Battery Question for the Knowledgeable

B

bbwhitejr

Well-Known Member
Apr 14, 2013
4,306
Lake Lanier GA
Boat Info
2003 420DA, 6CTAs
Engines
NA
Like a lot of diesel boat owners, I crank my gen before I ever unplug from shore power. Then I cut the gen when I am plugged back up. Whether it is for an afternoon swim or if we stay out on the hook for a few days.

My battery charger stays on continuously as well. That said, when I replaced my batteries, 2 for each main and one for the gen, I went with all cranking batteries because they never cycle down or up. What is the fallacy in this thinking?

Bennett
 
bbwhitejr said:
Like a lot of diesel boat owners, I crank my gen before I ever unplug from shore power. Then I cut the gen when I am plugged back up. Whether it is for an afternoon swim or if we stay out on the hook for a few days.

My battery charger stays on continuously as well. That said, when I replaced my batteries, 2 for each main and one for the gen, I went with all cranking batteries because they never cycle down or up. What is the fallacy in this thinking?

Bennett
Click to expand...
If I had a genny, I would do it the same way and use all cranking batteries. I look at it like a car battery, very rarely is it used when it isn't charging except for starting.
 
Should be fine from a practical sense as long as your usage pattern remains consistent. I personally would not want my genie running 24 hrs/day while at anchor. Going with deep cycles with sufficient CCA, gives you that choice.
 
In any case you certainly wouldn't want deep cycle batteries for any cranking loads.
I would probably use a dual-purpose Group 27M or 31M (8D's in my case) rather than cranking only. They can tolerate the deep cycling as well as provide the CCA you need. So, now you have all of the options on using the generator or not.
We operate the boat the same; the generator runs pretty much 24/7 when away from the dock. Some nights when it's cool the gen gets shut down and the boat opened up; that's where the deep cycle capability batteries come in.
 
That's the way The Office is setup. Older '89 model most everything is AC except some DC lighting.
 
I used to use Deep cycle then went to Dual purpose but last time I needed batteries I couldn't find Group31 dual purpose so I asked my mechanic and he said go with 1000CCA starting batteries and that is now my battery of choice. I have not had an issue yet and we've even spent a night here and there on the hook with two refrigerators running. I also run the battery charger when the gen is running or hooked up to dock side.
 
Brite Idea said:
I used to use Deep cycle then went to Dual purpose but last time I needed batteries I couldn't find Group31 dual purpose so I asked my mechanic and he said go with 1000CCA starting batteries and that is now my battery of choice. I have not had an issue yet and we've even spent a night here and there on the hook with two refrigerators running. I also run the battery charger when the gen is running or hooked up to dock side.
Click to expand...
I had dual purpose. Then tried all deep cycle. Doesn’t crank well in winter even with crossover switch on. Next experiment will be all four as cranking batteries. But, is group 27 the largest cranking battery? I haven’t found any group 31 cranking batteries. Although it may not matter. The interstate group 27 cranking are 1000 cca.
 
Nothing wrong with what you've done, but I'm a big fan of the AGM's instead.

For one, they are truly MX free...no need to check water level. They wont outgas or spill (normally), and from my experience, they last a lot longer than a standard wet cell battery. Supposedly much better in high vibration (like diesel engine boats)/rough conditions.

It use to be these types of battery were significantly more expensive, but recently, they are only about $50/pc more. I've been using the Duracell Marine AGM's from SAM's. Allegedly its a private label Deka battery that you can buy from other brand names, but they can cost more.
 
dtfeld said:
Nothing wrong with what you've done, but I'm a big fan of the AGM's instead.

For one, they are truly MX free...no need to check water level. They wont outgas or spill (normally), and from my experience, they last a lot longer than a standard wet cell battery. Supposedly much better in high vibration (like diesel engine boats)/rough conditions.

It use to be these types of battery were significantly more expensive, but recently, they are only about $50/pc more. I've been using the Duracell Marine AGM's from SAM's. Allegedly its a private label Deka battery that you can buy from other brand names, but they can cost more.
Click to expand...

Yes the Duracells are made by East Penn in PA. Same as the Dekas. The group 27s are working fine now. They are 18 months old and never had to add a drop of water. Could that be because they do not cycle up and down?

Bennett
 
bbwhitejr said:
Yes the Duracells are made by East Penn in PA. Same as the Dekas. The group 27s are working fine now. They are 18 months old and never had to add a drop of water. Could that be because they do not cycle up and down?

Bennett
Click to expand...

Anytime current is added back via recharging, the byproducts are hydrogen and oxygen from water. If just doing small charges, it may take a while, but eventually you'll need to top them up.
 
My wet cell Group 31 1000CCA's are sealed so I can't add water. If I get four to five years out of them I'll be happy.
 
I just installed Group 31 AGMs from X2 Power (through Batteries Plus). Not cheap, but 1150 CCA and 1000AH each is good. Got good performance from these batteries.
653747.jpg
 
I run my generator the same as you, comes on before I unhook the power lines, goes off once the power lines are reconnected.

I also flip the AC Converter breaker to off while the engines are running.

I know my boat has newer batteries installed by the previous owner, that allegedly don't require water, not sure which kind, now I want to check.
 
mrsrobinson said:
I run my generator the same as you, comes on before I unhook the power lines, goes off once the power lines are reconnected.
Click to expand...

Agree, I do the same always.

I also flip the AC Converter breaker to off while the engines are running. ...
Click to expand...

But, Why would you do that?

Any of the microprocessor controlled battery chargers will auto sense the alternator voltage and lower it's charging voltage. No harm no foul by leaving it on, no reason to turn it off.
 
bbwhitejr said:
Yes the Duracells are made by East Penn in PA. Same as the Dekas. The group 27s are working fine now. They are 18 months old and never had to add a drop of water. Could that be because they do not cycle up and down?

Bennett
Click to expand...
I have had 0 luck with the Sam's Duracells. Haven't had a single one of the three I have purchase last more than a year. Interstates have been great, so I'll stick with those. $50 more than the Duracells, but they last 3x longer. YMMV.
 
dtfeld said:
Nothing wrong with what you've done, but I'm a big fan of the AGM's instead.

For one, they are truly MX free...no need to check water level. They wont outgas or spill (normally), and from my experience, they last a lot longer than a standard wet cell battery. Supposedly much better in high vibration (like diesel engine boats)/rough conditions.

It use to be these types of battery were significantly more expensive, but recently, they are only about $50/pc more. I've been using the Duracell Marine AGM's from SAM's. Allegedly its a private label Deka battery that you can buy from other brand names, but they can cost more.
Click to expand...

What size Duracell's are you finding where the AGM is only $50 more than the flooded? I can't seem to find G31 AGM's from Duracell but the G27's look to still be $130 more +/-??? If they were that close I think they'd be a no-brainer. At double the cost it's still a head scratcher (to me)...
 
You must log in or register to reply here.

Forum statistics

Threads
113,182
Messages
1,428,056
Members
61,088
Latest member
SGT LAT
Back
Top