Electronic and voltage drops.

dvx216

Well-Known Member
SILVER Sponsor
Feb 1, 2012
2,692
Catawaba Island/Orrville,Oh.
Boat Info
340 Sundancer 2001
Engines
8.1s 370 v drv.
My boat 12 volt system has 3 newer group size 27 all are dual purpose batteries that are wet lead acid. Now please I don't want a debate about what batteries are best. My system is in working order. During starting either port or starboard first my electronics drop out. Now I could start both motors up then turn on my electronics I know this. With all that said what's the best way to keep my electronics from dropping out when I start up the motors.
 
Mine does the same thing. But I wonder if there isn’t a solenoid that cuts power to the electronics as a safety so they do not get a power surge.
 
Assuming there isn’t a solenoid dropping your electronics (mine doesn’t do this), start by checking all of your connections for corrosion and clean them if there is any.

You can add additional batteries or a larger battery to support the starting current.
 
I've owned a few Garmins over the years and every one of them cut of when I started the engines and I've had very large battery banks. The only time it doesn't happen is when I have the generator running with the battery charger on.
 
Your electronics should be on the house bank and that must be switched and isolated from the start battery. End of issue.
 
Your electronics should be on the house bank and that must be switched and isolated from the start battery. End of issue.
My system has three batteries one for the port motor and two for the house and starboard motor and a crossover for emergency starts.
 
Wiring in a capacitor to the electronics circuit is a possibility. I’ve been thinking about doing it to mine this spring. I need to look into it more.
 
My system has three batteries one for the port motor and two for the house and starboard motor and a crossover for emergency starts.
Change that. Your start and house batteries should always be isolated from each other. What you have is wrong and that is why you have a problem. Include a Mosfet battery combiner in the charge circuit from the alternators. If you have an adequate battery you should only need one to start both engines. The switching should allow emergency starting from the house bank.
 
Change that. Your start and house batteries should always be isolated from each other. What you have is wrong and that is why you have a problem. Include a Mosfet battery combiner in the charge circuit from the alternators. If you have an adequate battery you should only need one to start both engines. The switching should allow emergency starting from the house bank.
Well maybe your correct I thought the single battery was for port and the other two that are in parallel were house and starboard with that said I have no start problems besides my electronics dropping out during start up.
 
Sea Ray simply chose not to have dedicated house batteries on just about every boat they designed. They almost always share “house” stuff on starting batteries. They did it on my 300DA and on the 400 DB I currently own. It has two port batteries in parallel and two starboard batteries in parallel. The port batteries start the port engine and feed 12v to all the helm stuff, including electronics. The starboard pair starts the starboard engine and feeds 12v to the cabin 12v stuff (lights, fridge, vacuflush, water pumps, vents, etc). Sea Ray expects you to use your generator.
 
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You might want to run a 10ga wire from the starboard battery set and power the electronics as a test to see if that stops the rebooting. Also monitor the voltage while do that. If it drops below 11v then the battery bank is not what you think it is.

Personally, turning on the electronics after the engines are running might be the easier. Also splitting the house from the starting batteries is another way to go. But your electronics are most likely powered from your starboard battery, so rewiring would also be needed.
 
Sea Ray simply chose not to have dedicated house batteries on just about every boat they designed. They almost always share “house” stuff on starting batteries. They did it on my 300DA and on the 400 DB I currently own. It has two port batteries in parallel and two starboard batteries in parallel. The port batteries start the port engine and feed 12v to all the helm stuff, including electronics. The starboard pair starts the starboard engine and feeds 12v to the cabin 12v stuff (lights, fridge, vacuflush, water pumps, vents, etc). Sea Ray expects you to use your generator.

Not generally the best case. There are reasons to separate house and start batteries. The obvious reason is that using house applications cannot draw down the start battery to a voltage that makes starting impossible. Another important reason to isolate the engine batteries from the house batteries while being discharged, is the difference in the battery types. Engine, or starter, batteries are designed to deliver a high amount of power for a short time and if slowly discharged will provide only a fraction of their expected battery life. House, or deep cycle, batteries provide a relatively low amount of power for longer periods of time to power electronics, refrigeration, appliances, and so on. These batteries can look identical and the only way to tell them apart is to read the labels. There are dual-purpose flooded batteries, but the end result is that those do neither starting or deep-cycle applications very well.

A deep cycle marine battery has several design differences. One key difference is the battery plate: It has fewer, thicker plates allowing the battery to provide continuous power output over long time periods. Deep cycle batteries can be entirely drained and recharged many times over where as cranking batteries can't without damage. Deep cycle marine batteries are much less likely to overheat since their thicker plate construction can withstand high temperatures during heavy, prolonged draw-downs.

DVX: this is no debate but a statement of well-known fact.
 
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My 390da has two batteries in parallel for each engine. One bank starts the engine and runs the cockpit “house”, the other bank starts the other engine and runs the cabin “house”.

I’m not sure which side starts the generator.
 
Sea Ray simply chose not to have dedicated house batteries on just about every boat they designed. They almost always share “house” stuff on starting batteries. They did it on my 300DA and on the 400 DB I currently own. It has two port batteries in parallel and two starboard batteries in parallel. The port batteries start the port engine and feed 12v to all the helm stuff, including electronics. The starboard pair starts the starboard engine and feeds 12v to the cabin 12v stuff (lights, fridge, vacuflush, water pumps, vents, etc). Sea Ray expects you to use your generator.
Thankyou for clearing that up I thought I was thinking correctly. No generator in my case. That explains why when my batteries were getting tired one motor would start and the other needed the emergency switch to get the other started.
 
You want to hear a weird one? My boat has 2 port 8D batts, 2 Star 8D batts, and 2 Bow Thruster 8D batts. Each 2 battery sets are hooked up in series. Boat is 98% 24 volts. The Thruster Batts are quasi stand alone. So the other 4 batts are for Engines, Gen, and House. But here is the thing, I can unhook the 2 Port Batts or the 2 Star Batts and everything still works. I haven't tried to start the Gen or the engines but the point is the 5 main Battery switches, Gen, Port 12, Port 24, Star 12, Star 24 all stay hot. Pretty cool.
 
My Amberjack had the typical SeaRay setup with two 12vt Deep Cycles per side, using each bank as starters/house. I'd get the same thing happening with electronics going out upon starting the Stb Engine. The 8.1's must have drained enough juice from the twin batteries when cranked to cause the electronics to power down. Never bothered changing the system to have a dedicated starting battery for the engines. It was fine for the 14yrs I owned her. It did have a genny with a separate starter battery too. I did run the main 4 batteries down once while at anchor overnight, but decided in the morning to use battery cables to jump one pair of main batteries to the generator battery to get the one engine started immediately. I could have started the genny but would have had to wait for the charger to get the pairs up to snuff...

My current Formula has a dedicated Starting Battery for the engines, a spare Starting battery beside that which is easily switchable should the starter battery fail, and a VERY large (3 battery in one type of large) deep cycle battery to supply the house needs the optional inverter should I decide to turn it on.

I think the setup using a dedicated starter battery just for the engines while using deep cycles for the house makes more sense for a boats electrical requirements.
 

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