Dimming Electricity...

[OldDan1943]

Yes, I agree.

That one was built in Mainship's "non-trawler" days, so maybe their later DC systems designs evolved afterwards, when they "returned to their roots" (so to speak)...

But I think builder expectations were that those (and many similar) boats would likely be used primarily for day trips and marina hopping... and the design matches that mission fairly well at an affordable cost.

It's quite common in many brands with similar mission expectations... including ours.

-Chris

I do not recall a mention of a generator with an isolated gen start battery.

How do you handle this limitation or did you rebuild the electrical system?

 

[psneeld]

Most boats straight from the manufacturer don't have dedicated "house" banks like cruisers are used to...

Heck, small boats often only have just one battery at all, the second is an option.

My previous liveaboard, a 37' sportfish to this day 30 years later lives on 2 8Ds. The PO to me cruisdd to FL for 9 years, I cruised it lightly for 8 years and the current owner cruises it lightly to.

My next door neighbors Luhrs sportfish only has 2 group 27s or 31s in it, plus a group 24 genset start battery that is stand alone.

 

[OldDan1943]

I'll bet when you rebuilt the 12vt system, you removed LOTS of unused and unnecessary wires and 12 pounds of wire ties.


I didn't measure it, but I wouldn't have been hard to convince if I'd been told it was about a mile of wire and at least a dozen pounds of wire nuts.


I spent a little more than two years turning a floating bag lady into a 2 yr old boat in a 20 yr old hull under the close supervision of a good friend (who passed away at nearly 90 a couple of years ago) who was one of the top marine surveyors in the country. I learned more about systems other than plumbing in those two years than I'd learned in the previous 20.
--Peggie

My Nordhavn had lots of unnecessary wire ties. LOL and wire too.
I hate to think of how many pounds of wire ties and old unused wires,

 

[ranger58sb]

I do not recall a mention of a generator with an isolated gen start battery.

How do you handle this limitation or did you rebuild the electrical system?

Thought I saw him mention a genset in another thread... maybe wrong.

In our case, the short version is that we added battery capacity.

I switched to better and larger batteries (which happen to be no maintenance AGMs) as the original banks that came with the boat when we got it wore out. That increased capacity from approx 240-270 (?) Ah per bank to 300.

Then later I increased one of those from 300 to 440 Ah capacity with four deep cycle 6V batteries (two pairs).

Then later I separated our 3 banks so that our original 40A charger only services one 300 Ah bank, and I installed a 70A inverter/charger for the 440 Ah bank. That essentially means both main banks can receive a boatload of amps in a couple hours when we're charging with the genset and chargers at anchor. (And the AGMs can acctually accept that kind of charge faster than some other battery types.)

And we modified our behavior at anchor to deal with it. Didn't actually take much (any) modification in our case, since we have an electric galley and can charge batteries (and make hot water) a couple times per day while we're out.

The only real modification we found is that with the inverter I can make morning coffee and afternoon popcorn without having to start the genset just that minute. And we can adjust our Laz-Y-Boy lounge chairs any time we want.

We don't usually anchor out for more than a week or two at a time, anyway...

Anyway, no significant re-wiring involved.

-Chris

 

[BruceK]

Thought I saw him mention a genset in another thread... maybe wrong.
In our case, the short version is that we added battery capacity.
I switched to better and larger batteries (which happen to be no maintenance AGMs) as the original banks that came with the boat when we got it wore out. That increased capacity from approx 240-270 (?) Ah per bank to 300..... -Chris

My recall, genset was not functioning and he was exploring replacement.
The boat survived in current design for years. Easy first step is test the existing batts,maybe a high power stereo took them beyond their aged capacity. Newer higher amp batts may fit the space of old lower amp ones. Unless the batts are near stuffed, wouldn`t the charger recharge while owners sleep or are out at work.

 

[toocoys]

My recall, genset was not functioning and he was exploring replacement.
The boat survived in current design for years.

That would be correct. The first owner used it as a weekend express cruiser, the second owner used it as a full time floating condo. She was a single lady with not as many needs as us. So I'm having to retrofit everything and bring it up to par.

 

[OldDan1943]

Near as I read it, the battery was not holding a charge. It was reading 12vt until a demand was made on the battery. I had a 4D fail that way. That is why I wanted him to make a visual examination of the top and sides of the batteries.
My engine battery read 12vt as I was docking. I hit the bow thruster, the voltage dropped, the engine shut down because the battery could not support the required voltage to the engine. I would restart the engine, hit the bus thruster, engine shut down. I got tied up and went to look at the AGM battery. Bubbled top, swollen sides.
Time to replace the starting battery. Because I added a 3rd battery to the house bank, I felt confident when adding the bow thruster to the house bank which also supports the stern thruster. l really dont want the engine to shut down again while docking.
I can live without the bow and stern thruster but not the main engine.

 

[Jeff F]

20 amps @12v is not a lot of power. 240 watts. Sounds like batteries are marginal/bad, and you're using more than the charger can provide at times.

 

[ranger58sb]

That would be correct. The first owner used it as a weekend express cruiser, the second owner used it as a full time floating condo. She was a single lady with not as many needs as us. So I'm having to retrofit everything and bring it up to par.

Have you looked to see what size batteries you have now, and what kind of space you have available for batteries?

Maybe you have space to add some capacity at the same time, if you have to replace your existing batteries anyway?

-Chris

 

[toocoys]

Have you looked to see what size batteries you have now, and what kind of space you have available for batteries?

Maybe you have space to add some capacity at the same time, if you have to replace your existing batteries anyway?

-Chris

Just regular, cheapo 12v batteries. I guess they would be size 24 batteries? One behind each engine. I intended to crawl in there and get some photos over my last two days off of work, but I never got around to it.

I have PLENTY of room for extra batteries either under the master bed, or in the bilge, especially since there is no genset right now.

 

[OldDan1943]

Hmmm plenty of room? Consider 4Ds.
Please give serious consideration to have them installed professionally wish the proper switches and wire size.
Tell the installer you are considering a generator so he can wire them via the BIGGER battery charger.
WE dont want you to light yourself on fire during the nights

 

[toocoys]

Hmmm plenty of room? Consider 4Ds.
Please give serious consideration to have them installed professionally wish the proper switches and wire size.
Tell the installer you are considering a generator so he can wire them via the BIGGER battery charger.
WE dont want you to light yourself on fire during the nights

Oh trust me. This isn't something I would do alone. I fully intend on having a certified yacht service come out and install it.

 

[BruceK]

Replacing tired possibly undersized batts in the OEM system of a known boat brand which has functioned without drama for years, I think you`d be ok replacing batts without worrying about replacing switches, wiring etc. Just fitting new versions of what you have should be a major improvement.Especially in a boat you lease not own.
Unless of course you plan massively resized batts.

 

[OldDan1943]

Replacing tired possibly undersized batts in the OEM system of a known boat brand which has functioned without drama for years, I think you`d be ok replacing batts without worrying about replacing switches, wiring etc. Just fitting new versions of what you have should be a major improvement.Especially in a boat you lease not own.
Unless of course you plan massively resized batts.

Bruce, he will need isolation and parallel switches from the engine start batteries.

 

[toocoys]

Replacing tired possibly undersized batts in the OEM system of a known boat brand which has functioned without drama for years, I think you`d be ok replacing batts without worrying about replacing switches, wiring etc. Just fitting new versions of what you have should be a major improvement.Especially in a boat you lease not own.
Unless of course you plan massively resized batts.

I could swap out the batteries without problem. Maybe put some bigger size 27 batteries in there.

But adding a house bank etc, would be a job for the yacht service. It's beyond my scope of knowledge. And while I'm sure I could research, I'd rather not start fires in the engine hole of a gas powered boat! LOL

 

[BruceK]

Bruce, he will need isolation and parallel switches from the engine start batteries.

Yes Dan,I certainly agree if changing to a separate house/start system. But to start, I`d replace tired (as tested) batts,and see if that gives enough improvement.
I`m 9 years used to a "no dedicated house" system,it`s how IG design(ed) their boats.If I couldn`t make it work I`d readily change it. I recommend the same course to the OP.
I have a " one change at a time" rule, so I know if it made a difference. With 2 changes simultaneously, it`s not possible to know which worked, and to what extent.

 

[ranger58sb]

Just regular, cheapo 12v batteries. I guess they would be size 24 batteries? One behind each engine. I intended to crawl in there and get some photos over my last two days off of work, but I never got around to it.

I have PLENTY of room for extra batteries either under the master bed, or in the bilge, especially since there is no genset right now.

I could swap out the batteries without problem. Maybe put some bigger size 27 batteries in there.

But adding a house bank etc, would be a job for the yacht service. It's beyond my scope of knowledge. And while I'm sure I could research, I'd rather not start fires in the engine hole of a gas powered boat! LOL

BCI Group 24 batteries are pretty tiny. Wouldn't surprise me if they're already Group 27s, though. Maybe 80 Ah capacity each.

If so, a quick change to a pair of Group 31s on each side could more than double your current (Ha! Get it?) capacity to 200 Ah if you have easy space for that. Parallel connections are relatively easy. Individual G31s weigh less than single 4Ds.

Two pairs of BCI Group GC2 (golf cart) batteries would more than double that, to about 440 Ah capacity, again, if you have enough easy space. Might be overkill for you, but OTOH, it'd give you much more time at anchor. I say two pairs 'cause if one battery goes south, you can still work out a 12V configuration until you can get a real fix. Series/parallel connections aren't rocket science. Individual GC2s weigh less than 4Ds.

Since you mention having to "crawl in there" it suggests service wouldn't be all that easy. If that's the case, VRLA sealed AGM or gel batteries could be a better choice. Most folks gravitate toward AGM these days, for situations like that.

If you have to put batteries inside the cabin, as in "under the master bed," that too argues for VRLA batteries, since they don't off-gas as much as flooded lead acid batteries.

Good to recognize that hiring a good marine electrician would be the best path toward a total re-wire. Just swapping/adding batteries into the current (!!!) configuration is many steps below that in required knowledge and skill. And cost.

-Chris

 

[Raffy]

Dimming Lights

Turn off your charger and wait about 30 minutes to check your battery. I believe you will find out that you have a bad one and have been working off your charger. I just had a customer fly me all the way down to St. Thomas because Cat in P.R. told him his engine controls were bad. It took me about 30 minutes to determine the batteries were bad and he had been working off of the 100 amp charger. Batteries and bad grounds are the #1 Gremlins in the marine industry.

 

[OldDan1943]

Folks, even on your flash lights they say do not mix your batteries. You have to change them all together.
Why do you think it is any different on your boat?

 

[boatpoker]

Folks, even on your flash lights they say do not mix your batteries. You have to change them all together.
Why do you think it is any different on your boat?

Excellent point +1

 

[FF]

The big problem is a battery is not just a battery.

When start batts are used as house batts , they seldom last .

Only 2-6 deep discharges will trash a start batt , and it will need to be replaced.

The "marine" multi purpose do better at deep discharges , at least it doesnt trash them.

Deep cycles or golf carts WILL start most engines , especially if there are a bunch , 4 usually works, even at 50% SOC.

 

[CapnCrunch]

Batteries and bad grounds are the #1 Gremlins in the marine industry.

I was wondering why someone hadn't mentioned "connections" sooner. Although I completely agree that your batty banks are too small for a liveaboard, your problem sounds very similar to one I recently had. When my 12v fridge compressor started, it would cut off before reaching full speed and start all over again after a few seconds. By watching my battery monitor, I noticed that the amp draw would run way up and system voltage would drop drastically right before the compressor shut down. (I would also notice a drastic dimming of my lights when the fridge was trying to run)

It turned out that i had a poor connection where the neg cable connected to the shunt for my battery monitor. Cleaning the connection and tightening the bolt solved the problem. Regular cleaning/tightening system connections is a routine that we should get in the habit of doing.

 

[BruceK]

..The "marine" multi purpose do better at deep discharges , at least it doesn`t trash them.

Deep cycles or golf carts WILL start most engines , especially if there are a bunch , 4 usually works, even at 50% SOC.

How about AGM deep cycle batts? AndyG has the dual use set up common in IGs and reported great success with fitting AGMs years ago.
Is the AGM charge profile similar to conventional flooded LAs?

 

[OldDan1943]

Replacing tired possibly undersized batts in the OEM system of a known boat brand which has functioned without drama for years, I think you`d be ok replacing batts without worrying about replacing switches, wiring etc. Just fitting new versions of what you have should be a major improvement.Especially in a boat you lease not own.
Unless of course you plan massively resized batts.

You are leasing your boat? Check your lease and see who is responsible for the batteries. I sure wouldn't be redesigning the battery system on a boat I didn't own.

 

[ranger58sb]

Is the AGM charge profile similar to conventional flooded LAs?

It varies, as do charge profiles for FLAs. Our Odysseys want different charge profiles than our Lifelines for best longevity.

OTOH, when we first began the switch to AGMs, we just the same settings on our charger for both AGM and FLA banks... per directions in the manual for that charger... since it was older and only offered two profiles (FLA/AGM and Gel). Odyssey techs agreed that would be suitable, at the time.

These days, chargers often offer many more pre-set profiles, and some allow completely custom settings... so it can be easier to exactly match the battery manufacturer's specific recommendations.

-Chris