Question about my boats battery system?

[rdm190]

I recently aquired a 1984 Wellcraft 23' Aft Cabin, 260 Merc Alpha 1.

Let me detail the battery system as I see it:

The boat has two batts, one appears to be a dual purpose starting battery, the other appears to be a deep cycle "house battery".

There is a (bank1, bank2, both, off) rotary switch.

There appears to be a 60amp isolator bolted down by the engine.

The boat has a 110v AC system, I have found a distribution panel, but have yet to find the inverter/charger. Any advice on where this may be located would be great, it appears to be all factory installed equipment.

As the system stands I assume I have bank 1 for starting, and bank 2 to run the DC systems without engine power (and for additional gusto if needed to start), am I interpreting this system correctly?

If I am correct I would like to add an additional deep cycle in series with the current deep cycle batt. This would give me two deep cycles on bank 2 and my starter battery on bank 1. I just want to have a good line of power to run my lights and other basic equipment without engine power.

Any problems you see with this system? Or any advice in general would be great. I spent a good amout of time just learning what was in the boat. Everything is very neat and appears to be done right.

Thanks guys,
Ryan

 

[drewpster]

Re: Question about my boats battery system?

If all is as it seems, here is how it works.
Batt switch in 1 position= everything works off batt 1
Batt switch in pos. 2 = everything works off batt 2
Batt switch in pos. BOTH= everything works off both batts

The isolator uses the engine's alternator to charge both batteries regardless of switch position.

Its a good system but it has its limitations. Isolators have voltage drop across them. Meaning not all of the alternator's output reaches the batteries. If the house battery is deeply discharged after a night out it will take longer to recharge the house battery with the engine. May or may not be a problem depending on how you use your batteries and how long you run the engine. It can also be prone to user error. (a failing of my own) If you forget and leave the battery switch in the BOTH position power is drawn from both batteries. A simple mistake can leave you stranded with two dead batts. You have to remember to select the house battery at anchor for long periods. Seems simple but if your memory is like mine it can be a challenge.

Your boat may, or may not, have an on board charger/ inverter. My boat for example has AC power without the inverter. All the ac equipment runs off the shore power cord only.

Most inverters I have seen run directly to the battery posts themselves or to a main power buss close to the batteries. The battery cables powering it are normally larger gauge and have inline fuse links or breakers. If you think you have a hidden inverter, look for a pair of extra cables running to the deep cycle battery that have no obvious purpose. These are probably your inverter DC feed cables. You can trace them to the inverter's location generally.

 

[rdm190]

Re: Question about my boats battery system?

If all is as it seems, here is how it works.
Batt switch in 1 position= everything works off batt 1
Batt switch in pos. 2 = everything works off batt 2
Batt switch in pos. BOTH= everything works off both batts

The isolator uses the engine's alternator to charge both batteries regardless of switch position.

Its a good system but it has its limitations. Isolators have voltage drop across them. Meaning not all of the alternator's output reaches the batteries. If the house battery is deeply discharged after a night out it will take longer to recharge the house battery with the engine. May or may not be a problem depending on how you use your batteries and how long you run the engine. It can also be prone to user error. (a failing of my own) If you forget and leave the battery switch in the BOTH position power is drawn from both batteries. A simple mistake can leave you stranded with two dead batts. You have to remember to select the house battery at anchor for long periods. Seems simple but if your memory is like mine it can be a challenge.

Your boat may, or may not, have an on board charger/ inverter. My boat for example has AC power without the inverter. All the ac equipment runs off the shore power cord only.

Most inverters I have seen run directly to the battery posts themselves or to a main power buss close to the batteries. The battery cables powering it are normally larger gauge and have inline fuse links or breakers. If you think you have a hidden inverter, look for a pair of extra cables running to the deep cycle battery that have no obvious purpose. These are probably your inverter DC feed cables. You can trace them to the inverter's location generally.

Thanks for you great input. I am going to pull the 110v distribution panel and see if there is an inverter hidden behind it. Or better yet I'll just start up the boat and see if I have AC power!!

So,the only thing you missed; can I add a second deep cycle batt to the house side of the system? Is this going to be over kill? Or will it cause problems? If I can add it, should I add in a series or a parallel? My basic electrical science is rusty, who knew you would need this stuff someday!

Thanks
-Ryan

 

[drewpster]

Re: Question about my boats battery system?

My battery science is not great either but one thing is for SURE. If you add the second house battery the connections are to be PARALLEL. This means positive to positive, negative to negative. Connecting them in series doubles the voltage. (12v to 24v = fried electrics)

Increasing the battery bank is a question I also have as I am planning the same thing, adding a second house bank. It would seem the greater capacity would be easier to recharge because less discharge occurs in the larger, two battery, bank. However I am speculating on that. Hopefully another poster can enlighten us.

 

[rdm190]

Re: Question about my boats battery system?

My battery science is not great either but one thing is for SURE. If you add the second house battery the connections are to be PARALLEL. This means positive to positive, negative to negative. Connecting them in series doubles the voltage. (12v to 24v = fried electrics)

Increasing the battery bank is a question I also have as I am planning the same thing, adding a second house bank. It would seem the greater capacity would be easier to recharge because less discharge occurs in the larger, two battery, bank. However I am speculating on that. Hopefully another poster can enlighten us.

I did a small review of my 6th grade science. If I add a second = house batt in parallel, it will double the amp hours. Now my question to the guru's will be can the alt handle charging the extra batt.

P.S. I am not adding a second house bank, just a additional battery to my existing house bank.

 

[Silvertip]

Re: Question about my boats battery system?

Since by adding another battery, you have increased the electrical system capacity by roughly 33% so you will need to run the engine roughly 33% longer to fully charge all three batteries. How long that actually is depends on how deeply discharged each of the batteries are at the time and what the alternator output is. But to answer your question -- yes, the alternator will charge all three batteries. The unknown is "time".