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ContinuousWave: Small Boat Electrical
Blue Seas L-Series Automatic Charge Relay
|Author||Topic: Blue Seas L-Series Automatic Charge Relay|
posted 11-05-2005 11:11 PM ET (US)
I am trying to come up with an idiot proof way to set up my batteries. I have a single 250 Yamaha and a kicker.
I previously had a switch that allowed me to connect the two batteries I was using to start the batteries. This allowed me to charge both with the main engine while underway. Unfortunately, I started the kicker with the main engine still running and killed the stator. One thousand dollars later, I now understand that you cannot have two outboards charging one battery bank.
I am now thinking about isolating the kicker completely. It will have no switch and directly connect to the outboard. This way I can't accidentally turn the switch off while it is running and blow the stator.
I am also thinking about having using a starting battery to start my main engine and adding a deep cycle "house battery" to run my electronics. I am considering using a Blue Sea Systems L-Series ACR (Automatic Charge Relay), to connect the starting battery and the deep cycle battery. The ACR is suppose to automatically connect the batteries and charge the house battery once the Starting batery has a full charge. It is also suppose to prevent the house battery from draining the starting batery. In addition, in case of an emergency the ACR allows for manually overrride and paralelling the batteries to start the engine if the starter battery doesn't have enough charge. It will have no switch and directly connect to the outboard to the starter battery. This way I can't accidentally turn the switch off while it is running and blow the stator.
What do you guys think?
posted 11-06-2005 10:03 AM ET (US)
In general I like the concept of having a starting battery and a house battery. And I like the voltage sensitive relay approach to charging them from a single charging source. When I run out of other projects on my boat, I will probably re-wire the primary electrical distribution for this type of system.
In your installation with two engines, it may be more difficult to implement this in a straightforward manner. I also have some experience with interconnecting two motors to a common set of batteries, and I also obtained the same result (a blown stator).
If the auxiliary motor has charging capabilities, I would set it up with its own battery for starting. A starting battery for this engine is not as critical because you can probably pull start the auxiliary engine if there is a low battery problem. You could also use a smaller battery. There is no need to get a 1,000-MCA Group-27 battery to start a 9.9-HP; perhaps a motorcycle type battery would be adequate.
The main engine would be set up with a starting and house battery in the usual configuration.
posted 11-06-2005 08:21 PM ET (US)
I was thinking about a Group 27 starting battery and a Group 31 Deep Cycle. Do you see any problems with having a larger "house" battery than the "starter" battery?
In addition, I was going to put the "starter" battery in the transom and the "house" battery forward under the console.
Thank you for your help.
posted 11-07-2005 02:02 AM ET (US)
The only problem I foresee with a very large house battery is related to the voltage sensitive relay (VSR). You have to pick the size of the house battery to be in some proportion to the charging current available. Here is why:
The charging source will eventually charge up the starting battery until the voltage reaches the point where it triggers the VSR to close. (This is the ON threshold of the VSR). This brings the other battery in parallel. This new load will tend to lower the voltage. The VSR has to have some hysteresis or dead-band range so that it does not immediately decide the voltage is now below its threshold and open up. The OFF threshold voltage needs to be a bit lower than the ON threshold voltage. If it is not, the relay will chatter ON-OFF-ON-OFF, etc.
Some of these relays have adjustable thresholds, and in those designs you can tweak the ON and OFF thresholds to be where you want them. Other designs have the threshold voltages fixed. In those cases the manufacturers suggest that you size the house battery to be in proportion to the charging current. In doing that I think you will avoid the chattering problem.
For example, if you had a modest charging current available, say 10-amperes, and you had a huge house battery, you could get into a situation where the voltage on the house battery was so low that when it was dropped onto the charging system it dragged the voltage below the OFF threshold, and the VSR would not stay closed.
It is not a good idea to set the OFF threshold too low (or to allow the installer to set it too low), because this would result in a system where the house battery could tend to cause the starting battery to be drained while trying to charge the house battery. So having the house battery be in proportion with the charging current available is probably a good idea.
Don't ask me what the proper size battery for a particular charging current might be--ask the guys who make the VSR. I think the BEP website has some information on this.
posted 11-07-2005 03:31 PM ET (US)
Here's a recent thread on this topic that may answer some of your questions.
I installed a BEP Marine switch cluster with integral VSR on my Outrage. I wired my kicker motor to the house battery side of the VSR, per the recommendation of BEP Marine. Here's a modified version of BEP's diagram, showing how I did it:
posted 11-07-2005 08:37 PM ET (US)
Nice set-up and installation! The BEP cluster looks really sharp.
I think I am also going to install a VSR, but I am going to use the "house" battery strictly for electronics. I have a radar, gps, depth finder, VHF, spot light, bait tank, deck lights, instrument lights, compass light, cabin lights and Stereo all hooked up to the house battery.
For the kicker, I am thinking about a third battery. This battery would only be connected to the kicker. I have a 110V on board charger that I think I will connect to the main engine "starter" battery and the kicker battery when the boat is at its slip or on the trailer.
I like the idea of my back-up motor being completely isolated. It should not require any charging underway if its not being drained.
Thank you for the photo and diagram I quite a while looking at it and the BEP website.
I am pretty convinced that the VSR (aka ACR) is the way to wire this type of set-up. I am on the fence between BEP and Blue Sea Systems. I am in the process of re-wiring everything on the boat and I have thus far used Blue Sea Systems throughout.
posted 11-08-2005 10:57 AM ET (US)
Revenge 25, your proposed system sounds very workable, and with the bigger boat you certainly have more room for a 3rd battery. I chose to put my kicker on the house battery since I do a lot of trolling on it with the electronics running. My thought was that the kicker will put some charge on the house battery while I troll, rather than letting the house battery draw down from the electronics. My kicker has a recoil start as well as electric, so I figure I can always get it started and get home, regardless of any electrical problems.
I made a few phone calls to the BEP tech support guys as I designed my system, and found them to be responsive and helpful. They may have an off the shelf system that will do exactly what you are proposing. By the way, I purchased my unit directly from BEP.
posted 11-08-2005 12:55 PM ET (US)
A kicker isn't going to need much battery. A motorcycle
battery would do. I know of people who use motorcycle
batteries up into the 30-40 HP range on inflatables, where
space is in short supply.
But if the kicker can be pull started, I don't think I'd go
posted 11-08-2005 04:14 PM ET (US)
You make a good point about the electronics drawing down the "house" battery while trolling with the kicker. I also troll some with the kicker. Damn, just when I thought I had this thing beat. Back to the drawing board.
posted 11-08-2005 07:43 PM ET (US)
With the BEP system, it's a simple matter of closing the emergency parallel switch to combine the batteries, allowing you to jump start the "main" with the "house" or vice versa. This is a great feature, albeit one I have not had to use yet.
By the way, I'm currently using a pair of identical dual purpose marine batteries, group 27. I'm considering going with a deep cycle for the house, and a pure start battery for the start. I'm not sure if I'll get into the problem of chattering the VSR by mixing battery types, which is something I'll vet with the folks a BEP before I make the switch. I may still have one more season in my batteries, now that they are being properly charged.
posted 11-08-2005 10:17 PM ET (US)
It seems to me that with the start battery on the big motor and the house battery on the kicker, that if the big motor is running, the VSR will close and interconnect the two motors' alternators... not a good thing if the kicker is also running, which was the case in the original post.
posted 11-08-2005 11:31 PM ET (US)
Perhaps a diode in line somewhere to keep the current flowing in one direction is in order?
Or, get a regular Perko multi battery switch and wire it to use either the main or kicker. Connect the output of your current A/B switch to the common and the main to A and the kicker to B. Or, do you want to be able to start the kicker while the main engine is running?
posted 11-09-2005 08:16 AM ET (US)
Even with a diode isolator wired to tie both motors to the house battery, with both motors running, there is a potential the kicker alternator could see no load and be damaged by that. The only way I'd do that would be if the kicker also had its own battery on the motor side of the isolator (and the big motor had its start battery on the motor side of the isolator). Of course, a diode isolator is going to reduce the house battery charging voltage.
What's needed is some way to dummy-proof the system so that both motors can't be run at once. Having an ignition switch and key for the kicker, with its key on the same key ring as the big motor, might be a simple way to do that.
posted 11-09-2005 12:09 PM ET (US)
You make a good point. Depending on the charge state of the start battery, the VSR is often open when the main engine is at idle. There's an LED on the VSR to tell you if it's energized. That said, unless the battery systems are completely isolated, there is probably some danger of charging system damage if both engines are running at the same time. In sloppy seas, I really don't like shutting down the main engine until the kicker is started, but I do it to protect my charging systems. I do start and warm up the kicker at the dock before a trolling trip, to make sure it will fire quickly and reliably when switching from the big motor.
Jimh, can you describe in layman's terms (remember, I'm a civil engineer), how the charging system is damaged when both motors are running. In my application, each motor's positive cable runs via a switch to a distinct positive battery terminal. The batteries may or may not be in parallel, depending on if the VSR is opened or closed. It would seem that as long as each battery can accept charge, or there is load on the system, that everything should be OK. Your experience, and others here, says otherwise, and I'm sure I'm not understanding what's happening.
posted 11-10-2005 09:15 AM ET (US)
Here is my thinking about connecting two charging system outputs in common. [This is from another discussion on this same topic. See http://continuouswave.com/ubb/Forum6/HTML/000562.html for the full discussion.]
I bought a boat with twin outboard engines with simple charging circuits in them. They were hooked together in the battery distribution system. At the time of purchase, there was a problem with one of the engine tachometers. The tachometer is always a good indicator of the charging circuit as generally they share the same coil as their source of alternating current. The problem ultimately turned out to be a bad coil under the flywheel. The coil was overheated and had developed an open circuit. Getting this fixed cost about $300. It is quite a messy repair, as you have to yank the flywheel off to get to the coil. This is not a simple job. After you put the flywheel back on you have to tighten it with very high torque. If you were a purist you would then verify the timing marks and re-time the engine ignition timing.
About two hours of operation with the repaired engine in common with the other engine, and the coil blew on the other engine. This cost about $300 to fix, too.
At this point I was suspicious that the cause of these coils going bad was related to the fact they were tied in common by the battery distribution wiring. I have a fairly deep understanding of electricity, rectifiers, alternating current, etc., and I could see how this could happen and cause damage.
My options were to either re-assemble the boat's wiring the way it had been all along, and see if either of the engines failed, or to wire it up with more electrical separation between the two. Having already invested $600 into this project, I decided that it was a better choice not to wire it back the way it was to test if I was wrong about my conclusion. I wired them up separately, and they operated for many years without a problem or failure. Yes, it could be coincidence. If someone wants to spend some money they could test the theory, but, for me, I was happy with the way it worked and I lacked the financial resources and time to keep testing the in-common wiring arrangement until it was proven not to be the cause of the two rapid failures in succession.
Based on this, I cannot, in good conscience, suggest that other people just hook the charging outputs of their outboard motors together and see what happens.
If anyone has a set up where they have been operating with their twin engines with simple charging outputs wired in common and have had no failure, I encourage them to speak up. But I cannot say that because I had two failures in short succession.
In most electrical distribution systems, it is very common for there to be one source and many loads. It is not very common at all for there to be several sources combined into a single load. For example, I have never seen anyone build a Y-cord onto a table lamp and plug the lamp into two outlets in their living room. I have never seen people take two audio amplifiers and connect them to a single loudspeaker, and set the volume to different levels and see what happens.
Generally inside electrical devices that are supplying power to a load where several sources are hooked in parallel there are usually build-out resistors or some other method of balancing the load among the paralleled sources. The build out resistance is usually chosen to be greater than the output impedance of the source, so that the effect is to drive the output impedance higher and toward a more uniform value. If you don't do this, one source does all the work and the other source loafs along. I think this what was going in my twin outboard situation above, and in that case, although somewhat counter-intuitive, the source not taking any load may have burned itself up from eddy currents developed in the coils. Whenever you have wire in the shape of a coil, strange effects can occur that are not anticipated in simple DC analysis. The stator of an outboard motor is a coil with an alternative current being generated in it.
It may very well be that certain devices which are designed to charge batteries can permit themselves to be connected with other certain devices designed to charge batteries, and that no harm will result from this arrangement. I just think that it is prudent in the case of certain outboard motor charging circuits that they not indiscriminately be connected together in duplicate. And that is why I recommend against it.
It might very well be that a particular outboard motor has a charging circuit that can tolerate being tied in common with its twin, but this does not mean all outboard motors have such a charging circuit. It is no guarantee that someone won't end up spending $600 to learn this again, either.
So this is my dilemma. Because I have had the experience of two rather inconvenient and expensive failures of outboard motor charging circuits that were connected in common, my integrity prevents me from just going around willy-nilly telling people that it is OK to hook them up that way.
I know that people can construct situations where my proposed arrangement of engines and batteries can create a limitation or even perhaps a hazard, but I have not had anyone write or call to tell me they blew up the charging coil on one of their outboard after following my recommendation.
This, again, could be just a coincidence.
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