Reply
 
Thread Tools Search this Thread Display Modes
 
Old 10-04-2022, 04:37 PM   #1
Veteran Member
 
NWpilot's Avatar
 
City: Vancouver, WA
Vessel Name: Yukon Jack
Vessel Model: 30' Tollycraft sedan
Join Date: Nov 2020
Posts: 49
Confusing battery replacement

I really need the help from experienced boaters about a new battery system.
My 30' Tolly has twin 120 HP diesels and each has an 8d battery. The electrical loads are split between the two batteries with most of the load on the starboard battery.

My current thinking is that the batteries were oversized so they could share the starting and house loads as according to sources it should take only 440 CCA to start the engines and I assume the 8d's to be much larger (sides are hidden from view). Both batteries need replacing so I'm looking at starting from scratch with a new setup, but also watching the cost.

What I'm thinking is to isolate one start battery and use the other one plus a house bank (200 A) to power everything else. I also have decided on AGM batteries because of their increased drawdown and lower maintenance. I would use one engine alternator (105A) to charge the isolated start battery and the other alternator to charge the the start and house bank.

Questions:
- Do I need an 8d battery to start a 220 cu.in. diesel engine? I'm an old guy and the thought of muscling 150 lb batteries in the bilge is depressing. A Trojan AGM 31 has 730 CCA and only weighs 67 lbs.
- Many sources I've read say there is little difference between start and deep cycle batteries and you can use a deep cycle for starting.
- Most AGM batteries I've looked at take a max charge of 60A, but I have 105A Leece-Neville alternators. How do I limit the charge to 60A?
- For the start/house side I assume I could use an automatic charging relay to manage the charge between the needs of the start and house batteries.

To those who have suffered through my confusing story, am I taking the right approach to this and making proper decisions?
NWpilot is offline   Reply With Quote
Old 10-04-2022, 06:54 PM   #2
TF Site Team
 
Bacchus's Avatar
 
City: Seneca Lake NY
Vessel Name: Bacchus
Vessel Model: MS 34 HT Trawler
Join Date: Nov 2014
Posts: 6,851
My MS is a single eng but had a similar set up w 2 8Ds that served house & start. Also had a 3rd 8D for B&S thrusters. All AGM and I lije them for the reasons you stated.. I will not replace 8Ds for same reasons you cite. East Penn & Trojan confirmed to me that their AGM do start & deep cycle equally well and I see they list both AH and CCA/MCA for their AGMs.
A pair of GP31s are roughly equal to an 8D. A pair of GC2s also similar.
Why not use a GP31 for starting only and use 3-4 (depending on needs) GP 31s for a dedicated house. Use 1 alt for start & one for house. I'd add an emergency Sw to combine banks if/when necessary but if 1st eng started is the one w alt supplying start batty it will supplement the batty for 2nd eng start.
I believe alt output is determined by batty V rather than constant output and you shouldn't need to limit it... maybe others can confirm or correct me there.
__________________
Don
2008 MS 34 HT Trawler
"Bacchus"
Bacchus is offline   Reply With Quote
Old 10-04-2022, 08:22 PM   #3
Guru
 
Portage_Bay's Avatar
 
City: Coupeville Wa.
Vessel Name: Pelorus
Vessel Model: Californian 42 LRC
Join Date: Oct 2015
Posts: 1,853
8D is overkill to start a 220 cu in engine. I start a pair of 10 liter, 610 cu in, Cat 3208s with a single 8D. When the time comes to replace the 8D I will install a pair of group 31s.

I'm an old guy too. I don't move 8Ds or even 6 volt golf car batteries any more. That's what the local boat yard labor is for.
__________________
Some things are worth doing simply because they are worth doing.
Portage_Bay is offline   Reply With Quote
Old 10-04-2022, 10:39 PM   #4
Guru
 
BruceK's Avatar
 
City: Sydney
Vessel Name: Sojourn
Vessel Model: Integrity 386
Join Date: Oct 2011
Posts: 12,524
A reason they are 8Ds is because they do house and start.
Halvorsen and Island Gypsy are set up that way, as is their descendant Integrity. It seems to work.
At one stage I thought I would switch to drawing on one batt only while on the hook, preserving the other for start, but figured that risked drawing one too low while the other stayed 100%. I decided to draw on both. The genset with its separate battery becomes your savior, though in 12 years I only resorted to it once when the poor state of the batts on a newly acquired IG revealed itself.
Replacing each 8D with 2 AGMs of something else giving as much or more total amps is a good idea from the safety lifting angle.
__________________
BruceK
2005 Integrity 386 "Sojourn"
Sydney Australia
BruceK is offline   Reply With Quote
Old 10-04-2022, 10:57 PM   #5
Guru
 
City: Carefree, Arizona
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 9,494
NW
You’ve received some good advice. We’ve switched our start 8Ds to sealed FLA for about 1/2 the cost of AGM. I suggest you consider installing an ACR which will tie your two alternators together for charging the weakest link - usually the house bank.
sunchaser is offline   Reply With Quote
Old 10-04-2022, 11:54 PM   #6
TF Site Team
 
FlyWright's Avatar
 
City: California Delta
Vessel Name: FlyWright
Vessel Model: 1977 Marshall Californian 34 LRC
Join Date: Apr 2008
Posts: 13,694
Years ago I replaced my 8D batts with 6xGC lead acids and a single Group 31 start batt for my twin Perkins engines. I also recabled all the large cables and wired the alternators directly to their respective battery to avoid using the start cables for charging. I now have better control of all charge sources and loads separately. My house bank gained about 50% capacity and each battery weighs about 65 lbs instead of those 8D behemoths.

My stbd Balmar 120A alternator is derated to 100A to charge my 660AH GC house bank. My port stock 60A alternator charges the start and helps with the house charge with a selectable combiner. The single-bank 55A onboard charger charges the house bank and also the start batt when the combiner is switched on.

This system has worked as well as expected for about the past 10 years. I understand the advantage of AGMs but my batteries are easily accessed for servicing and my budget at the time didn't allow the battery upgrade. YMMV

If you search the forum for past threads on the subject, you'll see some great discussions.
__________________
My boat is my ark. It's my mobile treehouse and my floating fishing cabin. It's my retreat and my respite. Everyday I thank God I have a boat! -Al FJB

@DeltaBridges - 25 Delta Bridges in 25 Days
FlyWright is offline   Reply With Quote
Old 10-05-2022, 01:11 AM   #7
Guru
 
tiltrider1's Avatar
 
City: Seattle
Vessel Name: AZZURRA
Vessel Model: Ocean Alexander 54
Join Date: Aug 2017
Posts: 3,424
I would replace one 8d with group 31’s and do all my starting off of that bank. I would replace the rest of my 8D’s with golf cart batteries and run my house off of that. I would redirect alternator and battery charger to the GC bank and then use a smart combiner or echo charger to charge the start battery bank. This will give you the best of all worlds with out damaging dissimilar batteries during the charging phase.
tiltrider1 is offline   Reply With Quote
Old 10-05-2022, 02:52 AM   #8
Senior Member
 
jungpeter's Avatar
 
City: Everett
Vessel Name: LIBERTY
Vessel Model: TOLLY 48
Join Date: Mar 2013
Posts: 449
Quote:
Originally Posted by tiltrider1 View Post
I would replace one 8d with group 31’s and do all my starting off of that bank. I would replace the rest of my 8D’s with golf cart batteries and run my house off of that. I would redirect alternator and battery charger to the GC bank and then use a smart combiner or echo charger to charge the start battery bank. This will give you the best of all worlds with out damaging dissimilar batteries during the charging phase.
Hi NWpilot. tiltrider has provided sound basic advice for a suitable twin engine powerboat electrical system design. However, be aware there are a LOT of subtleties involved in a proper system design. The devil is definitely in the details. It's very difficult to provide such a design via anecdotes and advice from a forum such as this.

To minimize cost, maximize utility, and verify system function and safety, I would highly suggest you employ an ABYC-certified marine electrician to survey your existing electrical installation, and design and specify a proper electrical system design for your particular vessel. Then, you can plan and budget accordingly for the installation, adjustment, and sea trial of the resulting installation.

There are as many ways to skin this cat as Carter has pills; not all are correct. Marine electrical systems engineering isn't learned from the WWW, nor overnight. And while the majority of experienced boat owners feel competent to do this sort of work, the emphasis is on experienced. And I thoroughly share your pain as a fellow "old guy". Smart money lets the youngsters hump batteries in and out of engine rooms. Smarter money for the inexperienced lets the young professionals tackle this whole enchilada. It's money well spent in many, many ways.

Regards,

Pete
jungpeter is offline   Reply With Quote
Old 10-05-2022, 04:19 AM   #9
Guru
 
City: Belgium
Join Date: Jun 2012
Posts: 2,781
OP I also think post #7 is the best solution. However would not use AGM for the house bank. Use gels if you want sealed. For starting, AGM are fine.

If you need to watch your budget then go with typical wet cells and then water them every few months.
Mako is offline   Reply With Quote
Old 10-05-2022, 05:57 AM   #10
Guru
 
ranger58sb's Avatar
 
City: Annapolis
Vessel Model: 58' Sedan Bridge
Join Date: Aug 2013
Posts: 6,348
Quote:
Originally Posted by NWpilot View Post
What I'm thinking is to isolate one start battery and use the other one plus a house bank (200 A) to power everything else.

- Do I need an 8d battery to start a 220 cu.in. diesel engine? I'm an old guy and the thought of muscling 150 lb batteries in the bilge is depressing. A Trojan AGM 31 has 730 CCA and only weighs 67 lbs.
- Many sources I've read say there is little difference between start and deep cycle batteries and you can use a deep cycle for starting.

What problem do you solve by changing architecture?

(You could maybe replace each 8D with a pair of G31s without changing basic architecture. Or maybe 3x G31s if you have a little additional horizontal space (more house capacity). Or maybe 4x GC2s if you have that additional horizontal space (even more house capacity). Or maybe 4x L16s if you have additional height as well (Lots more house capacity). None of that requires a change in basic architecture.)

Hire a guy to deal with the weight issues. 8Ds, multiple G31s, GC2s, whatever.

If reading is true, Trojan "deep cycle" batteries are more like dual purpose. (I don't know that for fact.) Could be appropriate for your situation, though.

-Chris
__________________
Chesapeake Bay, USA
ranger58sb is offline   Reply With Quote
Old 10-05-2022, 08:57 AM   #11
Guru
 
City: Olympia
Vessel Name: Rendezvous
Vessel Model: Blue water 40
Join Date: Aug 2021
Posts: 726
Changing architecture takes away all the decision making and manual switching to choose the start or house bank. It keeps the start bank isolated from house loads so there’s always power to start the engine. Battery monitors or state of charge instruments are usually designed to monitor one main “house bank” and one or two other banks for voltage only. This way you can see exactly where the batteries are, and when you need to replenish them. The start batteries are automatically charged when the engine starts and the charge voltage rises above a certain threshold.
His current system works, but it takes thought and manual switching to keep a battery isolated for starting, or choosing what battery to cycle for house loads. Some people like that as they get full control of the batteries, but automatic frees you from having to give it any thought.
I like agms for house batteries. In fact, I like them for both start and house duty. I hate filling batteries, and inevitably run them too low. Luckily, my wife has taken that duty from me, and she keeps them topped off. When I replace them though, agms will be my choice. That’s a big budget item on my boat. 16 gc2s cost a couple of bucks.
Bmarler is offline   Reply With Quote
Old 10-05-2022, 09:27 AM   #12
TF Site Team
 
Bacchus's Avatar
 
City: Seneca Lake NY
Vessel Name: Bacchus
Vessel Model: MS 34 HT Trawler
Join Date: Nov 2014
Posts: 6,851
Brian
You hit on one of the major reasons I reconfigured my house / start to leave a pure house. I added a Balmar Smart Gauge for better house monitoring. It wouldn't work with switched batty bank.
Moving my start reduced the run by about 50% and I used an unused cable from the new house that increased the start cable size so reduced V drop starting.
Batty monitor wired directly to the new house bank working very well for monitoring SOC and V readout for start / thruster bank provides a reasonable indication of its SOC and I can monitor it returning to full charge easily while running.
I used a Sterling CVSR to share my measly 70A alt output to the bank(s) needing it.
__________________
Don
2008 MS 34 HT Trawler
"Bacchus"
Bacchus is offline   Reply With Quote
Old 10-05-2022, 02:43 PM   #13
Veteran Member
 
NWpilot's Avatar
 
City: Vancouver, WA
Vessel Name: Yukon Jack
Vessel Model: 30' Tollycraft sedan
Join Date: Nov 2020
Posts: 49
First of all I want everyone to know that I'm not ignoring you. The responses gave me a wealth of information and I realize that there are several ways to approach this. I've pretty much decided to print this page and sketch each of the results so I can see what fits.

I spent part of yesterday searching for batteries and found that just as confusing. It's almost impossible to compare them, but the search goes on.
One of the problems is that Portland, Oregon is not a boat town. There are few outfits selling parts or providing services and those that do are very expensive. The Seattle area would be heaven and I could hire an electrician or laborer. My main help is my brother who is an electrical engineer, but his background is in electronics.

Once I've looked at all the systems proposed I'm going to try and find an ACR that will use both alternators to charge both battery banks and battery monitors for each bank.

The electrical architecture of the boat will be designed around the new battery system because the boat has suffered greatly over the years (before I bought it) from a lack of maintenance. There are feeds off both batteries running everywhere and loose wires everywhere. Items like the windlass have a bypassed switch and bailing wire fix in the chain locker. Several of the dash switches are dead.

But the boat is a solid Tollycraft and worth saving.

ps - I did a search on this sub and learned a lot but still had questions.
NWpilot is offline   Reply With Quote
Old 10-05-2022, 03:43 PM   #14
Guru
 
Jeff F's Avatar
 
City: Guelph
Vessel Name: Escapade
Vessel Model: 50` US Navy Utility trawler conversion
Join Date: Nov 2015
Posts: 1,454
Quote:
Originally Posted by NWpilot View Post

Once I've looked at all the systems proposed I'm going to try and find an ACR that will use both alternators to charge both battery banks and battery monitors for each bank.

Do some research on DC-DC chargers as well. I have no experience with ACRs, but when I was re-architecting my system the ACR seemed like an outdated solution in comparison. The Victron Orion is a good example.

So for example you could have both alternators charging the house bank, with two dc-dc chargers maintaining two group 31 start batteries. All loads go to house bank. Lots of practical possibilities, and easy to build on in the future as you add solar, change battery types, etc.
Jeff F is offline   Reply With Quote
Old 10-05-2022, 04:21 PM   #15
Senior Member
 
sledge's Avatar
 
City: Jacksonville
Vessel Model: American Tug 41
Join Date: Sep 2018
Posts: 229
If the alternators have a too high output, there are advantages to a modern external regulator setup. It's complex enough, and you want to get rid of all the jerry-rigged wiring... that I too would just hire an ABYC guy to lay it out.
These Pacific Yacht Systems guys have good tutorials, like the one below. Best of luck to you and please let the forum know how things work out, we'd love to see how it turns out.
sledge is offline   Reply With Quote
Old 10-05-2022, 05:51 PM   #16
Guru
 
City: Carefree, Arizona
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 9,494
Quote:
Originally Posted by Jeff F View Post
Do some research on DC-DC chargers as well. I have no experience with ACRs, but when I was re-architecting my system the ACR seemed like an outdated solution in comparison. The Victron Orion is a good example.

So for example you could have both alternators charging the house bank, with two dc-dc chargers maintaining two group 31 start batteries. All loads go to house bank. Lots of practical possibilities, and easy to build on in the future as you add solar, change battery types, etc.
ACRs are not outdated at all. Rod Collins (as good a pro as one could ask for) put out good read on ACRs. I recently had a Blue Seas ACR installed per Rod's writeup and all is well.
sunchaser is offline   Reply With Quote
Old 10-05-2022, 06:31 PM   #17
Guru
 
Jeff F's Avatar
 
City: Guelph
Vessel Name: Escapade
Vessel Model: 50` US Navy Utility trawler conversion
Join Date: Nov 2015
Posts: 1,454
Quote:
Originally Posted by sunchaser View Post
ACRs are not outdated at all. Rod Collins (as good a pro as one could ask for) put out good read on ACRs. I recently had a Blue Seas ACR installed per Rod's writeup and all is well.
I shouldn't have used that term perhaps. Not suggesting they don't work, but that there are other solutions - dare I say more modern? - that should also be considered, especially when redesigning a system.

As was said above, many ways to solve for this. Sorry for any slight I may have caused.
Jeff F is offline   Reply With Quote
Old 10-05-2022, 09:14 PM   #18
Senior Member
 
av8r's Avatar
 
City: Anacortes
Vessel Name: Selah
Vessel Model: Ocean Alexander 40
Join Date: Dec 2011
Posts: 290
1. Not sure which engines you have, my 120hp Ford Lehmans are 380 cu.in. The manual specifies 140 ah battery capacity pulling 1070 amps with a locked starter (the moment you push the switch) and 670 amps running draw. That indicates 2 grp 31s paralleled, 2 gcs in series, a 4d or an 8d, and adequate cables.
2. Main difference is lead plate thickness — used to be start batteries had thinner plates which allows a higher current flow but a shorter overall life. The lines seem to be blurring now.
3. The batteries are essentially sefl-limiting. At the correct charging voltages you won’t “over-amp” a battery, it won’t accept the charge.
4. A simple solution is to use one isolated bank to start both engines, charged by one alternator. Power the house with the other bank, charged by the other alternator. Replace the 1-Both-2-Off switch with an On-Off switch for a backup interconnect. Clean-up can be done by running start battery to one bus bar, both starters and one alternator connected to that bus. Use appropriate fuse on the alternator feed. Run house battery to a seccond bus bar and connect 2nd alternator and all the non-starter loads to that bus, again with adequate over-current protection.
The last 30’ Tolly I was on had 2 8ds on the bulkhead aft of the engines, very difficult to get to and maintain. Group 31 AGMs would make life a lot easier.
With winter coming on you have time to do some research and analysis, recommend Nigel Calder’s book.
Before you get too far along it’s also worth considering what style cruising you will be doing. If you want to spend 5+ days off the dock at a time, you want t big battery bank, external regulators controlling the alternators, and both alternators fed through a charge controller. On the other hand, if you only do one or 2 nights off the dock at a time, a 400ah bank will probably do just fine.
The boat name seems familiar. Did you or do you commute to OAK? I might have run into you several years back.
av8r is offline   Reply With Quote
Old 10-06-2022, 12:48 AM   #19
Veteran Member
 
NWpilot's Avatar
 
City: Vancouver, WA
Vessel Name: Yukon Jack
Vessel Model: 30' Tollycraft sedan
Join Date: Nov 2020
Posts: 49
AV8R,

The boat (1979) has twin Volvo TMD40 engines at 220 cu.in. producing 130 hp each according to the sea trial.
It was originally sold to a couple in Seward, AK by Alaska Marine Engine. I more recently bought it in Portland, OR. It had been sitting idle in a marina since the current owner passed away. The owners lived in Calif. and he came up to Oregon only to fish, thus the lack of maintenance. I have no idea about the owners in between, but have an ad showing it for sale by Classic Yachts and located at Chinook.
NWpilot is offline   Reply With Quote
Old 10-06-2022, 01:12 AM   #20
Guru
 
tiltrider1's Avatar
 
City: Seattle
Vessel Name: AZZURRA
Vessel Model: Ocean Alexander 54
Join Date: Aug 2017
Posts: 3,424
Quote:
Originally Posted by Jeff F View Post
I shouldn't have used that term perhaps. Not suggesting they don't work, but that there are other solutions - dare I say more modern? - that should also be considered, especially when redesigning a system.

As was said above, many ways to solve for this. Sorry for any slight I may have caused.
There are ACR’s and then there are Smart ACR’s, Echo Chargers and DC to DC chargers.

Using an ACR to combine a start bank with a house bank is going to shorten the life of the start bank. Not the end of the world unless you have a combination of lead acid and gel type batteries.

You can improve the situation by upgrading to a Smart ACR, Echo Charger or DC to DC charger. These devices do not combine the banks but allow only the appropriate amount of voltage and amps to pass from one bank to the next. This way each bank gets what it needs with out being over charged.

ACR’s are outdated technology for most marine applications but they still work, sort of and do it very inexpensively. Unfortunately people tend to use ACR’s unaware that better technology exists.
tiltrider1 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 04:15 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012