Wiring Batteries (Fuses, Switches, Wind Gen etc.)

[pressuredrop]

i am finishing up a complete rewire of my seawind and i want to get the batterys fused properly.

now, i have a 220 ah house bank (2 6volts in series) and a group27 starting battery, i have them connected to a off-1-all-2 switch. right now the Alternator and the +bus bar are connected to the common post, the house bank and bilge pumps are connected to the #2 post and the starting batt is #1... is the correct set up? (this is how it was connected before i tore it apart and redid everything and it worked fine then so im assuming it is) and if so where on the battery cables do i want the fuses, between the battery and the switch?
also should i fuse the wire from the common post on the switch to the +bus bar?
some time next week i will be reinstalling a new air-x should i just wire it dirrectly to the house bank? with a fuse as close to the batteries as possible i assume...
in calders book he warns that "if most alternator types are connected to a battery with reversed polarity (i.e., the positive and negative leads crossed) instantaneous damage will occur that is not covered by warranty"
i am a bit confused what he means by this...
does he mean the if you connect it backwards you will fry it?
what i am worried about is that since my house batts are in series there is a + to - connection (indicating the leads are crosssed). will i have a problem with my battery set up or just plug and play?

i will have many more questions as i go ahead, thanks in advance for the advice

Ben

[svquest2]

I don't particularly like that switch you have because you always have to be on top of it to get your batteries charged correctly, but it does sound to me like you have it wired correctly. I prefer a single on/off switch from my house bank to the +buss with a combiner between the two battery banks, and another single on/off switch between the start battery and the starter. With this arrangement you charge the house bank from the alt., and the start bank from the house bank.
I think you are over-fusing your DC wiring. I don't use a fuse between my batteries and my switch, nor do I have one between my switch and my +buss. I guess its okay to do it but you have to size it to handle nearly all the combined loads in your DC panel, and it gives you 2 more connections to oxidize.
Don't worry about the + to - connection between your 6V batteries. It just forms a single 12V battery with a single positive and a single negative. If however you were to connect the pos from your alt to the neg on the battery, that would possibly fry your alternator.

Have fun

Joe S

[s/v Jedi]

Hmmm.... you must have a fuse as close to the house battery as possible. This regulation does not include the starter battery.

The size of the fuse is not the total load. The correct size is the max. current that the battery cable used can safely carry (without overheating). You can find the max. current for your wire-size on Google or even in the West Marine catalog. Remember that when the cables are bundled or in an engine-room, the max current goes down. This info with details can be found in the same places (read the small print!).

I agree with Joe that two simple on/off switches plus a combiner are better. But when you are used to the single switch you have, you can just continue using it. The wiring connections you describe are correct in that case.

cheers,
Nick.

[pressuredrop]

Jedi, quest -
Thanks, I understand that the style battery switch is not the preferred one, but like you said I am used to it an can make it work.
Jedi -
Just to clarify the fuse should be between the batteries and the switch? And do you have a link for the blueseas fuse bock you recommend, also do you recommend fusing the postive cable from the wind generator?

To manage my batteries I will use the wind gen to mantain the house bank and the engine to keep the starting battery charged, as I understand with the battery switch I have I can start the engine with the start batt and then switch to all if need be (read: if the engine is running I can switch between batteries so long as I don't switch them off, correct?)

I will be moving aboard soon and am getting very excited. My electricity needs are very simple: lights (sunsei LEDs) a fan and will need to keep my laptop/cellphone charged, and a stereo

I think all this will be very manageble with what I have, what do you think?

[Even Keel]

Bilge pumps should be connected directly to the biggest battery bank, and fused. As I understand your description, your bilge pumps aren't fused (I may be wrong).
As for charging devices (solar panel, windgenerator,...), they should be connected (and fused) directly (not thru a main switch) to the desired battery bank thru regulators and dedicated switch.
As you need to switch on/off the charging devices, one of the best way to do it is to wired thru a breaker assuming the fuse and switch functions.

As already said, the "fuse function" is only to protect the wiring from overheating and fire.
I don't have any fuse between battery bank , bus and main switch as it could be a problem for alternators in case of malfunction .

[pressuredrop]

evenkeel -
thanks, bilge pumps are fused at the switch. will fuse the windgen dirrectly to the house bank.

now im a little confused about fusing the house bank, jedi says yes, you say no?

[GordMay]

Fuse the positive cable from battery to house bank

[Bash]

the house bank should be fused. as has been stated previously, this should be done as close to the batteries as possible.

[Even Keel]

Originally Posted by pressuredrop

evenkeel -
thanks, bilge pumps are fused at the switch. will fuse the windgen dirrectly to the house bank.

now im a little confused about fusing the house bank, jedi says yes, you say no?

I don't know about US regulations and it looks like you have to fuse it.
By experience, and for the reason I gave (alternator) I wouldn't do it.
Could someoe can explain to me why for house bank and not for engine (is it a cranking amperage concern ?).
Due to new battery technologies, I design the electric on my cat with one big battery bank (house and engine) and one emergency battery (450CCA). I used to crank the engines on the main battery bank and use the emergency battery only in case of emergency (once a month for control).

[s/v Jedi]

I am sure the fuse at the house batteries is also required for EU boats.

Even keel: yes, you should have a fuse too. If your "emergency" battery can only be used for starting the engine, a fuse is not required.

A fuse is not a problem for your alternators. The only problem that can arise is that you can blow out the diodes in the alternator when the fuse blows. That, however, is the correct behavior because it's better to replace those diodes than too loose the boat with an electrical fire. The fuse will only blow when the max. amperage of the cable is exceeded. The cable should be more than able to handle the charging current from the alternators.

PressureDrop: there's those new fuses that you can directly attach to the battery post. I don't have a link ready but should be easy to find (saw them on West Marine site and in their catalog).

cheers,
Nick.

[GordMay]

ABYC Diagrams - Overcurrent Protection for DC Circuits:

➥ http://www.cruisersforum.com/gallery...r&imageuser=79

➥ http://www.cruisersforum.com/gallery...r&imageuser=79

➥ http://www.cruisersforum.com/gallery...r&imageuser=79

[Even Keel]

oups,
Sorry I did a mistake. I was stuck on the idea of a fuse between the battery bank and the main switch but after a look at the diagrams on links, I believe I get it right now.
So OK, you have to fuse everything fed by the house bank : on Even Keel I use the 50 Amps main breaker on the distribution panel for all the appliances and lights, and dedicaded breakers for windlass, fridge and toilets (in the port hull). The engines and alternators aren't fused, neither from the main bank, nor from the emergency battery.
And yes, EU regulations certainly require a fuse at the house bank.
Thanks to put me back in the good direction.

[Northeaster]

(someone correct me if I am worng, please)

Pressuredrop - Since your alternator is wired to the common post, you can use the engine to charge the house bank as well, by switching to the #2 position. If you leave the switch on the #1 position, all of the time the engine is running, you will only charge the start battery (which likely won't require much charging).

I realize that people recommend a combiner, or ACR nowadays, instaed of the 1,2,both, off switch, anf I will likely go to one someday. But, ofr now, I still have the same setup as you.. I would rather rewire in the winter, though, as it is prime sailing time right now!