Battery Question

[davel501]

One of my Blue Optima 31s is showing fully charged on the charger but not putting out any juice. I took it to AutoZone and they tested it at 5.6v. The test unit said to charge the battery then retest so they did. They got it to 85% charged before they had to stop because it was too hot. The thing is still pretty hot an hour later.

They said it passed the test on the second try but I am thinking they just did not wait for the voltage to dissipate. Tempted to take it over to Napa and get the process started swapping it out for a new one.

What does everyone think?

 

[jetboater4life]

Is it still under warranty?

 

[Island Jay]

what is the make and model of your battery charger?

 

[Murf'n'surf]

How long was it under charged? All winter?

Just for S's and G's take it to another place tomorrow for a test. I bet it's toast.

If you have a multi bank charger it is probably reading the charge of all the batteries and not individual ones. That would explain the incorrect reading on your charger.

 

[davel501]

Charger is a Guest 2620a dual bank charger. It seems to read the banks independently when everything is working right.

Battery is still under warranty for another 2 years. It is also still warm (and now sitting outside). I am guessing it was somewhere around 115F before and maybe 90F now.

It was dead the last trip of the season in the fall and never worked right after, even when I charged it. I figured maybe it was wiring or the charger but this whole hot battery bit has me thinking it is the battery.

 

[Gym]

Sounds like the battery's internal resistance is through the roof causing all the heat. It could be a fire hazard.

 

[davel501]

Found this on another site and it looks like what may have happened:

Overcharging, overcharging which causes thermal runaway. Basically your battery overheats from oxygen recombining with the negative plate, etc. Causes all kinds of internal damage. AGM are the most prone to this, Gells are more resistant, flooded batteries are the most resistant

Then I found this:

What is a thermal runaway?
The appropriate charge voltage depends on the battery temperature. A warmer battery requires a reduced voltage. If the voltage is not reduced the current accepted by the battery increases. When the current increases heating within the battery increases. This can continue in a loop feeding on itself with the battery temperature and charging current rising to destructive levels. This is thermal runaway. Gel batteries are much less susceptible to thermal runaway than AGM batteries. Batteries may become more susceptible with increasing age. Without a recombination reaction, flooded batteries convert most excess charging energy to gas, not heat. This makes them almost immune from the thermal runaway.
Thermal runaway can be prevented with:
* Temperature compensation monitoring at the battery – not at the charger.
* Limiting charging currents to appropriate levels
* Allowing for adequate air circulation around the batteries.
* Using timers, or Ampere-hour counters.
* Using smart chargers that recognize the signature of a thermal runaway which will shut the charger down.

http://www.discover-energy.com/faqs/thermal_runaway

Sounds like the battery is sleeping outside tonight and going back to Napa tomorrow.

In general it sounds like there is a lot to know about AGM batteries. If you short the terminals they can dump all of their energy very quickly, much more quickly than regular batteries. They can also leak, catch fire or explode due to thermal runaway. Seems there is always a trade off.

 

[jetboater4life]

Very interesting read. We have to mitigate this effect on the memories and chips I design. Your Guest charger must not have a mode to detect a battery entering the thermal runaway state. I'm using the Pulse Tech X2 Xtreme Charger and although it supplies half the effective current as your Guest charger I wonder if it has this thermal runaway state detection. My guess is no.

 

[davel501]

My Guest would shut off reporting it fully charged even though the battery would not put out enough juice to even run the nav lights.

I think AutoZone must have had a very high powered but not very smart charger that just dumped way too much current into the battery. Knowing what I know now I might have volunteered to return tomorrow to pick up the battery rather than go driving around with it hot in the back of my Armada.

 

[Island Jay]

Shy of the charger being defective, that charger is fine for AGM's. Low amp chargers can kill an AGM's life span, but I do not think that is the case here.

 

[Glassman]

Shy of the charger being defective, that charger is fine for AGM's. Low amp chargers can kill an AGM's life span, but I do not think that is the case here.

Really?
Is that true of ALL batteries or just certain ones? My Mercedes has an AMG battery in the trunk and I use a low amp charger to keep that in shape, it's the same specs as the charger the dealer sells for $150. It's a CTEK Multi US 3300 and they charge triple for it!! Specs: 0.8/3.3 amps. I don't want to ruin a $350 OEM battery.

I've always used low amp chargers on my small batteries with great success. I've had little motorcycle batteries last a long time, longer than usual, when I remember to hook up the 2 amp maintainers. My only issue is that I have so many batteries to keep track of I forget from time to time.

 

[Island Jay]

The thing with AGM's is they need to charge at a certain amp. Maintaining is a different story, so it may be fine there.
Now with smart chargers, low amps are not necessary as the charger is computer controlled.

 

[Glassman]

The thing with AGM's is they need to charge at a certain amp. Maintaining is a different story, so it may be fine there.
Now with smart chargers, low amps are not necessary as the charger is computer controlled.

Gotcha, thanks. The C-Tek is a smart charger, Charges 12-volt lead-acid batteries (Wet, MF, Gel, AGM and Ca) from 12Ah to 75Ah (charging) or 12-120Ah (maintenance)

 

[David Analog]

Some random thoughts.
Many chargers will go into their protect mode when faced with a 5 volt battery. Sometimes you need to use another charger or battery to build it up to a serviceable point. But monitor it closely.
C-Tek behaves a bit bigger than its amperage rating because of its pulse technology. For years and before they had their own chargers, Optima personnel recommended C-Tek.
You do not need high amperage to maintain a battery of a vehicle that is placed into storage with a full charge, ie, weekend car, airport car, motorcycle, ATV/UTV, tractor, etc. A deeply cycled battery with tons of amp/hour capacity is another story.
Those big roll-around blunt booster chargers or a garage emergency 2/5/10 amp charger can be dangerous and I wouldn't walk away from one.
I've seen tons of abused Optima batteries. Especially in store displays where they were used to stiffen a power supply voltage under load. If hot enough they will leak around the posts and the case will distort. Two easy clues they're done. But I've also seen more with an inordinately low voltage that will come back to life with the right capacity smart charger. 10 amps on a group 34 and perhaps 15 amps on a group 31 would be maximum for a limited duration.
If you are not in a hurry, you can get a good feel for a battery by leaving a fully-charged (once the higher charger voltage has dissipated) battery in isolation for several days. Self discharge, especially on an AGM, is very low. So any marked decline and inability to hold a charge with no load is a sign its done.
An alternator rebuilder told me he would be out of business if people replaced their batteries on time rather than pushing through the rest of the season.

 

[davel501]

That last bit about frying stators stuck in my mind from other posts. I figured I paid for the expensive battery with the good warranty so I should take advantage of it. Took the battery back to Napa today and they will have a brand new one for me tomorrow morning.

 

[MikeyL]

Some random thoughts.
Many chargers will go into their protect mode when faced with a 5 volt battery. Sometimes you need to use another charger or battery to build it up to a serviceable point. But monitor it closely.
C-Tek behaves a bit bigger than its amperage rating because of its pulse technology. For years and before they had their own chargers, Optima personnel recommended C-Tek.
You do not need high amperage to maintain a battery of a vehicle that is placed into storage with a full charge, ie, weekend car, airport car, motorcycle, ATV/UTV, tractor, etc. A deeply cycled battery with tons of amp/hour capacity is another story.
Those big roll-around blunt booster chargers or a garage emergency 2/5/10 amp charger can be dangerous and I wouldn't walk away from one.
I've seen tons of abused Optima batteries. Especially in store displays where they were used to stiffen a power supply voltage under load. If hot enough they will leak around the posts and the case will distort. Two easy clues they're done. But I've also seen more with an inordinately low voltage that will come back to life with the right capacity smart charger. 10 amps on a group 34 and perhaps 15 amps on a group 31 would be maximum for a limited duration.
If you are not in a hurry, you can get a good feel for a battery by leaving a fully-charged (once the higher charger voltage has dissipated) battery in isolation for several days. Self discharge, especially on an AGM, is very low. So any marked decline and inability to hold a charge with no load is a sign its done.
An alternator rebuilder told me he would be out of business if people replaced their batteries on time rather than pushing through the rest of the season.

Thanks for another 1 of your Thoughtful and VERY INSIGHTFUL posts.
Very much appreciated. Happy 4th upcoming to you and yours !
Mikey Lulejian - Lake Oconee, GA

 

[davel501]

New battery was dead today while plugged in and showing green on the charger. Blown fuse in the positive lead to the house battery. <facePalm/>

 

[Island Jay]

Well at least that is an easy fix.

 

[txav8r]

This is sounding like a faulty charger to me killing batteries dave. I would also double check the dvsr and make sure those batteries are totally isolated when charging on your dual bank.

 

[Island Jay]

was there a deeper issue that I missed?