Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 03-05-2018, 12:18   #1
Registered User

Join Date: Aug 2015
Location: Port Townsend, WA
Boat: Tashiba-31
Posts: 300
Images: 1
Drawing from battery while at dock

What affect does using 12VDC power have on the batteries while at the dock and connected to a battery charger?

Right now only the cabin lights are using 12V power for only a few hours each night. I'm considering adding a wifi router to 12VDC power and this would be on 24-7 unless I turn it off.
__________________

dmksails is offline   Reply With Quote
Old 03-05-2018, 12:28   #2
Senior Cruiser
 
Sailmonkey's Avatar

Cruisers Forum Supporter

Join Date: Sep 2009
Location: Houston
Boat: '76 Allied Seawind II, 32'
Posts: 7,293
Re: Drawing from battery while at dock

If youíve got a battery charger on and itís in float, unless itís horribly undersized your batteries are not providing current to your loads.
__________________

Sailmonkey is online now   Reply With Quote
Old 03-05-2018, 12:43   #3
Senior Cruiser

Cruisers Forum Supporter

Join Date: May 2013
Location: Oregon to Alaska
Boat: Wheeler Shipyard 83' ex USCG
Posts: 2,475
Re: Drawing from battery while at dock

ditto. I live aboard and I run many 12 volt items. Especially some hydronic heating controls and blower motors. My Dyno 8d batteries seem to last 8-10 years.
Lepke is offline   Reply With Quote
Old 03-05-2018, 13:03   #4
Registered User

Join Date: May 2016
Location: Hanging out along the Gulf Coast
Boat: 81 Hunter Cherubini 27
Posts: 367
Images: 3
Re: Drawing from battery while at dock

I liveaboard and am swinging on the hook about 80% of the time. When dockside I don't connect to shore power. My 200-watts of solar panels takes care of everything that I need. 2 House banks of size 24 deep cycle batteries and a 2500-watt inverter. Cloudy days may be a bit close on usage if I run the inverter too long (that and the laptops are power hogs).

Haven't connect to shore power in about 9-months I think. Solar or a wind-gen might be worth looking into in your case.
__________________
Cruising highly skilled Marine Electrician. Will work for beer, smokes and slip fees...and other important boat stuff
Teknishn is offline   Reply With Quote
Old 03-05-2018, 14:01   #5
Registered User

Join Date: Jan 2017
Posts: 11,844
Re: Drawing from battery while at dock

As long as the loads are drawing less current than the charger provides, the bank is not cycled at all.

And if it does get drawn a little bit, shallow DoD%, that will not have a significant hit on its longevity curve.
john61ct is online now   Reply With Quote
Old 03-05-2018, 14:06   #6
Registered User

Join Date: Aug 2010
Posts: 1,162
Re: Drawing from battery while at dock

If the battery charger can push more amps than your systems are pulling, then you should be fine.
Shrew is online now   Reply With Quote
Old 04-05-2018, 06:46   #7
Registered User

Join Date: Dec 2009
Posts: 281
Re: Drawing from battery while at dock

I have a Pronautics 1240 charger and 1 of the listing features is it also works as ‘Dock side’ power source. I assume this means exactly as to what you are referring to.
US1Fountain is offline   Reply With Quote
Old 04-05-2018, 06:58   #8
Senior Cruiser
 
John_Trusty's Avatar

Cruisers Forum Supporter

Join Date: Oct 2014
Location: Michigan, USA
Boat: Catalina 36 (1999)
Posts: 393
Re: Drawing from battery while at dock

Easy version -- things that do not heat or move mechanically use very little power (watts). Take a look at your proposed load (any 5 volt transformer will do), and you'll see that it draws almost no power (probably less than 1 amp). Your inverter probably loses more in heat than the load you are drawing. Your battery charger can absorb this small load without drawing on the battery at all.
__________________
John Trusty

Better to trust the man who is frequently in error than the one who is never in doubt." -- Eric Sevareid
John_Trusty is offline   Reply With Quote
Old 04-05-2018, 09:07   #9
Registered User

Join Date: Dec 2014
Posts: 600
Re: Drawing from battery while at dock

Thats exactly how my boats supply operates

2 separate battery systems selectable via rotary switch
Engine battery is a flooded cell with 1000 CCA
And the house are 3 AGMs

A 20AH xantrex truecharge 3 bank charger supplies all the batteries as per their individual requirements.

The 12v systems are made active by the rotary switch as Off-1-2-1&2, but the charger has access to the batteries all the time we are shore power connected.

There is also a dual socket 240v outlet principally used for tools for working on the boat. But the boat and everything on it are 12v including the hot pressure water. All of the shore power was a really dangerous set up so it was stripped out and replaced with wire in conduit to an IP67 RCD circuit breaker with just two runs also in conduit, one to the charger and the other to the dual outlet.
__________________
'give what you get, then get gone'
ZULU40 is offline   Reply With Quote
Old 05-05-2018, 08:11   #10
Moderator

Join Date: Jun 2015
Posts: 3,102
Re: Drawing from battery while at dock

Your battery charger will have a "read-out" that gives the number of amperes the charger is putting out. For understanding what has been said above, try this:

Turn off EVERYTHING you can so noting other than the batteries takes current from the charger. Say the read-out now sez "1.5". That means that the batteries are now consuming 1.5 amps of current for charging purposes, i.e the batteries are storing that quantity of power away for future use.

Now turn on the dome light over your dinette. The read-out might jump to "2.8" or so. That means that the dome light is consuming (2.8 - 1.5)A = 1.3A. The current put out by the charger simply "splits" so the batteries continue to take what they need, and the rest is accounted for by the "house loads".

Now turn on, say, the bilge pump. The read-out might jump to "7.9". The batteries are still consuming 1.5A and the light 1.3A for a total of 2.8A. The pump is therefore consuming (7.9 - 2.8)A = 5.1A.

Now turn off the dome light and the read-out will drop to (7.9 - 1.3)A = 6.6A, being 1.5A for the batteries plus 5.1A for the pump.

It's that simple. Just go play with it until the pattern becomes clear to you.

For these simplistic purposes you can envisage current flowing through a wire, measured in amperes, as analogous to the volume of water flowing through a pipe measured in gallons per minute. Current splits where there is a "junction" in the wiring, just like water splits where there is a "TEE" in the piping.

TP
TrentePieds is online now   Reply With Quote
Old 05-05-2018, 17:45   #11
Marine Service Provider

Join Date: Jan 2012
Location: Lake Ontario
Boat: Douglas 32 Mk II
Posts: 2,753
Re: Drawing from battery while at dock

Quote:
Originally Posted by dmksails View Post
What affect does using 12VDC power have on the batteries while at the dock and connected to a battery charger?

Right now only the cabin lights are using 12V power for only a few hours each night. I'm considering adding a wifi router to 12VDC power and this would be on 24-7 unless I turn it off.
None, if the total current drawn (by loads and batteries) is less than the charger can put out.
__________________
ramblinrod
ramblinrod is offline   Reply With Quote
Old 06-05-2018, 18:49   #12
Registered User

Join Date: Dec 2009
Posts: 281
Re: Drawing from battery while at dock

For clarification, as I'm not sure I understand with certainty

Say you have a 10A draw while plugged into shorepower and the 40A charger is in float stage. Is the charger providing the 10A and batteries 0A, or are the batteries providing the 10A and the charger is simple replenishing the batteries? If the readout on the charger shows its putting out 10A, how do we know where that 10A is going, to the batteries or to the load?
US1Fountain is offline   Reply With Quote
Old 06-05-2018, 20:01   #13
Marine Service Provider

Join Date: Sep 2008
Location: Victoria B.C.
Boat: CS27
Posts: 2,042
Re: Drawing from battery while at dock

Quote:
Originally Posted by US1Fountain View Post
For clarification, as I'm not sure I understand with certainty

Say you have a 10A draw while plugged into shorepower and the 40A charger is in float stage. Is the charger providing the 10A and batteries 0A, or are the batteries providing the 10A and the charger is simple replenishing the batteries? If the readout on the charger shows its putting out 10A, how do we know where that 10A is going, to the batteries or to the load?
If there is no current going to the batteries without a load (in other words they are fully charged) then when you turn on a 10 amp load the battery charger provides the current. The batteries are full so will not accept the current.
mitiempo is offline   Reply With Quote
Old 06-05-2018, 20:06   #14
Registered User

Join Date: Jan 2017
Posts: 11,844
Re: Drawing from battery while at dock

And all the 10A is being drawn from the charger, nothing's touching the energy stored in the bank.
john61ct is online now   Reply With Quote
Old 07-05-2018, 04:24   #15
Registered User

Join Date: Dec 2009
Posts: 281
Re: Drawing from battery while at dock

Thank you
__________________

US1Fountain is offline   Reply With Quote
Reply

Tags
battery, dock

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Dock to Dock Auto Routing RobD527 General Sailing Forum 0 07-02-2018 04:47
Navionics Dock-to-Dock Autorouting Boathooked Marine Electronics 7 11-02-2016 18:45
Scaling / Drawing Charts Netsurfer OpenCPN 1 05-02-2010 11:03
Sailplan and line drawing svsouthernstar Multihull Sailboats 3 11-05-2009 08:30
410: Lagoon 410 Hull Design Drawing Ian Pearce Lagoon Catamarans 0 08-04-2009 06:39



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 13:14.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.