Musing on DC Electrical Changes

[TrapperJohn]

While I'm busy working on my thru-hull issues in another thread, I can't help but be parallel planning the electrical systems on my 1982 Morgan 32. When I finally got access to the new-to-me boat, I did some crawling around to see what I was up against. Second on my priority list, after the hull integrity, was the electrical systems and, to be frank, I got the sh*t scared out of me when I inspected the DC and AC systems. This post is for some of your thoughts on the DC system, AC will be in a separate thread sometime soon. I don't need specific how-to information right now, I just want to draw up a plan so I can start buying bits and pieces as funds become available.

Here's what I found:

• The alternator was replaced a couple years ago according to the PO. The nameplate was pretty dinged up so I couldn't read much of the details but I did find a part number printed on the frame (12108N) which matched up with Yanmar's part number for the OEM alternator. It is rated at 35A so that's what I am assuming this is.
• The battery cables were laying in the battery box (unsealed but painted) with very little clearance for ventilation. The boat had two group 24 batteries (not installed at the time) connected to the traditional 1/2/B switch and the negative terminals jumpered and connected to the engine ground. The negative cables had 1/0 (105C) printed on them but none of the positive cables have any markings and visually appear to be larger than the 1/0 cable. Since the insulation had pulled back from the lugs, I tried to measure the OD of the actual wiring but, since they had been flexed so much and with a little corrosion, it came out somewhere between 1/0 and 4/0 depending on the angle I measured it.
• The 1/2/B switch terminals were all tight but the connections had corrosion all around them. The switch had no markings on which terminal is which nor any manufacturer information.
• Inside the battery box was an ancient, exposed ground bus bar with all the positions filled.
• There were no fuses anywhere except the DC distribution panel.
• Thankfully, the PO took the batteries home and kept them on a trickle charger over then winter until I had access to the boat again. When he brought them to me, I was shocked to see 2 Walmart G24 sealed lead acid "deep cycle" batteries. Dates on them were 2021. I do have a picture with them installed from the survey but didn't think to check it first.
• Nothing is labeled.

Here are a couple pictures:

I don't have a realistic load just yet. What I've been doing is taking the OEM listings for the fuse panel, adding the fuse requirements of the few things that have been added such as the auto-pilot or guessing from current components similar to what I have. I'm coming up with a rough estimate around 100A if everything is turned on. Of course, that's not probable. Currently I've got:

• 4 cabin halogen lights
• 6 cabin flourescent lights
• Fixed-mount VHF
• All halogen navigation/anchor lights with built-in halogen deck light on the steaming light
• Raymarine 4000+ auto-pilot
• Old Jensen car stereo with CD player
• Bilge pump
• Compass light (negligible)
• Raymarine depth and speed instruments
• Water pump
• Yanmar engine circuit
• Engineroom blower (currently non-functional)

Of course, I'm planning to replace a lot of it, especially to LED for lighting. The problem right now is getting to my new slip at a new marina about 15 miles away before my current marina sets me adrift and with fingers crossed and fire extinguishers handy.

What I'm thinking right now is, after the move, to rebuild the quarter-berth to house more batteries. Don't have much room to add depth but width & length are doable and should be able to fit 2-3 group 24 or 27 batteries as the house bank along with a group 24 starting battery. I don't think I can fit golf cart batteries. I'll stick with lead acid for now. I could switch to AGM but if I'm going to that expense, I might as well convert to lithium and I'm not ready for that right now.

Along with that, switch to a Balmar 6-series (either 70A or 100A) with an external regulator.

The distribution panel and all the other wiring I'm not concerned about yet so that isn't part of this discussion.

First question is the battery cables. Right now, I plan to add ANL fuses in the battery box. Since the negative strap is a known 1/0 cable, I've ordered 200A fuses so I can protect that wiring immediately. However, I've been toying with idea of replacing all of them. Using the calculator at Boathowto.com with 100A load, 30 ft total cable length (longest existing cable is just under 9 ft), 3% voltage drop and in engine compartment, I could use 1/0. Since I may add load in the future, I'm thinking of 2/0 cable and fusing at 250A.

While I'm on the topic of cabling, should I switch to yellow negative cable versus the traditional black?

Thinking of wiring the alternator to the house bank through a new 1/2/B switch and keeping the start battery charged with an ACR as has been discussed a lot here along with Mainsail & others' postings/web sites. My question is, how does the ACR handle equalizing charges? Do I need to connect the alternator/regulator directly to the start battery to do an equalizer?

The cable size is my first priority. I've ordered the FTZ crimper as Mainesail has recommended but held off on cables and lugs until I clear this up. BTW, did you know Home Depot sells Ancor 2/0 marine battery cable spools at a very competitive price?

Sorry to be long-winded. I wanted to explain my whys so we don't get into a long, pedantic thread on the "best" way to do it.

 

[mermike]

Since you have space constraints, why not go with a FLA start battery and house bank consisting of a pair of the mini 100 AH LFP batteries? Use a DC-DC charger between the start battery and the LFP bank. Eliminate the ACR. Replace the 1-2-All battery switch with a Blue Sea 5511e so you can combine banks in an emergency.

This might provoke some controversy, but rebuilding your storage around lead acid is like building a better buggy whip.

 

[jssailem]

rebuilding your storage around lead acid is like building a better buggy whip.

Or a Model T truck when you want a Ford F150 to cruise in.

 

[jssailem]

With the prices of Lithium batteries falling.
as an example..https://www.wattcycle.com/
I found that the LiFePO4 batteries are no more expensive than Lead Acid Deep Cycle batteries.

• exposed ground bus bar
  • Nothing wrong with the exposed ground bus bar. You can replace it with a new one, if you like but as long as the bus bar can handle the load it can be exposed. It has the same electrical potential as your exposed engine block.
• I plan to add ANL fuses in the battery box
  • Nothing wrong with this approach. You may find that MBRF fuses are easier to install.

Regarding batteries, establish your load demands then work out the size of the house battery bank you need. These new Lithium batteries are more compact and smaller footprint than the FLA batteries. They also have more usable stored power than the FLA batteries. Since you are planning a system install considering it now will save you money.

 

[Davidasailor26]

One thing I didn’t see you mention is any existing charge sources other than the alternator?

What I'm thinking right now is, after the move, to rebuild the quarter-berth to house more batteries. Don't have much room to add depth but width & length are doable and should be able to fit 2-3 group 24 or 27 batteries as the house bank along with a group 24 starting battery. I don't think I can fit golf cart batteries. I'll stick with lead acid for now. I could switch to AGM but if I'm going to that expense, I might as well convert to lithium and I'm not ready for that right now.

Personally I’d go through the effort of reworking the charging systems for lithium rather than the effort of reconfiguring the cabin for more lead. Your preference may vary, but if you’re replacing the alternator anyway and don’t have a decent existing shore charger the switch to lithium doesn’t seem too onerous.

Using the calculator at Boathowto.com with 100A load, 30 ft total cable length (longest existing cable is just under 9 ft), 3% voltage drop and in engine compartment, I could use 1/0. Since I may add load in the future, I'm thinking of 2/0 cable and fusing at 250A.

That all seems reasonable. Sounds like you’re on the right track.

While I'm on the topic of cabling, should I switch to yellow negative cable versus the traditional black?

If I were running new wire because the existing was corroded I’d probably go with yellow. I wouldn’t change it out just for the color change though.

My question is, how does the ACR handle equalizing charges? Do I need to connect the alternator/regulator directly to the start battery to do an equalizer?

The ACR will combine the banks whenever one is being charged. If you connect an equalizing voltage source to one bank it should get paralleled with the other bank as long as the voltage is above 13V

 

[dlochner]

The Walmart batteries may not be all that bad. All the major battery companies make private label batteries, the big difference between them is the label.

Redoing electrical systems can be expensive and time consuming. I'm on version 4 now. Make yours functional and make an up grade plan We can talk about it more in 2 weeks. My boat will be the one without a vertical mast and the filthiest one in the marina.

 

[colemj]

100A seems way too high of a top load for your DC distribution panel. We've got tons more that that on ours (9 bilge pumps, for example), and it is all through a 63A breaker that has never seen a load close to that. It is wired with 1AWG, and that is ~20' each way.

I'm also in the camp of going LFP now. You will get twice the usable capacity in your current use of space.

It doesn't matter if you use black or yellow. I know yellow is to differentiate from black AC wiring, but nobody is going to confuse these wire sizes you are using with AC, and sometimes a mixture of black and yellow DC can be confusing.

Mark

 

[dLj]

Get some Boeshield T9 - it is excellent to help clean up electrical connectors and keep them in good shape.

I would not invest in lead acid batteries at this stage. LiFePo batteries are the only way to go for house batteries. Start battery can certainly be lead acid but lead acid house batteries are just not in the game anymore from any perspective.

It's not clear to me why you would change the current battery cables. There is nothing in the pictures you attached that screams "change these cables" but I'm not at your boat. Looks more to me like get a stainless steel brush and some T9 and clean up some ends. Am I missing something?

I personally don't think any of the commercially packaged chargers do equalization properly. I use a dedicated (well used to before I went to LiFePo house batteries) programable power supply to equalize lead acid batteries. But that's another story...

dj

 

[MikeHoncho]

The Walmart batteries may not be all that bad. All the major battery companies make private label batteries, the big difference between them is the label.

Redoing electrical systems can be expensive and time consuming. I'm on version 4 now. Make yours functional and make an up grade plan We can talk about it more in 2 weeks. My boat will be the one without a vertical mast and the filthiest one in the marina.

the interstate batteries you buy from Costco are not the same as the Interstate batteries you buy from independent dealers. I agree with the labeling but the physical battery components can and are different.

 

[BAD ORCA]

Why do you have a black (negative?) wire connected to the positive post of the battery in top of pic? Is that an optical illusion or just repurposed black wire?

 

[dlochner]

Why do you have a black (negative?) wire connected to the positive post of the battery in top of pic? Is that an optical illusion or just repurposed black wire?

The batteries are not oriented in the same direction. One battery has DC+ on the right, the other on the left.

 

[BAD ORCA]

The batteries are not oriented in the same direction. One battery has DC+ on the right, the other on the left.

I see that but the top battery has red pos+ wire on right side stud. There is a black wire right behind it wrapped around the pos+ threaded stud. I'm assuming PO just repurposed some black wire otherwise i'd assume there would be some pretty obvious problems going on with the electrical but maybe worth checking out if OP is not 100% certain.

 

[dlochner]

I see that but the top battery has red pos+ wire on right side stud. There is a black wire right behind it wrapped around the pos+ threaded stud. I'm assuming PO just repurposed some black wire otherwise i'd assume there would be some pretty obvious problems going on with the electrical but maybe worth checking out if OP is not 100% certain.

Oh, that 10 ga (?) black wire. That's wrong in many ways even if it was a repurposed DC+ wire. @TrapperJohn needs to get rid of it.

 

[Scott T-Bird]

Nice boat! I like that model very much! What engine do you have? Yanmar GM2?? or 3??.

I agree with @mermike about replacing the 1+2+B switch with a DCP switch (especially if you plan to use an ACR - the 1+2+B switch is a dinosaur that was made when charging relays weren't available) if you are going to replace your switch. It's a much better choice. The only negative is that you should install 2 On-Off switches so that you can isolate the banks in an emergency (the switches should be hidden so they aren't inadvertently messed with). DCP is uncomplicated and separates the house and start banks while they can both be used simultaneously. I can't think of any reason to even install an ACR with a 1+2+B switch since the purpose of the switch is to selectively charge batteries together on the B setting or individually depending on the 1 or 2 setting. It's a stupid switch for today's methodology.

I also don't see a need to replace cables unless you just want to - no problem upgrading to 2/0 but that could be overkill. I'd use 250 A fuses either way. I would upgrade the charger instead of the alternator if you are on shore power. If you have shore power, your alternator won't need to do diddly squat probably.

I would wait to do LiFePO4 and get a pair of GRP 27 LA deep cycle and GRP 24 for start if you need to do something right away for batteries but don't want to pay the price. You will need a lot of new upgrades with the alternator, belts possibly, charger or dc-dc charger (there are other options to look into) at a high price and you will have to do all at once if you want lithium.

I've been upgrading my entire system before converting to lithium batteries so that when I need to replace my batteries, it should be relatively pain-free. I'm still running strong with 2 AGM batts (4D) with 400 ah capacity since 2015. However, if and when I get to do more intensive cruising, I'm ready to drop in lithium for greater capacity and less weight! With shore power, my batts are perpetually topped off and a few nights on anchor between charges is stress free.

Changing to yellow for DC Neg is always a good choice! Be sure your AC ground is Green and ultimately connected to your boat ground.
You should also look into the modifications that you should do for the AC system. You should either upgrade with an ELCI or an Isolation Transformer. They have different functions but either one is an important protection device that you should consider.

 

[Scott T-Bird]

Oh, that 10 ga (?) black wire. That's wrong in many ways even if it was a repurposed DC+ wire. @TrapperJohn needs to get rid of it.

Well, assuming that it is a ground for something, it should go to a NEG buss bar at least. (oops - now I see that it is on the + post!) Make sure you track that one down! BTW, trickle chargers suck! Don't continue to charge your batts with one. Chronically undercharged batteries die an early death.

 

[OS2Dude]

I would look over the articles on MarineHowTo.com He is a member of the ABYC electrical committee.
I would also keep an AGM start battery and switch to a Lithium Iron Phosphate (LFP) house bank.

On my boat, the alternator only charges the 98Ah AGM start battery. Two 175W solar panels take care of the 300Ah LFP House battery. LFP can be drawn down much further than any type of Flooded Lead Acid (FLA) battery, and they usually have a higher ampacity as well. With LFP, you may not even have to alter your battery box. However, LFP has different charging needs, so is not a 'Drop In Replacement' for FLA. Don't be fooled by the ads that say otherwise. (They're talking dimensions, not electrical requirements.)

Yes, if you are going to rewire, use YELLOW for the NEG cables. Black is too easy to confuse for AC HOT. And don't cheap out and use the same color for everything, with maybe a small piece of heat shrink of the correct color on the ends. It will make tracing the cables much harder for you or someone else. Make sure your cables are sized appropriately. Going small because it is cheaper can cause issues, including fire, down the road. Fuses are sized to protect the cable, so use ones that match the cable ampacity.

 

[dlochner]

Interesting and lots of suggestions here, yet the first and most basic question has not been asked of the OP, what's the intended use of the boat? The answer to that question is even more fundamental than then load analysis.

So, TrapperJohn, how do you intend to use your boat?

 

[dLj]

I'm often seeing where charging from the alternator is aimed at the lead acid battery and the LiFePo batteries are charged through solar and such.

On my boat the design is such that all charge sources go into the LiFePo house batteries. Then those LiFePo batteries charge the lead acid. There are several advantages to doing it this way. But a major advantage is that my lead acid batteries remain fully charged at all times. This greatly extends the life of the lead acid batteries. As someone above noted, one of the major killers of lead acid is not to be fully charged. An added advantage is that the house bank can take all the charging capacity available taking better advantage of when large supply is available.

This is a fairly simple design change from an all Pb battery system. Of course it's only useful when going to a lithium house bank. But I would suggest giving that some consideration in your process of redesigning you 12v system.

Another thing I hear a lot about is going to 24v house bank. That can have some advantages also. That had significant $'s repercussions in my case as I already had a new 12v charger/inverter in the boat and I wasn't going to spend the money to get a new one for the 24v conversion.

If you are seriously looking at redesigning and rewiring your boat there is plenty to think about. But adopting the best design - for how you sail and what your boat needs - is really beneficial to get right from the beginning to both building a highly reliable AND low cost rebuild.

dj

p s. i just saw Dave's post above as i was writing this. Indeed - that IS the question!

 

[colemj]

Yes, if you are going to rewire, use YELLOW for the NEG cables. Black is too easy to confuse for AC HOT.

I agree for a complete rewire where everything is pulled out and new wire installed.

For the cable sizes the OP is talking about, nobody is going to confuse those 1AWG-4/0AWG black DC wires with AC hot.

Doing a complete rewire solely for changing black to yellow is a waste of time and money.

Mark

 

[Intrepid-II]

Since you have space constraints, why not go with a FLA start battery and house bank consisting of a pair of the mini 100 AH LFP batteries? Use a DC-DC charger between the start battery and the LFP bank. Eliminate the ACR. Replace the 1-2-All battery switch with a Blue Sea 5511e so you can combine banks in an emergency.

This might provoke some controversy, but rebuilding your storage around lead acid is like building a better buggy whip.

Agree, I just upgraded to LiFE for my house battery exactly like you stated above and I love it.