Electronics shutdown when engine started

Ralph 123 · May 3, 2005

Re: Electronics shutdown when engine started

I use a similar approach kence. An isolator or a combiner with a separate house battery. No only does it prevent voltage drops to your electronics, is also prevent you from accidentally running down your starting batteries while your "camping" (i.e., anchored with accessories running). Read this: http://www.westmarine.com/webapp/wc...isplayView?advisor=creatingabatterysystem.htm You can find a schematic for the West Marine Combiner 150 here: http://www.yandina.com/acrobats/C150Data.pdf

Cricket Too · May 5, 2005

Re: Electronics shutdown when engine started

I've given up on the capacitor idea and decided to use a tractor battery as Bob suggested and then using the combiner that Ralph posted, I just have one question about that wiring diagram. The most basic setup is showing the single engine and 2 batteries on an Off-1-Both-2 switch with the combiner in between the + of both batteries and a common ground. Since this diagram is obviously showing 2 batteries that are capable of starting the engine, they have them both hooked to the switch. My question is since I am going to be using a tractor battery as a house battery, that I don't want to use for starting ever, I am just going to hook the + on the combiner in between the two + of the batteries and the negative on the combiner to the tractor battery negative post. Will this work? Also the way the boat is set up right now both batteries are in the stern, one on starboard and one on port. The port does not run up under the dash at all so it does not factor in. The starboard battery powers everything under the dash and all of the electronics. I am planning on putting the tractor battery in the cabin under the dash, as well as the combiner. Now do I need to run a cable all the way back to the stern (about 15 feet) to the battery or can I just tap the combiner into the main + feed from the starboard battery under the dash, and would 10 gauge wire be good enough, considering that is what is used for the main feed under the dash, or would this not hold the charging load? This would make things a whole lot easier and quicker than running through the bilge all the way to the back of the boat. Sorry for the long post but I wanted it to be clear. Many thanks, Mike.

Boatin Bob · May 6, 2005

Re: Electronics shutdown when engine started

Mike....a couple of issues I see with your idea is 1...the 2 negative posts on those 2 batteries need to be tied together. 2...as you have an outboard you will need to go inside and find the output wire from the alternator and disconnect it from the main battery cable so you can run a wire directly from the alt to the combiner

Cricket Too · May 6, 2005

Re: Electronics shutdown when engine started

Bob...I was going to tie the two negatives together, I just wasn't sure if I have to run a 15' cable to the stern of the boat from the cabin, or if I could just tap into the negative feed under the dash. The entire block under the dash is powered by the starboard battery, so wouldn't I be able to hook into the starboard battery under there, + and -? I'm not quite sure what you mean about hooking the outboard alternator up to the combiner, I don't see that anywhere in the diagram above. If you look at the diagram that they show for a single outboard, it doesn't show anything from the alternator being hooked up to the combiner, it only shows the positive feeds from each battery being hooked to it. Wouldn't it just work off the charging voltage at the starting battery? It really shouldn't make a difference whether it's an outboard or an I/O, if you look at the the middle of page 2, where it says Simple Installation, it just shows the combiner in between the two + posts of the battery and the negative going to a common ground. This seems the simplest to me, since I will never use the tractor battery for starting, and don't need it on a switch. I really just need to know if I can tap into the starboard-rear battery under the dash or if I need to run battery cables all the way to the stern, I think running 10 gauge wire underneath the dash to hook into the rear battery should work fine, plese let me know if it won't or what your opinion is on this. Thanks.

Boatin Bob · May 6, 2005

Re: Electronics shutdown when engine started

Sorry Mike...was confusing myself thinking about an isolator instead of the combiner however if you read through the installation part on the first page it talks about using 6 ga wire so you may find you need to run wires all the way to the rear battery.

amirm · May 8, 2005

Re: Electronics shutdown when engine started

I am not sure using another battery is a good idea. As soon as you try to isolate that battery from the rest of the system with anything that has a diode in it, you risk not being able to charge that battery fully (unless the charger is compensated for it by raising its voltage). As a result, the battery will die after a while. Even if this is not a problem, you will still have to replace the battery in the future and worry about maintaining it. I would go back to the capacitor solution but one at much lower cost. You do not NOT need one farad cap. Your instruments simply do not use enough power to require such an animal. These are made to back the power on high-consumption amplifiers that suck hundreds of watts. Just go to radio shack, and get a 24 V or higher cap, rated at 1,000 micofrarad or higher and a diode that has a current rating that is 30% higher than your instrument draws. Connect the negative wire on the cap to ground wire, and put the diode in series with its positive terminal. The diode is polarized and it should "point" toward the cap (the vertical line on -->| symbol should point forward). The above should only cost $5 and a few minutest to see if it works. Good luck, Amir

amirm · May 8, 2005

Re: Electronics shutdown when engine started

Forgot to say that the instrument simply goes to either side of the cap, as if it is the battery. Amir

Ralph 123 · May 9, 2005

Re: Electronics shutdown when engine started

Combiners are Voltage Sensing relays. As soon as the altenator puts out 13.8V or above the relay closes and puts the batteries in parallel to be charged. Once the voltage drops below 13.8 the relay opens and insolates the batteries. It's like having an automatic 1-2-All switch. There are no issues with not being able to fully charge the batteries.

waterone1@aol.com · May 9, 2005

Re: Electronics shutdown when engine started

Amir, if you read the original question, he is trying to keep a RADAR unit working......it draws several amps.

Cricket Too · May 9, 2005

Re: Electronics shutdown when engine started

Amir....I tried that Radio Shack thing already a ways back just as a quick test to see what would happen, and absolutely nothing happened, that's when I realized that the capacitor, any cap, would not realize where it's supposed to put the power, so the starting circuit would probably drain anything I put in and still give me a voltage drop. I actually spoke to the install tech (not one of the high school kids at the counter)for West Marine and he seemed to think that the combiner would work perfectly if I just tap into the 10 gauge feed under the dash for the one side of the combiner. Forgot to ask if having one battery in the parallel circuit being a lawn tractor battery will be a problem when charging. I can't really fit anything but something that small under there, so hopefully it won't be a problem. I know usually when batteries are hooked in parallel they should be of equal type and age, but since these will only be in parallel when charging, I should be OK, correct? Thanks.

amirm · May 10, 2005

Re: Electronics shutdown when engine started

Did you put a diode in the path? If not, it would definitely not work since the starter will suck the cap dry, just as well it did with the battery. The diode will feed the power to the cap and then the instrument but will stop the current from going back and feeding the starter. It acts as a one-way valve if you will, for electricity (it also causes a .6v drop and waste some power but that should not be a big deal int this application). Now, it is possible you need a larger cap. 10,000 uf may be a better bet but I could not find one online at Radio Shack so didn't want to suggest that. But you can always tie the caps parallel to each other (plus to plus and negative to negative) to increase their capacity. I agree the radar uses more power and might push the limit of what you can with caps. If the voltage drop lasts too long, this solution may not work. As to parallel charging two different types of batteries, this is definitely not a good idea with smart chargers. With the standard alternator on the motor, it may work better but I still would not count on long life. BTW, at the risk of asking a trivial question, how old is your primary starting battery? It is possible that it is old and that is the reason for the voltage drop. A fresh battery or one with higher capacity may hold the voltage better. Amir

Cricket Too · May 12, 2005

Re: Electronics shutdown when engine started

Does anybody have an opinion on whether or not this will be OK if I use a small lawn tractor battery rather than a full size battery with this combiner and the full size battery already in the boat? If it's just a matter of the smaller battery lasting 3 years instead of 5, that's fine, I'll deal with that, since they cost about $25. I just want to make sure that it's not going to cause any major problem if I use a smaller battery hooked by the combiner to the larger one. I need to get this thing in this weekend for an offshore 3 day trip. Thanks, Mike.

Ralph 123 · May 12, 2005

Re: Electronics shutdown when engine started

This is from the Mfgs web site: Q Can I combine banks of different sizes? A Yes, since the starting bank is typically smaller than the house bank, this is a common situation. Q Won't the smaller battery get overcharged if put in parallel with a large one? A The whole process of charging batteries in parallel is naturally self regulating, naturally governed by terminal voltage and current flowing through the internal equivalent resistances. For simplification, each battery can be considered as a perfect battery that holds the charge combined with a series resistor representing the internal resistance, and a parallel resistance representing the self-discharge leakage current. Lets say you have a charging source dumping out say 100 amps. If you have 4 batteries in parallel sharing this source the distribution of the charge current is governed by those internal voltages and internal resistances. From Ohm's law, the charging current that flows into each battery is the voltage divided by the resistance. In this case the voltage is the charging voltage arriving at the terminals minus the actual internal voltage divided by the series resistance of the battery. A discharged battery is going to put a larger voltage differential over the internal resistance so more current will flow to it. A charged battery is going to put less voltage drop across the internal resistance so it will take less or none of the available charging current. A large plate battery which has a correspondingly lower internal resistance will demand more current because of this lower resistance. A small motorbike battery in parallel will have a high internal resistance and demand very little current. All these demands for current result in a common voltage on the parallel circuit which is what the alternator or charger sees. None of the batteries will ever be "overcharged" as a result because the charging voltage is controlled. Even the smallest battery will only be seeing the same voltage so it is like the other batteries are not there. If you suddenly removed all the big ones and left just the tiny bike battery on the 100 amp alternator, the voltage would immediately rise because the amps trying to flow into the tiny battery have to pass through its internal resistance which is high. But instead of the voltage or current going to an excessively high value, the regulator in the alternator cuts the current back to a level that limits charging to a safe level. http://www.yandina.com/combInfo.htm#Q2

Ralph 123 · May 12, 2005

Re: Electronics shutdown when engine started

My pleasure. Let us know how it worked out when your done. If you have a little time you can find the 150 combiner on eBay at a big discount.

Cricket Too · May 12, 2005

Re: Electronics shutdown when engine started

Ralph....That is awesome, it explained everything I needed to know and more. Thanks for the help, to everybody, I really appreciate it. Mike

Cricket Too · May 16, 2005