Electrical Questions

[ezaction]

I am in the process of planning changes for my new 26M. Im a newbie at all this, and the most difficult (for me) is the electrical stuff - so please pardon my ignorance. After the questions I have listed the planned circuits; please comment if Ive overloaded them or missed anything I should have. The dealer installed two batteries with a WM Combiner 50 model 143268 (Click here)

I want to install a Blue Seas 8 position 8676 DC Breaker Panel because it will fit the existing spot without any serious modifications. Next to that I could fit an ammeter (Blue Seas 8254 Click here) and a voltmeter or a digital multimeter (Blue Seas 8248 Click here).

Heres the Blue Seas web site: Click here. The engine is a Suzuki DF70. Not sure what the charging amps are on the alternator - the manual says 51.5 kW as maximum output??

Now for the questions:
Why is the mast light on a separate circuit from the running lights? Wouldnt you always run them at the same time? Would it be too many amps for the circuit? Id like to combine them to free up a circuit for something else.

How does the voltmeter tell me the status of the battery? For example if I use the house battery will it show 6 volts rather than 12?

Does the amp meter show the real-time usage, i.e. the charge going into the battery from the alternator or the charge coming out of the battery from usage?

Is there a better way to monitor the status of the batteries?

Do the analog amp/voltmeters use any energy themselves? I was thinking of using a 3-position switch to toggle between battery 1, 2 and nothing (to prevent battery drain).

Here are the circuits I currently have planned:
* Cabin lights
* Running lights + Masthead light + Compass
* Auxiliary (12v power plugs)
* Outside & Inside LED lights (both with switches)
* Stereo
* VHF radio
* Water system
* What am I missing?

Thanks in advance!

[mike]

How does the voltmeter tell me the status of the battery? For example if I use the house battery will it show 6 volts rather than 12?

I'm not certain, but I believe a 12v battery is considered "dead" when it's voltage reaches around 10.5v.

Does the amp meter show the real-time usage, i.e. the charge going into the battery from the alternator or the charge coming out of the battery from usage?

Is there a better way to monitor the status of the batteries?

Do yourself a favor... skip the ammeter, and instead purchase one of these:

Xantrex Link 10 (single battery)

or these:

Xantrex Link 20 (dual battery)

These battery monitors will provide everything you need to know about the state of your battery (or batteries, in the case of the Link 20). In addition to measuring voltage, they track every amp going into and being drawn from the battery, and constantly updates the display of how many amp-hours and how much time is remaining (during the setup, you tell it how many amp-hours your battery can provide).

Another neat feature... you can set a threshold of the discharge level you want to be considered "empty" (they say you shouldn't regularly discharge your batteries more than 50%). It will use this threshold in it time and bar graph displays, telling you how much time remains before the battery is 50% discharged.

You can cycle the display between voltage, amps (shows negative number for power being drawn out, positive number for charging), amp hours (how many amp hours remain) and time (based on present usage), plus it has a bar graph that shows battery status at a glance.

Bottom line... it's the closest thing to a "fuel gauge" for your batteries that you'll find. Plus, the amp display is useful for checking on how much power each of your loads is drawing.

On my 26x, I have a starter battery, and a house battery, both of which are monitored through the Link 20 (though it's really overkill for me... I could get by with the Link 10 just on the house battery, and only got the 20 in case I wanted to add another house battery one day).

--Mike

(edited to fix bad link... also, for better prices on these, check http://www.brokenlegdave.com )

[Kevin]

Using a voltmeter you can make these approximate assumptions about the charge state. This will only be at all accurate when the battery has been at rest, no load, for about an hour.

Code: Select all

Charge      12 Volt     Volts per 
            battery     Cell
100%        12.7         2.12
 90%        12.5         2.08
 80%        12.42        2.07
 70%        12.32        2.05
 60%        12.2         2.03
 50%        12.06        2.01
 40%        11.9         1.98
 30%        11.75        1.96
 20%        11.58        1.93
 10%        11.31        1.89
  0         10.5         1.75

This is probably good enough, but I'm a gadget freak so I added a Link 10 batter meter. It tells voltage, batter state, amps in and out and time to discharge.

http://shop.store.yahoo.com/homegrownpo ... ebaba.html

For me this was the only way to go.

At the same time, I use solar panels and keep a coleman 2 fuel lantern on board.

[Duane Dunn, Allegro]

When sailing at night you only use the running lights, the bow red and green and the stern white. This light combination indicates a boat under sail. When motoring at night you turn on the mast light. Adding the white forward combined with the white aft gives a white all around which indicates a boat under power. There is a difference in who has right of way in these two situations.

Skip the voltmeter. They only give a accurate indication of battery charge state if the battery has been at rest for 24 hours. Out on the water while you are using the batteries they will not tell you how much use you have left. The same is true for a inline amp meter. You will find out the momentary load while you are looking at it but you get no help in knowing how much power you have used and how much is left.

As mentioned in the above post a amp hour meter, such as the link 10, is the only real way to manage you batteries. I have had one of these for years and it is the best $200 you will spend on your electrical system. It constantly adds up the power use over time and shows you all the key information. You get current voltage, current amp load (+ or - depending on the charging state), Amp hours used, and hours remaining at the current power consumption rate.

I don't even split my banks, both my batteries are in a simple parallel circuit which I manage using the link 10. I carry a small jump starter battery just in case, never have needed it for the boat, but I've used it on the truck twice. My Tohatsu 50 can also be easily started by hand so I feel comfortable with what is essentially a single battery bank system. The Link 10 let's you know way ahead of time if there are going to be power problems so you can take action to avoid a dead battery. It's a very accurate gas gauge for the battery and with it you won't have any rude surprises.

[Jack O'Brien]

Some hard-wired GPS units can read out voltage. My Garmin Map 180 lets me select DC volts for one of the display fields. As above posts say, voltage is not particularly useful - unless it were to show a significant problem.

Why not have your inside and outside LED lights on the same circuit as your cabin lights and compass?

When I installed a masthead anchor light I powered it from the circuit for the "steaming" light. I put a single pole 3-way switch at the mast base with power from the "steaming" light circuit. Down energizes the steaming light, middle is 'Off", up energizes the anchor light. I could have put the spreader light in the middle position and, if I wanted none of the three lights, could switch off at the circuit breaker panel. But there are times I want the spreader light and one or the other light on at the same time. So when I ran a wire from the pedestal to the "OoooGah" horn mounted by the spreaders, I included a circuit for the spreader light, which I can control from the pedestal. I have a 4-conductor screw-together connector between mast and deck. One wire is ground, second is steaming/anchor, third is horn, fourth is spreader light.

If I want to un-ground the mast for lightning strike avoidance I could do so by disconnecting this connector and the one for the masthead antenna. As I still have the original VHF stern-mounted antenna in place I could switch antenna leads at the back of the VHF and/or use the hand-held unit.

[norbert]

if your 26m is wired in the same way as a 26x (with lamp cord!) i'd highly suggest to rewire the entire boat.

[Chip Hindes]

51.5kW has nothing to do with alternator power output, it is the engine output equivalent to 70HP, in metric units. Just like with feet and inches, I believe only us metrically challenged Americans use HP 1HP=.75kW

[ezaction]

Thanks for the suggestions. It looks like the Link 20 is the way to go.

Good idea too Jack on combining the light circuits. The existing lights already have individual switches; I just need to add switches for the new LED's.

One thing I left off my list is a circuit for a future autopilot.

I am leaning towards an 8 circuit panel from PolarisPanels with an integrated Link 20. I will have to measure, but I think it will all fit on the existing cabin face without extensive modifications.