3 batteries

[kevinnice]

Sundancer 290 1996.

I have 3 batteries - can anyone explain what each is used for?

Also, port engine wont turn over, so one battery is flat. Can i swop the batteried around so that both engines start?

Finally, what is the charging system? Alternator? Dynamo? Other?

Thanks guys

 

[Tonka Boater]

Just a guess...

1. Starting/cranking
2. House
3. Generator

-or-

1. Engine 1
2. Engine 2
3. Generator or House



.

 

[kevinnice]

thanks, but that cant be right because the starboard engine cranks and starts with a very positive feel but the port started tunring slowly and now just clicks - so the engines must start from different batteries.

but that leaves me wolndering what the 3rd battery is for... plus my other questions

 

[fins1up]

thanks, but that cant be right because the starboard engine cranks and starts with a very positive feel but the port started tunring slowly and now just clicks - so the engines must start from different batteries.

but that leaves me wolndering what the 3rd battery is for... plus my other questions

On our 280, there are 3 batteries along with 2 battery switches. *SWITCH 1* , with the settings 1 - BOTH - 2 is for the PORT engine along with all of the gauges and the "house" power. In the engine room there are 2 batteries setting side by side that are controlled by this switch. The 3rd battery sits alone beside the first 2. Your layout may be different.

*SWITCH 2* is for the starboard engine and the generator, nothing else. It's either Off or On.

It sounds like one or both of your port batteries have failed. The 280 also has an "emergency" switch on the helm station that bridges all of the batteries together to get you enough power out of which ever bank has juice to get you started. I'm guessing you also have this setup.

I would try the following to see if you can get the port engine to crank. Set *SWITCH 1* on position 1. Start the starboard engine, then hold the "emergency" switch and at the same time push PORT engine start switch. If that doesn't give you enough juice to start, move *SWITCH 2* to position 2 and try again. Which ever setting lets it start, should determine if either battery 1 or 2 has a short in it which is draining all of the cranking power. They both could also be bad.

If the batteries are a couple of years old or more, might be a good time to replace all three before you are left hanging somewhere..... Hope that helps!

 

[rondds]

In a 3 battery situation, SR usually has 2 batteries in parallel - they start one engine and do house duties. The other battery is usually a stand-alone batt that starts the other engine and the genny.

 

[stevedore]

I have a '08 280, with twin 4.3 B3's. No generator. Two round switches controlling batteries. One on left (Switch 'A') labelled 'One', 'Both' and 'Two'. One on right (Switch 'B') labelled 'On' and 'Off'.

Here is how my battery set up was explained to me by dealer tech.

Switch 'A':
Controls cranking power for each engine. Thus, to start both engines (and then recharge both batteries), you want it set to 'Both'.

Switch 'B':
House battery which controls components/appliances when not connected to shore power. Also recharged by engine/alternator when switched 'On'.

 

[kevinnice]

thanks all 3 of you for useful info. turns out that fins1up got it almost right in my case. batteries 1 and 2 share a negative cable and are for STARBOARD engine and house functions. battery 3 is for port engine only. i also discovered i have an automatic battery charger installed that kicks in on shore power hook-up.

my problem is that the PORT engine will only click when i try to start it. my first thought was battery. i have tested the starboard engine on all 3 batteries (while disconnecting the other 2). in all cases the starboard engine fires immediately and cranks very sharp. then i tried the PORT engine on the other batteries and it still just clicks.

i guess that means a starter motor problem so tried to investigate. the problem is that the starter motor seems to be at the base of the engine (mercruiser 43 LX V6).
i cant get to that so i guess i have to get a professional to take a look.

unless anyone has any other suggestions?

 

[rondds]

Have you checked all the connections? Dirty or loose connections can cause a large drop in amperage. Check them and clean all with sandpaper or wire brush if you find any junk anywhere in the circuit.

 

[Jersey Mike]

Should be a relay...usually on top of the intake manifold behind the throttle body/carburetor. Make sure you have battery voltage there and a signal from the ignition switch in the crank position...the relay should close and pass current to the starter.

 

[boatmailster]

Should be a relay...usually on top of the intake manifold behind the throttle body/carburetor. Make sure you have battery voltage there and a signal from the ignition switch in the crank position...the relay should close and pass current to the starter.

what about blown 90 A fuse on starter? will click but not start

 

[Lauralex]

In a 3 battery situation, SR usually has 2 batteries in parallel - they start one engine and do house duties. The other battery is usually a stand-alone batt that starts the other engine and the genny.

How would you determine which is which? I have 3 batteries, one in front of each eangine and another mounted remomtely. The remotely mounted battery went flat on me and the house power (radio, exhaust baffle, GPS, etc) failed and I could not start the port engine at all. No sweat on the starboard engine, and once I limped around on one for a while, I could use the emergency short to start the port. I will note that when I discovered that the port battery was flat (wouldn't start the engine) I used the emergency short and it did NOT work.

Since then I have replaced the remotely mounted battery and all is well, but then I read on here that I should have replaced all 3. The starboard portion of the engine compartment has a spot to mount another battery (making 4) and I was thinking of running 2 banks in parallel and having them share duties insofar as the electronics and etc go.

What you tink?

b

 

[kevinnice]

based on recently aquired knowledge i would suggest that whichever engine is sharing duties with house services should be the one with 2 batteries and the other engine should have just 1.

if you read back up this thread fins1 has port engine and house on 2 batteries and my boat has starboard engine and house on 2 batteries.

in my case all 3 batteries are located in a row on the starboard side of the bilge, with battery one nearest the stern then battery 2 then battery 3. batteries 1 and 2 share a negative cable connection (series).

is it possible a previous owner has altered the layout?

do you have the same switch layout as fins1 and me?

 

[Lauralex]

based on recently aquired knowledge i would suggest that whichever engine is sharing duties with house services should be the one with 2 batteries and the other engine should have just 1.

if you read back up this thread fins1 has port engine and house on 2 batteries and my boat has starboard engine and house on 2 batteries.

in my case all 3 batteries are located in a row on the starboard side of the bilge, with battery one nearest the stern then battery 2 then battery 3. batteries 1 and 2 share a negative cable connection (series).

is it possible a previous owner has altered the layout?

do you have the same switch layout as fins1 and me?

Yes from what you described the switch layout is the same. I suppose it is possible that the wiring may have been altered, but I'm really not sure. I guess I just don't understand how with as little as I use my boat we have such problems. It may be that while we spend a good number of hours on the boat it's not running. Our cruise spot is about 5 mins away from the marina, and aside from an occasional 25mile cruise up and down the lake, the boat sits on the charger, which appears to be working. In retrospect, there was one time that I left the boat closed up and didn't turn off the dash switch from 12V to 120V to the refer and I think I most likely killed that house battery.

I've got a new boat mechanic in line for taking care of the boat this year and when he pulls it in a month or so I'm going to have him go through and bullet-proof that electrical system, even if it means a 4th battery for a redundant house battery (I firmly believe in overdoing everything.) We tend to NOT turn the refer on when out and I'd like to from time to time, but mostly we just run the stereo.

Anybody know how the boats electrical system charges each battery? I remember reading something once in a post that said that it does each one a little, and that there is a bette charger that will do each one individually..??? Or did I dream that.?

 

[rondds]

If two batteries are in parallel, you cannot charge each one independently unless you break the parallel connection. Thus, with the usual SR three battery set-up (one stand-alone and two in parallel) you will be using 2 charger banks. It's been recommended that the two in parallel be the same battery type, make and age. If you mix and match and one is running low on charge and the other isn't, the charger will continue to put out a charge and overcharge the good battery.

 

[James Lee]

Great info on here, thanks so much. I have a 2005 290 AJ and I'm needing to replace all batteries. From what I've read on here I believe I have From front to back. Bat 1 is star starting, bat 2 is star/house, bat 3 is port starting.

So, if replacing all batteries would batts 1 and 2 need to be the same type. I was thinking of putting "Starting" batteries or Cranking batteries on batts 1 and 3 and then a deep cycle battery on batt 2 for the house.

Would that be correct??

Also, my Emergency Start Switch at helm doesn't work?? What would cause this? Bad Solenoid??

 

[Ed_C]

My 05 28 Sundancer matches exactly with Fins1Up... and each bank (2 for Port and 1 for Starboard) is charged by that engines alternator. And somehow (not a electrical engineer) the Shore power tops up all of them as does the generator.

One tip I learned. Unless you are RIGHT on top of charging all the time, the previous owner put cranking batteries in all three spaces. Cranked great -- but when it went in for service on the trailer and was not on shore line for an extended time, those cranking batteries just plain expired. After a lot of reading and research, ended up replacing with 3 dual-purpose (with a LOT of cranking power) to give somewhat better disconnected tolerance.

 

[James Lee]

All of the cranking batteries expired or just the cranking battery that you had running the electronics or “house” battery. That would make sense if a cranking battery was used to run the boats electronics. But not all 3 going bad ?? Let me know im currently battery shopping. Planning on 2 starting batts. One for each engine then a deep cycle for the house electronics. Mine is set up that the starboard bats are wired together one for start and one for house electronics. Port is separate just for starting port engine.