Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 18-12-2011, 21:00   #16
Registered User
 
Tom.B's Avatar

Join Date: Sep 2009
Location: Cary, NC
Boat: 2000 Navigator 4200 Classic-Skinny Dippin'
Posts: 164
Images: 28
Re: Proper fusing of various charging sources

Isn't any way to expose an alternator to an unloaded state wrong? If the fuse blows for ANY reason, not just electrical, you'll lose your alternator too.
__________________

__________________
Tom.B is offline   Reply With Quote
Old 19-12-2011, 05:15   #17
Registered User

Join Date: Sep 2010
Posts: 793
Re: Proper fusing of various charging sources

Quote:
Originally Posted by R_C View Post
I really appreciate this discussion. The attached crude sketch shows what I am now planning. Anyone see any problems with this configuration? The wire to the DC breaker panel is probably 1/0 AWG because of its length and the 100A fuse at the battery has been in place for some time. I'll add the additional 100A fuse at the busbar. Note that the Iota and Xantrex chargers are never run at the same time so the 100A fuse at the battery is sufficient. Others may disagree, but I've been using the rule that FLA batteries should be charged at no more than 25% of their Ah capacity.
I just really looked at this drawing now. Conceptually it looks fine, but I think the wiring is under-sized across the board. If you have 1/0 going from the bus bar to the electronics, then I'd use at least that from the bus bar to the battery, preferably 2/0 or even 4/0. In general, it's wise to oversize main cables like that since it's typically way cheaper and easier to do it now than to try to fix it later. Also, it's well worth running the voltage drop calculations for the different runs in their worst case configurations. I suspect you'll find that all your #6 wires are two or more sizes too small.

I also still think that the main battery fuse should be 200A, not 100A. Even if you don't plan to run both chargers at the same time, doing so shouldn't "break" the boat. Additionally, the Iota and your solar at full charge could exceed 100A.

The battery to bus bar run is the backbone of your electrical system. If I were doing it, I'd make it as robust and upgradable as possible. If possible, I'd run 4/0 cable and use a min of 200A fuse, preferably 400A. Then, for example, if some day you wanted to replace one of the chargers with an inverter/charger, your bus bar can handle it and it's a simple upgrade.

Either way, it's food for thought.
__________________

__________________
twistedtree is offline   Reply With Quote
Old 19-12-2011, 08:10   #18
Sponsoring Vendor
 
Tellie's Avatar

Community Sponsor

Join Date: Oct 2007
Location: Hollywood, Fl.
Boat: FP Athena 38' Poerava
Posts: 3,046
Re: Proper fusing of various charging sources

Wire protection is very important on all circuits. I'd even suggest if you are going to do it yourself pay a few bucks and have a qualified marine electrician take a look at your work when you are done to sign off on it. I often work at the marina linked below. It would be bad enough if you lose your own boat, but taking a few others with you...I'd hate to think of that legal mess.


WSVN-TV - Crews to remove torched yachts from marina

The cause has yet to be determined, but I'd be willing to take a Mitt Romney bet that it's electrical.
Tellie is offline   Reply With Quote
Old 19-12-2011, 08:18   #19
R_C
Registered User

Join Date: Oct 2009
Location: Florida
Boat: 38' Marine Trader
Posts: 115
Re: Proper fusing of various charging sources

Quote:
Originally Posted by twistedtree View Post
I also still think that the main battery fuse should be 200A, not 100A. Even if you don't plan to run both chargers at the same time, doing so shouldn't "break" the boat. Additionally, the Iota and your solar at full charge could exceed 100A.
Thanks for catching that oversight. I just verified that the busbar itself is rated at 150A so I will increase the main battery fuse to that amperage and the size of the wire from battery to busbar. All of the 6AWG wires from the alternator and chargers to the busbar are less than six feet in length and show less than a 2% voltage drop. It's only two feet from battery to busbar so that's a simple upgrade.
__________________
R_C is offline   Reply With Quote
Old 19-12-2011, 08:29   #20
Registered User

Join Date: Sep 2010
Posts: 793
Re: Proper fusing of various charging sources

Quote:
Originally Posted by R_C View Post
Thanks for catching that oversight. I just verified that the busbar itself is rated at 150A so I will increase the main battery fuse to that amperage and the size of the wire from battery to busbar. All of the 6AWG wires from the alternator and chargers to the busbar are less than six feet in length and show less than a 2% voltage drop. It's only two feet from battery to busbar so that's a simple upgrade.
The specifics of everyone's situation are different. Sounds like you are doing all the right things to be sure yours works correctly.
__________________
twistedtree is offline   Reply With Quote
Old 19-12-2011, 15:11   #21
Sponsoring Vendor
 
OceanPlanet's Avatar

Community Sponsor

Join Date: May 2009
Location: Woolwich, Maine
Boat: Sold it!
Posts: 401
Send a message via Skype™ to OceanPlanet
Re: Proper fusing of various charging sources

Quote:
Originally Posted by CarlF View Post
MainSail. Hmm. Learn something new everyday. Now I know why there are two fuses in the alternator lead. Always thought the one at the alternator end was the more important but your explanation makes perfect sense.

Carl
This is especially true on multihulls or other boats where there is a long run from the alternator to the pos. bus (increased chance of a short somewhere). Another good idea to use a multi-pole breaker on the alt. end of the cable, with the alt. field run through one of the linked breakers. This way, if the wire is shorted and the breaker tripped then the alt. field is cut also.

Not necessarily applicable to the O/P; but here is a pic of such a breaker config. for a 250A x 14V alternator on a 55ft cat (cable run was 2 x 2/0 x 22ft from the breaker to the pos. bus).
Attached Thumbnails
Click image for larger version

Name:	110514d.jpg
Views:	87
Size:	366.3 KB
ID:	34910  
OceanPlanet is offline   Reply With Quote
Old 19-12-2011, 15:38   #22
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Proper fusing of various charging sources

Quote:
Originally Posted by OceanPlanet View Post
This is especially true on multihulls or other boats where there is a long run from the alternator to the pos. bus (increased chance of a short somewhere). Another good idea to use a multi-pole breaker on the alt. end of the cable, with the alt. field run through one of the linked breakers. This way, if the wire is shorted and the breaker tripped then the alt. field is cut also.

Not necessarily applicable to the O/P; but here is a pic of such a breaker config. for a 250A x 14V alternator on a 55ft cat (cable run was 2 x 2/0 x 22ft from the breaker to the pos. bus).
Ocean Planet,

You were going to send me a link to that breaker this summer but I totally forgot about it. Can you forward that on to me when you get a chance.

Sorry for the hijack...
__________________
Marine How To Articles
Maine Sail is online now   Reply With Quote
Old 19-12-2011, 15:51   #23
Sponsoring Vendor
 
OceanPlanet's Avatar

Community Sponsor

Join Date: May 2009
Location: Woolwich, Maine
Boat: Sold it!
Posts: 401
Send a message via Skype™ to OceanPlanet
Re: Proper fusing of various charging sources

Email sent...sorry that I forgot too!

Back to our scheduled programming....
OceanPlanet is offline   Reply With Quote
Old 19-12-2011, 16:24   #24
Registered User
 
mikefossl's Avatar

Join Date: Aug 2008
Location: Hawaii
Boat: CS 40
Posts: 171
Re: Proper fusing of various charging sources

When I bought our boat none of the charging sources were fused. Nothing mentioned in the survey and I really didn't understand the mess of wires behind the main battery switches. Last summer I decided that I needed to clean things up (precipitated by the failure of our battery bank). After documenting the current state in a diagram and reading up on proper wiring I realized that it was a disaster waiting to happen. I re-wired everything connected to the batteries and every wire leaving the battery compartment is properly fused. I can sleep much better now.
__________________
Michael Fössl
S/V Second Jump
British Columbia
mikefossl is offline   Reply With Quote
Old 19-12-2011, 16:38   #25
Registered User

Join Date: Jul 2006
Posts: 3,949
Re: Proper fusing of various charging sources

Quote:
Isn't any way to expose an alternator to an unloaded state wrong? If the fuse blows for ANY reason, not just electrical, you'll lose your alternator too.
It's far better to lose the alternator than to lose the boat! What other reason would a fuse blow other than electrical? I suppose you could physically break it, but that would be very odd.
__________________
Kettlewell Cruising
Kettlewell is offline   Reply With Quote
Old 23-12-2011, 10:35   #26
Registered User

Join Date: Feb 2009
Posts: 1,321
Re: Proper fusing of various charging sources

Quote:
Originally Posted by FlyingCloud1937 View Post
.then a fault develops on one of the other wires and blows the 100 amp main fuse,
According to the above scenario, a fault developed which fused a 100 amp fuse. The alternator is may be disconnected from the battery but is still connected to the fault which will overload the alternator. Two things among others could happen, the field collapse or the alternator overheat and burn out.
R C if it was my trawler I would do the following:
Assess how much current is likely to flow in the “DC panel” feed. 100 amp is unlikely and having two 100 amp fuses in series produce no discrimination.
Your drawing shows 3x150A batteries connected in parallel and also you intend to remove the isolator between the start battery and the house batteries. What is wrong with this is if one battery go down it bring down the lot. Also the batteries cannot be isolated and will mutually self-discharge. Instead of removing the start – house isolator I will provide each battery with its own isolator and fuse, I will keep the alternator connected to the start battery. I will have a simple voltage monitoring of each battery and the possibility to solar charge individually each battery. Also 25% Ah capacity for a 150A battery is 37.5A.
__________________
chala is offline   Reply With Quote
Old 23-12-2011, 12:34   #27
Marine Service Provider

Join Date: Oct 2011
Posts: 1,205
Re: Proper fusing of various charging sources

Quote:
Originally Posted by chala View Post
According to the above scenario, a fault developed which fused a 100 amp fuse. The alternator is may be disconnected from the battery but is still connected to the fault which will overload the alternator. Two things among others could happen, the field collapse or the alternator overheat and burn out.
R C if it was my trawler I would do the following:
Assess how much current is likely to flow in the “DC panel” feed. 100 amp is unlikely and having two 100 amp fuses in series produce no discrimination.
Your drawing shows 3x150A batteries connected in parallel and also you intend to remove the isolator between the start battery and the house batteries. What is wrong with this is if one battery go down it bring down the lot. Also the batteries cannot be isolated and will mutually self-discharge. Instead of removing the start – house isolator I will provide each battery with its own isolator and fuse, I will keep the alternator connected to the start battery. I will have a simple voltage monitoring of each battery and the possibility to solar charge individually each battery. Also 25% Ah capacity for a 150A battery is 37.5A.
Chala,

hehe, draw yourself a picture of the bat and a busbar, and various circuits attached to the busbar, now create short circuits to various of the loads and see what happens in all circuits.

Now fuse each circuit properly and create shorts in various of the loads and see what happens to the other circuits.

Lloyd
__________________
FlyingCloud1937 is offline   Reply With Quote
Old 24-12-2011, 07:56   #28
Registered User

Join Date: Feb 2009
Posts: 1,321
Re: Proper fusing of various charging sources

Quote:
Originally Posted by FlyingCloud1937 View Post
hehe,
I was not questioning the use of over-current protecting devices but the correctness of the statement below.
Quote:
Originally Posted by FlyingCloud1937 View Post
Now just imagine that the alternator is connected to the bus and the engine is running...then a fault develops on one of the other wires and blows the 100 amp main fuse, that event has just caused a loss of connection from the alternator to the battery, and that will then blow all the diodes in the alternator.
By the way I would have installed an over-current protecting device between the bus bar and the small wire feeding the fuse box. (change of gauge)
Quote:
Originally Posted by FlyingCloud1937 View Post
Attached is a pic
__________________
chala is offline   Reply With Quote
Old 24-12-2011, 14:03   #29
Marine Service Provider
 
AnchorageGuy's Avatar

Join Date: Mar 2003
Location: Wherever the boat is!
Boat: Marine Trader 34DC
Posts: 4,618
Re: Proper fusing of various charging sources

RC, In looking at your sketch, if this were me, I would not connect both chargers as you indicate. There is always the possibility that you might have both chargers on at the same time, not a good idea. You might disconnect the one you want for back up and if one fails, make a re-connection. Chuck
__________________
Chesapeake Bay, ICW Hampton Roads To Key West, The Gulf Coast, The Bahamas

The Trawler Beach House
Voyages Of Sea Trek
AnchorageGuy is offline   Reply With Quote
Old 24-12-2011, 14:25   #30
Marine Service Provider

Join Date: Sep 2008
Location: Victoria B.C.
Boat: CS27
Posts: 1,743
Re: Proper fusing of various charging sources

Or just wire the charger's AC input from 2 separate breakers and they can be switched on and off at will. They should each have their own breaker anyway.
__________________

__________________
mitiempo is offline   Reply With Quote
Reply

Tags
charging

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Battery Banks and Charging SVPennyLane Electrical: Batteries, Generators & Solar 60 18-02-2012 18:11
Questions About Wind / Solar Controller clayzone Electrical: Batteries, Generators & Solar 48 29-11-2011 23:16
Proper Refrigerant Levels unbusted67 Plumbing Systems and Fixtures 8 13-10-2011 11:32
Two Diesels: Double the Charging ? Jerry Woodward Electrical: Batteries, Generators & Solar 25 10-10-2011 06:45
Battery Monitor vs Voltage sailorboy1 Electrical: Batteries, Generators & Solar 51 20-08-2011 18:12



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 15:41.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.