Battery Problem

[Carl and Jule]

Hi, all. Is there anyone out there that has not had problems with batteries? Well, here is our latest, and we hope that someone can offer some help.Our house bank has three Group 27 AGM batteries. We live on the boat for much of the summer, so the batteries see steady, consistent use every day. We probably use a total of about 60-70 amp hours a day. We have a generator, and we re-charge daily. We have a Link 2000 battery monitor, and make certain that we consistently replace as many amp hours as we take out. And everything is just fine all summer while we consistently discharge and recharge on a daily basis.Then fall comes, and we return to weekends onboard. When we leave the boat on Sunday evening, the batteries are recharged to at least 12.65 volts. But when we return the next Friday, we find that the batteries have dropped to about 12.50. Of more concern, when we try to charge the batteries, the acceptance is very poor; we can only get a few amp hours in. Over the next two days, as we begin using the batteries, the acceptance improves, and by the time we leave on Sunday, things appear to be back to normal. But the next Friday, it is the same thing all over again; lousy acceptance, and we struggle to get the bateries to "wake up".This is the second year that we have gone through this scenario. Last year we took the batteries home for the winter, and all attempts to get them to take any charge over the winter failed. Being AGM's, however, they did hold 12.50 volts all winter, so we hoped everything would be OK in the spring. In the spring, we put the batteries into the boat, and although several discharge/recharge cycles did return some acceptance, we were not able to even come close to putting back what we were taking out, and we had to replace the batteries.We now have our second set home for the winter, with all of the same symptoms. We do NOT want to replace these batteries yet again after only one year. We have been very conscientious about adhering to charging specifications and using the battery monitor to make certain that we run in daily amp hour balance all summer.What do we do with these batteries for the winter to "rescue" them for next spring? What might we be doing wrong in our battery management?Thanks in advance for any help.Carl and Jule Dupres/v Syzygy

 

[RichH]

Go to the 'ample power' website .......

http://amplepower.com/primer/index.html Then go to "MANAGE, TEST and TROUBLESHOOT" then ---> 'managing', ---> equalizing, ---> and re-vitalizing, etc. Also look for the section on 'break-in' of new batteries, etc. It generally takes more than just watching a "Link 2000" etc. to keep a battery system well managed and long lasting.

 

[Don S/V ILLusion]

bulk charging

It is possible you may be confusing the charge rate with battery condition. AGMs at 12.5V may not accept a bulk charge but rather only an absorption or slow rate of charge. You probably know this already but it takes much longer to reach full charge than you might expect as the rate goes down with ability to accept charge as you described.

 

[Rich Stidger]

Be careful of the Link 2000 info

I have a Link 20 which is similar to the Link 2000 insofar as battery monitoring. The Link metering device has BY DEFAULT a characteristic that can fool you into thinking that your batteries are fully charged when in fact they are not. This problem is made worse by using the engine alternator as the recharging source.Here is the rub:The Link very nicely counts the AH used and replenished so you can see the SOC at any given time. However it has rules that govern how it counts.The default settings (for flooded cells, AGM is slightly different) are these:The load current is integrated over time to count AH used.Charging current is "discounted" by the Charging Efficiency Factor when counting AH returned to the battery. The automatic Efficiency Factor STARTING POINT is 0.95. Thus for every AH put into the battery credit is given for 0.95AH. This is because charging is not 100% efficient.Charging is considered complete (or 100%) when EITHER one of the following two conditions are met:A) The AH have counted back up to a positive number.B) The voltage is 13.2V or higher and the charge current is 2% of the bank capacity or less. Both the voltage and current criteria must be held for a minimum of 6 minutes.When EITHER condition A or B above is met, the 100% LED will flash indicating that the battery are completely recharged. When the batteries return to a discharge mode, the AH display will reset to zero.Also the Charging Efficiency Factor gets recalculated at each discharge/charge cycle. For example, suppose that you start charging when your batteries are down by 50AH. When the Link 2000 shows that there are still 10AH remaining to be replaced, the system measures 13.2V and a charge current below 2% of your bank size. At that point, the 100% LED begins to flash and upon removal of the charge current and discharge begins the AH display resets to ZERO. And since the Link 2000 "thinks" that the batteries were charged sooner than expected, it modifies the Charging Efficiency Factor and stores that value for the next charge cycle. BUT IN FACT THE BATTERIES ARE STILL DOWN BY 10AH.The problem with this method is that there are conditions that can cause the voltage and charge current to met the "Fully Charged" parameters. For instance suppose your battery bank is 300AH. 2% of 300 is 6A. If you are charging with your engine alternator and the regulator has tapered off to 13.6V at 9A charging and the refrigerator cycles on drawing 5A, the charging current will drop to 4A which is below the 2% parameter. After 6 minutes, the Link 2000 claims the batteries are fully charged. However, they are not.In this scenario you now have batteries that are undercharged and a meter that not only thinks they are charged but were also charged at a higher charging efficiency. WRONG ON BOTH COUNTS.As this cycle repeats the batteries progress to a lower SOC. When batteries are not fully recharged, sulfation occurs and batteries will not accept a charge as readily as they once did and because they are at a lower SOC they reach a given discharge point quicker.Eventually the batteries fail.What can you do to prevent this? First, change the default parameters in the Link 2000 so that it cannot declare the batteries fully charged unless the AH actually count to ZERO. Change the Charging Efficiency Factor so that the Link 2000 will not recalculate but remain fixed- 94% works well for me.Fix your batteries over the winter by using a desulfator circuit. Google "nanopulser" for some links to this commercially available equipment. I am currently evaluating a device that I designed and built on my own batteries and have seen substantial improvement in only 3 weeks.

 

[Landsend]

I'm waiting to hear the problem...

You haven't said you have a starting problem or a real problem that disable something. You are just stating readings that honestly don't seem that far off.

 

[Stu Jackson]

Link 2000 Operation

Rich has some extremely well explained descriptions of operation and important information.One item, Rich, U wrote: "As this cycle repeats the batteries progress to a lower SOC. When batteries are not fully recharged, selection occurs and batteries will not accept a charge as readily as they once did and because they are at a lower SOC they reach a given discharge point quicker...Eventually the batteries fail."If the skipper was using the Link 2000 ONLY to advise him of when to stop charging (as a simple meter like the Link 10) that would be true. If Carl was doing it that way, he would undercharge the banks.However, with a Link 2000 the charging is not done through the Link, the Link is only measuring in and out amperage, EXCEPT and unless he has it hooked up to a combination inverter/charger, like a Freedom 10-15-or-20, etc. for shorepower charging. If so, it WOULD affect his charging.It won't affect his alternator charging since the alternator would have its own separate regulator.Only if he has a Link 2000R would the alternator be impacted.Also, as I recall the Link 2000 manual recommends resetting the "meter" on a regular basis.I concur that it may well NOT be a battery problem at all.Carl, what do you have? and have you reset the Link?Rich, am I close? Your material was so good I'm emailing it to myself and putting it in with my Link 2000 manual. Thanks again.

 

[KennyH]

Over 35 years boating, what works best is solar

A solar panel matched to your battery bank is the best solution I have ever found for boat batteries. I have had batteries last 10-15 years with solar panels keeping them charged. It is an investment that pays great dividens. Something like 30-50 watts should keep all three of you batteries in great shape year round.

 

[Steve Dion]

What type of battery charger?

C & J:What type of battery charger are you using?

 

[Rich Stidger]

Stu, let me correct a statement

In the sentence from me you quoted I used the word "selection", and it should have been "sulfation". I have edited my original post. Guess I need to proof-read a little better.I defer to your knowledge of the Link 2000. I do know that it is (or can be) used with a Heart inverter/charger, but I have just the Link 20 which is similar to the Link 10 only for two battery banks.I didn't mean to infer that the alternator regulator was affected or controlled by the Link, I only meant that because the normal alternator regulator tapers off at an early stage, it is easy to have an additional house load come online and cause the charging current to drop, thus triggering the Link to think the batteries are fully charged.FWIW, I reset my Link 20 at the beginning of each boating season.

 

[Benny]

I suspect you may be undercharging in the fall.

There is no substitute for taking a voltage reading at the battery itself to determine state of charge. Allow the battery 15-20 minutes for it to stabilize before taking the reading.

 

[Stu Jackson]

Thanks, Rich, I understand

Also depends on what kind of alternator regulator setup Carl has. But it certainly sounds like he charges at the dock when he's away, so since the Link 2000 (just like your Link 20 as you say) DOESN'T affect his alternator, then it depends on how or if his Link 2000 works with his charger. I only brought that up because of the Link 2000, not anything you mentioned.The alternator is almost out of the picture as a charging "issue" because he uses a generator daily, which runs through his charger, right? So, we still need to know what he charges with.Two choices, either the Link 2000 controls his charger or it doesn't. How's THAT for heavy duty engineering, huh? If he has it connected to a Freedom I/C, then it will affect his charging. If not, but he depends on the readings to perhaps stop charging, then it might.But usually someone with a Link 2000 has enough battery condition smarts to know this.So, we go back to his original question, which could also be stated as: Why do my batteries loose voltage over a week, and why can't they recharge.He may be losing voltage over the week because of self discharge, but that seems rare with his AGMs which are supposed to minimize self discharge. Any parasitic loads? We just don't know.Why do they keep coming back during frequent use, but then "not accept full charge" at other times?If he's using the Link to measure the "full charge" then it's either the Link (reset?) or the batteries, or his charger.We don't know how he knows that he's not getting a full charge when he "took the batteries home for the winter, and all attempts to get them to take any charge over the winter failed."And dying AGMs after two years is very suspicious and good reason for his question. Also, as I understand it, AGMs may not have the sulfation issue that deep cycle wet cells have, and I forget if they shouldn't be equalized like gels.Given all that, first, we need to hear from Carl again. Then maybe we can help some more.This sure is fun! Thanks again.

 

[Carl and Jule]

More Info

First, thanks for all of the feedback so far. I have downloaded just about everything that Ample Power had posted. There is a lot of good info there.With regard to our Link 2000, it is not a battery charge controller; simply a monitor. We had discovered the low charging voltage cut off on the amp hour accumulaton early on, and set it to the lowest level possible. Our amp hour accumulator never cuts out unless we charge past full charge. We judge the state of the batteries by a combination of Link amp hours and battery standing voltage allowing at least 1 hour after charging.Our battery charger is a Mariner three-stage charger, and the generator charges through the charger. We have a Balmar Max Charge programmable regulator on the alternator. Both have been programmed for AGM batteries, and I have checked the charging parameters against battery specs, especially after the first year fiasco.One last piece of info; the AGM batteries are West Marine (East Penn; not my choice; what the place commissioning the boat put in there. My own choice would have been Lifelines, and if we end up replacing batteries again, it will be Lifelines.Keep the feedback coming. It's great!Carl and Jules/v Syzygy

 

[Jim]

What does the Links show when you

leave the boat on Sunday? Is it 4 bars lighted green? Never let them go under 40% charged. Why don't you charge them with shore power?Do you have a seperate start battery?

 

[Ross]

Carl and Julie, I think you are overly concerned

about your batteries. I use 2 group 31 batteries for the house and a group 27 for the starting battery, all AGM. I charge with my 50 amp. engine alternator and moniter the voltage with a digital volt-ohm meter. We often leave the boat for weeks at a time and the battery voltage holds within a tenth of a volt during that period. When winter comes I turn off all the switches and breakers, record the battery voltage in the log and walk away. When spring comes the voltage may have fallen off by 3 tenths but will start the engine with no problems. After my first set had been in service for five years with this level of care the voltage drop during storage was close the 3 volts and would lose that in just one week. That was a sudden change and I changed out the batteries. We are in the 3rd year on the new set and all is well.

 

[GuyT]

You never brought your batteries up

to a full state of charge.AGM's when fully charged should read about 12.9 VDC when the charger is disconnected and the batteries are in an open circuit condition.So, you left them at a lower charge state where they can sulfate and this reduces capacity.KennyH has it spot on and I'll tell you why - a solar panel will bring up the batteries up to a full state of charge over the long haul of the week.If you have a charger for AGM that does not have a Bulk/Absorption/Float charge mode, your charger may be going into a float charge too quickly and then you have to charge the batteries for 24 to 48 hours before they are charged up.If the charger comes up to 13.5 VDC and it floats the batteries there, the current will taper off and it will take forever to you to put the Amp-hours back into the batteries.

 

[BobW]

It's not the batteries.....

so don't go buying a whole new set... unless you send me your 'bad' ones!Here's my take on your situation, which doesn't consider your Link monitor or charging apparatus, which I'm not really familiar with.You wrote:"...consistently replace as many amp hours as we take out...'Batteries aren't about amp-hours - quite frankly, a battery doesn't know what an amp-hour is. Batteries are all about voltage. A battery is fully charged when its voltage won't increase. This level varies from battery to battery, and the amount of amps you pump into it won't change that level. Pumping some quantity of amp-hours into a battery doesn't mean much all by itself."...everything is just fine all summer..."You'll find that most cruisers 'work' their batteries between 50% and 80-90%, and that's probably what you are doing during the summer. 90% is the top end of the 'bulk charge' phase, where current accepted by the battery drops precipitously."But when we return the next Friday, we find that the batteries have dropped to about 12.50. Of more concern, when we try to charge the batteries, the acceptance is very poor; we can only get a few amp hours in."At 12.50 volts, your batteries are still at 90% of charge, so it is no surprise that acceptance is poor. It appears that while your batteries are in 'float phase', you think they should be in 'bulk phase'.As for sulfation, check out the link below. It doesn't sound like you have this problem, since there is no indication that your batteries have ever been seriously discharged - even below 50% - which is when sulfation becomes a problem."...we were not able to even come close to putting back what we were taking out, and we had to replace the batteries."I'm afraid I don't understand this. Did your batteries ever fail to keep your equipment running? Did you have to run your generator/engine for excessive amounts of time to give you the ability to keep your equipment running?Here's my bottom line (admittedly lacking in in-depth knowledge of the problem, but freely offered):Your batteries are fine, but you are fixated on secondary indicators. Charge your batteries and keep them charged when you're not living/sailing the boat(KennyH, you're spot on, there's no substitue to keeping your batteries at 100% if you can).Cheers,Bobs/v X SAIL R 8

 

[Don12364]

My Experience

I have had a Link 2000 with a Freedom Combi for 10 years.The Link IS a charger controller made specially for the Freedom and it plugs in via an RJ45 telephone jack - but it does not control the alternator (the 2000R does this).My Link 2000 has a constant drain of 45 mA so it alone uses 7.5 Ah per week, and just this constant discharge over a week will certainly bring the batt volts down somewhat, possibly to 12.5V. Then I note the Link's lowest current reading is 0.1 A (100mA) and so it constantly reads 0.1 A discharge. Now it counts this (0.1A x 24Hr x 7dys = 16.8 Ah) and shows a 17 Ah discharge over a week. Not a problem in itself but I sometimes don't go aboard for a month and see 67 Ah discharge which is of concern - especially as the actual loss is only half this.Of course when I try to poke 67 Ah back in it won't go - because there had only been half that lost.Hope this doesn't add to the confusion!!!

 

[Stu Jackson]

Link 2000 Reset

Donalex, I understand. Question is: what do you do about it? Your explanation, coupled with Rich's earlier comment and solution in Reply #3, seems to indicate a reset. In addition, then, to your experience what are your recommendations?

 

[Don12364]

Reset

The manual tells how to reset and I forget every time and need to read it up.Another way to reset the Ah counter is to open the 12 v fuseholder in the supply line - not the one which monitors the voltage - though it doesn't matter if you do open this one as well.On reconnecting the Ah counter is reset to zero - however this is still wrong as the battery will only have lost half the Ah which was previously shown. Also I cannot recall if it resets all the other parameters - but I think not.The link below is the manual for the latest Xantrex version of Link 2000. Mine is the original Heart Interface one with the row of LEDs. Anyway reset instructions are at bottom of page 20. Lousy Adobe (updated!) won't allow me to copy & paste so you will need to download the manual yourself.http://www.xantrex.com/web/id/83/docserve.asp