Voltage Drop in AGM Under Load?

[Ex-Calif]

Originally Posted by Paul L

I'm not buying 30% reduction in capacity after 1 year of use is standard and to be expected. It is a failure in my mind. Does their warranty cover anything after a year?

@Neelie thanks for the reply.

This does sound high. My 210ah bank has gone 7 years and while I didn't have robust monitoring I do reckon I was using 30-50 amps per day-sailing.

The variation on AGM lives is problematic. Unfortunately most of the reports on why are anecdotal and one rarely hears the whole story.

[neelie]

Originally Posted by Paul L

I'm not buying 30% reduction in capacity after 1 year of use is standard and to be expected. It is a failure in my mind. Does their warranty cover anything after a year?

All I can say is that the electrician told me that this degradation was not outside the "usual" range for 12 month old AGMs in the heat of the tropics.

Lifeline make 2 variants of Group 31s.. The GPL-31T rated at 105AH and the GPL-31XT (mine) rated at 125AH. Same sized case but 10 lbs heavier.

Could it be that their claims of 125 AH for the XT were on the extravagant side, driven by Marketing? If so, and the reality iwas actually 105AH when new, then a 10% degradation is quite acceptable.

My batteries are 10 months old and I'm 2000 nm from where I bought them. Warranty? What's that? I see a successful career in comedy for you!

Perhaps to avoid disappointment, when installing brand new batteries, one should get their capacities checked before handing over the cash.

Anyhow, theres not much I can do but learn from this experience.

[neelie]

Originally Posted by Ex-Calif

@Neelie thanks for the reply.

This does sound high. My 210ah bank has gone 7 years and while I didn't have robust monitoring I do reckon I was using 30-50 amps per day-sailing.

The variation on AGM lives is problematic. Unfortunately most of the reports on why are anecdotal and one rarely hears the whole story.

I don't yet know if this 30% degradation is just a " one off" due to the high ambient temperatures or whether it's a trend which will negatively impact the battery life. I'm hoping it's the former.

If you're only using 30-50 A and your 210AH has lost 50% of capacity, you probably won't even notice it especially at low discharge rates.

Were these batteries sourced from the Dong Wah No 1 Battery Factory via Alibaba, I would be laughing at myself and my stupidity.

Sadly, Lifelines are said to be lovingly handcrafted by a select team of artisans in their battery atelier in the USA. Hence they are 4x the price.

[Ex-Calif]

Originally Posted by neelie

I don't yet know if this 30% degradation is just a " one off" due to the high ambient temperatures or whether it's a trend which will negatively impact the battery life. I'm hoping it's the former.

If you're only using 30-50 A and your 210AH has lost 50% of capacity, you probably won't even notice it especially at low discharge rates.

Were these batteries sourced from the Dong Wah No 1 Battery Factory via Alibaba, I would be laughing at myself and my stupidity.

Sadly, Lifelines are said to be lovingly handcrafted by a select team of artisans in their battery atelier in the USA. Hence they are 4x the price.

I always worry about the "premium" prices - I get there is some technology in there but heck, these aren't the world's most complicated items.

My AGMs are "Delco Marine" whatever that means and, of course, we have pretty high ambients here as well. I am pretty sure they come off the same line as the auto batteries.

I lean towards an AGM capacity of at least 4X the daily consumption. Add "daily consumption" for each day of backup power you want.

I hear more stories of AGMs used at 30% draw doing well than AGMs at 50% draw. I think the 50% rule of thumb is a rule that kills AGMs.

[neelie]

"I hear more stories of AGMs used at 30% draw doing well than AGMs at 50% draw. I think the 50% rule of thumb is a rule that kills AGMs."

True. The lower your DOD the better. I had planned on not going below 70%. SOC when I decided on the 750AH pack. Now, I'm batting with the 50% team

And of course recharging to 100% every couple cycles is critical to longevity as well.

Fragile little buggers aren't they?

[sailinglegend]

Originally Posted by neelie

Ok.. I have had the batteries checked and the result is disappointing.

Prior to checking, I charged the batteries to what I believed to be 100%, rested the batteries for 4 hours and checked the voltage, they were all between 12.7 and 12.8 V.

Temperature is 32C or 90F

Battery capacities were checked and they averaged 93AH (the range was +/- 3AH)"........

Regarding equalization, the Lifeline documentation states it should be done if capacity is lost due to excessive discharges and should be performed by a battery technician......

I'm sad when I hear negative comments about AGMs, especially Lifelines, but from nearly all of your comments I have to come to the conclusion that the problems are of your making.

Just quoting you above Lifelines should have an open circuit voltage of 12.9v or more. You say you believed them to be fully charged but haven't said that you have followed Main Sail's advice to check that.

You say their capacity has been checked at 93 Ah - but was that done with a proper and very expensive conductance tester, or by the local garage mechanic with a load tester. An accurate capacitance test is not easy to do, so that might not be your problem.

Your quote about Lifeline equalisation shows you haven't read the manual properly. Equalisation can be done once a month if you don't get to 100% charged each month. Deep Discharge Recovery is what you are talking about. That must be done by a battery technician in a proper facility.

I have re-read all of this thread and in every post you seem to be talking knowledgeably but then let your self down so many times by not following the advice given or answering the questions.

Your solar charger only stays in absorption mode for 2 hours and then drops to float. For your size of bank this is not enough. When they fall to float, sometimes every day, they may be less than 90% charged and at a much lower float voltage the batteries may never get to 100% because there won't be enough hours left in the day, even with 700 watts of solar. Have you set the charge controller to Lifelines recommended voltage, now up to 14.6v, or just left it at the controller's AGM settings? Is your charging temperature controlled, if not you could have cooked the batteries with too high a voltage.

So the problem could be overcharging or undercharging if you rely solely on solar. Lifelines do need a good absorption charge greater than 0.2C, otherwise their service life is shortened, that means solar or shorepower or alternator charging of 150 amps!

You even said you hadn't checked the batteries individually because you couldn't be bothered to dismantle the bed to get to them. Your 0.6v drop through an isolator switch is a classic example of what can go wrong before you start blaming the batteries. How many more bad connections are in your system which could have been discovered by checking voltage drops from the battery terminals to the loads.

EDIT: Checking new batteries capacity when installing them is not an option because they can take up to 50 charge/discharge cycles to achieve the nominal capacity.

This may all be very harsh criticism, but people often come here asking for advice but don't help themselves.

[sailorboy1]

I don't accept the new reduced battery capacity as the cause of the large voltage drop under load that I thought the thread was about.

[neelie]

Originally Posted by sailorboy1

I don't accept the new reduced battery capacity as the cause of the large voltage drop under load that I thought the thread was about.

The voltage drop which affected my fridge compressor was when SOC was an indicated 80% at the 750 capacity, meaning there was 150 AH used.
So with 500 capacity, thus equates to 65% capacity! hence the voltage drop was magnified.

At least that's what I believe... Maybe, I'm wrong.

And then of course you have to add in all the other losses in the circuit, over which I have little control.

[Maine Sail]

Originally Posted by sailorboy1

I don't accept the new reduced battery capacity as the cause of the large voltage drop under load that I thought the thread was about.

It sounds like there are a myriad of other issues such as a .6V drop in a 4/0 wire which likely means poorly executed terminations, weak/bad switch, corrosion etc...

Batteries could very well have been at sufficient voltage to drive the inverter but the voltage drop in the wires caused the inverter to drop out on low voltage. If there is a 0.6V drop in the positive there is a good possibility there is a 0.6V drop in the neg side too. 4/0 wire needs a swage type crimp with properly matched dies to the lug. A swage type crimp is 360 degrees in compression making the entire lug smaller around its circumference & the overall lug at the crimp bands smaller in OD.

Dimple crimps, hammer & screw driver, pliers or vice grips, bench vices etc. need not apply for the job of crimping 4/0 wire or voltage drops will occur more readily.. All poor crimping does is distort the lug and result in a poor termination that can't adequately handle the current a 4/0 is intended for. There is one crimp tool maker out there that uses a hammer. They claimed, and perhaps still do, that the hammer crimp tool makes a UL Crimp. I asked them for UL documentation of this claim, FOUR TIMES, all I got was dead silence..... If you are pulling big current you need proper terminations.

Unfortunately I don't feel as if we have been given enough good technical information on this issue..

We do know that best charging practices, for Lifeline batteries, have not been employed. It is very possible they have diminished by the amount claimed but we really need to know a lot more of the finer details to determine if that is in fact the case.

The simple fact is that a 750Ah bank of Lifelines should NOT drop out an inverter under a 0.3C load. Even if slightly diminished they should still handle this type of load with ease. Even at 50% SOC .3C is cake walk for Lifeline batteries.

Details that would help:

* How EXACTLY was this capacity test performed? DETAILS, DETAILS, DETAILS......

*At what temp were the individual batteries when tested?

*What was the discharge cut off voltage when measured at the battery terminals? Was it all the way to 10.5V? What tool was used to measure this? Where was the discharge voltage cut off point measured?

*How were the Ah's delivered counted?

*Details on the Ah counter settings & set up for the capacity testing?

*What was the load applied to the batteries during testing? Each battery, if 125Ah's, should have had a load of exactly 6.25A (+/- 0.05A) applied and HELD STEADY at 75-80F battery case temp until each battery hit a terminal voltage of 10.5V? Doing the test any other way will not result in accurate measurements.

*Was this 6.25A load held constant for 20 hours or until each battery hit 10.5V?

*How was "full" determined? MUST BE 14.4V at the BATTERY TERMINALS & 0.5% of bank capacity being accepted in current. Full for a 750Ah Lifeline bank is 14.4V terminal voltage AND 3.75A or less in current flowing into the batteries. Your batteries must be truly full, 0.5% acceptance @ 14.4V, for any capacity test to be meaningful. They can NOT be "cruiser full" or 2% acceptance otherwise we have GIGO data (garbage in, garbage out)... For an individual 125Ah battery full is 14.4V and 0.625A of accepted current. Any thing other than 14.4V and 0.625A or less is not full enough for an accurate capacity test.

* You can do this test and stop at 2% acceptance and this will tell you your "cruising capacity" (a good idea actually) and this capacity will be LOWER than a true capacity test. If you base your Ah counter on factory Ah ratings (generally incorrect to do so unless you always get back to 0.5% acceptance) then to be fair, the capacity test must be done the exact same way the factory does it. You can't compare a 14.4V / 2% acceptance test to a factory capacity of 14.4V / 0.5%... Comparing cruiser full capacity to factory full new capacity results in GIGO data. A capacity test needs to be done the same as the factory does it to make claims sugch as "my batteries are XX% diminished"...


I am not doubting they are diminished at all. I see this in Lifeline batteries pretty regularly, more regularly than in quality deep cycle flooded batteries, but in almost every case best practices have not been adhered to for charging, discharging & wiring..

Lifleline batteries, and many other AGM's too, need proper charging more so than some other types of batteries which can be more tolerant of charge/discharge abuse.. There is little room for error as these batteries can not be regularly overcharged and have the electrolyte replaced and they sulfate rapidly when not brought back to 100% regularly.

Lifelines need things regularly such as;

*20% of capacity in charge current as a bare minimum. Low current charging of Lifeline, or Odyssey TPPL AGM batteries, DIMINISHES CYCLE LIFE!

*They need regular equalization (conditioning) charges if cruised.

*They need temp compensated charging especially in warmer climates.

*They need proper programing of the battery monitor so they are not over discharged. This means yearly 20 hour capacity testing to ensure you are taking out what you KNOW to be 50% of capacity.

*They need to get to 100% SOC as often as is humanly possible.

*They need proper voltage sensing so the batteries actually get to the target voltage before charge sources get turned off or the sun goes down. This is especially true for sailboats with short motor run times.

*They need proper float voltages.

*They need battery compartments that do not consistently exceed 80F or the coolest part of the vessel you can find to fit them....

etc. etc....

[sailorboy1]

Originally Posted by neelie

The voltage drop which affected my fridge compressor was when SOC was an indicated 80% at the 750 capacity, meaning there was 150 AH used.
So with 500 capacity, thus equates to 65% capacity! hence the voltage drop was magnified.

At least that's what I believe... Maybe, I'm wrong.

And then of course you have to add in all the other losses in the circuit, over which I have little control.

Even at 65% SOC your refrigerator should run fine. So don't start thinking this capacity loss is the reason you had the problem.

And SOC and capacity don't really go together except for programing in a battery monitor. SOC is about voltage, not capacity.

[neelie]

Sailing legend

OK, Fair enough. I am always happy to accept well founded criticism.

1) I have actually done as Mainsail suggested, I simply did not diarize my every day activities.

2) The batteries were dismantled and individually tested.

3) according to the Lifeline documentation that I have, rested, open circuit voltage of greater than 12.8V at 77F approximates 100% SOC. Not the 12.9V that you claim. I'm looking at "Document No. 6-0101 Rev. D".

What is your Lifeline reference ? By your tone, I'm guessing you're a Lifeline dealer. If you have any newer documentation, I would be grateful to get a copy of it.

4) Not all of us who cruise are electrical engineers or electricians. We're all trying to learn as we get along and do the best we can. As may have noticed, there is a lot of folklore associated with battery maintenance.

Should you wish to engage in a topic that I have expertise in and you don't, you can be sure that you would at the very least receive courtesy and understanding from me.

5) What I can tell you is the electrician who came to the boat and checked the batteries for me indicated that losing 30% capacity in the tropics in a 1 year old battery can and does happen.

There is little I can do anymore except live with these batteries until they die. I will get them equalized as soon as I find a suitable shop to take them to.

Lastly, as I posted earlier.. These are after all, Marine batteries, and should have some inbuilt tolerances designed and built in for the imperfect world in which we exist.

[colemj]

Originally Posted by Maine Sail

Lifelines need things regularly such as;

*20% of capacity in charge current as a bare minimum. Low current charging of Lifeline, or Odyssey TPPL AGM batteries, DIMINISHES CYCLE LIFE!

*They need regular equalization (conditioning) charges if cruised.

*They need temp compensated charging especially in warmer climates.

*They need proper programing of the battery monitor so they are not over discharged. This means yearly 20 hour capacity testing to ensure you are taking out what you KNOW to be 50% of capacity.

*They need to get to 100% SOC as often as is humanly possible.

*They need proper voltage sensing so the batteries actually get to the target voltage before charge sources get turned off or the sun goes down. This is especially true for sailboats with short motor run times.

*They need proper float voltages.

*They need battery compartments that do not consistently exceed 80F or the coolest part of the vessel you can find to fit them....

etc. etc....

For the life of me, I can't understand why people buy these batteries. Your first point alone disqualifies most cruising boats out there, and your last point disqualifies anyone cruising in the tropics.

Mark

[Maine Sail]

Originally Posted by neelie

5) What I can tell you is the electrician who came to the boat and checked the batteries for me indicated that losing 30% capacity in the tropics in a 1 year old battery can and does happen.

If this electrician did not do a physical 20 hour capacity test, as I described, you really have no way of knowing if your batteries are in fact diminished to that level or not. This is especially true if no baseline measurement was established with this particular tool.

Capacitance testing of Lifelines is rather in-exact and unless this electrician has done side by side 20 hour testing with his capacity tester then his results could be off by 20-25% or more. Even my Midtronics, the best capacitance tester in the industry, does not match up with a 20 hour capacity test. I have learned how to interpret it, been around and around with Midtronics, and it is pretty repeatable once I did, but this is only after conducting hundreds of real capacity tests followed by comparing that with my Midtronics or Argus analyzers...

These instruments work better on flooded batteries but not as well on AGM unless you first develop a baseline or know how to interpret them..

Don't beat yourself up just yet. Your batts may be in better health than you think or your electrician led you to believe.. If he was not even using a Midtronics test instrument I would ignore his results entirely. Without a baseline (taken when new) any capacitance test is rather questionable to try and decipher Ah capacity. Also these testers do not yield results in Ah's they render them in % but this percent is for cranking capacity compared to the rating and uses internal resistance to spit out a result..

Best bet is to take one battery out of the bunch and 20 hour capacity test it. If they were in parallel it will give you a fairly decent picture of the rest of the bank give or take a few Ah's...

[sailinglegend]

Originally Posted by neelie

...OK, Fair enough. I am always happy to accept well founded criticism.

There is little I can do anymore except live with these batteries until they die. I will get them equalized as soon as I find a suitable shop to take them to...

There is a lot you can do - listen to what people have told you here but don't so readily believe what an electrician in the tropics tells you. That is the problem with this industry, you don't know who to believe, which is why these Forums can be so useful. If two or three regular posters are telling you the same thing then maybe they are right.

I am sorry for my lack of "courtesy and understanding", but I think you have shown little respect for the help people have been trying to give you.

Answer and address all Maine Sail's points and make sure you have an installation that will keep the Lifelines charged properly and they may well last. You shouldn't have to take them to a shop to equalise, buy a charger that will do it and you can then equalise them regularly - if you are not getting them back to 100% monthly.

I am a full time Liveaboard and a Lifeline user and they are now 10 years old and still going strong. People who criticise them just don't understand them, and people who have them and have problems have usually abused them in some way. AGMs are certainly not for the average user, you must know exactly what you are doing or you are wasting your money. And for those who want to go for Lithium batteries then they need to be another ten steps higher up the knowledge ladder.

[neelie]

Originally Posted by Maine Sail

If this electrician did not do a physical 20 hour capacity test, as I described, you really have no way of knowing if your batteries are in fact diminished to that level or not. This is especially true if no baseline measurement was established with this particular tool.

Capacitance testing of Lifelines is rather in-exact and unless this electrician has done side by side 20 hour testing with his capacity tester then his results could be off by 20-25% or more. Even my Midtronics, the best capacitance tester in the industry, does not match up with a 20 hour capacity test. I have learned how to interpret it, been around and around with Midtronics, and it is pretty repeatable once I did, but this is only after conducting hundreds of real capacity tests followed by comparing that with my Midtronics or Argus analyzers...

These instruments work better on flooded batteries but not as well on AGM unless you first develop a baseline or know how to interpret them..

Don't beat yourself up just yet. Your batts may be in better health than you think or your electrician led you to believe.. If he was not even using a Midtronics test instrument I would ignore his results entirely. Without a baseline (taken when new) any capacitance test is rather questionable to try and decipher Ah capacity. Also these testers do not yield results in Ah's they render them in % but this percent is for cranking capacity compared to the rating and uses internal resistance to spit out a result..

Best bet is to take one battery out of the bunch and 20 hour capacity test it. If they were in parallel it will give you a fairly decent picture of the rest of the bank give or take a few Ah's...

Thanks for the reply.

I cannot answer some of the questions because I did not note the brand of instrumentation that was use.

One device simulated a load (I can't remember what it was) and the voltage drop was noted.. I think it was in the order of 0.3 V per (i.e 12.8 down to 12.5), this was consistent across all 6.

Then another meter was connected, this was able to deliver an AH capacity on its LCD screen. I did not take note of the brand, but it was relatively sophisticated in that it needed to be programmed for battery type and rated C.

There is little doubt, that these instruments are but approximations. If the margin if error is 20% then they're worse than useless.

The good news is that I do not have a dead battery in the pack... In the sense that they all had close readings... (or all 6 are duds)

In the next month, I will read up on his to do the 20 hour test, pull one battery off the pack and see what I get. I will post the results here.

Many thanks, for your help.

Ps.. It was Not the inverter which dropped out, that works fine. The symptom I had was when drawing 180A using the inverter, the low voltage protection on the fridge compressor shutdown the fridge. if the LED temp indicator on the fridge hadn't turned off, I would never have investigated what I thought was a fridge failure which turned out to be the voltage drop.

It only happened when SOC indicated 80% and did not occur when indicating 100.. (Yes, I know, SOC readings are not accurate.. Only mentioned it to indicate relative capacity).

Give me 3-4 weeks, I'll set up a 20 hour test and get back with the results.

One final question... All thing being equal, is the capacity of a battery is related to the surface area of the plates?
I ask this because my variant of Group 31 AGM has 20 more Ah than the standard, yet case sizes are identical, only the XT weighs 10 lbs more. With identical case size, I don't see how they increase surface area by that amount.