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View Full Version : Rethinking energy strategy - suggestions please



bbilly
23-10-08, 20:10
I'm looking at an 1989 classic 40' american cruiser as a liveaboard that has a Kubota 9kw genset and twin a/c units and watermaker. The gen is very intrusive occupoing a large portion of the aft berth sleeping space with the expansion tank on the bookshelf! It's a very practical but unacceptable arrangement and it needs to be removed along with the a/c. We can do without it, with fans and loads of opening hatches heat shouldn't cause us great problems. I do like showering so the watermaker is staying.

As I understand it the bigger the battery bank the bigger the alternator needs to be and you need a good battery management hardware, increasing the alternator output can strain pulleys/belts etc. It is also not cheap new batts, new alternator and digital batt mbgmt can be expensive $3000-4000, just a guess and daily main engine charging cycles.

Another strategy could be solar cells, and a suitcase genny to top up the batteries when stressed. Only work is to decommission the 9kw Kubota and the 2 cruiseair units. Only use the main engine when cruising.

Question is: Is a suitcase genny suitable for this sort of task and can I just plug it to the battery charger or is it more complicated?

TIA Billy



The strategies for having electrical energy while cruising can be to beef up the domestic holding capacity and keep it topped up by the engine or


















I don't like the idea of idling the engine to charge up the batteries, it cokes up the engine and is probably very innefficient. I don't want to spend on a sofisticated alternator of battery management I was thinking of cutting down consumption and to help keep the batteries charged a small portable 2kw Honda genset would suffice.





I could just beef up the batteries and add in a solar panel and keep a small "domestic" petrol honda 2kw genset

So can I throw out the gen and the a/c

Foxy
23-10-08, 22:22
Where will you be cruising? Makes a big difference as to what power is available. eg Caribbean good for wind
First things first, fit something which lets you know how much power you actually use. Second, do nothing for a couple of months, then work out a solution based on your real usage.
For me, petrol gen not a goer due to noise, inefficiency, carrying lots of petrol etc. There are however, lots of ways of doing ya cat in.....

HoratioHB
23-10-08, 22:59
Petrol gen great as a back up/emergency but wouldn't want to use it regularly - (we have a 1KW one). You need to audit your current requirements first - fridge, watermaker, tele, nav system etc then decide how many amps per day you need. We have a KISS and 2 80w panels and thats suits us fine in the Caribbean. However the watermaker uses 35 amps and so we need the engine for that, but as we want hot water and tend to motor somewhere fairly often that is not really a problem.
I reckon on keeping 420Ah batteres fairly full with the windy and solar panels and our normal consumption. But it really depends on where you are and what you want to use.
Oh and throw away the air con - we have Hella fans and they are all you need even when its hot.

TigaWave
24-10-08, 06:38
How much sailing will you be doing as against staying in one place, will you be staying in marinas/pontoons places with electric hook up.

If you are going to sailing avery few days then a towed generator is very good, and rather than use leectric get a belt drive for the water maker straight from the engine. This way you can get water quicker with a larger compressor.

This is my prefferred choice if I went for a water maker, in practice we never needed extra water. Our cruising was the North atlantic circuit down to Venzuela mainland.

saltwater_gypsy
24-10-08, 14:40
Its a trap!!!
If you want a big a/c, big watermaker, big freezer, big fridge
then you need a big generator and get big problems.
If you can properly audit your power requirements (as someone else suggested) there are some break points in the cost versus power graph which may help your decision making.
Since its an American boat, getting spares may be a problem and it may be worthwhile to simplify as much as possible

bbilly
24-10-08, 19:31
[ QUOTE ]
Its a trap!!!
If you want a big a/c, big watermaker, big freezer, big fridge
then you need a big generator and get big problems.
If you can properly audit your power requirements (as someone else suggested) there are some break points in the cost versus power graph which may help your decision making.
Since its an American boat, getting spares may be a problem and it may be worthwhile to simplify as much as possible

[/ QUOTE ]

Exactly, Tigas idea of the engine driven wmaker is a great tip, generator and a/c chucked. Somewhere on the net, somebody suggested 2 alternators instead of 1, lot's of plusses to this idea - I think. My boat should have a Yanmar 45hp diesel with I assume a 50 amp alternator, if I add a second alternator identical to the first (standard kit) I can churn out 100 amps and have redundancyin case of an alt failure - which sounds good to me, don't need to chuck anything (except a/c and genny). Is it feasible to add a second alternator what needs to be done and do I need "special" regulator/s to manage 2 alternators?

When the engine runs with 2 alts and the watermaker it's under load and should luv it and I'll be pumping 100 amps into my 3/4 battery domestic bank and into my cooling plate and gallons of fresh water into my tanks.

What do I need to make this work?

TIA

Billy

ccscott49
25-10-08, 16:07
Why not just dump the ac's and fit a 4-5kw diesel genny? Probably cheaper in the long run.

bbilly
26-10-08, 19:18
[ QUOTE ]
Why not just dump the ac's and fit a 4-5kw diesel genny? Probably cheaper in the long run.

[/ QUOTE ]

Visited the ample power and the adverc sites. For my needs an extra alternator an inverter, a decent battery bank and an adverc controller will probably suffice my needs. It's probably cheaper too, a marine diesel genset costs from $5000 upwards whereas a second standard alternator, controller and inverter is probably (??) < $1000. I'll chuck the A/C.

saltwater_gypsy
27-10-08, 12:54
Did you spot this ultraminiature 3.5Kw generator on one of the other forums?

http://i300.photobucket.com/albums/nn14/hectou/generatorpaintshop.jpg

bbilly
27-10-08, 13:51
No I haven't investigated this "model" in any depth. Any other view angles or collateral (!). Where did you run into it?

jamie_Cacique
29-10-08, 22:00
I'm planing to fit a second alternator this winter and a second house battery, my intention is to keep both circuits seperate this way if one bank goes right down I have an alternative option (I allready have a seperate dedicated engine battery with a split charge diode).

shamrock
29-10-08, 23:23
After a year living aboard in Carib and USA East coast I offer our perspective.

KISS works for us - no freezer, a/c, watermaker. We have AirX wind gen, 150W solar, 1000Ah batteries, 140amp alternator and a Link 2000-R control/monitor.

Normally (when not ocean sailing and using autopilot etc) we need to charge for avg. 1hr per day to keep up. When it's very windy, no need but we don't look for windy anchorages.

With big batteries, our normal pattern is to do nothing for 2-3 days then motorsail to the next place, charging as we go. In the carib, fridge uses more power but more sun on the panels, in New England the reverse, so it balances out.

The Link 2000-R is worth it's weight in gold, for knowing where we stand and managing charging. Wouldn't be without it.

We had a second alternator, nice but the engine isn't designed to have one and the bracket arrangement was very difficult, couldn't maintain tension and eventually sheared bolts and decided to upgrade the main alternator instead. If you can fit one with a well engineered mounting, great.

A watermaker would be nice, if we had one I'd do nothing different, just use it when motoring.

We do not miss a freezer, a/c or other high power things, from observation of other cruisers these lead to more maintenance of them and a genset, if you are willing to spend time/money doing that it's OK but we are not.

That said, we've not been south of St Lucia so not needed a/c but I reckon we'd cope even so.

shamrock
29-10-08, 23:36
PS - should have said, when we had the problems with the second alternator, I took the main engine alternator off (a wimpy 30amp one) and found that you can buy a 140 amp in the same chassis so I was able do do a straight swap. You may want to do that with your 50amp and keep the 50amp one as a spare rather than going to two with all the mounting and regulation issues.

From our 140amp alt we never get more than 100amp actual, it's normal to run an alternator below rated, Calder's book suggests about 75% of rated amps to prolong life.

Oh, and we have a Xantrex 3000W sine wave inverter, very good and not something to skimp on either. Once I reinstalled it (like so much of the boat, the previous owner had been absent when St Maarten companies installed stuff very poorly) with big thick cables, it works faultlessly.

bbilly
30-10-08, 07:38
Shamrock,

Thanks for the info, considerations and opinion. The 2 alternator setup is also very tricky on the Yanmar 4J. One of the boats I'm currently investigating has the following setup:

Heart 2000R Link Interface Inverter; External 3- stage regulator; Balmar 100 amp engine alternator; Four Winds wind generator with regulator; Four Siemens 75 solar panels with ProStar Controller; Note Solar panels provide power for refrigeration freezer; Total of six (6) Type 30 gel cell batteries in two banks (NEW 05); Guest battery selector switch;

I am completely ignorant on electrics but it looks very similar to your setup. I seem to understand that the Heart looks after everything on the DC side but on the above setup they say "Interface Inverter" what does this mean?

How's the weather in Annapolis and when are you heading south? The boat I'm looking (remotely - I'm in Rome, Italy) at is in Oriental, NC. My plan is to get a boat to Cuba in Feb and the broker suggest sailing down the ICW as opposed to an offshore passage to S.Florida, what do you think, I'm accustomed to the med, whats the Atlantic off the S.E. coast of the US like in Jan/Feb?

Thanks again

Billy

bbilly
30-10-08, 07:57
P.S.

The Yanmar 4J engine has 6000 hr. on it! When it's due for replacement this may be a good solution to AC needs, if ever needed.
The new Yanmar genset that bolts up between the engine and the transmission?
Model KMG65E currently only for 230v/50hz, 105mm extra.

See the Manual:
http://www.forsmarin.se/AlbinMotor/p...k%20KMG65E.pdf
And:
YANMAR Diesel Power - Optional Equipment KMG65E


Billy

jimbaerselman
30-10-08, 10:07
[ QUOTE ]
From our 140amp alt we never get more than 100amp actual, it's normal to run an alternator below rated, Calder's book suggests about 75% of rated amps to prolong life.

[/ QUOTE ] Yes. Just raising the alternator capacity only works if you've got a large enough battery capacity (and it is sufficiently discharged) to take the output.

Assuming 14.4v delivered at the battery terminal, about 400AH of deep cycle batteries (paralleled or whatever) discharged to 60%, you're only likely to absorb 40 to 50A or so after the first few minutes of charge. Depends on the plate surface area and how 'deep cycle' they are.

So, big amp alternators are only useful if they're matched to big AH batteries which can absorb their current.

It's a different matter for high CCA batteries ('starter' batteries). They take a much bigger charging current (just as they handle much bigger discharge amperages!). But they're short lifed if you deep discharge them.

HoratioHB
30-10-08, 10:28
Notice people talking abnout splitter diodes and alternator smart chargers. I have been taking a lot of advice on this after our first season where charging was an issue (shore power unit was faulty, original batteries were sulfated). Problem is that the advice varies depending on who you talk to. One elegant solution I have heard is to remove the splitter diode and only charge the domestic bank. You then use a 12v to 12v battery charger to keep the starter battery topped up and this then becomes just another DC load on the main bank, ie one simple charging system with nothing between the alternator and the batteries. Also some people swear by smart alternator controllers (Sterling for one!!) others say they are a waste of money. Does the panel have any views?

Also the guy in Trinidad is trying to sell me Trojan 6v deep cycle 'golf cart' batteries (also sold as their marine type) on the basis that the design is much more related to typical yacht usage - any one any experience of these??

bbilly
30-10-08, 11:52
[ QUOTE ]
[ QUOTE ]
So, big amp alternators are only useful if they're matched to big AH batteries which can absorb their current.


[/ QUOTE ]

That's interesting! So, assuming a 50% charged bank how big a bank is "efficiently" charged by say a 120amp alternator for example. Is there a formula or rule of thumb?

TIA

bbilly
30-10-08, 12:04
[ QUOTE ]
Notice people talking abnout splitter diodes and alternator smart chargers. I have been taking a lot of advice on this after our first season where charging was an issue (shore power unit was faulty, original batteries were sulfated). Problem is that the advice varies depending on who you talk to. One elegant solution I have heard is to remove the splitter diode and only charge the domestic bank. You then use a 12v to 12v battery charger to keep the starter battery topped up and this then becomes just another DC load on the main bank, ie one simple charging system with nothing between the alternator and the batteries. Also some people swear by smart alternator controllers (Sterling for one!!) others say they are a waste of money. Does the panel have any views?

Also the guy in Trinidad is trying to sell me Trojan 6v deep cycle 'golf cart' batteries (also sold as their marine type) on the basis that the design is much more related to typical yacht usage - any one any experience of these??

[/ QUOTE ]

Eliminating the diodes sounds good but what are down points of add a DC/DC charger?

Smart regulators seem to be the way to go as there function is to give a "better"/"fuller" recharge, good makes seem to earn praise based on their customer service.

Battery types? Depends on usage, I think /forums/images/graemlins/confused.gif

HoratioHB
30-10-08, 13:23
Down side in the UK is the only make is Sterling and its overspecified at 50Amps and quite costly - they say they are in the process of making a cheaper one but not yet. Unelss someone knows different?? Not sure what the other down points might be I was hoping one of the more expert readers might help me.

As for smart regs - some people say as you do, but I have also been told that an alternator with a battery sensing wire is just as good.

Thought I understood Mr Ohm and his laws but the more I look into what happens on yachts the less sure I get!!

Tranona
30-10-08, 13:49
Not so. There are a number of smart charge regulators on the market. Merlin for example offer two different designs and Driftgate is another. Google also shows up manufacturers in the US and OZ. One of the mags did a review of the ones on the UK market recently (forget which one).

HoratioHB
30-10-08, 14:03
[ QUOTE ]
Not so. There are a number of smart charge regulators on the market. Merlin for example offer two different designs and Driftgate is another. Google also shows up manufacturers in the US and OZ. One of the mags did a review of the ones on the UK market recently (forget which one).

[/ QUOTE ]

Sorry Tranona - I was talking about 12v to 12v DC battery chargers not smart charge regualtors. Uless we are at cross purposes??

ccscott49
30-10-08, 14:10
Alternator regulators are an excellent solution to charging deep (ish) cycle domestic batteries, the "machine sensed" alternator is plenty adequate for engine start batteries. I use both systems. as above. Trojan golf cart batteries are excellent deep cycle batteries, whch are ideal for yacht domestic banks.

Why do people go on about whether to use "advanced" alternator regulators? You never here the same people saying three or four stage mains chargers are not needed!

Use the technology now available, lead acid batteries have been around for centuries, but they never lasted as well as they dp today with new charging tecniques.
Why try to re-invent the wheel, use whats available.

I have been living aboard, permanently, for 14 years. I do I guess know what I'm talking about by now, and have only changed my domestic batteries twice, in that time. Thank goodness seeing as I have 16 x 12v x 110ah ones!!

Rather than run a main engine for charging, I have a 4.5 kw diesel genny, plus 320 watts of solar.
I also have a 140 amp alternator on my port main, for the domestic bank. When motoring.

Tranona
30-10-08, 14:21
No, you are right - I misread your original.

Anyway, there must be another make as my Bavaria in Greece is fitted with one. When it was on the charter register it had to have a completely independent power supply for the VHF and a new battery was fitted with a charger from the service battery. It is a very agricultural looking bit of kit, but I don't recall the make - even though I was there last week deciding what to do with it as the dedicated VHF battery is dead and I was going to rewire to an always on box and enlarge the service battery bank. However my electrician there has persuaded me to buy a new battery and keep the charger as there is insufficient room to fit a new big service battery. We don't at the moment live on board for lengthy periods and hook up to mains regularly so don't have the kinds of demands you folk do.

jimbaerselman
30-10-08, 21:57
[ QUOTE ]
So, assuming a 50% charged bank how big a bank is "efficiently" charged by say a 120amp alternator for example. Is there a formula or rule of thumb?

[/ QUOTE ] Sadly, no. The reason is that it's the plate surface area which determines the rate at which a battery can give (and receive) amps. The easily available measure of that is the CCA rating (cold cranking amps) of the battery. A typical starter battery for a 50hp diesel would be around 600 to 750 CCA from an 80 to 100AH battery. But if you often sent that down to 50%, the battery life would be very short (tens of cycles) before capacity was being lost. Lots of thin plates damage easily when they are deep cycled.

Your Golf cart batteries, on the other hand, may total some 600AH at 12vfor the same CCA. They have fewer, much more robust plates which accept regular 50% discharge and discharge with a life of hundreds of cycles.

But they'll only recharge at the same rate at the little starter battery, since there's only the same surface area working away down there. And it takes time for the chemical reactions to soak through those thick plates.

All this is assuming your alternator/charger can deliver 14.4v at the battery terminal (ie, it's sensors are connected to the terminal, not its own output - upstream of all sorts of resitances). Some call those chargers intelligent. Most are; if they switch their charge voltages to minimise battery gassing once the batteries reach a sufficient charge level (say, 85% - it varies).

Allowing for 20a of domestic loads, a 120A alternator may manage to push some 100a into some 800AH of golf cart stuff which is 50% discharged, but that's a bit of a guess on my part. I'm sure someone with a really big bank and a big charger can tell you the max that they've been able to charge at. Then we can start drawing graphs . . .