Advice requested on Battery Bank size & charging for our new boat.

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anniebray

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Building of our new Sadler 290 is about to commence. We would like comments from you as per subject.
Boat equipment includes Raymarine C80 multi screen with gps,radar,ais, tiller pilot, wind+log+depth instruments, vhf .Mikuni Heater, fridge, laptop, TV/DVD, battery monitor.
We plan on 3/4 month cruises in Northern Europe sometimes on anchor otherwise in harbour etc with shorepower facilities.
House battery size I have guesstimated at 300AH, engine battery say 100AH (800CCA) or maybe a micro start battery.
Engine will be a Yanmar 30 with standard 60A alternator to which I intend to fit a Merlin 4-stage smart charging alternator controller.
Shorepower circuit to have a 40A integral smart charger .
Finally I plan to fit a 40watt solar panel on the cabin roof. I would have favoured the addition also of a Rutland 913 wind charger but would rather not because of noise/appearance.
I would be glad of your expert opinion of my plans so far.
Rgds Richard
 
Hi Richard

You need to make yourself a spreadsheet with your electrical requirements when:
- underway at night
- underway during daylight hours
- at anchor
- plugged into the marina

eg:
electrical consumption underway at night you will require:
tri-colour (probably 3 x 10W / 12volts = 2.5 amps per hour)
C80, plus attachments (probably close to 4 amps per hour)
autopilot (depends on how you balance your sails, but close to 4 amps per hour)
and so on (so far 10.5amps x 12 hours = 126 amps)
Then take your worst case ie 222 amps per day (126 + 12 hours x 4 amps). The work out how many amps will be generated under the different circumstances and halve it. ie solar panel is 40w/12v=3.33 amps giving an effect 1.6 amps for 8 hours = 13.33 amps in ideal conditions.
Your 222 amps per day now becomes 222-13.33 = 208 amps.

Your batteries should last for three days without receiving any charge. You should also double the daily requirement because only about half of your AH are actually useful without killing the battery - ie 208 x 2 = 416AH per day, so a battery bank of 500AH.
 
Without using Capnslarty's calculator, that sounds like a 60 to 80AH a day consumption (the uncertainty depending on heater use and inverter load for TV etc) ), with a 15AH top up from the panel. Say, 65 AH a day net to replace when at anchor. That'll give you 2 to 3 days at anchor before you've got to do something radical, like start the engine - or trade some battery life by discharging it below 50%.

Would that work for you?

If not, bigger solar panels or portable petrol generator (noise, petrol around, no use under way) or wind.

Voyaging, you should have no problem. The chance of a lighter wind for a three period is reasonably high, so engine on.
 
Disagree Jimbo.
the C80 would, if on 24 7 draw around 100 AH per day, alone... let alone the fridge, he has a reasonably usable 100-150 ah.. less than a day..

alt =60A.... to put back 150, say, with inefficiencies be about 4 hours !!!
solar, forever !...
I would recommend bigger capacity bank, maybe 800.. better charging systems, bigger alternator, bigger charger etc.. make use of every hp generated. if you are plugged in its virtually free, if at anchor, and yo HAVE to run the big oiler, then at least get the best bang for yer buck, ie, as much output as the batteries can take.(edit - over a given period of time !.. usually.. size the alternator first, for your engine, and IF you can, fit the batteries that the alternator can charge in a sensible time period (for you), then, you got the limit, live with it.. sorry if I offend a small greay pussycat in Poland or something, but hey), no really /forums/images/graemlins/wink.gif , its the way to go...
More Power .. Egor.:!!!!!!!!!! - end edit)

towed genny at sea, anything ya can whilst at anchor.. petrol genny is probably the most cost efficient.
 
Richard, without spending an (unnecessary) fortune, you'll always be 'in defecit' with regards to electricity. You're going to have to run the engine for charging if you do many 'overnighters' without access to shorepower at the end of it. You certainly don't need an 800A battery bank for what you're intending to do, even if you could find space to fit all the batteries in a 29ft boat! Invest in a decent battery monitoring system. One thing, I'm fitting out a new boat myself at the moment for extended cruising. I was warned off a multi-stage charger (by somebody who could have sold me one) on the grounds of complexity, but I'm intending to go off the beaten track, it would probably work OK for you nearer to 'civilisation'. A wind charger would be a help at anchor, a towed generator for coastal cruising is probably more trouble than its worth. Do the exercise Stingo suggested and I'm pretty sure that you'll find you need the engine an hour or so a day. Enjoy!!
 
warned orf a multistage.. he musta bin convincing lol ! /forums/images/graemlins/laugh.gif

the monitoring system only tells you WHAT you know.. you need to recharge.. so ditch that..

make use of every bit of power.. it makes sense dood... you just fighting it... /forums/images/graemlins/grin.gif
 
Thanks for all your advice. I will try Joe's spreadsheet & see what comes out but for sure my little boat will not be carrying 800AH ! She's due for commissioning next April & our first cruise will probably be a months cruise of the Channel Isles so I'll see what happens. For sure if we had been cruising this year we would have spent very little time anchored.
Richard
 
He was, glad you find that amusing.
Not really, I can think of several scenarios where it would be good to know the remaining power in the house batteries.
Most systems don't have power to waste, so your point is?
If you bothered to read the guys' post you might find that his intention is to be hooked up to shore power as often as he can. Not what I intend to do and probably not what you intend to do.
 
Joe,

Cruising for 3 months around N Europe is going to involve moderate time at anchor, much time in marinas, most passages day sails, with (say) 3 or 5 passages over 24 hours.

Those 24 hour passages will have a half hour engine charge on departure, and a half hour on arrival.

You've assumed the C80 at 4a 24/7. That's easy to cut back substantially - radar off, manual steer for intervals. And thank heavens, fridges don't have to work so hard in N Europe!

The very rare even longer passages? Run the engine for an hour. It helps you to cross the traffic lanes at right angles when the winds are unfavourable! And if the wind isn't going to put you where you want to be (miss tide gate? gone calm?) that's another good excuse to use the iron tops'l.

Whilst it may be desirable to design for the extreme case, he's got a good starting point for his intended style of sailing. And with an A/H meter, he can soon see how things go. Adding a further 100A/H battery is a probable step (keep the space available) and add charging (100a alternator won't give you too much extra with only 400A/H to charge, and it's a pricy option; more solar? plug in ashore more often, run engine more often? Wind? portable petrol?) or change consumption.

Best to work out the future by trying it all out first.
 
Boats use more electricity every year. Always have, always will. It is very hard to expand properly-built storage space for batteries so I would recommend that you make a battery compartment as large as you realistically can at the build stage. You don't need to fill it with batteries on day 1 but it will be easy to increase if you need to.

Yes, definitely have a battery monitor.

Charging:- Remember that the net charge = alternator output - load. So if in the evening with the Mikuni, lights, fridge, telly, laptop on you run the engine to make hot water and put some charge in the batteries, you won't be charging as much as you think as net charge into the batteries.

60A alternator sounds a bit small. Would it be easy at this stage to increase to an 80A or so? At much above that you need bigger drive belts, but you won't regret fitting a bigger alternator. You are making the right decision to go for a 4 stage alternator controller. Consider buying the Balmar alternator and controller, though, it has an excellent reputation for this environment.

40A battery charger - same story about charging. Probably fine for your intended use but if you might buy a petrol generator you don't want that running for hours. Suppose you were to buy a 1000W generator you could manage a 60A charger so maybe increase that now? Consider fitting a sine wave inverter at the outset with a change over switch so the mains can come from shore, off, invertor. You would plug the generator into the shore power socket if you buy one. Trivial cost today, but a much more difficult job when built. If you don't want to buy the sine wave invertor now, have the wiring put in and allocate a space for when you do (you will).

The 40W panel is not going to do great things for your when you are living aboard but it will be superb when leaving the yacht without shore power. The 913 wind generator could be really useful if you are not sheltered from most of the wind all the time (one tries to anchor where it is calm, when possible).

Towed generators are fine when you are doing a lot of cruising under sail. Sadly most of us don't. They really come into their own when trade wind sailing and you are at sea for tens of days, under sail, making a good speed. That is not generally the case in Northern Europe unless you are exceptionally picky about the weather. We try to be picky and some years we manage 75% under sail though this year it has been closer to 25% /forums/images/graemlins/shocked.gif Even so, your boat will spend 98% of its time not under way so is towed worthwhile? We see lots of Duogens coming down to the Med but I seldom see them generating wind power. The Rutland 913 and the horrible noisy Aerogen are the most popular and seem to be in constant use. The folks who do the Caribbean are the ones to ask about wind. If money not looks was the constraint, I'd have the Rutland in place of the solar but the solar are silent and great for helping to get the batteries up to fully charged on a daily basis even if you are using the engine or generator.
 
I was advised against fitting a Merlin 4 stage regulator by Merlin. Instead they advised me to fit a Voltage sensing relay between the engine start battery and the domestics.
 
Another fine pice of advice Lemain! We did have a Rutland 913 on our last boat & therefore appreciate that it can produce up to 250w . May well decide to go for the Rutland rather than the solar panel. Just one question though... why would I need an inverter ? Our tv/dvd would be 12v/mains & so would our lap top. Can't think what else I would run from an inverter !!
Richard
 
Don't think you have that quite right John. The VSR (voltage sensing relay) automatically links the start battery & the house battery when the engine is running. The 4-stage smart controller converts a conventional alternator + regulator system into a smart charger.
Richard
 
[ QUOTE ]
Just one question though... why would I need an inverter ? Our tv/dvd would be 12v/mains & so would our lap top. Can't think what else I would run from an inverter !!

[/ QUOTE ]Most people buy normal mains TVs, etc. these days as you get a better choice and the price is much lower. Inverters are so efficient that the difference in power is trivial and can probably be compensated for by having a better choice of equipment. Apart from TVs and laptops, there is other stuff....mobile chargers, electric tools, the ladies like hairdryers, curlers, camera chargers, food mixers.....stuff!
 
Point on the alternator choice, work on about 1/2 it's output if running the engine just for charging as the revs are down low so that 60a may only be 30 - definatly low. I use a 100a and get about 60a at fast tickover then up to 80 odd with the inverter running. For N Europe charge rate is probably more important than large batt size as you tend to be doing more short hops than long passages so getting the batt up quickly when motoring out of port is probably more important than it lasting ages once charged. This also suggests smaller bank as once it has run down it will take much longer to charge. I would work on the basis of how much power you generate in 2 hours, given a max practicable alternator size of about 100a thats about 120a/h at tickover up to mabe 160 running. Assume the batt bank is down to about 60% so needs about 40% 50% of capacity put back to allow for inefficiencies then much over 300A/h as a bank and you are not going to get the battery topped up without running the motor especially for charging. If thats not enough to meet you needs when you calculate what the consumers use then look at being more efficient on use rather than generating more power or accept you will be useing the motor as a generator in the evenings at anchor and make sure its really quiet!!
 
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