Battery placement/ configuration 1999 340 - cranking vs deep cell

Soul Mate II

Member
Jun 28, 2015
193
New York
Boat Info
99 340 Sundancer
Engines
7.4 Mercruiser w V drives
Good evening,

Need some help - just replaced my batteries and put them back the way the owner before me did it...cranking/ starting batteries together on the starboard side and the house batteries together on the port side. The reason I think they should be 1 on each side is my port motor was having issues starting. Both cranking batteries were new and the house batteries were old. I purchase new (NOT CRANKING) house batteries deep cell and both engines started up no problem. My concern if they are incorrect is the batteries are different - I didn't but all the same. I bought all interstate batteries - cranking group 27 1000 MCA Interstate XHD and deep cell group 27 srm.

My question is around configuration of your batteries? And when you buy batteries do you buy all four the same? If so, all cranking batteries?

Thanks,
 
Tried setting that up once and it did take. Will try it again thanks!
 
Starting batteries, which crank the starter of your boat's engine, are the sprinters of your electrical system. They deliver between 75 and 400 amperes for 5-15 seconds, and then are recharged in short order by your engine's alternator.


Your boat's house battery bank uses deep cycle batteries, the marathon runners of the storage system. They power the electrical loads on your boat when no charge source (shore power charger, engine alternator, wind generator or solar panel) is available. Consider them a kind of savings account into which energy is deposited or withdrawn.

No matter what kind of battery chemistry you choose, follow these recommendations to get the best performance:

  • Stay with one battery chemistry (flooded, gel or AGM) Each battery type requires specific charging voltages. Mixing battery types can result in under- or over-charging. This may mean replacing all batteries on board at the same time.
  • Never mix old batteries with new ones in the same bank. While it seems like this would increase your overall capacity, old batteries tend to pull down the new ones to their deteriorated level.
  • Regulate charge voltages based on battery temperature and acceptance (manually or with sensing) to maximize battery life and reduce charge time. Ensure that your charging system is capable of delivering sufficient amperage to charge battery banks efficiently. This generally means an alternator with 25% to 40% as many amperes as the capacity of your entire battery bank.
  • Keep batteries clean, cool and dry.
  • Check terminal connectors regularly to avoid loss of conductivity.
  • Add distilled water to flooded lead acid batteries when needed. Keep them charged. Leaving them in a discharged state for any length of time will damage them and lower their capacity.
  • Clean corrosion with a paste of baking soda and water.
 
I have the same year make and model, 1999 340 Sundancer. When I replaced my batteries,I replaced them all at the same time with group 27 Interstate deep cycle marine batteries.Like in the previous post I would try to stick with all the same type of batteries. It’s my understanding that the four batteries power our boat like this. The two batteries on the port side are wired together for the house power, and also supply the starting power for the port motor. The third battery on the starboard side is the starting power for the starboard motor and the fourth battery Is the starting power for your generator.
 
Zim and Barlow - much appreciated! I have all flooded batteries. The configuration you talk about Barlow would suggest I have 3 cranking batteries (one for each engine and the genny) and one for the house batteries. I understand you went with all deep cell, which I have two of for the house batteries and two that are for starting. I would love to have all the same, should I buy all cranking/ starting then? Thanks for the help! Want to get this right so I never have an issue on the water!
 
We have two group 27 deep cycle per engine. One engine is stand alone the other provides the house 12 volt system. The batteries seem to last 5+ years. One set is 2011 the other is 2015. The 2011 I will replace next spring. I always put the new batteries on the house engine and put the older good ones on the stand alone engine. If you keep all batteries the same life is a little simpler. Write the year on top of battery with a felt pen.
 
I have the same year make and model, 1999 340 Sundancer. When I replaced my batteries,I replaced them all at the same time with group 27 Interstate deep cycle marine batteries.Like in the previous post I would try to stick with all the same type of batteries. It’s my understanding that the four batteries power our boat like this. The two batteries on the port side are wired together for the house power, and also supply the starting power for the port motor. The third battery on the starboard side is the starting power for the starboard motor and the fourth battery Is the starting power for your generator.
I use the same set up. Deep cycle all around. The short heavy draw for starting isn't going to harm the deep cycle batteries. The way the factory set up is wired confirms this. House batteries are starting batteries too. The starboard battery gets rotated into the house bank at the start of every season, and so on.
 
Steve, I think you’re gonna be just fine with what you have now. They are all our new correct? Yeah, I wouldn’t worry about changing out the starting batteries for your starboard and Jenny for deep cycle. However in four to five years when these four batteries take a crap just stick with all new deep cycle.Happy boating man!
 
Great advice all around but I can't help myself and just simply needed to know...I disconnected all of the batteries but one and work through each of the batteries. What I found was as follows - I am hoping I save someone else the time that might do this:

Starboard closest to the edge of the boat - closest to the generator - operates the generator only that I could find. It seemed to be a stand along battery meaning I could shut the batteries off in the cabin but the generator still would start. I made this a deep cell.

Starboard - closest to the middle of the bilge. This battery was for the Starboard engine, operated the bilge blower, depth finder, horn and wipers. I made this a cranking battery.

Port inside battery - closest to the middle - Port engine - again bilge blower worked as did the power vent

Port closest to the edge of the boat - this would be the "house" battery - covered all the lighting loads, fridge, head, - I made this a deep cell battery.

I am glad I did it and feel better understanding the configuration. If I had to do it all over again, I would do 3 cranking batteries and one house deep cell. Thanks again for all the help guys. I learn something new with each project...remembering for the next time is the challenge.

Enjoy the rest of your weekends!!!
 
On my 340 I replaced the generator battery with a group 24 starting battery and all the rest with deep cycle group 27's. Worked famously...

I think if you poke around here long enough you'll find some really fantastic threads on batteries. If I recall correctly one of them even explains how most of today's "deep cycle" batteries really aren't so "deep cycle". They are more dual purpose that anything. I think the term is a bit of a misnomer these days...

Also worth noting is that our BBC 7.4's are not particularly high compression. They don't necessarily need the uber high CCA's to get them spinning...
 

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