Design Problem - Electrical System Upgrade

[Dockhead]

Originally Posted by Joli

Your generator can produce 56 amps at full load so you have 28 amps per bank given no losses. The charger outputs 35 amps per side so it looks big enough.

Maybe add a switch so you can tie the banks together when not charging then disconect when charging?

Maybe belt a larger (180~220) high amperage alternator to the main engine so you can dump big amps in when needed?

I agree with Bill, do an energy management worksheet to determine what you're using.

Ice cubes are truly energy hogs.

Wait a minute; my generator produces 6.5 kW sustained, which is 29 amps at 220 volts, almost exactly equal to the typical shore power connection. That is 271 amps at 24 volts, so I am baffled where you get 28 amps per bank as my generator capacity.

28 amps at 24 volts is only 672 watts, a little more than one-tenth of the generator's capacity.

100 amps of charging capacity into 24v battery banks amounts to 2.4kW; call it 3kW after all the power factors and inefficiencies. That is less than half of my generator's capacity and should be fine. The Victron and some other chargers will cut back the charger current in case the power is needed for other purposes; you can set them to automatically prevent overloading the genset (or shore power)

[Dockhead]

Well, I've thought about all of your comments, and reflected a great deal on the matter (it's a lot more pleasant than actuallly thinking about work).

Although I am reluctant to tinker with the factory setup (the boat is beautifully and intelligently made, and I don't think it's right to jump to the conclusion that the designers did something stupid), I just can't justify the separation of the two main battery banks in my mind. It just can't make sense, that half the boat's battery capacity should be devoted to the pilot (since as someone pointed out, all the other things connected to that bank -- winches, thruster, windlass -- can't draw down any batteries, because they are used so briefly and/or only with the engine running).

So I'm going to do the following, I think:

1. Combine the "service" and "domestic" banks with a mechanical switch. If I have any problem with the electronics, I can isolate the banks when the windlass or thruste is being used.

2. Do whatever I can with power conservation (lots of LED cabin lights).

3. Install battery analyzers so I can see how the batteries are being charged or discharged.

4. Install an alternator-powered battery charger, like the Sterling, to get the best out of the powerful (100 amp x 24v = 2.4kW, yeeha!) engine-driven alternator.

Then I'll see. Improving the AC driven battery charger is the most expensive and smallest result line item, so I'll wait on that item for a while. The AC-driven battery charger has limited application, since the existing setup is quite enough when on shore power, the only question is on the hook when you don't feel like cranking the propulsion engine. After optimizing the work of the engine-driven alternator, I will have the possibility of rapidly charging the batteries with the propulsion engine, if I get stuck with run-down batteries.

Does this seem reasonable? What do you guys think?

[DotDun]

Originally Posted by Dockhead

Although I am reluctant to tinker with the factory setup (the boat is beautifully and intelligently made, and I don't think it's right to jump to the conclusion that the designers did something stupid), I just can't justify the separation of the two main battery banks in my mind. It just can't make sense, that half the boat's battery capacity should be devoted to the pilot (since as someone pointed out, all the other things connected to that bank -- winches, thruster, windlass -- can't draw down any batteries, because they are used so briefly and/or only with the engine running).

Don't confuse boat building with boat electrical, they are 2 completely different disciplines! The best boat builders most likely sub out the electrical. Don't worry about messing up your boat.

I would certainly combine the two house banks are you suggest, only I would do it by cabling it properly (not with switches). Properly means use all the same size/length bridging cables and keep all banks the same length from the (now) single charger/load (positive on one bank and negative on the other). During high current draw, the voltage drop goes up, so you want all batteries to be the same 'distance' from the load. Yes, 18" of cable length difference in 2 banks will make a difference over the long haul.

Good luck!

[daddle]

1. Trade the boat for a condo.

Or

2. Eliminate all those useless loads. Nobody needs that stuff.

[btrayfors]

Originally Posted by Dockhead

..... Does this seem reasonable? What do you guys think?

Maybe. But, before you do anything, finish the energy inventory and be sure you understand exactly how the boat is set up now.

One good reason to separate high-load items (like the starter, bow thruster, etc.) is to avoid spikes and low voltage sequences which could damage sensitive electronics. Perhaps this is what the PO or the designer(s) had in mind?

Bill

[Dockhead]

Originally Posted by btrayfors

Maybe. But, before you do anything, finish the energy inventory and be sure you understand exactly how the boat is set up now.

One good reason to separate high-load items (like the starter, bow thruster, etc.) is to avoid spikes and low voltage sequences which could damage sensitive electronics. Perhaps this is what the PO or the designer(s) had in mind?

Bill

Yes, of course that was what they were thinking about. The reason I would start with a switch is that if the electronics get bothered by spikes I could separate the banks briefly during thruster/windlass operations and still mantain the advantages of combined banks. But I want to try it, because 8 x 110ah x 12v batteries is a massive sink for spikes. If the banks are combined, I can hardly imagine that spikes not absorbed by a quarter ton of lead plates will manage to break out to trouble the plotter. All the more since there will be 100 amps of power being supplied to the banks from the alternator while the engine is running (and I wouldn't operate either thruster or windlass without engine running).

Starters (both propulsion engine and generator) are not in the equation, because they are on totally separate 12v banks.

[Dockhead]

Originally Posted by daddle

1. Trade the boat for a condo.

Or

2. Eliminate all those useless loads. Nobody needs that stuff.

Great idea. But which load, exactly, would be considered useless? Cabin lighting, maybe? Reefers? I guess I could buy kerosene lamps and salted fish and hardtack.

Or on second thought, maybe not.

[Dockhead]

Originally Posted by DotDun

Don't confuse boat building with boat electrical, they are 2 completely different disciplines! The best boat builders most likely sub out the electrical. Don't worry about messing up your boat.

I would certainly combine the two house banks are you suggest, only I would do it by cabling it properly (not with switches). Properly means use all the same size/length bridging cables and keep all banks the same length from the (now) single charger/load (positive on one bank and negative on the other). During high current draw, the voltage drop goes up, so you want all batteries to be the same 'distance' from the load. Yes, 18" of cable length difference in 2 banks will make a difference over the long haul.

Good luck!

That's not practical. One bank is under the aft berth; the other is under the saloon floor.

And I don't think it's needed. The existing splitters will handle the banks fine, separated, or combined over some distance. A long cable between the formerly separated banks is even good, it seems to me -- will equalize charge during long low-intensity discharges, allowing full capacity of both banks to be used for house loads, but will help isolate spikes when there are high intensity loads.

ALthough that may be my amateurish speculation? I am not exactly an electrician, although I sense that a few more years of cruising may change that, assuming I want to have uninterrupted fresh food, and light in the cabin.

[goboatingnow]

I ran into this problem in a Rassy with hydraulic power pack, whish had its own bank. This boat actuallh had 4 battery banks, ( hydraulic, thruster, domestic & engine start). I combined the main hydraulic & domestic set which improved things as there is no point in big seperate banks.

In your case I would

(a) combine the banks, with an optional switch, given the distance apart, youll need big cables and fuse them.

(b) INvest in a big main charger, somthing capable of at least 50 , preferably 80-100amps ( $$$ unfortunately). go for a reliable brand like Victron or Mastervolt.

(c) The engine alternator is too small, this is usually the case, ( remind me why boats costing $$$$$$$, have two-bit alternators). But going to a big case alternator is expensive and will require mods to the engine mounting Use your generator, via a big charger to charge the bank, it will be far quicker and more efficient. You have the alternator as a back up.

IN my experience the spikes from thruster and winches will not be an issue. especially electric winches as these are not huge motors. Thrusters can cause voltage drops, its thats a problem for the elctronics, the easiest thing is to put a voltage stabliser ( idustrial quality), but in my experience, and with a 24V system your unlikely to suffer problems.

fridges and freezers, once of high quality sould not cause a problem, especially if you are in a temperate climate. Again my experience of moody is that the fridge freezer system is not isulated enough( few northern boats are) for hot climates. unfortunately this is a big rework, either using higher R materials or vacumn panels.

[Dockhead]

Originally Posted by goboatingnow

I ran into this problem in a Rassy with hydraulic power pack, whish had its own bank. This boat actuallh had 4 battery banks, ( hydraulic, thruster, domestic & engine start). I combined the main hydraulic & domestic set which improved things as there is no point in big seperate banks.

In your case I would

(a) combine the banks, with an optional switch, given the distance apart, youll need big cables and fuse them.

(b) INvest in a big main charger, somthing capable of at least 50 , preferably 80-100amps ( $$$ unfortunately). go for a reliable brand like Victron or Mastervolt.


(c) The engine alternator is too small, this is usually the case, ( remind me why boats costing $$$$$$$, have two-bit alternators). But going to a big case alternator is expensive and will require mods to the engine mounting Use your generator, via a big charger to charge the bank, it will be far quicker and more efficient. You have the alternator as a back up.

IN my experience the spikes from thruster and winches will not be an issue. especially electric winches as these are not huge motors. Thrusters can cause voltage drops, its thats a problem for the elctronics, the easiest thing is to put a voltage stabliser ( idustrial quality), but in my experience, and with a 24V system your unlikely to suffer problems.

fridges and freezers, once of high quality sould not cause a problem, especially if you are in a temperate climate. Again my experience of moody is that the fridge freezer system is not isulated enough( few northern boats are) for hot climates. unfortunately this is a big rework, either using higher R materials or vacumn panels.

Thanks! That's useful -- real and relevant experience, and I think that's what I'm going to do.

I will buy the heaviest welding cables I can find and join the banks like that, with fuses and a mechanical switch. If I have any trouble with the thruster bothering the electronics, I can always disconnect the banks while the thruster is being used. One question I have is whether I can just leave the splitter attached the way it is. Will combining the banks not bother it? If not, then I'll leave it in place so that it will split the charge while the banks are separated. If this is not good practice, then I guess I'll connect the alternator directly to the former service bank, so that it can directly feed the high current loads from thruster, windlass, and so forth while these are being used and banks may be disconnected from each other.

Anybody with any insight into this question -- please comment.

The engine alternator is a large-case, 110 amp Leese-Neville jobbie (based on a Prestolite truck alternator) which I think surely is adequate for 440 ah of batteries, correct me if I'm wrong.

Although it has a very good electronic splitter (a Driftgate), it does not have a good regulator. So I think job one will be to remedy that. I am attracted by the "alternator to battery charger" by Sterling (Sterling Power Products: Alternator to Battery Charger). The idea of it seems good to me -- the charge current is produced in the charger using the alternator current merely as a power source. But I'm an electrical illiterate so maybe that's just my amateurish fantasy. In any case, it is vastly easier to install since you don't have to pull and dismantle the alternator. If any of you has any comments, I'd be grateful for them.

With the banks combined and the alternator properly regulated, I think I'll leave it at that for this season and see how it all works. Then sometime later a Victron inverter/charger to shorten generator runs on the hook. We'll be cruising the U.K. south coast and Brittany this year; so we won't be at anchor nearly as much as we are accustomed to in other areas.

What do you guys think?

[Dockhead]

On the other hand, the Sterling site itself does not seem to actually claim that the "alternator to battery charger" is functionally better than their advance alternator regulator. They emphasize that it is very easy to install.

Installing the normal regulator merely requires that wires be soldered onto the field regulator brushes. If I pull the alternator and have it serviced anyway, then the cost of this would be neglegible, and the regulator itself is much cheaper than the charger, by a few hundred bucks. You guys have any opinions?

[FrankZ]

Originally Posted by Dockhead

<snip>

Although it has a very good electronic splitter (a Driftgate), it does not have a good regulator. So I think job one will be to remedy that. I am attracted by the "alternator to battery charger" by Sterling (Sterling Power Products: Alternator to Battery Charger). The idea of it seems good to me -- the charge current is produced in the charger using the alternator current merely as a power source. But I'm an electrical illiterate so maybe that's just my amateurish fantasy. In any case, it is vastly easier to install since you don't have to pull and dismantle the alternator. If any of you has any comments, I'd be grateful for them
.<snip>
What do you guys think?

I installed one of these last year on the new (to us) boat when I added a battery bank. I installed 2 8D AGMs and figured with the cost of the bank it might be a good idea to have a multistage charger powered by the alternator.

Don't know how big your alternator is (I have missed it) but this unit will only handle up to 130A input, well that is what it is rated for at least.

[Dockhead]

Originally Posted by FrankZ

I installed one of these last year on the new (to us) boat when I added a battery bank. I installed 2 8D AGMs and figured with the cost of the bank it might be a good idea to have a multistage charger powered by the alternator.

Don't know how big your alternator is (I have missed it) but this unit will only handle up to 130A input, well that is what it is rated for at least.

Well, how do you like it? Do you perceive any advantages compared to a multistage regulator?

My alternator is a 110 amp x 24v Leece-Neville (Prestolite truck job).

[FrankZ]

While I have it I may not be the best person to give a good technical review. I like I can watch the panel and see what's happening (you have to pick that up separately but it wasn't expensive).

I don't know if it is rated for 24VDC or not though. That might make your decision for you.

[Dockhead]

Originally Posted by FrankZ

While I have it I may not be the best person to give a good technical review. I like I can watch the panel and see what's happening (you have to pick that up separately but it wasn't expensive).

I don't know if it is rated for 24VDC or not though. That might make your decision for you.

Yes. they do make one for 24v. That remote panel (I like it too) is also available for the normal regulator. Hmmm.