Electronics shutdown when engine started

[Cricket Too]

I just installed a full Raymarine RADAR and GPS system on my boat this season. When I start the starboard engine I get a voltage drop down to approx. 10v and the Radar system shuts down and restarts, which is a pain because the Radar has to perform a warm up every time it is powered down and then back up. This is a hassle because when fishing the motors are started and stopped often and I don't like clipping the system out every time I start the starboard engine. <br /><br />I have 2 engines and two batteries, they are each on there own switch and not linked together, this is the way it was when I bought it and up until now it has not been a problem. It looks like everything under the console is wired from the starboard battery because when I go down the terminal strip of all the connections underneath it, they all have a voltage drop when starting the starboard engine and not the port. I know how to link the batteries together with the two switches the correct way for two different charging systems, but I am not sure if this will cure my voltage drop when starting the starboard motor.<br /><br />So my question is, is there a way that I can wire these two batteries together so as not to get a voltage drop when starting or is there a way I can wire a 3rd battery into the port battery switch and just run my electronics off of the 3rd designated battery, that will not be used for starting, but will be able to be charged by the port motor's charging system? I realize that I can run 2 batteries on the port switch and they will both be charged by the port motor, but will that circuit have a voltage drop upon starting also?<br /><br />Thanks in advance for any help, Mike.

 

[Boatin Bob]

Re: Electronics shutdown when engine started

Mike...on my last boat I had 2 I/O's and 2 batteries, had a similar problem as you only with a Raytheon LoranC, what my boat had was a 12v solenoid that was fed by both batteries and energized when the key was turned to start, this in effect combined my 2 batteries only while starting. My problem was the solenoid was defective, replaced it with one from an auto parts store and my problem went away.

 

[Cricket Too]

Re: Electronics shutdown when engine started

Bob, so what you are saying is that the solenoid combined the two batteries for starting so as not to create a voltage drop but after they were started the solenoid is de-energized and the circuits are separately charged. How was that wired in, do you know?

 

[jtexas]

Re: Electronics shutdown when engine started

Here's an interest piece of equipment that might do the trick:<br /><br />www.stealthcharging.com/

 

[Boatin Bob]

Re: Electronics shutdown when engine started

Mike...thats right. Basically a battery cable came from each one and attached to each side of the solenoid and then carried on to the starter. A wire came from each ignition switch to the solenoid so that either key would energize the solenoid. I believe there were some diodes in there as well to prevent a back circuit. With the 2 batteries momentarily wired in parallel the voltage drop wasn't enough to bother the electronics anymore.

 

[Cricket Too]

Re: Electronics shutdown when engine started

Bob....Do you know exactly what that was called and where I can find it. I really like that Stealth 1 that jtexas put up there, and am seriously thinking about just running my electronics off of a 3rd battery with the Stealth on it, but I would rather try something easier like putting this solenoid in bewteen my existing batteries and having them be in parallel for cranking only. <br /><br />One other question, if I was to hook a 3rd battery up to either one of my batteries in parallel, then it would be charged by the engine obviously, but would there still be a voltage drop below 10v upon cranking, if they were in parallel? It's really no problem for me to hook up a 3rd battery in parallel with one or the other of my batteries, I guess I could try it and see if I get the voltage drop, if I don't then I don't need the Stealth 1, and can just charge it off of the engine, I just figured if I put the Stealth on it then there's no doubt that it will be isolated from cranking, and will never have a voltage drop.

 

[Boatin Bob]

Re: Electronics shutdown when engine started

Mike...it was very similar to the solenoid shown here at iboats at this link sw622 12v solenoid <br /><br />If you add a 3rd battery in parallel with one of your others, first of all it should be on the starboard side that you are having problems with. Normally if you put 2 in parallel they should be the same size, type and age otherwise the charging characteristics could cause you problems and if they are not isolated from each other then if one goes bad it will pull the other one down with it.<br /><br />Are your engines I/O's? If so they should be tied together ground wise so another option could be to use a simple on/off battery switch between the 2 positive battery posts, turn switch on before starting to tie the 2 batteries together and then turn off after starting, same principal as the solenoid but has to be done manually.

 

[Cricket Too]

Re: Electronics shutdown when engine started

Bob...I have twin 200hp outboards. If I did use a 3rd battery I would put in on the starboard side as that is the battery that is powering all of the electronics. I thought about just running them parallel with the switch, but then I would have to go into the back of the boat and put the switch on ALL every time I wanted to start and that is real pain when fishing, especially in a 20mph current where you have to start and stop the engines every 5 minutes or so. <br />So I would really like to try out that solenoid idea so I can just use my existing 2 batteries and have them crank in parallel and be separate the rest of the time, that would be perfect, as long as I don't still get a voltage drop when starting. Does wiring batteries in parallel stop a voltage drop or just give me less of a voltage drop that won't affect the electronics? The book says anything 10v or under will shut the unit down.<br /><br />Another thing I just realized is that I don't have any room in the back to put a 3rd battery, so I would have to put it up front in the cabin and then I would have to run at least 17 or 18ft of battery cable to the back to get to the starboard battery and wire them in parallel, which I don't think would be too fun or practical. So that might be out also. I checked into that Stealth1 charger and that is like $320 for the DC only model, add that with $100 for a new batt. and I'm into this thing for over $400 after I just spent $4,000 on the RADAR. So I'd really like to try and get that solenoid idea to work for me, if parallel batteries will solve my problem.

 

[gss036]

Re: Electronics shutdown when engine started

Stop by a Marine Radar shop and chat w/them about your problem and maybe they can do or show you a quick fix. If you don't do this right you can cook your electronics real quick.

 

[Cricket Too]

Re: Electronics shutdown when engine started

Well there's nothing really that tricky about wiring batteries in parallel, I'm really just looking for an opinion or a fact on whether or not wiring batteries in parallel will solve a voltage drop problem when starting. I would try going and asking a shop about it, but around by me your not gonna get any free advice without buying something from the shop. That's why this site is so invaluable to me.

 

[jtexas]

Re: Electronics shutdown when engine started

A large capacitor? Across the radar leads? Just thinking outside the box here.

 

[waterone1@aol.com]

Re: Electronics shutdown when engine started

I think Jtexas has a good idea. A large capacitor right at the radar unit should hold voltage for a second while the battery discharges to start the motor. I'm thinking that this is really a combination of a few problems because your battery should not get below 10 volts when cranking. I am thinking that there is some resistance in your battery cables or the wires running to the radar unit, in either case, the capacitor at the radar unit should keep it alive long enough to start the engine. If that doesn't work by itself, a diode in series with the positive lead going to the radar and cap should prevent the cap from being discharged by the engine crank ( I would try without the diode first).

 

[Boatin Bob]

Re: Electronics shutdown when engine started

Mike...you are always going to have a voltage drop when starting but there are variables that determine how much, how good is the starter motor, how good are the connections at each end, how good is the battery itself. By putting 2 batteries in parallel you are in effect doubling the available cranking amps, the voltage drop should not be as much. Don't know the physical layout of your boat but can you easily rewire your electronics to the other motor/battery just to see if it has the same effect when starting? If you don't have room for another fullsize battery I saw a boat where a guy was running his electronics off a garden tractor battery, it was attached to his main battery through a big diode (in effect a cheap isolator) there was a small voltage drop across the diode (less than 1 volt) but it kept the tractor battery well enough charged to run his electronics.

 

[Cricket Too]

Re: Electronics shutdown when engine started

I like that capacitor idea, I would just have to put that under the dash where the 2 units get their power and see if it works and if it does than I'm done. Really good idea. I guess I could just cut the leads under the dash and solder the capacitor in between them for both units. I have 2 units that are being affected, the actual display RADAR unit and the sounder module that runs the depth finder. What size capacitors should I use? Should they be in series with the + lead or across the + and -? Thanks.

 

[Boatin Bob]

Re: Electronics shutdown when engine started

The capacitor gets wired across the + and -, I think it will need to be a pretty good size, one source for these could be your local car audio shop they usually have big caps for hooking up to audio amps.

 

[Cricket Too]

Re: Electronics shutdown when engine started

Ok, I will try a local car audio shop, I have one right around the corner. Just so I know, how are they categorized or labeled, by the amount of voltage they hold? Thanks.

 

[Cricket Too]

Re: Electronics shutdown when engine started

Hey guys, just wondering if you think this car audio cap would do the job, it's about the cheapest one I can find, but I don't want to buy it and try it and if it doesn't work, I have to eat the $80+, because I doubt I would be able to return it:<br /><br /> http://www.crutchfield.com/S-4arKRf...?g=725&I=495LS053&search=Car+Audio+Capacitors <br /><br />Thanks, Mike.

 

[waterone1@aol.com]

Re: Electronics shutdown when engine started

Mike, that is pretty expensive. For instance you might want to try www.mcminone.com they have a 1 farad cap. part number 60-5201 for $64.95. That thing is pretty close to a battery (twice as much capacitance as the one you quoted).

 

[Boatin Bob]

Re: Electronics shutdown when engine started

Mike...I'm not so sure that when you go to start your motor that it might actually suck the charge out of the cap and you end up being no further ahead. I still like the idea of a garden tractor battery (around $20-25 at Walmart), hook it up in parallel with your main battery except put a big diode in the positive line so that the little battery will charge from the big one but not the other way around and then run your electronics straight off the little battery. The little battery will lose about .7 v across the diode but you'll still have lots of juice to run your stuff.

 

[kence]

Re: Electronics shutdown when engine started

I run three batteries with an isolator and one engine. All of my electronics are powered by the third battery or house battery. When starting the engine there is no voltage drop as the third battery is isolated from the starting batteries but when the engine is running the third battery is constantly charged. I use a 1-2-all-off switch for the starting batteries so that I can start off of either or both and allows you to charge 1-2 or both but the third battery is always being charged while running. I know that Guest Electronics makes an isolator that allows two engines to charge multiple batteries without backfeeding into either alternator which would allow you to charge all batteries while running either engine and allow you to maintain a third battery for your electronecs.