I don't take the chance of running both batteries down. Then, usually, I just go ahead and start off the battery that's been used when on the way back.
I might agree if I hadn't done it myself over a hundred times. If I had ever once had a problem I would agree with you. The keel could fall off at any moment as well, but I still go sailing. If you want to avoid all possible stay in bed in the morning. As I said before you can avoid the problem by running on all batteries as much as possible, which is better for your batteries anyway, but if you find yourself in the situation where you have to switch while running, I promise, the keel wont fall off.
There is absolutely no question that my switch is a make before break....I have tested it and examined it phyisically and it does not have this field protect device....whatever that is. So I'm still back to what harm to the alternator if I all of a sudden connect in a parallel battery?
There is no question that the switch is a make before break...I have tested it and examined it physically....and there is no field protect device....whatever that is. So what is that would damage an alternator by all of a sudden connecting in a parallel battery?
There is no harm in connecting in a parallel battery. It's no different than suddenly having a larger battery.
Using a battery switch that has a field disconnect only works if you have an externally regulated alternator, as far as I know.
Battery switches are very simple devices. The chances that it will fail in a way that disables the make-before-break connection and does not completely disable the switch all together is extremely remote. If you worry about this possibility I would say you take much much bigger personal risks setting foot on a boat in the first place than you do putting your alternator at risk by switching batteries while the motor is running.
That's not necessarily true. If the new battery is severely depleted, you'll be suddenly throwing a high load on the alternator while it's running. I don't know as that would be a problem, but I don't know that it wouldn't, either. Besides: We're not talking about suddenly adding additional load, we're talking about accidentally removing all loads.
The chances that it will fail in a way that disables the make-before-break connection and does not completely disable the switch all together is extremely remote.
I've been working with things electrical and electronic for some 40 years. I can tell you from long and varied experience that nothing could be further from the truth. It is not at all uncommon for switches to become intermittant, especially as they age.
You must hook up the AFD (alternator field disconnect terminals) to both the alternator and the external regulator for it to operate properly. Since you have an internal regulator, you cannot use the AFD feature and you will harm the alternator by going to or through the Off position of the switch with the engine running.
**********
Note that nothing is said about going through batery1, both, or battery2 with an INTERNALLY regulated alternator.
Perhaps those that have said, they've gone through the off position have the AFD terminals and external regulators?
I think the best advice is to install a battery combiner and never worry about it again. We've had one since we aquired our boat 9 years ago and it works flawlessly. I feel like it's pretty cheap insurance and assures all battery banks are charged, makes sense too.
ketch --- i have one also. i installed it for the previous owner a year before i bought the boat from him. a combiner does not have voltage drop like diode isolators which causes the the regulator cut the charging before the batteries are fully charged.
You don't need to worry about your charger running off shore power. That's almost certainly connected directly to the batteries, so moving the battery switch will have no effect on it.
I'm with Steve on this one. we've had this discussion many times.
The Off-1-ALL-2 switches are not designed to go thru OFF from one position to the next. OFF is at the one end of the choices of positions. So you can't go "thru OFF to get to whatever".
And I agree with Steve that I have many hundreds of time switched from one bank to the other while the alt is charging and have never had a problem because of it.
Let me clarify my point: It is very likely that if you switch the system off while you're charging that you'll blow some diodes (and for the record, that doesn't mean that you'll "burn the altenator out"). But the switch does not go thru OFF to reach any other position. If you have a switch that can, change it ASAP.
Also loading up suddenly by connecting another flatter battery will not damage your alt. Think about your car. Switch on the lights, aircon, wipers and press the brake all at the same time. No problem. Even though this represents a significant spike in current. Alternators are not that sensitive. I can't remember how many times I have jump-started other cars from mine and then it's a case of connecting the cables to one battery then the other. The car that is running has a little surge as the alt catches up and then provides all the power you need.
It may be so that the switch may become "intermittent". This happens with everything from widgets to girlfriends. That is a extraordinary event. It will not do that 1 in every 10. It will do it once in a lifetime. Maybe. As Steve says and I agree, I have been switching these things from one bank to another for decades and guess what? I haven't had an intermittent switch yet (I have something else to look forward to). These switches are MADE to go from one bank to another. WHAT OTHER PURPOSE is there for them?
If you want to regulate your actions based on the extreme outside possibility that something could go wrong, you're likely to have an entertaining time sailing at sea.
Just my personal experience and opinion, as always
Most of the 1/2/both/off battery switches I've seen are rotary and can go from 1-both-2-off or 1-off-2-both... I prefer the Dual Circuit plus design, which reduces the problem, but you do need either a battery combiner or echo charger with it.
Most of the 1/2/both/off battery switches I've seen are rotary and can go from 1-both-2-off or 1-off-2-both... I prefer the Dual Circuit plus design, which reduces the problem, but you do need either a battery combiner or echo charger with it.
Coincidentally, most, no make that all, the switches I've had on my boats over the years are not rotary and look like this:
Maybe I've been lucky that the original owners chose wisely, maybe this is the one that is just commonly used in South Africa. But my present boat was built in the US and has one like the above as well.
The one that you're referring to obviously looks like this:
Like I said in my first post, if you have one like this, change it ASAP. Why would anyone choose this option? The instruction re the OFF position is clear enough on both switches but no doubt not many people have noticed that.
I believe you experience much more mechanical failure "risk" by the process of shutting down the motor, switching the battery switch, and then restarting than you do by simply switching the battery switch while running. There is a very small amount of "wear and tear" every time you start and stop the motor. This wear and tear creates risk of component failure. For those of you who are risk adverse to this level you should carefully consider your options here.
I believe you experience much more mechanical failure "risk" by the process of shutting down the motor, switching the battery switch, and then restarting ...
Maybe I'm missing something obvious (it wouldn't be the first time), but why would you need to do this? By "this" I mean: Switch battery use while under way under motor?
When we start from the slip we start in "BOTH." We keep it in "BOTH" until the sails are up and the engine off. That way both batteries get equal charging time--which is only "fair," being as both batteries were used to start the engine.
Then, usually (forgot yesterday, for example), I switch to "1" or "2." The reason for not leaving it in "BOTH" is to reserve one of the two batteries for starting. Whichever battery upon which we've been running is the one with which we re-start on return, so it gets all the charging from the engine. Which is only "fair," being as it's been running the instruments and started the engine on its own.
(The above procedure also gives me the opportunity to exercise each battery on its own, so, hopefully, a weakening battery can't hide behind a stronger one.)
In neither scenario do I see the need or sense in switching the battery switch while under way with the iron genny.
I agree for the most part. I can see needing to switch if you totally run down one battery and the other is partially discharged. You may not want to risk combining them with the battery switch prior to cranking the motor. If you did, the one battery with a partial charge would be trying to charge the dead battery and crank the motor at the same time, which is at best very hard on the battery and at worst will leave you with no ability to start the motor.
The practice of using one battery at a time is old school. The modern thinking is that you should use both at the same time. Your batteries will last longer if you discharge them both a little than one a lot. You should either have a dedicated starting battery, or a monitoring system, or know your usage well enough to not get yourself in trouble, or all of the above.
Am I the only one who does not have a typical battery swich?
This subject comes up a lot and I was wondering if my system is any better or worse or what you guys think.
Our boat does not have a battery switch as it is commonly reffered to, we have (3) T-Handles mounted down in the aft berth. (1) for the Gound, (1) for Battery 1;starting, and (1) for Battery 2; House Bank. I have tried to find a photo but I don't have one and I can't find an example of the set up anywhere on line.
With the handle in the Vertical position the battery is off, and in the Horizontal position the Battery is on.
I always leave the House on and use that to start the engine, when I want to charge the starting batt I flip the lever to Horizontal. No problems and it seems a lot less confusing than the typical 1, 2, Both. I simply have to remember to NEVER switch off both batteries or to flip both the handles to the Vertical position when the engine is running.
Did anybody see my post?
I am still wondering what you guys think of this set up?
I like it. It seems to be a little easier to use. Its obviuosly not fool proof. I never had a boat with this type of switching before and I am curious as to why there are not more out there like this.
Or just ignore it......
Bump
Am I the only one who does not have a typical battery swich?
This subject comes up a lot and I was wondering if my system is any better or worse or what you guys think.
Our boat does not have a battery switch as it is commonly reffered to, we have (3) T-Handles mounted down in the aft berth. (1) for the Gound, (1) for Battery 1;starting, and (1) for Battery 2; House Bank. I have tried to find a photo but I don't have one and I can't find an example of the set up anywhere on line.
With the handle in the Vertical position the battery is off, and in the Horizontal position the Battery is on.
I always leave the House on and use that to start the engine, when I want to charge the starting batt I flip the lever to Horizontal. No problems and it seems a lot less confusing than the typical 1, 2, Both. I simply have to remember to NEVER switch off both batteries or to flip both the handles to the Vertical position when the engine is running.
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