battery maintenance

[Don S/V ILLusion]

How do you maintain your batteries at the dock?

I'm faced with having to replace my Trojan T125 bank this winter and consequently have renewed interest in this issue.

On another board, someone posed this question and I though I'd reiterate it here to get a more thorough cross-section of responses:

Many of us spend long periods working and living at the dock. Since we've got deep cycle batteries that aren't designed to always stay on a float charge, I'm wondering what sort of regimen most people are using to keep their batteries healthy while at the dock for prolonged periods.

The conventional wisdom is to discharge the bank occasionally to keep them healthy, presumably to 50-60% on some routine schedule. My two questions are:

What are others doing for a healthy battery life while the boat is at the dock on the charger?, and more importantly than practices,
Do you know or are you aware of any dats which actually proves that constant float charging is damaging or decreases capacity or longevity of a bank?

 

[Stu Jackson]

Don, you may be interested in our C34 Message Board

discussions. Read the link and use the links to other threads that are in the linked discussion.

 

[Don S/V ILLusion]

Thanks Stu

Excellent read full of useful solid info. I have a spare 50a Astron Ac-Dc power supply and now I know what to do with it. Nice simple winter project to convert the refrgerator and freezer to their own separate power source which will save my new batteries from another premature death.

I got 7 years from the present set so I consider myself fortunate.

I encourage others to read Stu's link

 

[Maine Sail]

Don..

I too have not found a good answer, even after talking with the folks at Trojan, about leaving a battery on "float" charge even just with my solar panel 24/7.

I have personally seen many more batteries left on "float" have short battery life than ones that did not float. Again this is a small "n" but something that I feel is there. Of course all the makers of three stage charges with 12.9-13.4 volt float charge levels will tell you it's okay to leave them on charge 24/7 but again they are not the ones buying your new bank every 3-6 years..

I tried leaving my solar panel on 24/7 (about 7-8 effective hours of charging per 24 hours) and I saw a direct correlation between how often I had to re-fill the batts with distilled water. This to me is data enough to not constantly charge my batteries especially when they are already full. For instance last summer with teh solar panel on 24/7 I topped up my batts twice by mid July. In mid July I went to the "on @ 90% off @ 100%" routine and I have only needed to add water to my batteries once, about two weeks ago, since last summer..

On my mooring I now turn off the solar panel when my batts are at 100% charge. I also have a .1 amp per hour draw that draws some off my batteries each day. When they hit 90% of charge I flip the solar panel back on again. So far this seems to be working and I'm filling my batteries much less. We'll see in another couple of years how the batts hold up but for now I have yet to see any empirical data that suggests "24/7 float" is actually good for your batteries.


So my routine is a .1 amp constant draw for some exercise and on at roughly 90% off at 100% on at 90% (I usually flip them on either way on Thursday mornings so by the weekend they are back at 100%).... It would be cool if there were an automatic device that could do this...

 

[Stu Jackson]

You're welcome, Don

Here's another link re: batteries, chargers and fridges.

 

[Stu Jackson]

It would be cool if there were an automatic device that could do this...

My understanding is that the new Xantrex chargers claim to do this, see my earlier link.

 

[Don S/V ILLusion]

automatic charge interval

I will need to think this through more before doing anything - the triple P theory (planning prevents problems) - but after reading your links Stu, it would seem a "no-brainer" to simply eliminate the battery/charger circuit as a power source for the refrig/freezer and, in lieu of that, run a properly sized dedicated AC-DC supply 24/7. Shutting them down while not aboard is not an option to the Admiral...

Even a blind squirral can find an acorn in the forest if given enough time.

Mainesail - in answer to your question, the bank has been relatively well maintained and is 7 or 8 years old but it's useful capacity is obviously much reduced. That is all I'd reasonably expect and in itself, doesn't prompt me to change anything except i'd like to ensure I maximize the life of the new bank of 4 x T125s.

 

[Rick D]

Faced With The Same Issue....

...namely that I leave the frige and freezer compressors on 24/7/365 I approached this a different, but not unique way. I put my two banks of (Sam's Club) six volts into one bank and then added an economical group 24 deep cycle battery as the second bank. Now, when at the dock, I run all my DC loads through the cheapie battery, hoping to get a couple of more years out of the 6's. I use the boat often enough to top the big house bank and if I don't, I just combine the banks long enough to charge them fully. There are a couple of minor complications with this, but I think at the end of the day, they are manageable. Rick D.

 

[Maine Sail]

I'd say

Quote: "the bank has been relatively well maintained and is 7 or 8 years old but it's useful capacity is obviously much reduced."

I'd say you got a decent run/life out of them and perahps you don't need to change anything?

I replace at five regardless and have never had to deal with any diminished capacity. I did give a set of 5 year old Superior 6V batts, that came off my power boat, to a guy at the boat yard who did stretch them another four years though? Just not within my comfort realm...

 

[Buck2796]

Stu, Question ...

I have 2 (now 5 year old) 4D AGM's as house batteries, & a Link 2000R / Xanetrix 2500inverter/charger.
Out of ignorance of the above float discussion I have left the A/C, D/C charge system on "float" 24/7 as a matter of routine for the past 5 years. The house batteries appeared to be continuing to hold charge about as well as ever this Summer.

Question, if I leave the Link/Xantrix battery charger "On", and turn the "1-2-Both-Off" battery selector switch (always left in the "Both" position) to "Off" after batteries have reached full charge, will that leave the charger energizing the D/C panel for refrig, etc., but prevent further "Float" charging to batteries? ... Or will it do damage to any aspect of the system...?

 

[Maine Sail]

Thanks Stu..

Quote: " My understanding is that the new Xantrex chargers claim to do this, see my earlier link."

I had read they have new programing too but I'm on a mooring and need something that works on a solar charge controller. I can't seem to find one that will do this.

Again, I am still undecided if constant float is bad or good due to lack of real evidence either way but I've been doing non-constant since of last July and wish i could automate it with solar..

 

[Stu Jackson]

Buck, It all depends on how it's wired.

U wrote: "Question, (at the pier), if I leave the Link/Xantrex battery charger "On", and turn the "1-2-Both-Off" battery selector switch (always left in the "Both" position) to "Off" after batteries have reached full charge, will that leave the charger energizing the D/C panel for refrig, etc., but prevent further "Float" charging to batteries? ... Or will it do damage to any aspect of the system...? "

Generally chargers are wired: A.C. current shorepower IN, to
either A.C. panel and switch / breaker to charger, then D.C. power to batteries, or directly from shorepower IN to charger to batteries. The 1-2-B switch doesn't enter into the A.C. side.

Power to the fridge is D.C. (unless you have a Norcold-type A.C./D.C. auto switching fridge). That means the 1-2-B switch needs to be in an ON position to run the fridge (even while you're not at the boat).

If you have 2 4Ds and you leave your 1-2-B switch on both, it seems you have a split house bank, so why would you leave the switch on B at any time, other than charging from an alternator?

The position of the 1-2-B switch will have no effect on the battery charger, unless you've wired your charger output to the 1-2-B switch common post. If it's OFF, so's your fridge.

 

[Stu Jackson]

Don, you may need to rethink your

#6, since most fridges (at least Alder Barbour) require that the load be placed on a battery, rather than direct connect to a DC source. Check your fridge manual.

 

[Buck2796]

Stu,

Boat is wired as you describe...
After posting the question, I realized that it was a foolish question; as you say, the 1/2/Both/Off controls D/C. Turning it to "Off" simply turns off DC to all DC breakers... and has nothing to do w/ A/C.
I should engage my brain a bit more before engaging my keyboard.

 

[GuyT]

Leaving a wet battery on float charge

and doing nothing else(other than maintain electrolyte level) will yield at least a 20+ year life - the power plants expect this life from their batteries!
Since most boat owners actually discharge their batteries, we will/should see 7-10 years depending on the depth of discharge we have taken out of our batteries and how quickly we put the charge back in.

Here is the thing about float charging 24/7 - you must have temperature compensation! PERIOD !!! If you do not have a compensated charger, you will chronically undercharge your batteries in the cold weather and overcharge them in the hot weather.
Maintaining the battery at 100 percent state of charge will get the most life from your battery - I dont see any argument that can be made about that.
"Propper" float charging will extend the life of your batteries.

If you have wet batteries, equalize them - once every other month for 6 to 12 hours. Make sure to maintain the electrolyte level - never use tap water!

 

[Maine Sail]

Can you..

Quote: "Maintaining the battery at 100 percent state of charge will get the most life from your battery - I don't see any argument that can be made about that."


Guy,

Can you link us to some sources for this other than perhaps manufacturers of chargers? Having spoken with Trojan about this they led me to believe that leaving your batt on a constant float charge was bad for it so I stopped. I'd really love to see something from a battery maker that actually suggests doing so but as of yet I have not been able to find any maker that flat out suggests 24/7 float is what to do or suggests this. I'm hoping you can point us in that direction!

I'm still on the fence and would love to just leave my batts on 24/7 as it's a LOT easier but for now I'm doing what Trojan suggested..

 

[Don S/V ILLusion]

Stu 0 charger or battery load?

Stu
Being an engineer, I tend to want to know why something has to be done a specific way - in this case, can you explain what difference it would make to the compressor motor whether it is supplied 13VDC from a battery or any other source?
("since most fridges (at least Alder Barbour) require that the load be placed on a battery, rather than direct connect to a DC source.").

I will ckeck the manual today but I doubt it would have an explanation.

My charger is a Xantrex Truecharge 40 to a bank of 4 T125s plus a separate start battery running off an ecocharger.

thanks agn

 

[Maine Sail]

From what..

From what I've been told a charger is not a stable 12v "power supply" and a purpose built 120v to 12v "power supply" is designed to have loads connected directly where a battery charger is set up differently and not intended to be connected to loads directly. Don't know the whys just what I was told by my charger manufacturer (who BTW did not make "power supplies").

I wanted to do the same thing years ago and called the manufacturer of my charger and they advised me to not connect my charger directly to my loads without going through the batteries.

I guess we have lots of questions?? Perhaps today there are some chargers that will also work as a stable 120v to 12v power supply?

 

[Stu Jackson]

from the Adler Barbour Installation manual

"The cold machine has a brushless DC motor which is controlled by the electronic module (the finned device located on the compressor unit). This control unit sends small amounts of current back to the battery during operation. [italics] Operating the cold machine directly from an AC/DC converter, battery charger or other DC source without a battery will damage the unit's electronic circuitry."

That's why. Good question, comes up every once in a while.

Nice charging system arrangement, Don, we know your new batteries will be very happy in their new home!

 

[Don S/V ILLusion]

back to the planning stage...

nm