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A previous owner upgraded the electrical system on my sailboat. It has two - 4D size batteries for the house systems and a single starter battery for the engine. My understanding is that the starter battery is supposed to be isolated and completely dedicated to starting the engine. However, the other day, I had to remove one of the 4D batteries and found out that the engine would not turn over. When I hooked the 4D battery back up, the engine started. The upgraded electrical system was done by a professional marine services company ( according to the documentation on the boat ).

There are a maze of wires that lead to a custom board with shunts and connections. The wires are labeled but over the years, they have become faded and some are unreadable. There is a xantrex digital echo charger on the custom board too.

My dumb question is whether or not it's normal for the isolated starter battery to be tied into the house bank? Or is more likely that something has been mis-connected?

Any insights would be appreciated. Thanks
 

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Barquito
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Welcome to SailNet! The starter battery needs to be tied into the other batteries if you want to charge all of them at the same time. Normally, there is a selector switch to choose which batteries you are drawing the juice from, and charging to. There are lots of ways to wire, and to use batteries, however, typically when you are motoring you would have the selector on BOTH to charge all batteries. When you are at anchor, you would switch to HOUSE to only discharge the house batteries. If you accidentally run the house batteries, you will still have the starter battery to fire up the engine.
 

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Is it possible that you removed a common ground so things went dead. Maybe look for an either/neither switch and trace some cables too.
 

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It's actually a good idea to have a selector switch, which allows one to use the house bank to start the engine, if the start battery dies. Could this switch exist and be set this way.
 

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The starter battery should be able to start the engine by itself no matter whats going on with the house Bank.

As a non - electrician I can tell you I have never had one in my boat who does anything but slag off previous electrical work... but all has been done by professionals! So I reckon none know anything. (Except MaineSail, but he's in Maine).

So slowly work out what you want and get it installed and proved to work the way you want it before you pay the bill.

My banks appear to have been separated. Thats fine, as long as they both charge. What I did to solve the problem of an accidental drained starter battery was to put in a jumper lead cable just in case. If I ever need it I can wire it up in 3 minutes. Cost: Zero. :)
 

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Learning the HARD way...
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The first thing that you should do is get a current working diagram of your primary electrical system. Do it yourself or pay someone to do it. It will save you time and aggravation in the future.

For example; this is the current version of my electrical system:


It's not fancy, but it helps me, and I maintain this as a guide.

Here is what the engine manufacturer provided;
 

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The separate dedicated starter battery system with its various tendrils and whatevers seems very antiquated.
If you like worry beads, a $100 Li batt starter pack will spin her into orbit....with fewer worries
 

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My understanding is that the starter battery is supposed to be isolated and completely dedicated to starting the engine.

My dumb question is whether or not it's normal for the isolated starter battery to be tied into the house bank? Or is more likely that something has been mis-connected?

Tell us what you have for a battery switch set up and we may be able to help. A large majority of boats do not use a dedicated starting only battery. This is because they use the very common 1/2/BOTH switch...

If you could list the switches and their labels, or even better, draw us a diagram of the positive battery wires and switches it would help us help you..
 

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Tell us what you have for a battery switch set up and we may be able to help. A large majority of boats do not use a dedicated starting only battery. This is because they use the very common 1/2/BOTH switch...

If you could list the switches and their labels, or even better, draw us a diagram of the positive battery wires and switches it would help us help you..
a few pics are worth a thousand words....
 

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It's actually a good idea to have a selector switch, which allows one to use the house bank to start the engine, if the start battery dies. Could this switch exist and be set this way.
When I discovered that my house batteries could not be used to start the motor, I fixed the problem by adding another switch. Now, if the starting battery dies—as it once did at an inconvenience moment— I can switch over to the house batteries.

BTW, since the starting battery and house batteries are different sizes, it took me 2 hours to swap out the starting battery and tie down the larger house battery. That lost time meant I made the passage westward in the Cape Cod Canal with a 7 kt current. Glad the RR bridge wasn’t down!
 

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I have a dedicated engine starting battery in my sailboat. It only supplies power only to the diesel engine starter motor and is charged by a Xantrex Echo Charge.

A problem with my present wiring is that the "ignition" key switch is powered by a circuit breaker labeled 'engine' on the circuit breaker panel that is powered by the house bank. That is probably because the key switch in its 'on' position supplies power to the engine gauges, engine alarm horn, engine alarm lights, the engine drive refrigeration system, the electrical fuel pump, the alternator regulator... all things other than the starter motor. But, the "ignition key" also supplies the engine start button and thus the engine starter solenoid. So, I can't really start the engine with the engine starting battery alone without combining my starting battery and house battery bank.

Fixing that is on my list (and has been for years).

You may have similar.

Bill Murdoch
 

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I have a dedicated engine starting battery in my sailboat. It only supplies power only to the diesel engine starter motor and is charged by a Xantrex Echo Charge.

A problem with my present wiring is that the "ignition" key switch is powered by a circuit breaker labeled 'engine' on the circuit breaker panel that is powered by the house bank. That is probably because the key switch in its 'on' position supplies power to the engine gauges, engine alarm horn, engine alarm lights, the engine drive refrigeration system, the electrical fuel pump, the alternator regulator... all things other than the starter motor. But, the "ignition key" also supplies the engine start button and thus the engine starter solenoid. So, I can't really start the engine with the engine starting battery alone without combining my starting battery and house battery bank.

Fixing that is on my list (and has been for years).
Bill Murdoch
My wiring is similar... To start I require both banks to be ON. But I don't see this as a problem. The house bank is not starting the engine. The house bank will allow the gauges to work, and for the solenoid to engage. The start batt is what drives the starter motor.... Of course it can't unless the solenoid is enagaging the starter.

A starter solenoid (or starter relay) is the part of then engine which switches a large electric current to the starter motor, in response to a small control current, and which in turn sets the engine in motion. Its function is thus identical to that of a transistor, but using an electromagnetic solenoid rather than semiconductor to perform the switching."

Perhaps if you moved all "starting functions" to the house bank... it would add some drain in the starting function. My key switch also powers several blowers. So the wiring puts all starting amps to ONLY the starter motor. Why change that?

My BlueSeas batt switch DOES allow the house bank to be combined with the Start batt for starting if and when the start bank is too drained/weak to do it on its own. But my Start batt is always topped up because it is on a Echo Charge... so the house bank is keeping the Start batt charged.

If you refer to my wiring diagram (not "schematic") to can see the "charging" side of the system is shown on the right side of the diagram... the "load" side is on the left side and the BATTS are in the center. You can see that the Key Switch is providing current to the Blower and Engine gauges... same as you describe. The batt Switches are separate but have COMBINE feature (I called "both") which allows the House bank to provide amps for starting function. This was NOT the actual wiring circuit from the boat builder which came with a 1-2 - both switch... no alt charging sources, no monitor feature (just a voltmeter), no smart charge regulators and no high output alternator w/ smart regulator. Every electrical component shown in the diagram as been added by me except the gauges, distribution panel and the starter. This includes:
batteries
busses
fuses
wiring
solar panels
regulators
battery switch
inverter
heater
windlass
link monitor
 

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Master Mariner
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My personal preference is to have the two systems completely separate. On the wind gen and the engine alternator, all charging goes to the house bank only. Solar charges house and engine start at 90/10%.
My main reasoning is that occasionally when I would go to start the engine when both banks were connected together, the load would cause my electronics would wink out. I do not think this is good for them and it is worth separating the systems to prevent it from ever happening again.
Of course, in a perfect world, all my batteries would be fully charged and ready for whatever load I might need to put on them, but I'm sorry to say that it just ain't so.
 

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My personal preference is to have the two systems completely separate. On the wind gen and the engine alternator, all charging goes to the house bank only. Solar charges house and engine start at 90/10%.
My main reasoning is that occasionally when I would go to start the engine when both banks were connected together, the load would cause my electronics would wink out. I do not think this is good for them and it is worth separating the systems to prevent it from ever happening again.
Of course, in a perfect world, all my batteries would be fully charged and ready for whatever load I might need to put on them, but I'm sorry to say that it just ain't so.
Don't use house bank for starting solves the sensitive instrument problem.

But you can install a small motor cycle batter in line with your sensitive instrument circuit. This acts as a filter and will maintain power to the instruments... and be kept charged by the house bank as well.

Many instruments will see voltage drop when the house bank is used for starting and that drop may cause them to "restart" and in the case of GPS... re acquire.
 

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Don't use house bank for starting solves the sensitive instrument problem.

But you can install a small motor cycle batter in line with your sensitive instrument circuit. This acts as a filter and will maintain power to the instruments... and be kept charged by the house bank as well.

Many instruments will see voltage drop when the house bank is used for starting and that drop may cause them to "restart" and in the case of GPS... re acquire.
The problem was easily solved by separating the banks completely and having the electronics on the house bank. I have the old 1-2-both switch, should it ever be needed.
 
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The problem was easily solved by separating the banks completely and having the electronics on the house bank. I have the old 1-2-both switch, should it ever be needed.
Which is what one should do!!!!!!!!!!!!!

The BlueSeas batt switch are separate for HOUSE and START and have a separate switch to combine batts if needed. Never had a need to combine as START bank is always fully charged!
 

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Which is what one should do!!!!!!!!!!!!!

The BlueSeas batt switch are separate for HOUSE and START and have a separate switch to combine batts if needed. Never had a need to combine as START bank is always fully charged!
When I bought this boat, and many others I've been on, the battery systems were combined and in poor condition.
I am rarely aware when a battery/bank is about to fail, so on a number of occasions I have indeed had to combine the banks to start the engine. Down here getting a replacement isn't as easy as it is in the states and sometimes I must operate with a bad battery/bank for a week or two until I can find a replacement. So far, I haven't had both banks die on me at once.
 

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The OP has 2 house banks plus a starting battery..Solution to what runs what could be a starter button on the dash.Run a fused line up from the starter hot to it and back to solenoid. Now its a separate system . Complications like electric fuel shut down,glowplugs fans and stuff still on the key may not be addressed by this but understanding your wiring may help.
 
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