Bad Batteries?

[TJ&LadyDi]

We were in a "rehab" state with the coach at that time so the coach remained stationary and the batteries never saw any use. They remained connected to shore power and should never have discharged enough to need the inverter/charger to "catch up".

Is it possible, then, that they were constantly being overcharged? I could understand one battery going bad in a relatively short period, but four going bad kind of points to some external cause.

Not trying to find blame here, but since the battery system in your previous coach was put together by you, I'm wondering if there was a mismatch between components. Engineering a 12 VDC system can be tricky and especially when retrofitting it into a coach that initially came with a different system.

TJ

 

[Jim]

Is it possible, then, that they were constantly being overcharged? I could understand one battery going bad in a relatively short period, but four going bad kind of points to some external cause.

Not trying to find blame here, but since the battery system in your previous coach was put together by you, I'm wondering if there was a mismatch between components. Engineering a 12 VDC system can be tricky and especially when retrofitting it into a coach that initially came with a different system.

TJ

I’ll be the first to agree that 4 batteries going bad at the same time is highly unlikely. To be honest, lately I've begun to wonder if they hadn't been damaged somewhere along the line, prior to my receiving them?

Attached is a diagram of how I wired them, let me know if something looks incorrect. The AIMS inverter/charger was brand new, but I guess that doesn't guarantee it is working correctly. But at the same time I installed the batteries and the AIMS, I also installed the shunt/monitor so I could monitor them, and everything always looked normal to me.

Except for 1 trip to the local campground, the coach was always connected to shore power, and on that trip, I made sure to monitor the batteries and to run my generator when the SOC started getting low. I tracked everything and kept detailed notes of it all. Upon return, we parked the coach and connected to shore power. And although I didn’t look at the monitor every day, I did check it from time-to-time, and it always looked normal.

When the new coach arrived, I removed the AIMS, the batteries and some other switches and wiring from the older coach. While the batteries were out, I tested each one individually (different charger) and that’s when I noticed each battery was slightly under 6 volts.

I took the batteries back to the dealer, he put them on his charger for a few days, and then called and said they were fine. I reinstalled them in the new coach, minus the shunt and monitor and that’s where they sat for several weeks. The coaches display always indicated a full set of bars so I assumed the batteries were charged and OK. To be sure I put a handheld tester on them and they always indicated a full charge.

Not long ago, I installed a solar controller in the basement but hadn't wired it to the solar panels yet. I turned off the shore power to watch the LED on the controller and I noticed the batteries were indicating a low charge. (Note: At the time, there was an electric heater in the coach which drew hard on the inverter/batteries.) I then hooked up the shunt and meter and started to run some tests.

And that’s how we got to where we are today. Probably more information than you needed but there you go. The batteries indicate a full charge until I put a load on them, and then they start to discharge abnormally fast.

So, I guess they could have been overcharged, but they’ve always been treated well when in my possession. Perhaps the store caused some damage when I took them back to be inspected? At the time I picked them up he told me that he had to “blast” them for a couple of days to get them to respond but that they were fine now. So maybe they suffered some damage at that time. All I know for sure is they were treated well while in my possession..

Let me know if the diagram looks OK to you.

Thanks!

 

[Jim]

Is it possible, then, that they were constantly being overcharged?

All the above withstanding, the fellow I spoke with at Crown Battery seemed to think that the batteries were "undercharged", not overcharged. His feelings were that when the batteries were moved from the older coach (with AIMS charger/inverter) and placed in the Phaeton, that the Phaeton was set to charge/maintain AGM batteries, so over time, the Flooded Acid batteries were not getting charged.

My battery background pales compared to his, so who am I to say he's wrong? But I've never heard of that before. My understanding (when it comes to charging AGM batteries) is that they need to receive a slightly lower charge rate or they will get hot and can be damaged. But I've never heard that Flooded Acid batteries will suffer damage if charged with a slightly lower charge.

 

[TJ&LadyDi]

Well, @Jim, we've pretty much reached the end of my battery expertise. Maybe some of the other folks here will have some better answers.

Hopefully, a new set of batteries will resolve the issue for you. I know how aggravating a problem like this can be; after while it seems like every avenue is a dead-end street.

Good luck on resolving this.

TJ

 

[Jim]

Well, @Jim, we've pretty much reached the end of my battery expertise. Maybe some of the other folks here will have some better answers.

Hopefully, anew set of batteries will resolve the issue for you. I know how aggravating a problem like this can be; after while it seems like every avenue is a dead-end street.

Good luck on resolving this.

TJ

Well one thing is for sure, the batteries didn’t commit suicide and die on their own. Something got em, and it would be nice to know what it was before I subject new ones to the same fate. Hate to relive this same scenario again later.

 

[NWIP]

I would think a call to manufacture of converter/charger would help make sure you have correct settings for the new batteries

 

[Neal]

No battery expert here but if ONE of them are bad it may affect others so each battery needs to be tested to find the one bad one in the group.

 

[Chuggs]

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I would fully charge the batteries...then disconnect the batteries...let them sit for at least 2 hrs to dissipate any surface charge...take voltage readings for each battery...and specific gravity reading for each cell. This will help identify a weakened battery or cell. Crowne is a reputable mfg...I feel somewhat confident that plate erosion is NOT your concern. Sulphation is the enemy. When you discharge the battery the sulfuric acid reacts with lead to form depisits of Lead Sulphate on the plates. Recharging should dissolve this deposited and put the irons back into the liquid solution. Your specific gravity measures this. A fully charged battery should have a particular specific gravity...if you notice your batteries do not meet this benchmark...of note, you are victim to suplhation that has not dissolved back into solution. This robs your battery of capacity. Ideally, we all would be measuring our specific gravity each quarter...and if a battery is low, or I individual cells show variance...we do the equalization or conditioning charge. There are some commercial tonics which are claimed to help with this...and Battery Minder uses high frequency pulses to help desulohate a battery. May be worth a try on such young batteries.

The way you have them wired...although I am guilty of the same...is not ideal. Ideally, the pathways should be equal. Your leads take a shorter path across the front two...and a longer path across the rear two. This will make one pair work more than the other. In future cabling design...especially since your shunt goes to one location...best practice is most positive and most negative. The pathway across any pair should be equal length...length of cables or jumper bars... This way the resistance is the same. It goes along with the idea that batteries should all be changed as a set...of equal capacity and age.

I kinda wave the BS flag on amperage. Amperage is a rate. I may be wrong, but equalization/desulphating is done off of voltage... I think it is quite possible that you didn't do this often enough...again, we all are probably guilty of this. The longer sulphate are left on the plates...the more difficult they are to redissolve.

The enemy is allowing a battery to sit in a discharged state. If you had your batteries on a charger, they should have stayed fully charged. I rarely see amperage get much above 10A each day when my solar system wakes and brings my bank up to absorption voltage, then drops down to just a couple of amps to float the remainder of the day. Can high amps be good? I guess heating the solution may make a difference...but charge is charge...if the battery reaches full charge, you've done what you can to redissolve the lead sulphate.

I will probably do a few equalization rounds on my own batteries...and see if the voltage follows the common drop proportional to aH used... But don't really expect a miracle. They are 4 years old...and I expect for the capacity to go down with age. I'll hopefully notice a change in S.G. after each round...but we'll see.

Without being able to take a drop of battery acid out for testing, I'm not sure what AGM owner's use to quantify a time to equalize...

 

[Jim]

Thank you for that @Chuggs

Is the attached drawing correct ? Or have I missed the boat ?

 

[Chuggs]

Perfect...once the electron passes to the most positive or most negative...I see two lengths of copper to make the journey regardless of front pair or rear pair. It looks to me you have a balanced pathway. Sorry, but I really can’t quantify the importance of this...it just seems to be the “best practice“.