First batt refit: Criticize my plan

[Pete7]

Originally Posted by TenaciousH

Pete and wd, I do plan on getting a controller of some kind but I dont know exactly what kind to get. Something with an easy readout separated by banks would be great... Especially one that recognizes what I'm trying to do with splitting my engine and house banks with a charging emergency battery.

You don't need to monitor the engine start battery because you are not going to run it down with domestics (I hope). After all you don't monitor your car battery. So that is only one house bank to measure then.

Some of the cheap options (UK suppliers but also available in the US)

BM-1 Battery Monitor

Sterling Battery Monitor

Victron Battery Monitor

There are lots of others too.

Pete

[GILow]

Originally Posted by TenaciousH

Here are some bits of how I calculated my 240Ah. These numbers are from an inexperienced electrician's light research on comparable devices, not necessarily my own equipment as observed under sail. Translation: I dont yet know what I'm talking about, but heres where I'm at at the moment.
* 60 Ah for a full 24 hr day of refrigeration @~2.5a
* 50-60Ah for 10-12 hours of stereo at medium volume @ ~5a
* 36Ah for Instrument panel (not yet installed) 20-24 hours @ 1.5 a
* 21Ah for Garmin GPS 14 hours @ 1.5a
* 30Ah for 22" flat panel screen and a throwback N64 (no moving parts) or hard drive w movies for 2 or 3 hours

A lot of these figures look like you are taking PEAK use and extrapolating it over the hours of use. In practice the figures should be a lot lower. For instance, my fridge draws 2.5 amps also, but only comes on for about five minutes every half hour if I leave the door closed. (Maybe a bit more often in summer, don't know about that yet)

And seriously, if my GPS (handheld) used 21Ah for 14 hours use, I would have a problem, because it runs from a couple of AA batteries and they would not last a minute at those figures, as it is, they drive the GPS for days. The GPS you describe would need a car battery to be able to use it. Even our 19" screen chart plotter only draws less than 0.25 amps once it has started up.

I am taking the approach of building up capacity to our needs, following a couple of the good threads on CF on the matter. Our current battery bank of 400AH is totally stuffed, probably only good for 10 or 20% of that, and we cope fine with the Aerogen 6 and some totally buggered solar panels (4 x 60 W putting out a MAXIMUM of 60 W between them). We are only overnighting at the moment but we don't use shore power when at the pen. But like you, we have what we see as very light power requirements, and our boat elex are very much no frills.

I think you'll find this is a lot easier than you thought, once you get some real power consumption figures to work with. And to this end, I have found temporarily connecting a handful of small, cheap, reasonably accurate ammeters to individual devices around the boat gave me a much better picture over time on what was really happening to our power. The peak figures are quite misleading, in both directions.

Matt

[onestepcsy37]

if you truly have a 240ah requirement, which i doubt, only a generator would be a practical answer on your boat - i'm familiar with the morgan 38. and not a permanently installed one either (not enough room). a honda 1000 will easily drive a smart 45 amp charger, takes little room, and can be stored below after being run out of gas. total cost under $1000. not that i recommend this as the only choice.

try mounting hard solar panels above the stern pulpit, using either a store bought arch or your own design from stainless tubing. i've decided against a wind gen because it's too 'mechanical' for me, but that can also be mounted on an arch or on the stern.

also check to see if you can improve the size of your engine alternator. it's good to have multiple sources of battery charging - engine, generator, solar, wind. my 50hp perkins has a 90 amp alternator which probably realistically puts in about 50 to 60 amps when the batteries will accept that much.

four golf cart batteries will give you 450ah capacity and may be the limit of what you can put in your boat, plus a size 29 'start' battery.

start with a strong plan. then improve on it with experience. i think much of the advice you've been given here is really good. and if you're headed for the tropics, don't discount the importance of a bimini.....

[rcmpegasus]

On a 56 ft sailboat with led lights, a crappy fridge and some tv and DVD use I use about 250 Ah per day on the average. I suspect for a smaller vessel it would be less.

[Stu Jackson]

Your energy budget is way too high.

The All-Important Energy Budget:
Energy Budget

[cheoah]

Agree with others that 240 sounds high and reducing with LED, insulation etc is smart move.

Maybe the Honda is the right way to go. I'd be inclined to bump your alternator up to a 70 and put a smart regulator on it. Should see 50A at times. Better than having a gas engine chugging along in the cockpit IMHO

Also recommend a victron battery monitor.

Finally, I think your 6V series/parallel is a good move. With solar you will keep your batts in good condition.

Add proper fuses throughout if not already protected, and use all good cabling, labels, heat shrink, etc etc.

[sailinglegend]

Originally Posted by Stu Jackson

Your energy budget is way too high.

The All-Important Energy Budget:
Energy Budget

The ONLY way to determine your Ah usage is with a battery monitor not a spreadsheet of possible Ahs used by each piece of kit. Measure over several 24 hour periods with different conditions - including night sailing - and decide your worst case scenario.

If you haven't got a battery monitor then fit one - or better still get a Digital Voltmeter, a digital Amp meter/Ah counter, and a SmartGuage to accurately and reliably measure battery State of Charge.

[noelex 77]

Originally Posted by sailinglegend

The ONLY way to determine your Ah usage is with a battery monitor not a spreadsheet of possible Ahs used by each piece of kit.

I agree actual battery monitor measurements are more accurate than estimates, but their are many cases where spreadsheet can be useful.

The major use of a spreadsheet is predicting a consumption (and production) in a new or changing situation. A New yacht, new major equipment ( what happens if a fit a fridge / freezer, new stereo, washing machine, watermaker etc), a new situation (more crew for example)

In short a lot of these "what if" questions are best answered with a spreadsheet estimation. A battery monitor only tells you about the current usage.

[laika]

I've got a Yanmar 3gm30f which came stock with a 35A alternator (your's is perhaps the same?). It was swapped out with a 105A alternator and an external Balmar regulator. Works well. Does not bog the engine down as much as I would've guessed.

I personally don't like using it to keep my batts topped off though. Don't like the habit of long engine idling.

FWIW

[barnakiel]

Da boat 30% longa da budget 10 times higha?

Gosh. Pur shoka. Go get da genset man!

b.

[sabray]

My set is with criticism not perfect. But it's simple and has some years on it. 3 lifeline Agm 4d batts on the house side. Each battery goes straight to a bus. The bus is tied to ATN fuse. Seperate switch for inverter. Engine is group 27 Agm similar fused leads. Solar is managed by blue sea controller and fused at multiple points. A meager 160 watts of solar. But it handles my load as a solo sailor. More people and fall sun it's not as good. I need to up the out put on these.
The combiner is. Blue sea auto sense. Switches can combine engine and house by manual switch. All the cable is oversized by at least one cable size. Led lighting and nav lights.
Batts are about 7 years old and still hold voltage. They have been cycled a lot but never below 12.2 volts. Once a Year I equalize them.
I set the float charges at spec for the batts. Think its 14.2 volts. If you set it up right at the get go you will save yourself head aches later.
Your propped usage seems high. Mine is kept low with great intent. All this stuff gets pricey but if you shop around and plan well the pay off is long term for a good system. I don't have any regrets or complaints with this set up.

[d design]

step one is allways efficiency
Step two is how to get electricity
Step three is to size your battery bank to make it all run smoothly

Also, if you could elimiate batteries completely, you would have a very efficient system.

[barnakiel]

At any given point, battery capacity is fixed / falling (we are stuck with what we have and the capacity drops due to aging).

However, at refit, we can modify things and either reduce or expand vital components.

In our case, we got her with 240 Ah house battery.

10 years down the road we are with a 110 Ah house battery.

So I think start with what you have, see where you want to get, then modify and adjust components as you go.

In our case we decided to make more (doubled the solar area), regulate better, consume less (LEDs and tablets in place of old style bulbs and laptops).

Evolution of sorts.

b.