AGM Battery Failure - Two Sets in Two Years

[sailjumanji]

Originally Posted by sailorboy1

I still dont see info that verifies that the batteries ever get fully charged. All i see are voltages and that the system went through bulk/absoption and float. That means nothing far as fully charged.

In one post the the OP says he is fully charged by 12-1. How many times does it need to be posted how unlikely that is.

The question being asked is:

Why do my batteries only last 1 year?

Well the answer is:

Because they aren't getting properly charged.

But i got dismissed and am going to stay out of it.

Actually, I wrote 1-2 pm fully charged. I am also aware that is a hot button for you. But if overnight usage is 60-80 amp-hours, and you have 800 watts of solar, in bright and sunny Bahamas, is it not possible to be fully recharged by then? We are seeing 50 amps coming out of the solar controller.

I do like the possibility though that this might be caused by undercharge. I can fix charge systems, although we've run about a dozen charge tests in the past month specifically to evaluate the shore and solar chargers, and I listed the issues above.

How do you determine you have a fully charged battery? In an on-anchor situation. Because I am well aware that most times we are reading voltage from the charge source, and not the battery. We are also monitoring amp-hours via the DCSM, but I know that is not accurate, and gets to be a bit of a mess as sometimes the VSR is on and we are pulling from both batteries. Both batteries have calibrated shunts. The profile of amps going in vs time typically show pretty low amps (<10, sometimes 5 amps) on absorption before dropping to float. And the amp hour count to 100% and the changeover to float usually coincide.

Note that when we disconnected the two house bank batteries and let them stabilize to see if we had a bad cell, after two weeks they were at 12.99 and 13.01 volts.

[sailorboy1]

Not a hot button to me, not my batteries only lasting 1 year. If your batteries are only -60-80ah in morning and your have 800w solar AND your batteries only last 1 year........ what is your theory? If you were truly getting recharged you could discharge to 50% every night and the batteries would still last way more than a year. If you have 1 year old batteries and their capacity is only 50% etc. to me that indicates a charging problem.


Btw that 800w of solar has nothing to do with being fully charged by 1 pm all that matters it time at absorption and charge tail amps

[Bycrick]

Are all the various voltage readings you’ve presented been made with the same meter? I ask because you’re describing measurements to 2 decimal places as significant. My Fluke 177 has a DC volts spec of +/- 0.09% + 2 counts. So on the 20 volt range, the inherent inaccuracy is about +/-4 counts in the low-order digit. If the numbers are from different measuring devices, then measurements are even less reliable.

[sailjumanji]

Originally Posted by Pete7

I am just looking at the second and third photos of the bus bar. Looks like one post has severe corrosion. Is that copper in the third photo sitting on top of the silver metal? If so that has taken some power. What was that connection?

Also do all the existing batteries now have a similar capacity, or is one substantially lower than the rest? They will need to be tested individually.

Pete

Yep, one post had severe corrosion. It was the one with the solar charger negatives, and the two outboard motor negatives on it. All three of those terminal ends had corrosion, as well as the buss bar immediately below. It was not a lot, but was green and obvious. None of the other posts or terminals had any corrosion.

The third pic is showing what the buss looked like after I cleaned off the corrosion. The buss is copper, with some kind of shiny (silver) plating. Where you are seeing copper, is where the plating has corroded off. Or my rigorous cleaning took it off. Either way, that is going to be replaced. A buss is relatively cheap.

We tested each battery individually. The two 225 AH AGMs: one has 23 amp-hrs remaining, one has 31 amp-hrs remaining. As I suspected them to be bad, Mastervolt agreed we could run a shortened 10-hr test, which was 21 amp draw down to a battery voltage of 10.8 volts. Both tests lasted less than 1-1/2 hours. Then we did quick recharge, and were able to evaluate the MassCombi in that process. Mastervolt accepted the test results, and replaced the batteries (which we upsized to 270 AGM's).

The start battery, Mastervolt didn't have any interest in replacing. As we have a VSR in the system and the house and start batteries are commingled in charge condition, I wanted to know whether the start battery was bad. I did a 20-hr capacity test (which is what the official Mastervolt warranty guidelines require) at 6.4 amps to 10.8 volts. That battery had 104 amp-hrs remaining capacity. Warranty says if under approx 80% capacity within first two years, it will be replaced. We were right at 80%, and they are replacing. I noted to them that their instruction manual also says not to mix old and new batteries, and that might have helped. If they chose not to replace, I was going to do it anyway.

[sailjumanji]

Originally Posted by Bycrick

Are all the various voltage readings you’ve presented been made with the same meter? I ask because you’re describing measurements to 2 decimal places as significant. My Fluke 177 has a DC volts spec of +/- 0.09% + 2 counts. So on the 20 volt range, the inherent inaccuracy is about +/-4 counts in the low-order digit. If the numbers are from different measuring devices, then measurements are even less reliable.

I have a new Klein meter, which states 1% accuracy. I also have a GB meter, that consistently reads 0.02 volts lower than the Klein. When doing the tests, I would frequently move the Klein meter to check that GB was still same differential. It was.

[sailjumanji]

Originally Posted by sailorboy1

Not a hot button to me, not my batteries only lasting 1 year. If your batteries are only -60-80ah in morning and your have 800w solar AND your batteries only last 1 year........ what is your theory? If you were truly getting recharged you could discharge to 50% every night and the batteries would still last way more than a year. If you have 1 year old batteries and their capacity is only 50% etc. to me that indicates a charging problem.


Btw that 800w of solar has nothing to do with being fully charged by 1 pm all that matters it time at absorption and charge tail amps

Well, if I only had 100 watts of solar, I surely couldn't be back to fully charged by 1 pm! Unfortunately, all I can show detailed graphs, etc., for now is a couple of trashed batteries. They are on bulk for minutes, then absorption for a long period, and the tail current before dropping to float is typically down around 5-6 amps (from a start at around 50 amps).

My theory? Frankly, I am out of them. I've inspected, measured, tested ... In some respects, I wonder if the Deka AGM's that I had on my last Seawind cat that lasted 12 years were just more robust than Mastervolt AGM's, as the setup is very similar. Initially my concern was that we were trashing them by motoring in 7 hour stretches, on full batteries, and maintaining them at 14.1-14.2 volts during that period. Essentially a high voltage float. Mastervolt's reply was that 14.2 volts wasn't a problem. Plus the second set of batteries only has 60 hours motoring on them.

And also, when motoring, the VSR has the start and house batteries commingled. We are still on the original start battery. Although it has lost capacity as well, it's only down 20%. The house batteries have lost 90%. And this second set is only a year old.

Then we did all of the charger tests. Absorption for the solar controller is 0.10 volts above spec; float is 0.10 volts below spec. That doesn't sound like much to me, but I was hoping for someone knowledgable to say it is or isn't.

On MassCombi, which is what the second set of batteries lived on for the last year, the absorption and float voltages are 0.10 volts below spec. Again, that doesn't sound significant, to me.

I've measured all of the equipment individually, and haven't found anything excessive re: amp draw. And the shunts are both within 18 inches of the battery negative posts, and there is no equipment connected directly to the posts. (So the shunts see all loads.) The background load for the stereo memory, the gas alarms, bilge pump alarms, etc., is about 0.6 amps. We've spent weeks calibrating shunts and come to realize that zero value is highly affected by ambient temperature. But compared to the Klein clamp meter, we are always within 0.5 amps of display vs meter, and sometimes less.

I wish I had a stronger theory. Seawind is going to add more monitoring equipment, and apparently separate out the start battery from the system and keep the outboard charge from the house bank. I have new batteries waiting to go in (with a slight change in their position, as we are going to add more air space BETWEEN the two batteries.)

Otherwise, I am honestly on here trying to get ideas from the battery guru's. Trust me, I am not trying to justify or spin anything. I'd prefer to find out that I am doing something stupid, and fix it. Rather than my fear is that we think minor changes have this fixed, and next year I experience failing house batteries while in the Bahamas.

[sailjumanji]

Originally Posted by sailjumanji

Yep, one post had severe corrosion. It was the one with the solar charger negatives, and the two outboard motor negatives on it. All three of those terminal ends had corrosion, as well as the buss bar immediately below. It was not a lot, but was green and obvious. None of the other posts or terminals had any corrosion.

Actually, the post wasn't corroded. The terminals of the cables attached had corrosion, and the area between the lowest terminal end and the buss plate had corrosion. Note that I think it matters, but I wanted to correct that the actual post was still plated and not green.

[CharlieJ]

@sailjumanji
Four conditions lead to premature death of AGM batteries: 1) Improper charging profiles; 2) non-temperature compensated charging sources, 3) leaving them in a partial state of charge (PSOC) condition for any period of time and 4) high ambient temperature.

1) Improper charging profile
You said that you verified that your charging sources are programmed correctly. The next step, and in light of the condition of the bus bar in your photo, would be to check the voltage at the battery posts during bulk, absorption, and float.

2) Non-temperature compensated charging sources.
This is a big deal. Lead acid batteries all have a negative temperature coefficient; the higher the battery temperature, the lower the charging voltage.

3) PSOC
I sell thin plate pure lead AGM batteries. They are excellent batteries but, until the paste composition was changed, they would not tolerate PSOC and could fail prematurely. The actual recommendation was that they needed to be fully charged after every cycle. This, of course, is impractical on a cruising boat so I would tell my clients to recharge to 100% as often as possible but not to exceed 10 cycles between full re-charges. I also told my clients that this was a compromise, that by not recharging every cycle, they were consuming cycle life.

4) High ambient temperature
High temperature kills lead acid (and LFP) battery cycle life. Per the Master Volt AGM Manual; battery life cycle is halved for every 10C rise in battery temperature.

Maybe this will help.

[sailjumanji]

Originally Posted by DeValency

LFP batteries will not help you and their loss will just be more expensive.
As it looks, something (a partial shortcut, moisture, electrical device, wiring issue) is sucking your juice. Once AGM battery discharges below 60% or so, you notify the low voltage but that’s almost too late. Few discharges like that and your batteries are permanently damaged.
You need to continuously measure the current out of the battery in different loads and situations. Make sure nothing else is connected directly to the battery. If you’re lucky you’ll find the leak right away. If not, you better install a must-have battery monitoring device (such as Victron BMV) that should tell you what and when the discharge is going on and then you’ll have to connect and disconnect circuits one by one until you identify the bandit...

Best of luck

I checked all of the loads, when we were calibrating the meter in the DCSM. None seemed out of whack, as I was hoping for one that cratered the system when turned on. The freezer is not on the list as the cold plate was being replaced. But that has since been done, and it's a ~ 5 amp draw (around 7 amps at startup, and slightly less than 5 amps after its been running a while, but compressor still on.)

We have an electric winch - which is used when raising the main - and a windlass. Both are only used when the outboards are running.

There are no direct connections to the battery, and the shunts are within about 18 inches of the batteries. So all loads go thru the shunts. House load is usually around 0.6 amps with equipment off, but alarms, gas sensors, DCSM, etc., on.

We avoid using the inverter, and have only turned it on a few times to charge a laptop. Its use is avoided.

Amps Equipment
0.72 Fusion Stereo Radio
0.34 Aft Bedroom Fan on High Speed
0.40 Kitchen Fan on High Speed
0.29 Master Suite Fan on High Speed
0.08 Autopilot on Standby
2.08 Zeus 3 Chartplotter (12 in) & N2K Network & Transducers
0.36 Vesper AIS & Antenna Splitter
0.17 Radar Off, Breaker On
0.30 Radar on Standby (incl Breaker On)
1.40 Radar Transmit (incl Breaker On)
0.45 VHF On Receive Only
1.30 Inverter On, No Loads
0.14 Anchor Light
0.19 Navigation Lights
0.24 Spreader Light
0.52 Cockpit Hardtop Lights (3 quantity)
0.06 Cockpit Red Lights (2 quantity)
0.28 Head Light (single, ceiling)
0.34 Kitchen Ceiling Lights (2 quantity)
0.35 Kitchen Undercabinet Light
0.84 Master Suite Ceiling Lights (3 quantity)
0.86 Saloon Ceiling Lights (5 quantity)
0.63 Stair Red Lights
0.44 BEP DCSM (Panel) & BEP 600 GDL (Gas Alarms)
11.76 Fresh Water Pump
4.20 Refrigerator (startup 4.2 amps, high 6.5 amps, 4.2 amps at 25 min - compressor still on)

[sailjumanji]

Originally Posted by CharlieJ

@sailjumanji
Four conditions lead to premature death of AGM batteries: 1) Improper charging profiles; 2) non-temperature compensated charging sources, 3) leaving them in a partial state of charge (PSOC) condition for any period of time and 4) high ambient temperature.

1) Improper charging profile
You said that you verified that your charging sources are programmed correctly. The next step, and in light of the condition of the bus bar in your photo, would be to check the voltage at the battery posts during bulk, absorption, and float.

2) Non-temperature compensated charging sources.
This is a big deal. Lead acid batteries all have a negative temperature coefficient; the higher the battery temperature, the lower the charging voltage.

3) PSOC
I sell thin plate pure lead AGM batteries. They are excellent batteries but, until the paste composition was changed, they would not tolerate PSOC and could fail prematurely. The actual recommendation was that they needed to be fully charged after every cycle. This, of course, is impractical on a cruising boat so I would tell my clients to recharge to 100% as often as possible but not to exceed 10 cycles between full re-charges. I also told my clients that this was a compromise, that by not recharging every cycle, they were consuming cycle life.

4) High ambient temperature
High temperature kills lead acid (and LFP) battery cycle life. Per the Master Volt AGM Manual; battery life cycle is halved for every 10C rise in battery temperature.

Maybe this will help.

It does help. Several are consistent with what Mastervolt tech has said has well.

1) In the charge tests, we always have a electronic meter on the battery. A second meter is moved back and forth between measuring amps (clamp on the battery), and the charge source. Initially we were very concerned that we might have excessive voltage drop. I posted those earlier, but max we have measured is 0.29 volts (2.1%) at 98 amps. That is a lot, but we rarely have that many amps coming thru. By 30 amps, voltage drop is 0.1 volts.

2) Both the MassCombi and the Solar Chargemaster have temperature compensation probes. The two separate probes, are connected to the top of the batteries - one on each battery. We have run tests with temp probes removed, to check the base voltages. And run tests with them connected, to test the correction. Our downfall is that we measured ambient temperature, instead of battery temp. I posted some numbers on this earlier, but overall it appears the voltages are being overcorrected. In some instances, the correction is exceeding the 0.30 volt limit that Mastervolt states.

3) PSOC. A couple of thoughts on this. We carry a Honda gen as backup, and to run the AC at anchor (about 5 times, in Florida, no wind, and crazy fly population.) I could easily start that up if needed.

Other thought though, is that we occasionally run the outboards. That's another boost. But the manufacturer's concern is that overcharge is damaging the batteries. What is your thought on that? If we are in an undercharge situation, isolating the outboard charge to the start battery as they are now proposing, would be the wrong direction? Mastervolt said they were not concerned about the 14.1-14.2 volts we are seeing after hours of motoring ICW with full batteries. Would you be concerned?

ANother question. We have trashed two sets of house batteries. The start battery is still original. It gets the outboard current same as the house batteries when the VSR is on. Either the outboard current is not an issue, or the larger batteries are more susceptible to overcharge than the smaller start battery. Comment?

4) Yeah, Mastervolt said the same thing about temp. I replied to them that my Deka AGM's - albeit only group 31 size - lasted 12 years in this Florida and Texas heat on our previous Seawind. The saloon on the Lite though is closed up, whereas the previous boat saloon was open. So it gets hotter - probably over 100 deg F in August. That might be issue for second set of batteries. But first failed with a month of marina air con, and Apr-June of being at anchor in Bahamas.

I'd really be interested in your thoughts on 3) remarks. THANKS

[rslifkin]

I wouldn't be too concerned about 14.2 volts or less from the outboards. But if you're worried, you could always add a DC to DC charger to regulate voltage down a bit.

Personally, I'm on season 3 with a pair of 400ah L16 6v Mastervolt AGMs for my house bank and they're performing just fine so far. No solar, but the boat is rarely away from shore power for a few days at a time, so they don't see much PSOC use. Mine are out of the engine room, so they stay fairly cool. Engine alternators settle down to 13.7 - 14 volts once everything gets good and warm depending on outside temperature (voltage is a bit higher after a cold start). Higher outside temp means higher engine room temp and lower alternator voltage. No apparent issues with overcharging after running for 8+ hours with already fully charged batteries.

[sailjumanji]

Originally Posted by Captain Bill

I fried a set with my solar charger. The default agm setting was misprogrammed at the factory and severely overcharged the batteries. My controller automatically goes into bulk/absorption anytime it goes through a dark period. At the dock even when the batteries are fully charged and on float the unit would go to absorption mode for 3 hours. This is chronic overcharging which eventually kills the battery. I made a custom program for when I'm at the dock that sets the absorption voltage only .01V above float (it won't accept them being the same) so that I am not overcharging with the solar panels while the batteries are being maintained by the shore power charger. I don't know if your solar controller is doing the same thing mine does, but it could be the source of your problem.

For the last year, when at the dock, the MassCombi was on. It left the batteries at float voltage (~ 13.4 volts, w/temp compensation) and 0.0 amps. When refrigeration would kick on, it kicked up the amps, but was still typically at the low voltage. Solar controller would do the same. If MassCombi was off, it would kick up amps to cover the load, but then drop back down to float voltage. If Solar and MassCombi are both on, the Solar sits in the background, registering 0.1 amps.

I've also done this check. Run solar controller and recharge battery, and wait until it gets on float. THen turn off solar for a few minutes, then kick on MassCombi. It immediately raises the voltage to 14+ volts and is on bulk, but within a minute it drops down to absorption. That might go on for a few more minutes, then at float. To me, that says the battery was full when I started the MassCombi. BUt whenever you go from one to the other, it always kicks in at bulk - if only momentary.

[Stu Jackson]

Originally Posted by sailjumanji

>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


ANother question. We have trashed two sets of house batteries. The start battery is still original. It gets the outboard current same as the house batteries when the VSR is on. Either the outboard current is not an issue, or the larger batteries are more susceptible to overcharge than the smaller start battery. Comment?


>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

I've read through this twice, and would like to summarize what I've learned, make some observations, and ask some questions:


1. You do NOT seem to have a voltage problem, at least in your sources.


2. I might have missed it, but were you measuring these voltages AT the banks?


3. This ^^ last post talks of over charging. That simply can't happen if you have the voltages you keep mentioning. In one of my Electrical System 101 threads, Maine Sail noted, about using ACRs and concerns about over charging a start bank: "The bottom line is that current simply flows where it is needed, batteries will take what they need when batteries are combined, and the voltage becomes equal among the new combined bank. Unless your charger, alternator or solar/wind system is pumping out an incorrect voltage for you bank you will not over charge using an ACR." This means, to me, that if Item 1 is correct, then you can't be over charging, because of battery acceptance at those reasonable voltages.


4. Sailorboy1 has mentioned trailing amps at absorption voltage. Have you done that? The consensus of the electrical gurus is that this is THE way to determine when you are fully charged. And switching to float is NOT full.


5. At one point you mentioned "...going from bulk quickly into absorption..." after a night on the hook. Why would any charging source, (other than your constant output outboards), do this? One would expect a longer bulk phase.


I suspect chronic undercharging or two faulty sets of batteries (less likely, but still possible).

[Bycrick]

Sailjumanji — You’re doing a lot of work. But your response about your two Klein and GB meters just proves my point. If a meter has a stated accuracy of 1% of 20-volts-full-scale, that means a reading of 14.00 volts can mean a voltage between 13.80 and 14.20. One percent of 20 volts is 0.2 volts. Very few DVMs are accurate to fewer than +/- 2 counts in the low order digit. So, best case, measuring a 14.00 source, your reading could be anywhere between 13.78 and 14.22 volts.

The fact that the two meters agree isn’t a reliable indicator either. If they didn’t, you still wouldn’t know what "right" answer was.

It seems to me that, if you’re killing batteries as quickly as you say, then the answer is should be fairly obvious. A few hundredths of a volt or an amp probably isn’t significant.

In your position, I’d be looking for a good meter that, when measuring at the battery, really tells you what the charging voltage is. Plus or minus a real tenth of a volt is important.

[Bycrick]

A short story about how obvious things often aren’t except in hindsight, and how big problems are often a collection of little causes.

Fellow arrives in the mooring field. 50’ catamaran, wife, 2 kids, two freezers, fridge, 1200Ah of AGM batteries which are deader than doornails.

“I just installed them 8 months ago. Can I buy replacements here?" Of course you can’t. Why do you want AGMs? Well if the boat turns over, they won’t leak. If the boat turns over, you’ve got way more problems. He replaced with golf-cart batteries.

Why did he murder $4-5k worth of batteries? Twice.

He had a 150a DC genset. It would run "a while" then start to surge, so he’d shut it off and charge with the engine alternators. The boat builder had installed bigger alternators, but had left the #8 wire from the bigger alternator. Both engine wires were burned. No telling how much voltage drop he had during charging. So he was always undercharging the batteries.

But why didn’t his big-enough genset do the job? He’d had the Genset installed in Australia. It surged. He’d had it worked on, modified, butchered, etc. in Suez, Turkey, Cypress, Malta, Gibraltar and twice in the Caribbean. It still surged.

Final, resolution to the problem? The starter battery had a shorted cell. Weak starter battery was enough to start the little Yanmar engine. Start one and the other started just fine with the alternator working. But the weak starter battery would rise above 13.2 volts very quickly. That caused an ACR that he didn’t know about, which was completely hidden behind a bunch of aluminum bus bars to close, connecting the house bank to the alternators. Voltage dropped because of the little wire from the alternators, so the AGMs never, ever got charged much.

Fire up the Genset and it put out 150a into the house battery with no problems. But when the house bank got to 13.2 volts, the ACR would put the dead starter battery in parallel, which overloaded the Genset, causing it to surge.

We replaced the starter battery for $110, and everything worked fine. He told me that he’d replaced two battery banks and paid mechanics/electricians almost $12k.

I suspect that when you find the problem, it will be "obvious." And not the least bit subtle.

Good luck.