Odd (and alarming) failure mode of Optima 12V battery

I have read on this forum that the Prius takes 8 hours or so to charge a 12v battery that is that low. I don't think the charging system could of got your battery that hot in that short of time. Sounds like a short in the battery to me.

 

I think that the time to reach full charge is more a function of the relatively low charging voltage than the lack of available charging current. I'm pretty sure member Britprius recently measured his Prius supplying quite large charging currents into a new battery.

Interesting post priusenvy. If the optima was low in charge but otherwise in good condition (so low resistance) then I guess the jumping battery could also have given it a huge current surge that damaged it. I wonder if the outcome would have been different had you attached a charger to the battery for an hour or so instead of jumping? My battery charger has a "boost" setting designed for rapidly getting a battery to cranking condition. I haven't tested it on the prius but I'm pretty sure it could jump start it easily enough.

 

The Prius can charge the battery at high rates. With a 60 AH battery discharged 20% I recorded a charge rate of
43 amps for a few minutes, dropping back to around 10 amps.

I am in the prosses of taking more readings to discover the maximum charge rates and times, but this will vary with different batteries and different capacities.These numbers will be made available on PC when complete, but take considerable time to gather and I cannot have my car in a condition where it is not useable for long periods.

It would not supprise me to find a charge rate of 50+ amps for a short period. It is likely that your Optima had one or more shorted cells causing the other cells to be over charged and heated rapidly.

The charging system could in theory put 750 watts into your battery ( 50 amps x 14.6/8 volts) much of wich would come out as heat.

John (Britprius)

 

Optima give the charge rate for the yellow top as 10 amps, quick charging can be carried out but the battery temperature should be monitered and not to go above 50c / 125f.

John (Britprius)

 

Yeah it's definitely a failed battery then. Thanks for the info.

BTW, what was the warranty period on that battery?

 

I have several Optima "red top" starting batteries and find them to be exceptionally powerful and long lived (15+ years). I have little experience with the Optima "Yellow top" deep cycle battery, except what I read on the internet.
It seems that Optima recommends using the yellow top as a starting battery in rigs that have accessories ( Winch, off roaq lights, high power sound system, etc, which tend to deep cycle the battery a lot. In optima's mind it is better to subject a deep cycle battery(yellow top) to heavy starting loads, than to deep cycle a red top starting battery. This seems to work as long as you do not cycle the yellow top below 50% charge. Discharge them below 50% charge often, and they die an early death, many uhappy customers.
The total discharge /recharge several times may have caused enough warping of the battery plates to cause a shorted cell. as others stated, a 12V battery with a shorted cell is now a 10V battery, and the cars charging system will attempt tthe impossible task of bring a now 10V battery up to the normal system voltage of 13.5-14 volts.
This will put enough amps into the remaining 5 cells to cause the excess heating and gassing.
If your prius must set unused long enough so the cars "always on" electronics drain it to 50% charge or less, I would install a good charger / maintainer designed to maintain sealed AGM batteries.
I have a BatteryMINDer brand unit permenently mounted to the battery on my 10 Prius. I plug it in to maintain the battery any time the car has/ will be parked unused for more than a week. It will maintain and desulfate the battery to increase it's life.
BatteryMINDer Charger/Maintainer/Desulfator System — Model# 1500 | Battery Maintainers| Northern Tool + Equipment

 

after experiencing the dangerous failure mode? This doesn't make sense to me but I suppose some are more risk tolerant than others.

 

In all of the hundreds of posts concerning Yellowtops, this is the first time somebody has reported a failure. That indicates a pretty low MTBF rate, and I would have no hesitation replacing my yellowtop when it finally bites it!
I ran a redtop in my 4Runner for years, also trouble free. Until I took it to the dealer for some service where they had to move the battery. When they put it back in, they did not tighten the battery clamp down had enough, if at all, and vibration rattled the battery up against the fan belt pulley. It chewed through that plastic in minutes, next morning battery was dead, put the charger on it, it took a charge. When I pulled into the driveway it bounced the battery off the pulley, braking the grounding short. Ran fine for a couple of days, then dead again. I finally looked closely, saw the gash, noticed the battery holder was loose, CRAP!
I drove it up to the dealer, got the Service Manager who wrote up the initial service request out to the truck. I popped the hood, and asked, "By the way did you have to remove my battery for the service your guys did?"
Well yes he replies, we have to. I asked him to inspect the battery hold down, he picked up pretty quickly on the small problem and said, it should not be this loose, I will get one of the guys to tighten it up for you.
Too late I said, and lifted the battery up, he saw the gash, I said, I guess this is why the tie down bar has to be tightened, right!
Toyota bought me a new battery, and were actually nice about it!
Sweet!

 

Whenever any battery is discharged below 12.4 volts and left sitting in that state, sulfation begins to form on the plates, which diminishes both capacity and lifespan. Fully-charged, our YellowTops will measure about 13.0-13.2 volts. The longer any battery sits in a deeply-discharged state, the more damage is done. While this damage can sometimes be reversed to some extent, through proper charging, jump-starting a vehicle or even charging a battery for a short period of time with a battery charger to get a vehicle going will not typically fully-recharge a deeply-discharged battery.

At that point, the vehicle's charging system begins working very hard to get the voltage back to fully-charged levels and sometimes the outcome is overcharging either due to the vehicle's charging system or the amount of internal resistance that was created in the battery, because of the sulfation that was allowed to build up on the plates.

Do a google search for "jump start battery hissing" and you'll see all kinds of conversations with similar stories with all brands of batteries. Once electrolyte has left our batteries (or any other sealed batteries), some irreversible damage has been done. That doesn't mean the battery is no longer functional, but that certainly could be the case.

I would suggest fully-charging the battery with a battery charger at a 10-amp rate for up to two hours, to help break up the sulfation that formed in the battery while it sat in a deeply-discharged state for months at a time. Be sure to monitor the temperature of the battery during charging. It's ok if the battery gets warm while charging, but if it gets hot to the touch or begins venting or hissing, you should discontinue charging immediately and recycle the battery.

Once it is fully-charged to about 13.0-13.2 volts, it should be able to hold close to that voltage for 12-24 hours, when disconnected from your vehicle or any other draw. If the voltage level drops significantly during that time frame or you are not able to fully-charge the battery, you should recycle the battery. If it does hold voltage, but you'd still like to make sure it is ok, you can take it to most auto parts stores in a fully-charged state and have them perform a load test for you.

Going forward, it is a good idea to either keep your battery on a quality battery maintenance device when your car goes into storage or make sure the battery is fully-charged and disconnected from your vehicle when it goes into storage.

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.
OPTIMA® Batteries (optimabatteries) on Pinterest

 

Thanks Jim, well written.
And who says that manufacturers do not read this forum, and then respond????
SWEET!

 

Hey, that was my 3500th post!

 

Hi Jim,

From the above, do I glean correctly that, in the most common case of an Optima being deep-cycled (because a dome light was inadvertently left on), one should either drive the car for a couple of hours for the Prius charging system to fully charge the battery back up or if that's not possible, use an external charger at a 10Amp setting for up to 2 hours to fully charge the battery? Also, IIRC the Optima can withstand 300 deep cycles? Has the Optima been tested for deep-cycle recovery by the Prius charging system (not an external charger)? The Prius charger has been seen by some to use currents as high has 60 Amps to charge the battery. Has the Optima been tested to withstand this high-current?

Thanks.

 

That's a great question srivenkat. If any battery becomes deeply-discharged, I would strongly encourage fully-recharging it with a battery charger and not the vehicle's charging system. Vehicle charging systems are generally designed to maintain batteries that are near a full state of charge. Relying on the charging system to recover a deeply-discharged battery can lead to premature failure of the charging system and often does not result in the battery getting fully-recharged.

We recommend a maximum rate of 10 amps when charging our batteries with conventional battery chargers. The DS46B24R Prius battery is a 38 Amp/hour battery, so in theory, it could take up to 3.8 hours to recharge the battery, if it has been completely discharged. In reality, most chargers begin tapering both amperage and voltage early in the charging cycle, so an additional 10-20% should be factored into the equation for that reason.

Vehicle charging systems are a different story and many alternators are rated at far more than 60 amps, which is not an issue for our batteries as long as the voltage is properly-regulated. I don't know if any of our batteries have specifically been tested for deep-cycle recovery by a Prius charging system, but as I mentioned earlier, I wouldn't suggest it for our battery or any other, if it can be avoided.

Jim McIlvaine
eCare Manager, OPTIMA Batteries
OPTIMA® Batteries on Pinterest