Starter Battery Issue - Troubleshooting advice Needed

[Cdn_bacon]

I have the traditional 2 battery setup on my boat. One house battery (2-6V in series) and (1) 12V starter battery. Both go to a battery switch on my DC panel where I can select, 1, 2 or Both. When I select the starter battery to start the boat, I am getting a tone from the Yanmar starter panel when the key is turned but nothing when I push the button to start the engine. No clicks or starter attempts at all. Switching to the house battery it will tone and start the engine right up on the first push of the button. Theoretically that eliminates any wiring issue from the DC panel to the starter.

Wiring wise everything looks in order. Nothing has been changed other than I added a fuse block on the starter (+) post when I installed a AC-DC battery charger this spring. To check I removed the fuse block but there was no change. Putting a meter on the battery it appears to have a full charge based on voltage. Open to suggestions how to proceed? I was thinking of swapping the leads to the house battery to eliminate the wiring issue. Other than that, I'm at a loss.

Worst case, how bad is starting the engine off the deep cell 6V house batteries?

[Peregrine1983]

When you check the voltage on the starter battery, are you removing it from the charging source? If the charging source is still hooked up when you check the voltage, the battery could actually be dead and the "fully charged" voltage you're seeing could be from the charger. This sounds like a dead battery to me.

[Statistical]

Originally Posted by Cdn_bacon

I have the traditional 2 battery setup on my boat. One house battery (2-6V in series) and (1) 12V starter battery. Both go to a battery switch on my DC panel where I can select, 1, 2 or Both. When I select the starter battery to start the boat, I am getting a tone from the Yanmar starter panel when the key is turned but nothing when I push the button to start the engine. No clicks or starter attempts at all. Switching to the house battery it will tone and start the engine right up on the first push of the button. Theoretically that eliminates any wiring issue from the DC panel to the starter.

Wiring wise everything looks in order. Nothing has been changed other than I added a fuse block on the starter (+) post when I installed a AC-DC battery charger this spring. To check I removed the fuse block but there was no change. Putting a meter on the battery it appears to have a full charge based on voltage. Open to suggestions how to proceed? I was thinking of swapping the leads to the house battery to eliminate the wiring issue. Other than that, I'm at a loss.

Worst case, how bad is starting the engine off the deep cell 6V house batteries?

What is the voltage on the starter battery when you push the starter button and with the charger off? Battery voltage without load can be deceptive. Have you tried starting with the switch in all configuration? What is the result?

Worst case, how bad is starting the engine off the deep cell 6V house batteries?

It isn't ideal longterm but a half dozens starts aren't going to cause problems especially if the SoC is high. That is why the switch exists.

[OldManMirage]

If the starter battery is a true flooded type starter battery and it is more than a few years old - it's probably dead. I would replace with a decent deep cycle battery - it will start your engine just fine and it will give a reserve bank of power.

It doesn't hurt at all to use the 6v batts for starting. My "start bank" is actually the same thing - 2 6v golf cart batteries.

[ltd]

Is there a fuse somewhere in the system? Check voltage and continuity. Unless a battery is dead flat (which is unusual), it'll usually at least try to crank the engine. If it is dead flat, look for why. Even a crappy battery will hold a little voltage if left to its own devices.

[SailingHarmonie]

Almost any battery can show a full charge based on voltage, even when it is close to fully dead. It IS fully charged, it just has no capacity left to do anything useful with.

As has already been suggested, check the voltage WHEN you are attempting to crank the engine. If it is less than 11V, change the battery. If the voltage doesn't change when you try to crank the engine, there is a bad connection that needs attending to.

If it is a flooded lead acid battery, open it up and check the electrolyte level. If it is below the plates, replace the battery.

Buy or borrow a battery CCA test tool. If it shows less than 80% of original capacity, replace the battery.