How to test a battery combiner?

[NBE]

I have a 50A battery combiner that I have been running for the last year or so and have been very satisfied by its performance. It's a two battery system, one for starting and one for trolling motor, and are wired separately except for the combiner wiring connected to the two. <br /><br />Recently while making a night fishing trip I encountered a problem that I didn't expect. After 5 hard hours of trolling motor use (15 - 20 minutes running to navigate very shallow water and then four hours fishing) I noticed that the trolling motor battery was getting kind of weak, not unexpected after all of that use. What was unexpected was that when I attempted to crank the motor a short time later (older Merc 500E), the starting battery was too weak to turn the motor over but maybe two or three times very slowly and that was it. Had to get out the old rope and start it by hand. <br /><br />Seems like using the trolling motor and running that battery low also drained the starting battery somehow. I was under the impression that the combiner would separate the two batteries when either one was under a load and then allow them to charge back up as needed. <br /><br />My question is, how do I check the combiner to see if there is something wrong with it? The charging aspect of it works fine but seems there may be a problem with the isolation part.<br /><br />Thanks!!

 

[Richard Petersen]

Re: How to test a battery combiner?

Does the MFG. say that running down EITHER battery will definately NOT run down the other? If yes. Get ready for a new battery.

 

[Dunaruna]

Re: How to test a battery combiner?

There is a plethora (always wanted to use that word ) of combiners/isolators on the market. What you got?<br /><br />Some older types don't isolate when the key is 'on', only when the key is 'off'.

 

[ricksrster]

Re: How to test a battery combiner?

Try this link. It might be helpful. http://www.yandina.com/combInfo.htm

 

[Richard Petersen]

Re: How to test a battery combiner?

ricksrster. That is a great site if the questions and answers are all correct. can one or more of us who really deals with combiners pass their judgement onit as a good reference site.

 

[ricksrster]

Re: How to test a battery combiner?

I was checking out combiners myself to hook up two batteries for when I am fishing for long periods of time. I found the link on a Google search.

 

[Richard Petersen]

Re: How to test a battery combiner?

I read the first statement on the site. ---What is a combiner?--- A 13.3 volts sensitive relay that connects both batteries together when ever there is a charging voltage greater than 13.3 volts available. Not good. If a battery starts to short out 1 cell it will begin pulling current from the charger ( alternator ) AND the good fully charged battery also. It WILL definately pull the good battery down by at least 2 volts over time and start heating the daylights out of the charger. When you stop the engine you now have 2 batteries at 10 volts, troll around and now the batteries are in the fast rundown part of their charge. Could be tough to spin the starter fast enough.-------------------------------------- Since I don't know if they have a working diode isolator to prevent this. I have to assume one bad battery. Simple check is to charge each battery from a outlet on a bench. Don't cook them!! Then take each to the boat and have each 1 crank the motor for 10 seconds. The weak battery will show itself.

 

[Dunaruna]

Re: How to test a battery combiner?

Which is exactly what I said 5 posts ago. But some combiners DO also isolate which brings me back to my original question - what brand/type have you got?

 

[NBE]

Re: How to test a battery combiner?

Sorry for the slow reply....been out sick. At the time of my original post I did not have the paperwork with me or I would have mentioned the specific model at that time. Also, guess I didn't realize that there were so many different types of combiners out there.<br /><br />Anyway, mine is a West Marine Combiner 50, Model 143268. I quote from from the installation instructions: "The West Marine Combiner 50 is a voltage-sensing relay (13.3 volts) which connects two batteries together when either is receiving a charge. When the charging ceases, the relay opens so that each battery operates independently". <br /><br />Maybe I am not quite understanding how this thing really functions but it seems to me that with the engine off (key off too) and no charging taking place, the combiner should separate the two batteries and not allow one to draw off of the other. <br /><br />Both batteries have been checked and both are ok, at least according to the local AutoZone guy.<br /><br />Regardless, I am here to learn so what do you all think?<br /><br />Thanks!!

 

[NBE]

Re: How to test a battery combiner?

Well, I think I may have solved my problem. I have been to the Yandina several times before and this time I did notice there was something different in the FAQ section. This does address using the combiner to charge a trolling motor battery. <br /><br />If I remember correctly, being I am not home right now, I do not have the negative posts of the two batteries connected as shown in the picture at this link. I'll have to check when I get home but am most certain I do not. Trolling motor <br /><br />As the website says, "Just connect a West Marine Combiner 50 between the starting battery and the trolling battery. Whenever the outboard engine is running, the combiner will share the charging output with the trolling battery. When the engine is off, the trolling battery is separated from the starting battery and will not accidentally discharge it." Also: "Connect the negative terminals of both batteries together. This provides a return path for the charging current that is going to the trolling batery. As mentioned above, this could be the black wire of a duplex cable going between the batteries." <br /><br />I am thinking that I do not exactly have this hooked up correctly, although I have been using this combiner for almost a year and have really liked how it works. Normally, after a full days fishing I just have to top off the two batteries when I get home as the combiner does a great job of maintaining the charge all day while running and fishing.<br /><br />Oh well, we live and learn. I guess I should connect the two negative posts as shown. What do you all think?<br /><br /><br />Thanks again!

 

[Richard Petersen]

Re: How to test a battery combiner?

By the statement " both are charged together" . Bad, bad, bad. One of the 2 is being overcharged and having the water used up very quickly. Not a design I would give to a enemy.

 

[jhebert]

Re: How to test a battery combiner?

The negative terminal of the two batteries in your system should be bonded together with a conductor that can handle the starting current of either motor. This is probably a significant cause of your problems.<br /><br />The approach to charging two batteries from a single source using a voltage sensitive relay is a good design in my opinion. I cannot imagine a better way to do it when you cannot alter the charger output--and this is the case for most outboard motor systems. Using diode isolators will reduce the charging voltage and leave your batteries undercharged.

 

[Richard Petersen]

Re: How to test a battery combiner?

With just a few cents more of IC's inside. The unit would charge 2 bateries at the same time and drop off 1 at a time as EACH ONE reached full charge. The IC chips are over 20 years old and proven in service. They charge each battery on a alternating cycle based on who is more run down. So that jumpering the 2 together does NO harm to anything.

 

[NBE]

Re: How to test a battery combiner?

Well, I do not have the two negative posts connected as referred to in my last post up above. I will definitely connect them and see what happens.<br /><br />As far as using the combiner, I have not have any problems with it such as overcharging, etc. I have not had to add water to any of the batteries more than you normally would during the fishing season. I am very well satisified as to how this system works other than the problem I described in my first post. I would still install one in any other boat of mine that has the same two battery set-up. <br /><br />The combiner works great at sustaining both batteries and allows me to use the boat the whole weekend with no loss of power from the batteries. As I have said in other posts, I mostly just have to top them both off with the regular charger when I get home from a full weekend at the camp. <br /><br />This is important to me as I fish 2-3 days at a camp 15 miles back in the swamp with no electricity except at times when I do bring a small generator. Yes, I could charge the batteries using the generator if needed but have never had to. The worse that can happen if the batteries do run down is that I have to start the motor by hand which is really no big deal.<br /><br />I do think that something is still amiss though as it seems that the combiner should seperate the two batteries when the key switch is in the off position. I did run the trolling motor way longer getting through that shallow area than I normally would when fishing a whole weekend. Just not sure why the starting motor got weak also. <br /><br />I'll continue to fool around with this system and see what I can figure out. Thanks to all of you for your input and comments!