New AGM discharged to 4 volts.

soylentgreen

A friend who owns my old van was having house battery charging issues. Turns out he mixed up pole 86 and 30 in the isolator relay. As a result his brand new optima blue top battery was discharged in 12 hours to 4.5 volts. He asked me whether this one time event had ruined his battery. Any ideas?

solar_dave

Re: New AGM discharged to 4 volts.

Get a full charge on it and see how it holds up under loads. Pretty sure that he has at least shortened its life.

Cariboocoot

Re: New AGM discharged to 4 volts.

How important is the battery?
If it has to supply power where there is no other choice and having it suddenly go dead would create real problems, replace it.
Even if it will charge up it will not last and may suddenly fail without warning.

soylentgreen

Re: New AGM discharged to 4 volts.

He's been living with a nearly dead house battery for over a year so i would not rate this one as critically important. Mostly used for lighting and the water pump.

He got the battery on a charger as soon as he noticed so we figure it was sitting at low voltage for under 8 hours.

Do AGMs deal with severe under charge any better or worse than flooded lead acid?

Cariboocoot

Re: New AGM discharged to 4 volts.

Nope.
Same chemistry, different construction.
If it had been discharged a bit longer you might have even seen polarity reversal.

BB.

Re: New AGM discharged to 4 volts.

At this point--Recharge the battery and see how well it works.

If it is new and none of the cells went reverse polarity--It might work OK. It will probably have a few years knocked off its life--But if not critical application, what the heck.

If it is an older battery (few years old)--It may recover and seem to work OK, only to die a week or two later of daily use. I have seen this type of behaviour very often on automotive batteries. Somebody cranks the battery until dead or leaves the headlamps on. Gets a jump start, and car works fine for 1-2 weeks. Until the owner one day goes out to the car and tries to start it--and dead battery again (can be over night, or even just parking for a few hours while out shopping).

-Bill

john p

Re: New AGM discharged to 4 volts.

Honestly you just wasting time and effort. That battery is as good as dead. What use is reviving a battery if its only going to give a sudden total failure in next few weeks..???

sell it to someone you dont like.

soylentgreen

Re: New AGM discharged to 4 volts.

My buddy left for a 6 day camping trip, so I bet he'll find out how well it works (or doesn't) soon. Thanks for all the advice!

soylentgreen

Re: New AGM discharged to 4 volts.

To flog an expired equine here...

Does anyone have hard data showing, for a typical Lead Acid battery (flooded, AGM or whatever), the lifetime vs. # of complete (100%) discharges?

I've done some googling, and the best I can find:
http://www.batteriesinaflash.com/deep-cycle-battery-faq which suggests that for a Gel battery, 100% DOD only drops the cycle life to about 450.

http://pvcdrom.pveducation.org/BATTERY/charlead.htm which suggest for flooded battery, 100% DOD drops the cycle life to 200 or so.

http://www.solar-electric.com/media/wysiwyg/cyclelife2.gif suggests the same (100% DOD = 200+ cycles).

Now, I suppose one could argue my friend, having discharged his AGM battery to 4V, was way beyond 100% DOD?

Anyone have actual data (or just some good anecdotes?)

BB.

Re: New AGM discharged to 4 volts.

The problem (in my humble opinion) is that the 100% discharge, while very hard on batteries, is not the immediate killer.

It is when you take a lead acid (or many other rechargeable chemistries) down to "zero" state of charge is that unbalanced cells can end up causing a cell to be "reversed charged"--Basically, if the cells are not "balanced" in state of charge/capacity, for a 6 cell/12 volt battery, you can have one cell go "zero" first, and actually have its voltage reversed, and begin to be "reversed" charged by the energy left in the rest of the cells (that have have a few percent of charge left).

And for most (all?) standard rechargeable chemistries--If the battery cell voltage is reversed, it is generally death to the cell.

So, for flooded cell lead acid batteries, we assume that there can be a miss-match of "cell capacities" of upwards of 20%--So, if you take a typical battery down to 20% state of charge, you run the risk of one (or more) of the cells going dead and reversed.

AGM batteries have less of an issue of out of balanced cells (less to no equalization needed)--I am not sure about the ultimate "energy differences" can happen with AGM (same as or less than 20% miss-match than Flooded cell?).

For R/C and other applications--The hobbyist or manufacturer can match cells and make a pack so that they "discharge" to zero at the same time--To prevent a "weak cell" from going reverse voltage when deep discharged.

-Bill

waynefromnscanada

Re: New AGM discharged to 4 volts.

BB. wrote: »

The problem (in my humble opinion) is that the 100% discharge, while very hard on batteries, is not the immediate killer.

It is when you take a lead acid (or many other rechargeable chemistries) down to "zero" state of charge is that unbalanced cells can end up causing a cell to be "reversed charged"--Basically, if the cells are not "balanced" in state of charge/capacity, for a 6 cell/12 volt battery, you can have one cell go "zero" first, and actually have its voltage reversed, and begin to be "reversed" charged by the energy left in the rest of the cells (that have have a few percent of charge left).


-Bill

And THAT could well explain the 4 volts.

niel

Re: New AGM discharged to 4 volts.

if it's a 12v battery then 100% dod is at 10.5v. i would be shocked if this battery is still viable for very much longer, but stranger things have happened i guess. a proper load test would most likely show a significant loss of capacity.

john p

Re: New AGM discharged to 4 volts.

SOYLENT GREEN yes in fact a long time ago for a poster who wanted to know why 12v inverters were not designed to keep going when battery voltage got to 6 v or something like that..
I connected up loads to a 12v as new lead acid batt and measured the available output .at different voltage levels .. Icant find the orig data bit it was something like only 15w available at 6v.. After testing the battery was destroyed .. It would not fiully recharge no matter how we attempted to recharge it... This was done at work under very controlled conditions.So its about what can be most likely expected.

PNjunction

Re: New AGM discharged to 4 volts.

Optima's aren't that dainty folks, even when taken down to 4.5v. Not that you ever want to do this, but it is not doom and gloom. I've done this accidentally to a few Optimas and Odysseys, actually down to about 2v of terminal voltage. They did not immediately reverse-charge a cell.

Note that there are TWO types of "Blue-Tops". The one with the light-gray casing is the deep-cycle. If it is a black-casing with blue top, then that is the SLI version. Hopefully you have the deep-cycle version.

You got to it in time before hard sulfation set in. It is also new, so while you have put a little bit of hurt on it, as long as you were able to recharge it, you should be good. If all you had was a typical garage-variety smart charger, it may have balked at the low voltage trying to protect you from charging what it thinks might be a 6v battery.

A brand-new deep-cycle (light gray case) blue-top fully charged should read about 13.0v after a few hours rest. If it reads about 10.5 - 11v or so after a few hours rest, then you have a dropped cell IF you really were able to provide a full charge. There is plenty of info on the Optima site about alternative ways to charge too.

Tip: if this happens again, have an AC charger handy. In the case of the Optimas, I can vouch for their Digital 400 or Digital 1200 chargers. They have more or less replaced my stable of Vectors, Battery Tenders, Battery-Minders, NOCO's, Stanley's and so forth. I watch chargers like a hawk with my own Fluke gear, ammeters and so forth to watch and verify their claimed charge algorithms. You just missed an event to get the Digital 400 for free, or the 1200 for half-off. I was skeptical so I initially went for the 400 and really liked what I saw when I brought it to my bench for my own blue and yellowtops. The other chargers, while good, are getting sold/recycled just to reclaim some very valuable bench space.

The Optimas aren't made of paper-mache, but yes like all batteries can be abused to death. You got to yours in time, so I wouldn't sweat it too much. Not putting it on a charger after a jump-start, and relying on 20 or 30 minutes driving with the alternator is NOT ideal. This is similar to those who do parking-lot swap-outs, and their brand new battery never actually receives a single full charge.

Rely on your own experience. There is plenty of anti-optima bs out there, and if you follow the threads over the years, you find that the agenda is typically political about being made in Mexico (with the rants about it coming from entirely Chinese built computers!), or foiling the "I want to fool costco, wallmart, pep-boys etc into giving me a free battery for life" with total abuse indicating warantee fraud. Either that, or just total abuse from improper charging, mounting right next to headers, torque on the terminals, using red-tops for deep cycling, setting voltages with pos multimeters, or buying cleaned up used batteries from the back of some guy's van down by the river. Other tactics include anonymous dealers for other batteries starting FUD as if they were normal consumers. I have tracked all of this over the years, and a simple sentence 3 or 4 years into a thread like "what I tell my customers is ..." - caught ya!

Sorry about that - guess I had a little rant of my own there. While I have moved on to LiFePo4, I still respect my time with the Optimas and Odysseys.

CDN_VT

Re: New AGM discharged to 4 volts.

I now work on Fancy equipment! I came across a dead Vehicle with a gel-cell or AGM (Not FLA) Vent supply & discharge lines supplied to the battery. What I was told was the car needed charging and the gent who was to look after the cars was away. Someone hooked the charger up Backwards ?? But the 2012 car would still not work (Come awake , Keys or remote keys) Seems I did have 12.6 volts , I even load tested the battery (AVR Snap-on , And a quick Midatronics electronic battery check) . Im working off Jump stud ( Hidden Battery ) and frame . Seeing a positive earth is normal for some Shadowed Cars Rolls is normal with many shunts & extra backup wiring . I can't get into many areas of the locked down car . I call AG (Merc) and give the VIN etc. I now find out it's a Negative earth Vehicle.. SAM (Computers are not working ) is not working waking up etc. I know that the battery can or has the power to crank the system (Abit starter won't engage in reversal ) . so I now use cheap sealed beam head lights (hot wired to the main battery stud & frame )to drain the battery back to squat , and recharge back as a Neg earth Vehicle. It worked with much less damage as I would of thought . New Battery installed (600.00 I hear it cost ) . Plus time & travel from AG SSI.

So you can reverse the battery polarity or poles , Who-da thunk .. Let alone not KILLING the 90+ On-board Nodes .. Don't know if the battery would live out it's life like that.
Battery took 1/2 day to exchange & two gents to help me with their strength .

VT

ILFE

Re: New AGM discharged to 4 volts.

BB. wrote: »

The problem (in my humble opinion) is that the 100% discharge, while very hard on batteries, is not the immediate killer.

I agree. I left the lights on my Jeep once, with two Optima Yellow Tops inside (isolated, so only one was discharged) for about five hours or so. Came back out and the Jeep wouldn't start. Switched the dual battery switch to enable the second Optima and started 'er back up. Switched back to the "dead" battery and drove around doing what I needed to do all afternoon. The battery was fine until the day I sold the Jeep.

CDN_VT wrote: »

.62 of a decade & still can't spell

.62 of a decade? You are a young whippersnapper.

Cariboocoot

Re: New AGM discharged to 4 volts.

Optimas are spiral-plate AGM's. They can drop dead just like any other battery. By the same token, a good standard battery can 'recover' as described too. I have a friend in Alberta who will not buy Optimas because one left him suddenly stranded in Winter despite not being old or abused.

There's no magic; only physics.