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Trickle charging on twin Batteries

Printed From: The Fishing Website
Category: Saltwater Fishing
Forum Name: Reel Questions!
Forum Description: Reel answers from a reel expert - Steve at Swordfish Marine
URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=133645
Printed Date: 27 Jan 2026 at 11:24pm


Topic: Trickle charging on twin Batteries
Posted By: bergster
Subject: Trickle charging on twin Batteries
Date Posted: 01 Jun 2020 at 11:20am
Has anyone got some advice on keeping twin batteries charged while in storage. Would like to buy a charger that I'm told just slowly keeps batteries charged up by trickle charging as the batteries start to lose their charge. As my boat is in storage quite away from my home I can't just go and turn on and off as it's needed. Would really appreciate some advice on this, thanks



Replies:
Posted By: MATTOO
Date Posted: 01 Jun 2020 at 4:46pm
Bergster,
Your in the wrong forum section.
Put this up in "The Boat Shed " forum.

I and others can certainly help you out.

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Still cruising in my now sweetas pimped out Southern 755 HT0!


Posted By: Steps
Date Posted: 02 Jun 2020 at 2:17pm
I think a mod will move the thread.. better than having a double post.
 OK it is not good practice to charge 2 batteries that are different at the same time.. things like cell balance/ resistance kinda stuff.
 In reality if similar ratings same type eg lead acid and not say ld cad  or what ever.. long term will be ok.. but not good practice.
 I have used solar units for yrs..
 The little cheapo $35 (??) from supercheap.. but pull apart and seal with good silcone if going to be in the weather.
 That price would go 0ne for each battery.
 No need for charging modules cause the out put is not high enougn to over come and destroy battery cells

 Get into the bigger 10w units need a module for charging batteries.. and make sure the module Volt out put is for your type of battery

I do not know if can have say 1 10w or bigger solar panel the hook 2 modules in to charge 2 different batteries..
 But this route cost more any way.. getting well over $100
 as to 2x $35 elcheapo .. and mine lasted from early 90s thru to about 3 or 4yrs ago. Included  keeping charged batteries on family camping trips etc.


Posted By: Bounty Hunter
Date Posted: 02 Jun 2020 at 3:43pm
Originally posted by bergster bergster wrote:

Has anyone got some advice on keeping twin batteries charged while in storage. Would like to buy a charger that I'm told just slowly keeps batteries charged up by trickle charging as the batteries start to lose their charge. As my boat is in storage quite away from my home I can't just go and turn on and off as it's needed. Would really appreciate some advice on this, thanks

youre thinking of battery chargers from a previous generation.

these days you can only really buy 'smart' chargers - digitally controlled which will only charge as the battery requires - essentially 'set and forget' until the next use of the boat.

something from C-Tek or Victron will set you right - something like:

http://www.cteknz.co.nz/charger/product/MXS-10" rel="nofollow - http://www.cteknz.co.nz/charger/product/MXS-10

or 

http://victronenergy.co.nz/collections/chargers/products/blue-smart-ip65-charger-12-10-dc-connector-au-nz" rel="nofollow - http://victronenergy.co.nz/collections/chargers/products/blue-smart-ip65-charger-12-10-dc-connector-au-nz


both have models which are 'quick connect' - ie: ring terminals which are permanently on the battery and a convenient plug between them and the charger - no need for 'alligator clamps'...

Steps is correct - charging two dissimilar batteries does present complicating issues. if both 'start' and 'house' batts are AGM chemistry - which they prolly are - you can charge both at once through your VSR battery select switch. Battery manufacturers website will have data sheets which suggest recommended charging voltage - if theyre both within about 0.1v-0.2v of each other then no real issue... 


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No disintegrations!


Posted By: Catchelot
Date Posted: 02 Jun 2020 at 6:50pm
What BH said above ^^ all sensible.

But, also you don't have to connect and run this device all the time.

Once a month is fine to give a top up and then float charge.

If 3 or more months, charge it over night and even for an entire day before heading out.

Basic rule of thumb on a lead acid start or deep cycle battery, same with automotive;

Charging Voltage 14.25V

Float Voltage 13.2V



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"The sea, once it casts its spell, holds one in its net of wonder forever." - Jacques Cousteau


Posted By: bergster
Date Posted: 02 Jun 2020 at 7:59pm
Cheers for that boys, really appreciate your help.


Posted By: Titahi
Date Posted: 02 Jun 2020 at 8:13pm
I have a Ctek M200 ( 25 amp) charger connected  to my BEP switch panel, You can either charge through the VSR or parrallel tha batteries and leave it on.  The M200 is waterproof and perfectly happy charging and monitoring the batteries without any need for me to check them.



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"I love standing by the ocean and just knowing what its for"


Posted By: Steps
Date Posted: 03 Jun 2020 at 11:15am
Keep the surface of the batteries between the terminals CLEAN .. very clean
 Assuming everything is turned off, isolated...it is fine dust or salt combine with a humid day, bit moisture that you will get most off your charge loss over time..

Can test with a digital multi meter.. prob on 1 battery terminal to other .. full voltage.. prob top of battery beside 1 terminal with voltage range tuned down , may see residual voltage between there and other terminal, and as move proble closer it will get higher.

That alone will have your batteries lasting long periods, even out to yrs charged.



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