Here is some information I found looking at information on Optimas and other AGM batteries. If your AGM battery will not take a charge after being run down, a conventional charger will no longer 'recognize' the AGM battery and will not charge it as it is supposed to do. The specialized AGM battery chargers are nice to have for sure, but they run in the neighborhood of $200, about the price of a new Optima.
Here is the trick to get your regular garden variety battery charger to charge your gel cell/AGM batteries. You can rig the jumpers between the two batteries with regular jumper cables:
How To Charge an AGM Battery - A Current Affair - How To Do It
HOT ROD Untangles A Mystery: How To Bring An AGM Battery Back From The Dead. Before You Replace That Expensive Piece, Try This.
By Bill McGuire, Photography by Bill McGuire
Hot Rod Magazine, September, 2010
At HOT ROD, we hear stuff. Lately we've been hearing about hot rodders' love/hate relationship with their sealed, leakproof batteries. You adore their ability to take punishment and their paint-friendly nature, but they have developed a reputation for refusing to take a charge once they have gone dead. Here's how to bring them back to life.
First, some background. While the spill-proof batteries currently on the market are often referred to as gel batteries, most are AGM batteries-short for absorbed glass mat. Optima and Odyssey batteries are common examples. Unlike a gel battery, in which a silica agent is added to the electrolyte to form a semisolid, an AGM battery uses an ordinary sulfuric acid solution like any standard automotive battery (about 60/40 water and acid at full charge). However, here the electrolyte is absorbed and retained by layers of boron-silicate glass matting between the lead plates. While both battery types can rightly be considered leakproof and spill-proof, AGM is currently considered the superior technology, especially for automotive use. Some AGM batteries employ spiral-wound, cylindrical cells (Optima), while others use flat plates and box cells (Odyssey) like conventional batteries. Also, sealed is something of a misnomer-lead-acid batteries generally are capable of venting when necessary.
How To Charge A Agm Battery With Another Battery
Here's the magic fix: When an AGM battery won't charge by ordinary means, simply connect a
Hot rodders are tough on batteries, but the extreme heat and vibration we deal them aren't the half of it. Between these rounds of serial abuse, often we let our cars sit unused for extended periods-like between race events or cruise nights, or even for the entire winter. Also, the electronic gadgets in newer cars (engine and body computers, entertainment and security systems, and so on) often employ keep-alive memory functions that place a small but constant current draw on the battery.
That's an awful thing for automotive batteries, because they all will self-discharge over time-even the more expensive deep-cycle models (just more slowly). At room temperature, a standard battery loses nearly 5 percent of its capacity per month just sitting on the shelf. And once the battery's voltage falls below around 1.75 volts per cell, permanent damage begins to take place in a process known as hard sulfation. Essentially, the plates become coated with gunk (dense lead sulfate crystals), reducing the battery's capacity. If a battery is allowed to discharge long enough or not properly recharged between discharges, it's a dead player. Its plates are completely sulfated and nothing will bring it back.
How To Charge A Agm Battery Optima Yellow And Red Top Batteries
Some AGM batteries, like the Optimas shown here, use spiral-wound plates in cylindrical cells-hence the six-pack appearance. Among other things, spiral-wound cells allow purer lead to be used in the plates, it is claimed, since they need not support their own mass. Other AGM makers say conventional construction is superior, claiming greater plate area for a given case volume. In the Optima line, the RedTop is the performance piece, while the YellowTop is a dual-purpose battery for both performance and deep-cycle use. (A race car with no charging system would be an ideal application.) A dark-gray case denotes a conventional Optima battery, while light gray indicates a deep-cycle model. Deep-cycle batteries deliver lower peak current but can withstand deeper discharges. A BlueTop Optima is for marine applications. It will start your car but is not optimized for automotive use.
How To Charge A Agm Battery Optima Yellow And Red Top Batteries
Some AGM batteries, like the Optimas shown here, use spiral-wound plates in cylindrical ce
To replicate these diabolical conditions, we obtained two new Optima AGM batteries, a standard RedTop and a deep-cycle YellowTop model, and submitted each to a constant 2.2-ampere load. At regular intervals over many days, we removed the load and attempted to recharge the batteries using a standard, repair industry-style, 2/10/40-ampere, roll-around charger, known in the biz as a bulk charger. At no point did we have any trouble getting either battery to accept a charge-that is, until the around-the-clock discharge drove the batteries below around 4.2 volts. Then the batteries refused to charge, replicating the common complaint-"won't take a charge."
However, the trouble isn't really with the battery or even, necessarily, the charger. Here's the real problem: Once the battery's voltage falls below a certain level, the charger can no longer sense the battery's presence and will refuse to deliver the current. In some cases this can occur at any point below 10.5 volts. Older and more basic chargers are more prone to this hang-up than newer, fancier models, which are equipped with control circuitry to deal with these issues. So there are two solutions available: Buy a new, expensive charger equipped with the extra brainpower, or employ a simple trick the Optima engineers laid on us.
How To Charge A Agm Battery Top And Side Termernals On Batteries
For maximum model coverage, many aftermarket batteries are equipped with top and side term
Here's all you need to do: Grab another car battery with a decent charge on it (12.4 volts or better) and connect it in parallel to the problem battery using a set of jumper cables. Then activate the charger and charge the battery normally, being careful to follow the manufacturer's instructions for current and voltage limits. It's as simple as that. The second battery supplies the voltage that tricks the charger into supplying the necessary current. After an hour or so, you can remove the second battery and continue charging. We tried it and it works. No matter how deep the discharge we applied, we were able to bring the battery back to a full state of charge using our cheap but trusty bulk charger.
You can now find chargers that are specifically marketed for AGM batteries. They're nice but by no means necessary. However, some recent chargers have a switch position on their control panels marked AGM/gel. Since AGM and gel batteries have rather different charging requirements, that position is somewhat bogus, according to several AGM battery manufacturers. They recommend selecting the conventional switch positions with these chargers.
Of course, you can avoid all these headaches with deep discharge and parasitic loads in the first place simply by using a float charger. Also known as battery tenders, these units deliver a small (500 to 800 milliamperes) but constant charge to the battery, keeping it fresh and fully charged. Just connect the float charger to a wall socket and to your battery when your car is not in use and you're good to go. We've seen basic versions of these chargers on sale for as little as 10 bucks-which is the deal of the century, especially when compared with the hundreds of bucks you'll pay to replace a dead AGM battery. As an added bonus, you'll know that whenever you want to drive your rod, the battery will be ready and waiting.
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Optima AGM 12V Batteries - Deep Cycle Batteries by Optima
By Bill McGuire
From the Optima Website FAQ:
How do I charge a deeply discharged battery?
If an OPTIMA is deeply discharged (below 10.5 volts) most basic chargers will not supply a charge. Also keep in mind an OPTIMA 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+V) to the discharged AGM in parallel (+ to + and Ė to Ė). Then hook up the charger to either 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 (11.2V) 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 the AGM battery. Itís okay for the AGM battery to get slightly warm during the charging process. If itís hot to the touch it means thereís a short and the process should be discontinued.
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Can you trickle charge an OPTIMA? And what type of charger can I use?
Yes and you can use any charger on an OPTIMA as long as the voltage is regulated properly. If your charger will remain on indefinitely, the voltage should be at 13.8 volts maximum with a one amp maximum current.