AGM Battery Failure - Two Sets in Two Years

[alaite]

Actually when you pry out the plastic lid there are small rubber caps that you can remove and and add water in the cells. I did this to experiment with a damaged Matervolt AGM battery.

[sailjumanji]

Originally Posted by mitiempo

If the battery is at a lower SOC, say 60 % or even 70 %, it doesn't make sense that the charger brings it up to 14.4 immediately. During bulk the charger should take a while, maybe hours on a large bank, to raise the voltage of the battery to absorption level.

I didnt say immediately. The original question that someone posted is why is bulk voltage higher than absorption for the masscombi, whereas the solar charger bulk just ramps up to absorption voltage limit. Both have lengthy bulk periods but what i pointed out is that the masscombi ramps up voltage and just gets to that 14.4 voltage for an instant, before it drops down to absorption.

[sailjumanji]

Originally Posted by mitiempo

Notice the line above the warranty information. They - like most 8D batteries made - are basically starter batteries.



Between that and the fact that you ended up with batteries that were sitting (not charging) for a long time their short life in a deep cycling situation isn't a great surprise. This is in addition to the fussiness of AGM batteries that they require being charged fully as often as possible for any kind of lifespan.



I would replace with a true deep cycle battery if possible or it will likely happen again. Mastervolt doesn't make (label) a true deep cycle AGM battery based on their web information.



Sailboats most often have batteries that suffer from PSOC as it is not always easy to fully charge as often as possible. Powerboats, especially those not long term cruising often do better with AGM batteries as they are usually fully charged on arrival at least.

Seawind has put these on all of their sailboats for years now, i dont know exactly how long. The outboard powered 1160 Lite has been in production for five years, but the diesel version for almost 20 yrs. There are only 2-3 of us having problems. Most have the dual 225 AH setup. A few have the dual 270 AH we are about to change to. Like i said earlier, when these crap out i will replace with lithium. But right now my replacements are sitting on a pallet in the garage. Fully charged, 13.01 volts. They should be in the boat in a week or two. The stored temp is ok.

I think Mastervolts true deep cycle battery is their lithium line. Ungodly expensive vs other brands. Some of their marketing comments might be to try to direct purchasers to that direction.

[sailjumanji]

Originally Posted by alaite

Actually when you pry out the plastic lid there are small rubber caps that you can remove and and add water in the cells. I did this to experiment with a damaged Matervolt AGM battery.

Thanks for the pic. I will probably pop the caps to see if any of the cells are low on electrolyte. Might give some insight as to if they were overcharged.

[Captain Bill]

Originally Posted by sailjumanji

Thanks for the pic. I will probably pop the caps to see if any of the cells are low on electrolyte. Might give some insight as to if they were overcharged.

Absorbed Glass Mat batteries do not have any electrolyte that you could visually see like in a FLA battery. The electrolyte is confined to the mats between the plates. The small amount of water in the electrolyte won't be visible.

[sailjumanji]

Originally Posted by mitiempo

Here are the specs of the 270 AH super 8D AGM from Mastervolt:

Excellent starter function.
Perfect upgrade for flooded lead acid batteries.
Same initial power surge in an AGM 12/90 Ah as 180 Ah flooded lead-acid battery.
Glass-fibre technology ensures low internal resistance.
Use of thicker plates extends lifespan.
Can be combined with every standard battery terminal.
Also for medium cyclical use.
Two year warranty.

Notice the line above the warranty information. They - like most 8D batteries made - are basically starter batteries.

.

Well, I looked into this further, and the Mastervolt catalog agrees that their gel battery line is a better candidate, and of course, Li Ion would be the best.

https://www.delzer.com/powerproducts/mas_cat_003/64/

[sailinglegend]

There were so many errors in your first post in this thread that I have quoted the errors and commented on therm.

Originally Posted by MarcoPoloMark

The one thing that prematurely kills AGMs is overcharging, so you most likely have an overcharging issue.

Overcharging is most unlikely as high voltages will be seen by the OP who seems to be aware of the Battery Monitor readings. Too high a voltage will cause gassing. but nearly all AGM batteries are "recombinant" - which means that the Oxygen and Hydrogen gas recombine INSIDE the battery and turn back to water. This is typically 99+% efficient, so almost no water is lost.

If you charge from multiple sources at the same time (engine, solar, wind...), you definitely have an overcharging issue.

This is absolutely not true.

Each charger is volt/amp/pulse limited to avoid bubbling the electrolyte, which in AGMs is very very precious....

Chargers are not amp limited - the battery determines the amount of current they will take from any charger.

The charging profile is very precisely calculated, sometimes with precisely timed pulses of electricity filling the last 80% to 100% charge (absorption).

Batteries never get to 100% in absorption mode as the charger will switch to Float well before the batteries are 100%.

Absorption = very precise charging profile (0.10 volt or amp for 0.10 second too long, and you've started ripping the water molecules into oxygen and hydrogen gas, which Sealed Lead Acid batteries (like AGMs) then have to burp out or crack open from the building gas pressure).

This again its not true. Too much current doesn't cause gassing - it's too high a voltage for too long - not 0.1 sec too long - that does the damage. But AGMs can cope because they rarely gas.

Float = constant 13.62 volt (temp adjusted) "charging" at very low amperage ...

Float mode doesn't limit the amperage. The lower float voltage will limit how much current the charger can deliver.

If two precisely controlled charging systems are simultaneously charging, their overlapping "absorption" charge profiles are usually ignorant of each other, thereby bubbling the electrolyte and likely burping out precious hydrogen and oxygen.

Just not true!

An unrecommended proof is to inject a CC or four of distilled water into each damaged sealed battery cell, seal the injection site, charge singly with a proven AGM charger, then capacity test again.....

Never inject extra water into AGMs. As you said above they are 'starved electrolyte' batteries which means the Glass Mat only absorbs 95% of the electrolyte. If a cell is overfilled and floods the mat it will initially behave like a vented cell and will gas too much to recombine ALL the H and O2 and so discharge quickly through the Valve Regulated vent.

These valves are usually designed to release excess gas once the internal pressure is about 2psi higher than the external air pressure. If the AGMs are burping or brapping or farting or raspberrying, you are slowly killing them again.

These valve are more likely to be set at 6psi. My Lifeline AGMs never burp even when being equalised at 15.5 volts for 8 hours - usually twice a year.. They can emit a very very slight bubble of air if the vent is covered with water. They lasted me 14 years.

[sailjumanji]

Originally Posted by Captain Bill

Absorbed Glass Mat batteries do not have any electrolyte that you could visually see like in a FLA battery. The electrolyte is confined to the mats between the plates. The small amount of water in the electrolyte won't be visible.

Ok, well that will save me a mess.

[rslifkin]

Originally Posted by sailjumanji

Well, I looked into this further, and the Mastervolt catalog agrees that their gel battery line is a better candidate, and of course, Li Ion would be the best.

https://www.delzer.com/powerproducts/mas_cat_003/64/

I wonder if their 6v AGMs are also beefier or better for deep cycling, going by the not-great experience you've had and others have mentioned with the 12v ones. My pair of 6v/400ah (L16 form factor) AGMs from them have been exactly on par with what I'd expect from any decent battery (so far at least). Brand wise, I ended up with them just because they were the only ones I could get locally in that size.

[Bycrick]

Your bus bar must have hair, because we’re splitting them now.

The bus bar is made of tinned copper. The stud/nut/washer are most likely stainless steel. So, on the bottom you have one interface, copper-to-copper (the tinning is thin enough to be ignored) between the terminal and the bus bar. On the top however, you have at least 4 interfaces, terminal-to-washer, washer-to-nut, nut-to-stud, stud-to-busbar. All of that is through SS which is only about 4% as conductive as copper. So the current through the nut and the stud is negligible for this discussion.

Corrosion doesn’t just happen. In this case, it happened because moisture intruded into the open space between the terminal and the bus bar. If the gap was enough to permit moisture to intrude, it wouldn’t have conducted electricity well either. So that connection was always higher resistance than it should have been. Corrosion might have made the situation worse over time, but it wasn’t right to start with. Putting dielectric grease on the terminals before assembly is putting an insulator ( look up dielectric if you don’t believe me) between the terminal and the bus bar. The theory is that it will squeeze out when you tighten it, allowing good contact. But where it doesn’t squeeze out, there’s no conduction. So the grease might stop future corrosion, but does nothing to improve the conductivity of the joint.

So I assert that the bus bar in question is just fine with proper cleaning, but that at least the bottom-most terminal is questionable and should be replaced.

Yes, I’m splitting hairs, just like the two old farmers walking along the road. One looks up at a flock of sheep on the nearby hillside and says to his friend, "I see farmer Jones has sheared his sheep." His companion blandly replies, "On at least one side."

[Bycrick]

Splitting hairs further, since you’ve got all the wires off of the bus bar, when you reinstall it, you shouldn’t just hook up the wires in random order. There are very specific rules.

1. If only one wire per stud, the highest current wires go in the middle, and closest together in order of decreasing current towards the ends.
2. For really high current wires, they go in the middle on the same stud.
3. If there are multiple wires on a stud, the higher current wires are closer to the bus bar.
4. If you have two heavy wires as in #2 above, eg the battery bank and an inverter, the source(battery) wire is closer to the bar.

In most cases, this is just a tiny detail, but if you’re putting it together new, you might as well use "best practice." Blue Sea has a description in their tech documents.

[sailjumanji]

Originally Posted by Bycrick

Splitting hairs further, since you’ve got all the wires off of the bus bar, when you reinstall it, you shouldn’t just hook up the wires in random order. There are very specific rules.

1. If only one wire per stud, the highest current wires go in the middle, and closest together in order of decreasing current towards the ends.
2. For really high current wires, they go in the middle on the same stud.
3. If there are multiple wires on a stud, the higher current wires are closer to the bus bar.
4. If you have two heavy wires as in #2 above, eg the battery bank and an inverter, the source(battery) wire is closer to the bar.

In most cases, this is just a tiny detail, but if you’re putting it together new, you might as well use "best practice." Blue Sea has a description in their tech documents.

Can you provide a link? I did find a technical article which was less detailed, and it was consistent. But it pointed to balancing the feed wire with the applicable load wire. Feed wire on bottom. For instance, outboard on bottom, and windlass on top - both on same stud. (Since we run the OB's when operating the windlass.) I guess house bank would be middle stud, on bottom, and solar be above that on same stud. I think the overall idea is to get the feed and associated load wire on the same stud, so that current flows from terminal to terminal contact, instead of through the buss bar.

[Bycrick]

Corrosion doesn’t CAUSE a high resistance joint unless one is misguided enough to connect two dirty, corroded pieces. Otherwise, it’s an indication of moisture intrusion into a bad joint that wasn’t properly gas-tight in the first place. I’ve taken apart joints with 2/0 terminals on 600A busbars that we’re crusty-green on the outside from an engine problem. Corroded badly enough that it was hard to get the socket on the nut. The contact surfaces were clean.

[Bycrick]

It sounds like you found the same Blue Sea article that I did. I embellished a little bit based on experience. The whole idea behind the order is to minimize the current/distance path in the bus bar to a minimum to reduce heat rise. Their description of balancing source/load wires is just one way. Even their 600 amp bus bar is rated for 40* C heat rise. That’s 104*F heat rise. Put that in an engine room at 120*F ambient and the temperature of the bus bar can be higher than you might think.

[Bycrick]

Just thinking, I wouldn’t think that the windlass wire placement would be as critical. It draws "a lot" of current, but a a small duty cycle. My windlass wants 15 seconds on and a minute off. I’d think just offhand that various charger and inverter wires are the priority because those are long-duration loads.