AGM And Wetcell Battery Charging

[alldodge]

I have two engines, each with its own alternator. Each engine has its own starting battery, with a battery switch. The current charger, is a 3 bank, I believe with one to each engine, and the 3rd to the house batteries. The generator has its own battery, and is not charged by the charger. I'm fine with keeping it that way.

Thanks

OK, I guess. Something doesn't add up between the house the statement of charger does not charge the Gen battery.

This will work, use an ACR and where the house battery is listed use it as your AGM's.

 

[300sflyer]

When I first got the boat, I discovered that the generator did not have its own battery. It was wired to the house battery. First time out overnight, the house battery was weak next morning, and the generator would not start. I had to jump it with one of the starting batteries to fire up the generator. I have since added a separate starting battery for the generator. It charges while the generator is running, so I figured I would just leave it like that.

Having said all that, there is a battery isolator in the engine compartment too.

 

[alldodge]

Having said all that, there is a battery isolator in the engine compartment too.

The isolator is normally connected to the output of one ALT and then goes to the start bat and house bat. Another way of charging the AGM is changing the 2-bank isolator to a 3-bank


This is how my Formula is connected and I have only on engine

 

[300sflyer]

I am not sure how many banks are on the current isolator. I suppose I can always get a new one with more banks if I need to. With both new chargers installed, I will have a total of 5 charge banks, so I should be ok there.

 

[300sflyer]

I was at the boat on the weekend, and took a picture of the isolator.

 

[alldodge]

That's a 2 alternator, 3 bank isolator. Each alternator can change 3 banks of batteries with only one running, but can also both can charge 3 banks at one time

 

[300sflyer]

Would it be ok to put another 2 alternator 3 bank isolator, in parallel with this one, in order to charge additional battery banks?

 

[alldodge]

I would suggest disconnecting one of the start batteries from the 3-bank isolator along with corresponding ALT connection, My guess would be the house Bat is in the middle of the isolator and start Bat's are on the outside. Don't take my assumption you need to verify. The ALT sense lead comes straight from the ALT to the Start Bat and must remain with it. You don't need to find it, most likely it is on the starter post. The key is to make sure the ALT output stays with it's Bat.

On the Bat side of the isolator terminal that was removed, connect one of your new bank of Bat. Now one ALT will charge One start, the house and one new Bat bank.

Now add a new 2-bank one ALT isolator with at least 100 AMP capacity, go larger if you wish. Connect the ALT to the input terminal on the new isolator. Then connect the original start Bat and the other new Bat bank

This way one ALT wil charge 3-banks and one will charge 2-banks. Cover the ALT input terminal not used on the original 2-ALT 3-bank isolator.

 

[300sflyer]

Thanks for your reply.

I was hoping to just put 2 isolators in parallel, so both alternators would charge all the battery banks, especially the one connected to the two AGMs for the bow thruster being installed. The 12V bow thruster has a 500amp fuse, so I know it going to draw lots of power. Is this method somehow unsafe?

Thanks

 

[alldodge]

Thanks for your reply.

I was hoping to just put 2 isolators in parallel, so both alternators would charge all the battery banks, especially the one connected to the two AGMs for the bow thruster being installed. The 12V bow thruster has a 500amp fuse, so I know it going to draw lots of power. Is this method somehow unsafe?

Thanks

I thought about it before replying and it should work, but I'm hesitant because I have not seen it done and cannot find a manufacture which makes a 2-ALT 5-bank isolator. I don't believe it is unsafe, it's just trying to change that many Bat's at one time.

The ALT sense lead is on the start Bat, so once it gets charged to full the ALT will reduce. There will still be charge going to the other banks just not as much.

Edit: now if you went ACR then this would stand a better chance of reaching full charge

 

[300sflyer]

I could not find a 2 Alt 5 bank isolator either. It likely doesn't exist. Hence my thought of just putting 2 three bank isolators in parallel. I am changing out the house batteries anyway, so it will be lots of work regardless.