Just had a second thought, if each bank has two batteries in parallel, and the Port Bank has the two deep cycle batteries for the house load, then the Starboard Bank should have two starting batteries for both the engines and the genset since they are in parallel. Does that make sense?
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"...then the Starboard Bank should have two starting batteries for both the engines..." No.

The port bank starts the port engine and the stbd bank starts the stbd engine. The port supplies the house loads and the stbd supplies the helm alectronics (gps/radar...) and bow thruster (or visa versa.)

Stick with matched Deep cycle batteries all around. The house bank needs deep cycle and the bow thruster needs deep cycle. They have more than enough cranking amps to start the engines. Since you only have one battery charger, you should match the banks anyway. Don't let anyone talking you into starting batteries in a boat unless that is absolutely all they do, no pumps, backup power,... Even then I would still go with deep cycle.
 
Also, at the helm near the starting switch is an emergency start which combines both banks for emergency starting power.
 
Now that
"...then the Starboard Bank should have two starting batteries for both the engines..." No.

The port bank starts the port engine and the stbd bank starts the stbd engine. The port supplies the house loads and the stbd supplies the helm alectronics (gps/radar...) and bow thruster (or visa versa.)

Stick with matched Deep cycle batteries all around. The house bank needs deep cycle and the bow thruster needs deep cycle. They have more than enough cranking amps to start the engines. Since you only have one battery charger, you should match the banks anyway. Don't let anyone talking you into starting batteries in a boat unless that is absolutely all they do, no pumps, backup power,... Even then I would still go with deep cycle.
Now that makes sense. All batteries appear to be the same, so I assume they are all deep cycle. From everything I've heard, it sounds like I have some batteries in need of replacement. Thanks!
 
I would also clean the Genny battery terminals (both at the battery and the Genny if you can). Doesn't take much crud to knock down the voltage.
 
IMG_4230.JPG
Genny should have its own battery that is isolated from the others. It should be charging when you are plugged into Shore power with the charger turned on. It should be charging when the genny is operating. This set up allows you to charge the other batteries should they become totally discharged. In that case, you start the genny, power up the charger and wait for the other three batteries to gain enough charge to crank the mains. The emergency start switch helps with this by connecting the other banks together for extra cranking power. Once you get one main going the other will start with the help of the emergency switch. You can avoid this whole scenario by taking care to not allow things to discharge to such a level that you need emergency procedures. Turn one bank off and save the other, for example, if you are one the hook.
 
Th
I would also clean the Genny battery terminals (both at the battery and the Genny if you can). Doesn't take much crud to knock down the voltage.
Thanks, I'll definitely have those checked.
 
That
View attachment 78646 Genny should have its own battery that is isolated from the others. It should be charging when you are plugged into Shore power with the charger turned on. It should be charging when the genny is operating. This set up allows you to charge the other batteries should they become totally discharged. In that case, you start the genny, power up the charger and wait for the other three batteries to gain enough charge to crank the mains. The emergency start switch helps with this by connecting the other banks together for extra cranking power. Once you get one main going the other will start with the help of the emergency switch. You can avoid this whole scenario by taking care to not allow things to discharge to such a level that you need emergency procedures. Turn one bank off and save the other, for example, if you are one the hook.
View attachment 78646 Genny should have its own battery that is isolated from the others. It should be charging when you are plugged into Shore power with the charger turned on. It should be charging when the genny is operating. This set up allows you to charge the other batteries should they become totally discharged. In that case, you start the genny, power up the charger and wait for the other three batteries to gain enough charge to crank the mains. The emergency start switch helps with this by connecting the other banks together for extra cranking power. Once you get one main going the other will start with the help of the emergency switch. You can avoid this whole scenario by taking care to not allow things to discharge to such a level that you need emergency procedures. Turn one bank off and save the other, for example, if you are one the hook.
 
Makes perfect sense, but it does not look like I have a stand alone battery for the generator. Both banks of two batteries each are connected in parallel. I've turned the boat upside down looking for another battery, just can't find it!
 
As mentioned above the item linked below is a good low-dollar investment for boat owners with multiple batteries.

This will sound silly...but have you checked around for a fifth battery? On the floor between the engines possibly? Any other spots that could hold a battery dedicated to the generator?

https://www.amazon.com/gp/product/B000AMBOI0/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

stee, I have ten vehicular batteries to maintain. Never thought about getting one of these. I just ordered one. Thanks.

Boat and automotive batteries should be tested at 200 amps and should hold above 10 volts for 10 seconds
The inexpensive tester posted will only draw 100 amps.
 
I find the best service comes from 4 deep cycle group 31 agms and a smart charger. Searay has kind of strange configuration of what's considered house loads imo.
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My thought is that with 4 batteries:
1 battery starts one of your motors.
2 batteries start the other motor and power “the house”.
1 battery starts your generator.

You can tell which is which by following from the motors and generator back. Or if the bilge is tight and following cables is tight, you can disconnect batteries one at a time and see what doesn’t work.
 
IMG_4230.JPG
Makes perfect sense, but it does not look like I have a stand alone battery for the generator. Both banks of two batteries each are connected in parallel. I've turned the boat upside down looking for another battery, just can't find it!
Many boats purchased used have systems that have been modified by previous owners who were primarily interested in saving money as opposed to doing things correctly. You have a chance to set the boat up properly. Might cost a few bucks but no ever said boating was a cheap hobby.
 
I looked at his owner's manual. I started to elude to this above, so to follow up... it appears his pictures are bone stock as compared to the original setup from Sea Ray in the OM. Two battery banks, port and stbd. Each bank consists of two batteries in parallel. Each bank runs through an on/off switch. Genny is hooked up to the stbd side bank (specifically, the battery in the top, right of the pic). However, as mentioned a few times, the setup can be improved upon - but at least we know there is no "previous owner" confusion going on here.
 
Mine is setup with a pair of deep cycles for one engine and half the house, another pair of deep cycles for the other engine and other half of the house, and a separate starter battery just for the genny. I also keep a spare set of jumper cables in the ER. They sure come in handy for those times swinging on the hook on marginal main batteries when you want to get up and moving to another spot first thing in the morning.

A separate battery for the genny gives you the option to always start it up and slowly recharge your main batteries - but it also gives you the option to jump a pair of main batteries to the starter's battery while the genny is up and running. This enables you to start that one engine without waiting. While that main is running, you can then hit the emergency parallel switch to start the other engine. Remember to disconnect the jumpers without shorting them.

This is all assuming that you can actually GET into the ER and access the batteries. On my model there is a large day hatch between the helm and passenger seats where I can access the entire ER. With yours, you may have to electrically raise the ER hatch - quite the chore with spent batteries...
 
Boat and automotive batteries should be tested at 200 amps and should hold above 10 volts for 10 seconds
The inexpensive tester posted will only draw 100 amps.
I just ordered this one - variable. Inexpensive $80 and had good reviews. I will give it a try. I have two batteries I know are bad. Thanks for the instruction. The other will get returned.
Clore Automotive 1874 500 Amp Carbon Pile Battery Load Tester
 

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