8D's & Golf Cart batteries

[eze2bme]

OK ... I've been reading all these threads on batteries and inverters and have the following observations/questions:
1. If golf cart batteries are able to start our Detriots if they fire off relatively quickly, then why can't we use one set of 8D's on the port engine/generator and golf cart batteries on the starboard engine? If the golf cart batteries are too weak to start the engine then use the parallel switch.
2. The starboard bank (golf cart) could then be used for the engine and also for the house panel and inverter which would work better as they are deep cycle batteries.
3. When the engines are running they would recharge both banks.
4. Wouldn't this be easier than having a third bank of batteries for an inverter?

I currently have two sets of 8D's. Port supplies engine and genny. Starboard supplies engine, house panel and inverter. I use my boat year round here in South Carolina and use block heaters in the Winter. My Detriots (671N's) start almost immediately with the block heaters, even if the outside temps are in the 20's.
Unless you guys can come up with a reason not to do this, this is what I'm going to try next time I replace batteries. Thanks!

[Genesis]

That's how my boat is wired too.

However, if I change it, I will do it very differently.

If you don't anchor out, then it doesn't matter. If you do, then it does.

Simple fact is that you must always be able to get ONE engine running. Whether that's a genset or a main is not material - but that you get ONE started is.

So long as you are comfortable with being able to do that, you're cool.

I like the combined bank for both mains and a separate bank for house. The combined bank for mains can be three G24 AGM batteries, which will provide close to 3000 amps of CCAs (!) - more than a 50% overage from Detroit's recommendations.

The other three boxes can have golf car batteries in them in series/parallel and run whatever - house, inverter, etc.

Then take a small (e.g. motorcycle-size) AGM battery and dedicate that to genset starting. Light, does the job.

Now you've got a nice degree of redundancy..... and if the inverter has a bulk charger in it, you can recover the house bank off the generator in a BIG hurry.

[Pascal]

it really depends how you use your boat and what kind of loads you have.

yes, golf cart batteries start engines just fine. mine also fire right up (i have too hold the shutdown switch much longer than the start switch...) but even when i had priming issues, i was able to crank them for reasonably long periods... 10 seconds at time, couple of minutes total with no apparent loss.

if you normally run the genset most of the time, then there is no problem doing what you are suggesting. on the other hand if you're spending a lot time with the genset off, and relying on a lot of juice, I'd be a little concerned in relying on one bank and a paralel switch for routing start ups. I'd prefer having a dedicated inverter/house bank. asuming you have enough room.

i have 2 banks, each made of 4 8v gold cart batteries, used for the mains. i have a selector switch to choose either one for house duties. Genset has its own 12v battery, and i have a 12v battery for electronics and accessories. Finally i have the recently added inverter bank (8 6v batteries). I dont have much house loads on my boat, just a few lights, vacuflushes, water pump so i never draw much on the house bank. Most loads are 120 thru the inverter.

if i has more DC loads, I'd probably run them from something else than one of the main banks.

you never have enough batteries on a boat... i have a total of 18, it's no big deal to add water every 4 to 6 weeks... having 12 or 18 doesn't make a big difference once I'm crawling down there...

just my opinion... :-)

[double eagle]

OK ...It really does matter how you use the boat...
It also matters how you draw down your batteriues...
when I finnally found my boat ...I ws glad to find one that had been used a lot...you have to keep things fixed...the boat used to go from baltimore to the keys ..then down to the turks and cacios...the boat always had a captain..
the last 5-6 yrs he became lazy on the cosmetics but the mechanicals were always done..
that being said ...I was worried about the gen and it's age and hours ...even thiough things had been rebuilt when needed...also could see where the gen had smoked up the gen room at least once...so.......I did not want to use the gen all the time while running ...we dont use the air when running even though we are in fla and the bahamas a lot...I like warm air and the breezze blowing..thus the inverter made sense...save the gen ...keep a separate system just like the gen system is...some people also add another gen..
I just know I wont draw down the batteries that start my engines..and that makes sense to me...I use a really good marine electronics guy and he has said most of the boats he fixes have problems from systems that are linked together on elec stuff...
again ...you are right it's how you use the boat
it doesnt matter which type of batteries you use to start the engines..its how you draw them down...
just more for you to think about..
more 2 cents
bill

[Jaxfishgyd]

Am I better to use 6v golf cart batteries as opposed to 12v golf cart batteries?

The setup on my little 43' Hatt is the same as you have mentioned. I too have a separate battery for the genny.

The MAJOR hangup on my boat is getting access to the batteries as it means pulling up 4 floorboards to get to them.But after getting access, the amount of batteries, like Pascal said, isn't the matter.

But from what I have read and been told by others, the Gels don't seem to last as long or go bad easily if the charger screws up.

"Battery Depot" here in Jacksonville also has the brass bar that fits the 24 group batteries if I want to use them instead of 8D's (plastic cover on the bars for protection) so I wouldn't need to run cables to each post.

Unfortunatly, there was no one there that could actually tell me the differences and what my best option (in their opinion) as all the full time workers were off.

Will have to check with them again during the week.

Know I will need to do something soon, my port bank is about dead and my starboard one is on life support.All are 8D's (Checked the log, I did buy them in May, 2000 so figure I got my use out of them)

[DickB]

I've not heard of a 12V golf cart battery. If it exists, it would likely weigh as much as the 8D. The advantage of the 6V golf cart battery is that while heavy at 70 lbs or so, it's half the weight of the 8D. One person can easily muscle it around.

I found that three fit in the footprint of an 8D. So, if you have 2 battery boxes, you might be able to get 6 6V golf cart batteries in their place.

[Jaxfishgyd]

Found the 12v golf cart batteries while surfing the net... But (After further review) they are only rated at 31AH for 20 hrs as opposed to 180 AH for 20 hrs for the 6v golf batteries (www.batteriestogo.com) so case closed on that issue.

[jim rosenthal]

Based on what Karl posted a while back, I had my boat rewired to use two GR24 starting batteries, which start BOTH engines (dedicated starting bank), and I use my two 4Ds for the house bank. I have a parallel switch, which I have not had to use as yet. I have two alternators set up with Balmar regulators, which make them much more efficient and charge faster, and a third Gr24 which is only used to start the genset and lives in an 8D case along with the two Gr24s. My 4Ds are under the aft deck. (I would have two 8Ds as house bank but the cases won't fit in there without major surgery).
As it turns out, happily enough, the 4D cases will each accommodate two 6v golf cart batteries. When the 4Ds wear out, I will put four Trojan golf cart batteries in there. That should more than take care of the modest house loads that I have, and that bank will easily start my diesels if needed.
The idea of dedicated starting and house banks, composed of different kinds of batteries (starting versus deep-cycle) is one that should be on all of our boats, at least if any of us ever plan to anchor out or tie up where shore power is not readily available. I think the system performs much better and I worry about it far less than previously. I also have a Link 20 battery monitor which I heartily recommend- it can do all sorts of things to keep track of the battery systems that I have yet to explore.
Finally, I have found that paying attention to the temp range on the battery charger is important- or having a battery temp sensor- otherwise in warm weather they WILL get overcharged and boil off water.

[Nonchalant1]

Every boat owner has different ideas and uses. Here's mine:

We anchor out frequently and use the inverter a LOT to keep the referigerator running full time. However, I'm in the camp of having a big house bank to handle ALL loads, and a separate starting bank, like the boat was designed for. The battery charger and/or port alternator charge the house bank and the sb alternator charges the starting bank, which is almost always full. My generator starts with 32 volts from either bank.

My house bank is 4 big 8 volt Rolls 8HHG25PM's (275 amp hours, 130 lbs.). Their battery size is "HATT" and they exactly fit my battery boxes. Life expectancy is 10 to 20 years, warranty is 10 years. Running the referigerator on inverter plus 32 volt heads, lights, anchor light, water pump, etc., we can go 2 days before we get down to 1/2 charge where the inverter shuts off. If we cruise 4 hours per day and usually run the genny 1 to 2 hours for stove, water heater, etc., we can go forever. That keeps it simple.

If I needed more power, I'd add to the house bank before I'd install a 3rd bank to worry about. That way whichever power is used comes from the one large battery bank so you don't have to worry about which bank has how much power left. Bigger Rolls batteries come with removable smaller internal cells so one person can easily install or remove them. But I don't feel like I need anything more based on how we use the boat. We just returned from a month long cruise to the North Channel in Canada (Lake Huron) and it worked great.

My starting bank is 4 Interstate 8V195's (120 lbs ea. - 5 year life). They are usually fully charged since all they do is start the engine and it recharges them when it runs. Again, simple.

I added a manual parallel switch so I can parallel both banks permanently if necessary to equalize or charge the starting bank off the charger or house bank, plus the factory starting parallel switch is there for starting, if necessary.

I understand why others have 3 or 4 separate banks, but I just don't see any advantage to that for me, so I keep it the way it was designed.

Doug Shuman
1978 53MY

[SKYCHENEY]

Doug,
I agree with your logic on this subject. And, maybe that's because we use our boat in much the same way as you do. I'm planning on adding an inverter and I would like to set it up just like yours. How did you hook up your house loads to the inverter? Subpanel? Direct to the main panel and turn off all unessential loads? Or.......something else? Just curious.