Battery banks

I have a 1986 Albin Trawler. Here is a basic question: how do I identify which bank of batteries is the house and which are the stating batteries. I don't see any idenifying labels.

The easiest way I can think of is to (with the engine off) disconnect a
ground on one bank and see if the house still has DC power.

You probably have the basic DC wiring system, which is each bank is wired to a 1,2,all switch so that either or both can be used for DC power. So the house bank is the larger one with deep cycle batteries and the starting battery is a standard, well starting battery.

Sometimes boats are delivered with one of each and both are of the same type, so called dual purpose batteries.

David

Follow the cables to see which are hooked to the engines and which are hooked to the electrical panel.

What is the number and type of battys you have in each bank?
It's a worthwhile exercise to trace cables to switches, panels, starters, etc and draw yourself a diagram. Good idea to fully understand all switches as well as which bank any key equip (thruster, windlass, etc) is connected to.
Also how each are charged from alternator & shore charger.

Ok. That make a lot of sense. I will do that!! All four batteries look identical. Do you think that it doesn't matter which is the starting batteries? Perhaps I should just turn off one of the banks when anchoring.

OMG. I knew I shouldn't have posted this question. Of course, follow the cables!!!! Thank you.

Check your batteries. Ideally you will have a set that list cold cranking amps. These are start batteries. Hopefully the other set will be marked deep cycle.

A little search on this sight and you will learn a lot about the deference between the two.

Phil Enscoe said:

OMG. I knew I shouldn't have posted this question. Of course, follow the cables!!!! Thank you.

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No problem. We love to help, and sometimes we actually do help.

I agree with several of the comments and would do all of them: trace wires if you can (may be easier said than done), look at battery banks and types of batteries to see if deep cycle or start, disconnect a battery to see what what does and doesn't turn on, and put a volt meter on a battery with the switch in various positions to see what is getting a charge or drain.

My first power boat (the Scout 30 SHADOW FAY) had two identical banks - each bank was 2 x Group 31 deep cycle batteries. You couldn't tell which was start and which was house, or which was connected to "1" and "2" on the battery switch without doing some research. Funny things happen on older boats.

And once you figure it out, label them so that a year from now when you have forgotten, you won’t have to go through it again.

twistedtree said:

And once you figure it out, label them so that a year from now when you have forgotten, you won’t have to go through it again.

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Good plan. I always think that I will remember stuff but I sometimes have CRS disease…

Tracing cables can be difficult...

If it's too difficult to trace the cables, you could start by disconnecting a battery positive terminal and see what stops working... house banks or engine start circuit?

Note - do so only with engines OFF. NEVER disconnect an engine start battery while engine is running (or you'll blown the voltage regulator diodes).

I'll plug Jeff Cotes videos here - hours of applicable learning available online.

4 batteries?
1 engine start
1 house
1 generator
1 ???

Phil Enscoe said:

I have a 1986 Albin Trawler. Here is a basic question: how do I identify which bank of batteries is the house and which are the stating batteries. I don't see any idenifying labels.

Click to expand...

You are at a huge disadvantage not being able to glance and know what’s what. My first suggestion is to get help from someone willing to help you out. You can make a mess of things if you “wing it” without a basic knowledge of electricity and boat mechanics. There are “gear heads” and “no assembly required” people. Play your strengths.

Bkay said:

I agree with several of the comments and would do all of them: trace wires if you can (may be easier said than done), look at battery banks and types of batteries to see if deep cycle or start, disconnect a battery to see what what does and doesn't turn on, and put a volt meter on a battery with the switch in various positions to see what is getting a charge or drain.

My first power boat (the Scout 30 SHADOW FAY) had two identical banks - each bank was 2 x Group 31 deep cycle batteries. You couldn't tell which was start and which was house, or which was connected to "1" and "2" on the battery switch without doing some research. Funny things happen on older boats.

Click to expand...

I am beginning to believe that the two banks of batteries cannot be isolated. I tried various configurations/positions, and it doesn't seem to make a difference as you implied. Thank you for your feedback!!!!

Comodave said:

No problem. We love to help, and sometimes we actually do help.

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I did follow the leads and found which battery bank is attached to the starter motor. Now, I have to figure out how to isolate that bank. It doesn't appear that changing from number one to number two makes any difference. Further investigation required!!! Thanks again.

twistedtree said:

And once you figure it out, label them so that a year from now when you have forgotten, you won’t have to go through it again.

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I am going to diagram it so that I will remember the whole thing. Thanks for your suggestion!!

bvaldyke said:

If it's too difficult to trace the cables, you could start by disconnecting a battery positive terminal and see what stops working... house banks or engine start circuit?

Note - do so only with engines OFF. NEVER disconnect an engine start battery while engine is running (or you'll blown the voltage regulator diodes).

I'll plug Jeff Cotes videos here - hours of applicable learning available online.

Click to expand...

I did as suggested, and it didn't make a difference. So, I think that the two battery banks are wired together. I need to change that so that I can isolate the starter batteries. Thank you.

High Wire said:

4 batteries?
1 engine start
1 house
1 generator
1 ???

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Two sets of two batteries, plus a dedicated battery for the generator.

JRO said:

You are at a huge disadvantage not being able to glance and know what’s what. My first suggestion is to get help from someone willing to help you out. You can make a mess of things if you “wing it” without a basic knowledge of electricity and boat mechanics. There are “gear heads” and “no assembly required” people. Play your strengths.

Click to expand...

You are a wise man. I finally did give you just a few hours ago and have a trained boat electrician going to the boat today. Thanks!!!

yeah -all this previous advice is valid- except a lot of boats originally were delivered with two battery banks - usually 1 port bank & 1 stbd bank with a 1-2-both-off switch. Yours may still be original. In this configuration, there was no start/house separation, and start & house loads were combined. Typically, the 1-2-off switch was a "make before break" switch so you could switch batteries with the engines running (as long as you don't turn to "off" which fries your alternator diodes). The plan with this set-up is to run with the switch set to "both" thus charging and using both banks while running. At anchor, many of us would switch to "1" on odd numbered days or "2" on even numbered days. The next morning, even if you left something running and drained one bank, the other bank was good for an engine(s) start. With the advent of solar, inverters etc. most boats have been converted to a start/house bank configuration. The only way you will know how yours is connected is to follow the positive connections, then disconnect one bank at a time to see what does/doesn't work. Draw a simple diagram. I guarantee, you will learn a lot and that it will help you down the line.