DC to DC charger - not needed for boats with proper alternators.

[sailingharry]

Originally Posted by CaptainRivet

@sailing harry: the limit is 4 because long term experience of dozen installers involved in creating this regulations saw in reality that due to added serveral factors, raising resistance is main, from 5 lugs the problems arrising.
You simply have to set somewhere a limit. And yes as always there will be exceptions where at 3 lugs the boat is burning down while someone else stacked 10lugs running 250A and all is ok.
And no my starter or alternator cable is not the biggest...on my cat there are dozen that are bigger and the inverter cables are the biggest ones, on my mono it was a 13m long 240sqmm cable that ran a bowtruster made for a 18m on a 12m longkeeler ketch and sucking cont 800A out of the batteries (bought ketch like this)

I really don't disagree with the abyc limit. I get it. It's like the rules that require a 12-year-old swim team member fishing in a 100 ft wide Creek 3 ft deep that has to wear a life jacket. Or the more similar rule that says plugging a power strip into a power strip into a power strip is an overload ready to lead to a fire. Even if you just have 12 cell chargers plugged in. Exceptions are so hard to write. I really do get it. It's also why I read rules, understand them, and then sometimes will plug 12 cell chargers into daisy chained power strips!

I also get that the starter is really one of the lightest (big) loads on the boat. It's the reason I find it so funny that everybody says your starter has to be lead because AGM can't handle it, but my inverter can draw three times what the starter does. But in Newhaul's example, none of those loads were involved.

[Putt-Putt]

In my opinion the connections shown on the 2 pictures and the commentary provided, are not something that I would accept.

On most stud type connection points there is a relatively large conductive surface that the lug lands on that is designed to pass the current. The stud itself is just there to provide the clamping force in order to achieve a gas tight connection. If this stud is copper it likely has more to due with making the connection on the plunger end, inside the solenoid rather than passing current from the lugs.

Don't you think there should be a flat and lock washer on this high current connection to a rattling 2 cylinder diesel?

That being said, the stacking order appears to be back assward.

This connection point is directly connected to the battery that can provide enormous current, with no fuses in sight or apparently planned. All battery connections should have overcurrent protection, yep even this starter, which is likely about 1kW and therefore easy and cheap to do.

Although I crimp and solder all of my small conductor open barrel lugs, I fail to see the need or how you would actually produce an effective soldered connection on large conductor closed barrel lugs. A proper crimper and heat shrink should be all you need.

You state your alternator's output is 75 Amps and you plan to have it produce the 60+/- Amps to power the dc-dc for potentially hours on end, plus power the house loads. All through a 10 AWG conductor that has an ampacity in the engine space of about 50 Amps, unless you plan on using a 200º C rated insulated conductor. Conductor length has nothing to do with it's ampacity.

One would expect that a retired Shipwright, a retired OTR trucking firm owner, and Engineer (all noble professions) would produce a design that would indeed "negate all possible negative issues."

On this subject I'll shut up now, except to say good luck and ask who is Tusstuss?

[newhaul]

Originally Posted by Putt-Putt

In my opinion the connections shown on the 2 pictures and the commentary provided, are not something that I would accept.

On most stud type connection points there is a relatively large conductive surface that the lug lands on that is designed to pass the current. The stud itself is just there to provide the clamping force in order to achieve a gas tight connection. If this stud is copper it likely has more to due with making the connection on the plunger end, inside the solenoid rather than passing current from the lugs.

Don't you think there should be a flat and lock washer on this high current connection to a rattling 2 cylinder diesel?

That being said, the stacking order appears to be back assward.

This connection point is directly connected to the battery that can provide enormous current, with no fuses in sight or apparently planned. All battery connections should have overcurrent protection, yep even this starter, which is likely about 1kW and therefore easy and cheap to do.

Although I crimp and solder all of my small conductor open barrel lugs, I fail to see the need or how you would actually produce an effective soldered connection on large conductor closed barrel lugs. A proper crimper and heat shrink should be all you need.

You state your alternator's output is 75 Amps and you plan to have it produce the 60+/- Amps to power the dc-dc for potentially hours on end, plus power the house loads. All through a 10 AWG conductor that has an ampacity in the engine space of about 50 Amps, unless you plan on using a 200º C rated insulated conductor. Conductor length has nothing to do with it's ampacity.

One would expect that a retired Shipwright, a retired OTR trucking firm owner, and Engineer (all noble professions) would produce a design that would indeed "negate all possible negative issues."

On this subject I'll shut up now, except to say good luck and ask who is Tusstuss?

And all part of my past life . Yes I have the papers to prove it all.
As I stated originally this is a simulation of what is on the boat using the spare westerbeke 10-two engine at my shop. The actual order of the wires here is immaterial. They are stacked main power second will be dc2dc then alternator , glow plugs, then ignition wire all using appropriate copper solder type ring terminals.

Lastly my boat my install .

[sailingharry]

Originally Posted by Putt-Putt

On this subject I'll shut up now, except to say good luck and ask who is Tusstuss?

Oops. Not Tuss Tuss. Putt Putt. I'm almost as bad at names in real life!

[newhaul]

Well update I got a great deal on an open box 40amp dc2dc renogy unit $60 usd so it's decided I'm going with a 40 amp unit in my install.

[Wandering]

Originally Posted by sailingharry

I really don't disagree with the abyc limit. I get it. It's like the rules that require a 12-year-old swim team member fishing in a 100 ft wide Creek 3 ft deep that has to wear a life jacket. Or the more similar rule that says plugging a power strip into a power strip into a power strip is an overload ready to lead to a fire. Even if you just have 12 cell chargers plugged in. Exceptions are so hard to write. I really do get it. It's also why I read rules, understand them, and then sometimes will plug 12 cell chargers into daisy chained power strips!

I also get that the starter is really one of the lightest (big) loads on the boat. It's the reason I find it so funny that everybody says your starter has to be lead because AGM can't handle it, but my inverter can draw three times what the starter does. But in Newhaul's example, none of those loads were involved.

The inrush current on DC loads can be multiple times higher than an AC inverter load of the same running current. Apples and oranges

[svtickles]

Originally Posted by bgallinger

I have used a 100 amp Balmar alternator with a Balmar MC-614 external regulator to charge my batteries (3x Lithium house batteries and 1 x AGM engine start) for several years now without a DC-DC charger. I always charge the batteries to 100%. I also fitted a Balmar Transient Spike Protector on the alternator.

Do you have the batteries in parallel, or are you using something else, like a relay, in between the banks?