No instructions for battery hook up

[potter water]

Still Crazy, 22 ft cruiser, 2007.

The manual for this boat is EXTREMELY basic in regards wiring.

There are two batteries, one in each stern well, port and starboard, that are dedicated to each of the twin engines. There are 4 separate battery switches in the starboard compartment along with some other electrical whiz bangs.

All four are red, on off swivel switches and are labeled:

A. Port engine
B. Starboard engine
C. House battery(s).
D. Emergency all batteries

On the port side stern compartment is the battery for the port engine, and one house battery.

A second house battery is on the floor of the stern well next to the bilge pump.

As I run each engine, it is clear that they will each charge their dedicated battery as checked with a volt meter.

It appears that the house battery in the port compartment is charged by one of the engines. I'm not sure that the second house battery by the bilge pump is charged by either engine.

All this leaves the question about what is the proper wiring hardware to allow either engine to be charging two dissimilar batteries, one a starting battery, and the other a house battery. A no no I believe. Is there some hardware in there normally that isolates the house battery through a big ol' diode to keep it from providing current back to the engine that is charging it and makes it okay for the engine to charge two dissimilar batteries at the same time?

These are probably stupid questions, and some more poking around and measuring battery voltages may help answer my own question. But, any thoughts out there on what is proper in terms of running twin engines, and starting and house batteries would be well appreciated. I'll check the forum archives and do some looking on RV sites, but I don't know of any RV's that would have twin engines.

I think what I'd like is to have either engine or both be charging the house batteries when one or the other or both are running, as well as be charging their own dedicated starting batteries.

Also, any part numbers or sources for my dilapidated wiring boot that is in the splash well starboard wall?

 

[thataway]

There are any number of ways to do this. If you put in diodes, it will drop the charging voltage about 1/2 volt. This may lead to over charging one, and under charging the other battery, but this has been done for a long time.

Second is just adding a relay, which energises with the engine. This combines the "house" on each side. with that engine start, when the engine is running.

Another way is to combine the two "house" into one "bank"--this would require two same age, same capacity and same type batteries. Once you have done that, then you can use the BEP switch combiner 717-100A. This has two switches, and two combiners--which allows one engine to charge both house batteries, and that engine start, the other engine to charge its engine start.

Some outboards have a dual output--and you can directly charge both batteries of each of the engines.

You can use voltage sensitive relays to combine the engine start and house bank (each engine)--when the engine comes on, it selectively charges the start battery until its voltage reaches approximately 13.7 volts, and then the second battery is combined. If the voltage drops below 12.7 (or so), the combiner separates the batteries.

If the batteries are close to the same age and size, and you are using a typical outboard low amperage charger, you can get away with slightly dismilar batteries. The "engine start" vs combination or even deep cycle, are close enough, plus the output on the 40 and 50 hp outboards are relitatively low.

Finally you can use manual switches to do what you want; that is to combine the batteries. Tie an engine start and the house battery together.
Most likely the second house battery (or even the first house) was after market. There will be no wiring diagram. Many boats came with a single battery. I prefer a separate house bank, and use the VSR.

 

[potter water]

Thanks for the nice reply. I'm going to get a lot of wire tracing in today and I'll see just what the current connection scheme is.

 

[thataway]

That is exactly what you should do. You may not be able to trace out the circuit until you actually disconnect some of the wires, and see what is affected. Then you can label and draw out a schematic. From there, you can make the decision.

 

[Les Lampman]

Hi,

It sounds like you already have a BEP battery cluster in place. In addition to the four switches are there also a couple of square shaped enclosures above the port and starboard switches?

If so the switching and wiring is rather simple. The port switch connects the port starting battery to the port engine; ditto for the starboard switch.

The house switch connects the house battery to the main panel and accessories on the boat.

All you generally need to do when getting underway is to turn each one of those three switches to the "on" position...but not the fourth "emergency" switch, that one stays off.

In each upper corner of the switch cluster is a VSR (Voltage Sensing Relay). Once an engine is started and the voltage comes back up on the starting battery (usually pretty quickly) the VSR on that side with close and send charging current to the house battery. This happens independently for the port and the starboard engine.

Once the engines are not running and the system voltage drops the VSRs with open their switch and isolate the starting battery from house loads.

I don't know where the second house battery comes in since that's not a typical installation. In fact it's highly doubtful that there's enough amperage from the engine alternators to charge two house batteries.

Les

Still Crazy, 22 ft cruiser, 2007.

The manual for this boat is EXTREMELY basic in regards wiring.

There are two batteries, one in each stern well, port and starboard, that are dedicated to each of the twin engines. There are 4 separate battery switches in the starboard compartment along with some other electrical whiz bangs.

All four are red, on off swivel switches and are labeled:

A. Port engine
B. Starboard engine
C. House battery(s).
D. Emergency all batteries

On the port side stern compartment is the battery for the port engine, and one house battery.

A second house battery is on the floor of the stern well next to the bilge pump.

As I run each engine, it is clear that they will each charge their dedicated battery as checked with a volt meter.

It appears that the house battery in the port compartment is charged by one of the engines. I'm not sure that the second house battery by the bilge pump is charged by either engine.

All this leaves the question about what is the proper wiring hardware to allow either engine to be charging two dissimilar batteries, one a starting battery, and the other a house battery. A no no I believe. Is there some hardware in there normally that isolates the house battery through a big ol' diode to keep it from providing current back to the engine that is charging it and makes it okay for the engine to charge two dissimilar batteries at the same time?

These are probably stupid questions, and some more poking around and measuring battery voltages may help answer my own question. But, any thoughts out there on what is proper in terms of running twin engines, and starting and house batteries would be well appreciated. I'll check the forum archives and do some looking on RV sites, but I don't know of any RV's that would have twin engines.

I think what I'd like is to have either engine or both be charging the house batteries when one or the other or both are running, as well as be charging their own dedicated starting batteries.

Also, any part numbers or sources for my dilapidated wiring boot that is in the splash well starboard wall?