FRC batteries wont charge

[DeadlyJohny]

Our FRC batteries from 2010,2011,and 2012 all are not charging. We have used two different chargers and both are giving the same thing, no charge.

Anyone else have this same issue? What's the solution?

[BugByte]

When was the last time you charged them?

[DeadlyJohny]

well, last summer really, but that was only one of them. (This is, of course, besides their individual uses in each years competition.)

[kevin.li.rit]

These batteries must be recharged on a regular basis. If not they will die a premature death. This has to do with the construction and material of the battery. We typically top them off every month. If they've are stored in the cold they eill also discharge quicker.

[F22Rapture]

Also, avoid vibration when they are discharged. Try to keep the ones that are on the robot topped off as well as possible. This is due to the chemical reactions inside the battery, as Lead Sulfate forms a powdery residue on the surface of the lead plate which can be shaken off and eventually degrade the entire terminal. This is also how deep-discharged batteries fail.

[DonRotolo]

So the bad news is, those batteries have failed. You need to replace them. Sorry.

Keeping them charged all the time is important, as you now have learned.

[Ether]

Originally Posted by Coffeeism

If they've are stored in the cold they eill also discharge quicker.

"Self-discharge is a chemical reaction, just as closed-circuit discharge is, and tends to occur more quickly at higher temperatures. Storing batteries at lower temperatures thus reduces the rate of self-discharge and preserves the initial energy stored in the battery."

http://en.wikipedia.org/wiki/Self-discharge

[DonRotolo]

Ether is correct. The cold weather myth regarding lead acid batteries comes from the fact that a car's engine requires more energy to start in cold weather than in warm weather, because of the difference in lubrication viscosity and in the combustibility of fuel at low temperatures.

Since you need more energy at low temperatures, a slightly weak battery won't have enough energy to start the engine. This makes people believe the cold weather is bad for batteries, whereas hot weather is worse for battery life.

[kevin.li.rit]

Originally Posted by DonRotolo

Ether is correct. The cold weather myth regarding lead acid batteries comes from the fact that a car's engine requires more energy to start in cold weather than in warm weather, because of the difference in lubrication viscosity and in the combustibility of fuel at low temperatures.

Since you need more energy at low temperatures, a slightly weak battery won't have enough energy to start the engine. This makes people believe the cold weather is bad for batteries, whereas hot weather is worse for battery life.

Think about it twice... you're both right. I recall this statement being told to me by the guy who sold me my motorcycle...

[Mr V]

If you've let them discharge to far then some chargers won't charge them as they don't see the extremely low voltage as a valid battery and won't turn on. If you can find an old school charger you may be able to get them to charge. If you don't have access to a old school charger you can hook the battery up in parallel and charge them both for a short time. That should trick the charger to turning on and get them to a high enough voltage to make them accept a charge. However you have comprimised the batteries capacity and it may not have the power and length of use you desire. They may be suitable for another year as a practice only battery though.

[Ether]

Originally Posted by Mr V

...they don't see the extremely low voltage as a valid battery and won't turn on... If you don't have access to a old school charger you can hook the battery up in parallel

Did you mean "series" ?

[DonRotolo]

No, I think he meant parallel. The myth is that good battery fools the charger into supplying energy, applying charge to the bad battery.

The sad reality is that permanent damage has already occurred, and no snake oil is going to change the chemical facts. Yes, you can get some charge into it, but hardly worth it, as even fully charged they will be woefully inadequate.

[Ether]

Originally Posted by DonRotolo

No, I think he meant parallel. The myth is that good battery fools the charger into supplying energy, applying charge to the bad battery.

Yes, that's a possible interpretation. But since he never mentioned a good battery, what he appeared to be saying is that two of the bad batteries -- in series -- would present enough voltage to the charger to fool it into thinking there was one partially discharged battery.

But if the two bad batteries are so bad that it takes two of them in series to mimic a partially-discharged good battery -- and they've been stored that way for some time -- then the following is almost certainly true:

The sad reality is that permanent damage has already occurred, and no snake oil is going to change the chemical facts. Yes, you can get some charge into it, but hardly worth it, as even fully charged they will be woefully inadequate.

[Mr V]

Originally Posted by Ether

Did you mean "series" ?

Originally Posted by DonRotolo

No, I think he meant parallel. The myth is that good battery fools the charger into supplying energy, applying charge to the bad battery.

The sad reality is that permanent damage has already occurred, and no snake oil is going to change the chemical facts. Yes, you can get some charge into it, but hardly worth it, as even fully charged they will be woefully inadequate.

Sorry I wasn't clear last night, I was tired after getting up at 5am to judge a FTC event and then not getting home until late.

Yes I meant hook it up in parallel with a charged battery. That will fool the charger into turning on and charging the battery. That is no myth, that is what is recommended by manufacturer of the best known automotive application AGM batteries, Optima.

From the FAQ on their website.

If an OPTIMA battery is deeply discharged (below 10.5 volts), most basic chargers will not supply a charge. Also keep in mind that an OPTIMA battery will not recharge properly if treated as a regular flooded or gel battery. To charge the battery, you can wire a second fully charged automotive battery (12+volts) to the discharged AGM in parallel (+ to + and – to –). Then hook up the charger to the deeply discharged battery, setting the charger at 10 amps. Leave for two hours, monitoring frequently. During this process, if the discharged battery gets very hot or if it is venting (hissing sound from vents), then stop this process immediately. When the discharged battery reaches 10.5 volts or more, remove the standard battery and continue charging the AGM until fully charged.

For normal charging, a relatively low current, such as one or two amps, can work well, but when the battery has been deeply discharged, some sulfation of the battery plates may have occurred. If you charge at 10 amps, the higher current will help to break up this sulfation.

If you have an automatic charger, let it run until the charger indicates charging is complete. If you have a manual charger, you can get a rough estimate of the charging time in hours of a completely discharged battery (11.2 volts) by multiplying the capacity (amp hours or Ah) of the battery by 1.2. If your battery is not completely discharged, the time would be less.

In most cases these steps will recover an AGM battery. It’s OK for the AGM battery to get slightly warm during the charging process. If it’s hot to the touch, it means there’s a short and the process should be discontinued.

Note the 2hour/10 amp recommendation is for an automotive sized (44AH and larger) battery not a FRC sized battery. Do not exceed the 4A recommended rate for the FRC battery and I would not charge it for more than 30 minutes at a time, before trying to get it to charge by itself. Pay special attention to the parts I've italicized in red above, with everyone in the area wearing safety glasses.

Even if they do come back to life, I would not consider the batteries to be competition worthy.