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Adrift
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Discussion Starter · #1 ·
I'm sorry for starting another charging thread!!

I have two batteries, house and starter and simple 1-2-both-off dial for selecting which battery to use.

My question is (and I realize this might depend on how the boat is wired) is if when the engine is running 'both' is selected, are both batteries being charged? Or is it generally dependent on how the alternator is wired to the batteries?

Other than the house battery in some way being charged by the engine, I see no way that is can ever be charged.....I realize I can get into solar and dual battery charging controllers, etc. but trying to find out what's what in my current set up.

Boat also house shore power, but I see no way batteries are charge whilst connected to this either....very strange.

Thanks!!
 

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Learning the HARD way...
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Typically, the alternator output was wired to the high amperage starting lug by the manufacturer. This high amperage lug is then connected to the C post of the 1, B, 2 switch. By turning the switch to B while the engine is running, you are applying a charging voltage to both batteries.

My system fits your description. I have 2 group 29 batteries and an EchoCharger. I use the 2 battery as my house bank. When I start the engine after a night on the hook, I switch to B, and after it starts switch back to 2. The echo charger keeps battery 1 topped up. When I am at the dock, the battery charger is connected to bank 2, and again, the echo charger keeps battery 1 topped up.
 

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With an EchoCharge there's no need for switching anything.

Wire the starter to the start battery, with it's own ON-OFF switch (the Blue Sea Systems #6006 is a good and inexpensive one).

Wire the house bank to another switch or just use one position of the existing 3-way switch, e.g., position #1.

Wire the EchoCharge as it's supposed to be installed between the house bank and the start battery.

It's a good idea to run ALL charging sources directly to the house battery bank.

Install appropriate fusing thruout.

Then....

  • The engine starts with the start battery.
  • The house loads run from the house battery bank.
  • The EchoCharge maintains the start battery.

No need to switch anything. And, it's not a good idea to change the position of a 3-way switch with the engine running because, even if it has a make-before-break design and a protective circuit for the alternator field current these can always fail. Or, by mistake the switch can be turned to OFF. Either way, you risk blowing the diodes in your alternator.

Much better to use the EchoCharge as it's designed, and don't switch anything.

Here's a basic wiring diagram with the EchoCharge.

http://wdsg.com/gallery/main.php?g2_itemId=301&g2_imageViewsIndex=1

Bill
 

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Adrift
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Discussion Starter · #4 ·
Thank you both for your replies and although I'm not that good at electrical stuff I understand the logic and also very much appreciate the advice on not switching with the engine running.

It sounds like it's SOP to always charge the house bank and then use the Echo Charge to top off the starter battery, so I'll work under that assumption.

The diagram is also very useful, thanks!!
 

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My question is (and I realize this might depend on how the boat is wired) is if when the engine is running 'both' is selected, are both batteries being charged? Or is it generally dependent on how the alternator is wired to the batteries?
Yes and no. Your batteries will equalize charge when connected to each other with the "Both" or "All" switch position because there is a direct connection between the batteries through the switch.

My solar panel is wired to one battery in a bank of two deep cycle batteries. I leave my switch on "Both" or "All" all the time, without a dedicated starting battery. The direct-wired battery will show a slightly higher voltage than the other when the sun is shining, reflecting the charge it is receiving from the controller. They even out overnight. Both stay roughly equally charged all the time.
 
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