Switching battery banks with engine running - Page 3 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #21  
Old 09-27-2008
Senior Member
 
Join Date: Jun 2007
Posts: 2,710
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
SEMIJim will become famous soon enough SEMIJim will become famous soon enough
Quote:
Originally Posted by Giulietta View Post
OK..Just in case, from now on I will make sure all is off when switching.
It's the engine that needs to be off, Alex, not the rest of the stuff on the boat. Even then, again: As long as you have a make-before-break switch that is in proper condition and you don't accidentally hit "OFF," it shouldn't be a problem. My point is: Why take the chance? Is there some good reason for switching between "1," "BOTH" and "2" while the engine is running? None I can think of.

I tend to start on "BOTH" and then switch to "1" or "2" after the sails are up and the engine's off. That way I don't take the chance of running both batteries down. Then, usually, I just go ahead and start off the battery that's been used when on the way back.

Jim
Reply With Quote Share with Facebook
  #22  
Old 09-27-2008
.
 
Join Date: Nov 2006
Posts: 10,851
Thanks: 0
Thanked 4 Times in 2 Posts
Rep Power: 12
Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice
Jim, what I meant by stuff off was stuff feeding the bateries, alternator or shore power. I did not mean the consumers.

Either way, I know there is a lot of electrical stuff near my switch, includeing some boxes don't know what they are..

I am not goiung to move the switch again while on power charging. Just in case
Reply With Quote Share with Facebook
  #23  
Old 09-27-2008
Senior Member
 
Join Date: Jun 2007
Posts: 2,710
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
SEMIJim will become famous soon enough SEMIJim will become famous soon enough
Quote:
Originally Posted by SteveInMD View Post
There is no harm in connecting in a parallel battery. It's no different than suddenly having a larger battery.
That's not necessarily true. If the new battery is severely depleted, you'll be suddenly throwing a high load on the alternator while it's running. I don't know as that would be a problem, but I don't know that it wouldn't, either. Besides: We're not talking about suddenly adding additional load, we're talking about accidentally removing all loads.

Quote:
Originally Posted by SteveInMD View Post
Battery switches are very simple devices.
That they are, but...

Quote:
Originally Posted by SteveInMD View Post
The chances that it will fail in a way that disables the make-before-break connection and does not completely disable the switch all together is extremely remote.
I've been working with things electrical and electronic for some 40 years. I can tell you from long and varied experience that nothing could be further from the truth. It is not at all uncommon for switches to become intermittant, especially as they age.

Jim
Reply With Quote Share with Facebook
  #24  
Old 09-27-2008
Senior Member
 
Join Date: Jun 2007
Posts: 2,710
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
SEMIJim will become famous soon enough SEMIJim will become famous soon enough
Quote:
Originally Posted by Giulietta View Post
Jim, what I meant by stuff off was stuff feeding the bateries, alternator or shore power. I did not mean the consumers.
Ah, ok .

You don't need to worry about your charger running off shore power. That's almost certainly connected directly to the batteries, so moving the battery switch will have no effect on it.

Jim
Reply With Quote Share with Facebook
  #25  
Old 09-28-2008
Omatako's Avatar
Senior Member
 
Join Date: Sep 2003
Location: Auckland New Zealand
Posts: 2,425
Thanks: 0
Thanked 28 Times in 25 Posts
Rep Power: 12
Omatako will become famous soon enough
I'm with Steve on this one. we've had this discussion many times.

The Off-1-ALL-2 switches are not designed to go thru OFF from one position to the next. OFF is at the one end of the choices of positions. So you can't go "thru OFF to get to whatever".

And I agree with Steve that I have many hundreds of time switched from one bank to the other while the alt is charging and have never had a problem because of it.

Let me clarify my point: It is very likely that if you switch the system off while you're charging that you'll blow some diodes (and for the record, that doesn't mean that you'll "burn the altenator out"). But the switch does not go thru OFF to reach any other position. If you have a switch that can, change it ASAP.

Also loading up suddenly by connecting another flatter battery will not damage your alt. Think about your car. Switch on the lights, aircon, wipers and press the brake all at the same time. No problem. Even though this represents a significant spike in current. Alternators are not that sensitive. I can't remember how many times I have jump-started other cars from mine and then it's a case of connecting the cables to one battery then the other. The car that is running has a little surge as the alt catches up and then provides all the power you need.

It may be so that the switch may become "intermittent". This happens with everything from widgets to girlfriends. That is a extraordinary event. It will not do that 1 in every 10. It will do it once in a lifetime. Maybe. As Steve says and I agree, I have been switching these things from one bank to another for decades and guess what? I haven't had an intermittent switch yet (I have something else to look forward to). These switches are MADE to go from one bank to another. WHAT OTHER PURPOSE is there for them?

If you want to regulate your actions based on the extreme outside possibility that something could go wrong, you're likely to have an entertaining time sailing at sea.

Just my personal experience and opinion, as always
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

__________________

"Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying."

Arthur C. Clarke
Reply With Quote Share with Facebook
  #26  
Old 09-28-2008
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
Andre-

Most of the 1/2/both/off battery switches I've seen are rotary and can go from 1-both-2-off or 1-off-2-both... I prefer the Dual Circuit plus design, which reduces the problem, but you do need either a battery combiner or echo charger with it.
__________________
Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
Reply With Quote Share with Facebook
  #27  
Old 09-28-2008
Senior Member
 
Join Date: May 2007
Posts: 547
Thanks: 3
Thanked 3 Times in 3 Posts
Rep Power: 8
SteveInMD is on a distinguished road
I believe you experience much more mechanical failure "risk" by the process of shutting down the motor, switching the battery switch, and then restarting than you do by simply switching the battery switch while running. There is a very small amount of "wear and tear" every time you start and stop the motor. This wear and tear creates risk of component failure. For those of you who are risk adverse to this level you should carefully consider your options here.
Reply With Quote Share with Facebook
  #28  
Old 09-28-2008
timebandit's Avatar
Senior Member
 
Join Date: Sep 2002
Posts: 928
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 13
timebandit is on a distinguished road
Here is something I have done a lot when out in the boonies.

A buddy's buggy dies because the battery is DEAD because of a faulty altenator and you are hundred miles from base camp through two hundred foot sand dunes.

What to do?

Start up the good buggy and idle at about 1500 rpm and remove the battery (yes, while it is running)

Put the charged battery into the disabled buggy and start.

Put the discharged battery in the good buggy for charging while you continue your trip.

Swap as needed.

I have done this many times and it is a well known fix.

It has never caused problems for the good altenators.

So what is the difference between doing the above and switching from battery to battery or switching to off with the motor running?? Why do some people get away with it and others have horible stories to tell??

Here is what I think----

In the OFF position the multi battery switch breaks the conection between the batteries and the output side of the altenator.
BUT
The input side of the regulator may still see 12 volts because of improper wiring.
SO
The regulator tells the alternator to increase output but does not see an increase in voltage so the regulator increases voltage to the field untill bad things happen.

You could even have a problem where the regulator sees batery #1 and is charging battery #2. That might cause excessive gassing when not run in the BOTH position when charging.

Rick


Quote:
Originally Posted by SEMIJim View Post
You may disagree, but that doesn't change the fact that if you remove the battery while the alternator is running, the sudden surge can, and quite frequently will, damage or destroy the alternator. This is why they make switches with field disconnect circuits.

Jim
Reply With Quote Share with Facebook
  #29  
Old 09-29-2008
Senior Member
 
Join Date: Jun 2007
Posts: 2,710
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
SEMIJim will become famous soon enough SEMIJim will become famous soon enough
Quote:
Originally Posted by SteveInMD View Post
I believe you experience much more mechanical failure "risk" by the process of shutting down the motor, switching the battery switch, and then restarting ...
Maybe I'm missing something obvious (it wouldn't be the first time), but why would you need to do this? By "this" I mean: Switch battery use while under way under motor?

When we start from the slip we start in "BOTH." We keep it in "BOTH" until the sails are up and the engine off. That way both batteries get equal charging time--which is only "fair," being as both batteries were used to start the engine.

Then, usually (forgot yesterday, for example), I switch to "1" or "2." The reason for not leaving it in "BOTH" is to reserve one of the two batteries for starting. Whichever battery upon which we've been running is the one with which we re-start on return, so it gets all the charging from the engine. Which is only "fair," being as it's been running the instruments and started the engine on its own.

(The above procedure also gives me the opportunity to exercise each battery on its own, so, hopefully, a weakening battery can't hide behind a stronger one.)

In neither scenario do I see the need or sense in switching the battery switch while under way with the iron genny.

Jim
Reply With Quote Share with Facebook
  #30  
Old 09-29-2008
Senior Member
 
Join Date: May 2007
Posts: 547
Thanks: 3
Thanked 3 Times in 3 Posts
Rep Power: 8
SteveInMD is on a distinguished road
I agree for the most part. I can see needing to switch if you totally run down one battery and the other is partially discharged. You may not want to risk combining them with the battery switch prior to cranking the motor. If you did, the one battery with a partial charge would be trying to charge the dead battery and crank the motor at the same time, which is at best very hard on the battery and at worst will leave you with no ability to start the motor.

The practice of using one battery at a time is old school. The modern thinking is that you should use both at the same time. Your batteries will last longer if you discharge them both a little than one a lot. You should either have a dedicated starting battery, or a monitoring system, or know your usage well enough to not get yourself in trouble, or all of the above.
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
READ THIS TODAY-It may save you an engine or at least some time and money! Marleetet Gear & Maintenance 6 07-14-2008 04:28 PM
Electrical Problem - Newbie Not Sure Where to Start wolfmt Gear & Maintenance 32 07-14-2008 09:17 AM
Installing a Automatic Battery Selector Switch artbyjody Gear & Maintenance 24 07-08-2008 07:07 PM
My New Catalina 25 42ndstreet General Discussion (sailing related) 23 09-06-2007 12:17 AM
A Little Help from the Sun Don Casey Cruising Articles 0 12-20-2001 07:00 PM


All times are GMT -4. The time now is 08:40 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.