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Author Topic:   Battery Charger Doesn't Reach Topping-Off Phase
lhpdiver posted 11-13-2011 04:56 PM ET (US)   Profile for lhpdiver   Send Email to lhpdiver  
Hi. We recently purchased a battery charger for the Boston Whaler boat. I haven't mounted it yet, but I have used it charging our brand-new deep-cycle batteries. The charger has three states; charging, topping off, and ready. I have never seen the charger reach the ready state. Granted I have not let it charge over night. The manual says if the charger stays in the topping off state for 24 hours (which it hasn't done) then "on-board DC systems are drawing between 1.5 to 3.5 Ampere".

Does the above quote indicate a short? We have a battery switch on each battery. We don't have much electronics on the boat; fish finder, vhf, stereo, lights. With all the electronics turned off, from time to time when I turn on the battery switches the stereo will start playing all by itself. Does that indicate a short? If so does it indicate a short in the radio wiring or could the short still be anywhere ?

Aside from hiring a professional, would a sensible approach be to one-at-a-time pop a fuse and see when or if the charger completes its charging ?


Buckda posted 11-13-2011 05:03 PM ET (US)     Profile for Buckda  Send Email to Buckda     
The above quote does not indicate a short - it indicates that onboard systems are drawing enough current to keep the battery depleted just enough so the charger continues to try to "top it off".

I don't know about the radio turning on by itself, but you may want to re-check the wiring to ensure that the circuit to the radio does indeed go through the switches - so it can be turned off. It may be wired directly to the battery, in which case, a loose wire may cause a current surge that would turn it on. (pure speculation).

Let's start by seeing if your batteries will take a full charge from this charger. While you do that, inspect the wiring circuits to ensure that they are all set up correctly. Older boats usually have some kind of hodgepodge of wiring, unless the owner is vigilant in how things are installed, or has done the work themselves and made sure it is all done first-class.

A great resource to purchase and have handy is "the 12-volt Bible" - it is available from and is a great reference for understanding the basics of your boat's electrical system.

The great news is that most boat 12-volt systems are easy to work with and on - and that makes it much more fun (in my opinion) than the 120/240 VAC systems in houses...


lhpdiver posted 11-13-2011 05:55 PM ET (US)     Profile for lhpdiver  Send Email to lhpdiver     
Buckda--The "12-volt bible" looks like an excellent resource. We live in one of the smaller little towns in South Florida and was shocked to see that our community library actually has the book on hand :-). I'll pick it up tomorrow.

Our boat is a 1990 Outrage which we picked up in 1998. Until last year there were so many things attached to the battery terminals it was a wonder the attaching screw worked. The port-side battery does still have a couple of things connected directly to it - but I think it would be pretty involved to trace that back to the helm since they are under the deck.

I'll try and see if the battery takes a full charge.

Thanks again.

jimh posted 11-14-2011 09:09 AM ET (US)     Profile for jimh  Send Email to jimh     
[Moved to SMALL BOAT ELECTRICAL. Please use SMALL BOAT ELECTRICAL to discuss topics related to the electrical system of small boats.]

The battery charger probably defines its various charging phases based on the terminal voltage of the battery. The phase of "topping off" probably refers to a low-current charge applied to the battery after its terminal voltage has reached a level that is near the full-charge voltage. The "topping off" current may take a while to raise the battery terminal voltage to a level that the charger considers as indicative of the "ready" phase. The time needed will depend on the battery capacity. A new battery with plenty of charge storage capacity might take a long time during the "topping off" phase to have its terminal voltage rise to the "ready" state.

If you are charging the batteries while they are in place on the boat, and there is a parasitic current drain from the batteries, the charger may never reach the "ready" state. The parasitic current will be consuming most of the charge current provided in the "topping off" phase, and the battery terminal voltage will not be rising very fast, if it rises at all.

On small boats there is usually a primary power distribution switch that is wired to disconnect everything from the battery, with the exception of the battery charger and perhaps one special keep-alive circuit such as a bilge pump or perhaps a memory circuit in an electronic device that keeps a clock alive or preserves some settings. To prevent parasitic currents from consuming the battery charging current, the battery is normally charged on the AC-powered maintenance charger with the primary power distribution switch in the OFF position.

There should not be any significant parasitic current on the boat. A current of more than a few milli-Amperes will cause the battery to lose charge while sitting in the boat. In general, when the primary power distribution switch is set to OFF, there should be no current flowing in the boat.

Jerry Townsend posted 11-14-2011 12:10 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
And then, an electrical multimeter is a requisite on my boat - with a auto-ranging multimeter, connect it between a battery terminal and the leads normally connected to it - and see what you get. If there is a current draw, something is on and bypassing the switch - and then you start isolating which "something" it is. --- Jerry/Idaho
lhpdiver posted 11-14-2011 01:48 PM ET (US)     Profile for lhpdiver  Send Email to lhpdiver     
I did pick up "12-volt bible" and it has a lot of info in such a tiny book. At the moment I am just jumping around reading the things that are interesting at the moment.

The charger has never gone into the 'ready' state.

I have a multimeter and almost immediately after disconnecting the charger the starboard battery read 13.3 and the port battery 13.18. I'm going to leave the charger disconnected and recheck a little later.

The port battery has 2 connections in addition to the switch on the positive post. Both of these have fuses. As a first step would it make sense for me to remove the fuses and see if the charger gets the batteries charged ? Is there something I can do with the multimeter where the inline fuses are on these connections that would tell me something ?

btw - that is my first use of a multimeter :-)

Jerry Townsend posted 11-14-2011 02:19 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
lhpdiver - my apologies - the 13+ voltages you are seeing are normal. When charging, the voltage across the battery terminals will be 14 or slightly above.

To measure the current (amps), remove the cables from either battery terminal and put one multimeter contact on the terminal and the other multimeter contact on the removed cables. Any current flow goes through the meter and measures the current being drawn.

If you have an auto-ranging multimeter - good - if not, select the higher current rating and if not seeing any current, then select the next lower current rating - until you see some current flow.

As Jim mentioned, a seemingly small current flow (milliamps) can discharge a battery - over time. -- Jerry/Idaho

lhpdiver posted 11-14-2011 02:55 PM ET (US)     Profile for lhpdiver  Send Email to lhpdiver     

I apologize for asking what are probably stupid questions.

I understand you to say I should disconnect either the positive or negative cables from one of the batteries, then test by putting either of the multimeter pins on the terminal itself and the other pin on any one of the disconnected cables, probably working my way through them all one by one. Is that correct ?

From my auto battery jumping experience I always thought you needed to disconnect the negative connections before the positive connections ??


lhpdiver posted 11-14-2011 03:25 PM ET (US)     Profile for lhpdiver  Send Email to lhpdiver     
For me - even the 'bible' is a little unclear on this. "To make a milliamp reading, open the circuit by disconnecting a wire end at some convenient point and seperating the parts. Touch the red test lead tip to the positive end and the black test lead to the negative end."

I have 2 batteries. Each battery has 2 terminals. Each terminal has between 3 and 5 cables connected to them.

Do I isolate a negative cable, remove it from the terminal leaving the others in place, then touch the red test probe to the positive battery post and the black probe to the recently removed cable ?

Sorry for being so dense - but you are teaching me and those who follow how to fish.

Jerry Townsend posted 11-14-2011 11:02 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
If you have 3 - 5 leads connecting to each terminal of two batteries - you have some serious re-wiring to do. Read the information that Jim has put in the "reference" section of the web-site.

And after seeing his recommendations and deciding how you want it - consider having an electrician make those changes.

To measure current, "break" the connection someplace - it doesn't make any difference if at a battery terminal, fuse or someother place and basically put the meter, selected to current (amps), between the terminal and the disconnected cables. It doesn't make any difference if you use the positive or negative terminals - one way it will be a positive number and in the other way, it will be negative. ---- Jerry/Idaho

jimh posted 11-15-2011 08:49 AM ET (US)     Profile for jimh  Send Email to jimh     
I describe some recommended practices for electrical power distribution on a small boat in

Boat Electrical Circuits and Wiring Practices

To measure electrical current you need an Ammeter. The current passes through the Ammeter.

lhpdiver posted 11-15-2011 09:02 AM ET (US)     Profile for lhpdiver  Send Email to lhpdiver     
The batteries were off the charger overnight. First thing this morning I checked them. Starboard battery 12.66. Port battery 12.74. The starboard battery has direct connections at the positive poll. I removed one of those connections and placed one multimeter probe on the end of the connection I had removed and the other on the positive terminal. The meter wasn't steady but measured between 8 and 9.

"When both the green and the red LED’s are on, the 2611 is charging at an "ABSORPTION" rate of between 3 and 9 Amps stage 2). This mode of charging gradually "tops off" your batteries"

I then removed the 2 direct connections completely from the positive terminal and then measured the battery at the terminals. Now I have 12.66 on both batteries.

I turned on the charger with the fuse pulled on the connector I had measured. It is in the topping off state. I'll let it charge for now.

The connector I removed seems to control the radio, running lights and the bilge pump.

lhpdiver posted 11-15-2011 09:41 AM ET (US)     Profile for lhpdiver  Send Email to lhpdiver     
Thanks Jim, I've printed that off.


So now I guess I need to determine which device controlled by that connector is mis-behaving. There is the fact that the radio seems to power itself on all by itself. I also wonder if something could be screwy with the bilge pump / super switch.

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