Question about bulk / boost / float charge of my charge controler and blue top battery

Re: Question about bulk / boost / float charge of my charge controler and blue top batte

I work with all the colors / flavors of Optima AGM with solar, and can say you want the "cyclic" type of operation.

That is, set your bulk/boost to 14.7v. Set your float to 13.6v.

Ok, so the Optima is not a dedicated RE battery, but it does fine in the casual solar application. Much better than a large ups-style agm.

Do not just go by the labeling in your controller, pick the correct voltage. I'm also assuming your controller has temperature compensation, which is important. Best at the battery terminal, but otherwise ambient temp will have to do. If you have no temp comp capabilities, if you are in a hot region like 85+ degrees much of the time, set your voltages a bit lower, like 14.4v bulk/boost, and 13.5 float. Of course precise compensation is the word of the day.

A little history might help explain things:

Originally, the "tppl" or thin-plate-PURE-lead battery was introduced by Optima. Also near that time 1998 was it's nearest competitor, Hawker, which produced the much smaller (5-10ah) "Cyclon" pure-lead agm's. Later, Optima split off into Optima for consumers, and Odyssey for commercial interests. The visual difference is that the Optima retained the circular cell shape, while Odyssey went back to a more traditional flat-plate shape. Of course these days they are built by different manufacturers and have different internal chemical recipes.

Optimas are built basically the same. The SLI versions (Red top and Blue top with black case) have a higher concentration of sulfuric acid in the agm electrolyte. The dual-purpose Yellow and Blue-Top / light gray case) are the same physically but have less acid in the electrolyte, but have convenient wingnuts for light duty connections. If you choose the Blue, don't get the black case unless you are doing just simple SLI duty.

Originally, the charging specs for the Optima's were VERY detailed and oriented much towards the Electric-Vehicle market. Thus, rapid recharge capability with pure-lead was possible - the target time was 8 hours or less, but this necessitated high voltages and large current. Over time, the consumer may have been too confused by charging specs (much like the Odyssey's with their EXACTING specifications today - should be because basically they are the same chemistry overall, ie TPPL). Many good Optimas and Odysseys were ruined by either not understanding the charging specs, or using dumb chargers that had little to no voltage regulation. In the case of Odyssey, you can void the warrantee by not charging them with enough current, typically 0.4C *minimum*. Optima does not have this limitation. (but you ask yourself why since they are both basically tppl!)

Optima over the years has tried to explain these charging details to the average consumer, but as a TPPL battery, it all depends on what you want to do with it.

Solar in a cyclic application? Stick to 14.7v bulk/boost/absorb, and 13.7v float - temp compensated. Current? A TPPL-based battery can handle a LOT of current without getting too hot - because of it's extremely low internal resistance. This does not mean that you should charge unattended, nor pound it with HUGE currents without a voltage-limitation. Of course, this is with batteries that have not been damaged or previously abused.

Consider that Optimas own charger does 12A, 2A beyond their "recommendation". Yet at the same time, these batteries are also used at the racing track, which may include no-alternator recharge capability. To get back in lane quickly for another run, you can hit them HARD, as long as you watch the voltage limit! Unbelievably, this means you can take them to 15.6v, but you will quickly reduce it's cycle life that way. Racing is a different world.

Using pure-lead they have very low internal resistance and that's part of the reason they can handle a lot of current. BUT the safe person will not charge unattended, will be using temp-compensation, a proper upper voltage limit, and perhaps an IR hand-pointing temperature meter to see if any cells are overheating. But this may be too much for the average consumer, so a safe limitation of 10A is easy to remember.

Being able to hit Odysseys, Optimas, and Hawkers with a lot of current is one reason I'd recommend them for casual use where you have little solar insolation, but have a lot of panel power to recharge them quickly. Being able to hit them hard can also save you generator fuel.

The KEY issue is voltage. Not at the track? Then just keep your voltage to no higher than 14.7v, and make sure your current is reasonable. Personally, I go no higher than 0.5C, for which my D34M at 55ah means no more than 27A charge current. At that rate, when I measured mine with an IR probe, they got no higher than 5 degrees above ambient. I wish I had that much current via solar, but my little 80w panel does fine with it as long as I have enough solar insolation.

Do not fear an Optima (or Odyssey or Cyclon for that matter). They are *designed* to handle a lot of current, as long as the operator has quality voltage-limiting gear and is doing it safely. If you do that, you will not witness any drama. Although they are well built, do NOT swing them around and dent the cells! This WILL cause a hot spot. Rough 4x4 handling is ok if they are in a sold battery holder, but will not survive if left to bang around the chassis - like most any other battery. Beware of clumsy shipping - always buy from a reputable dealer.

TIP - do NOT USE Schumacher Speed-Chargers on these. Schumachers will go to 15.6v and unless you are at the track, or trying to revive a badly abused zombie battery, they are not your best choice for maintenance of normally functioning Optimas. Even if you set it for AGM, it can go to 15.6v behind your back, which unless you absolutely have to, is something to avoid.

Re: Question about bulk / boost / float charge of my charge controler and blue top batte

From what I've heard, QC improved a LOT since 2007. I've had no troubles with them especially since they are pampered with good care here.

Lots of choices out there for casual solar use. I'm not saying Optima is the absolute best, but if I wrote off every battery maker due to a few duds received here and there, I'd be using nothing but earth-batteries.

Re: Question about bulk / boost / float charge of my charge controler and blue top batte

louisbanens wrote: »

Oh yeah, how do I know if my battery is fully charged?

Cariboocoot is right - unlike FLA's we can't measure specific gravity of each cell, so the SOC voltage is the closest we can get.

An easy way to tell is to allow for at least 4 hours of NO charge, and NO load. Measure battery terminal voltage. Don't use a $5 shirt-pocket multimeter.

If it is 12.8v or more, then you are fully charged. A nice new Optima with a full charge will actually read somewhere close to 13.1v.

How about half-charged? Normally one doesn't want to go below 50% DOD. Again, with a 4 hour rest period, 50% DOD would be about 12.2V.

Under load, it is a different story, but with very light loads such as you have, just try not to go below 12.2v while your circuit is active.

For future use, know that agm voltage may indicate SOC, but NOT the health of the battery. You can have a badly abused Optima sitting at 13.1v, but as soon as you put just a tiny load like an LED on it, the voltage could drop rapidly. However if you treat your battery right from the start, the above is a good ballpark.

Re: Question about bulk / boost / float charge of my charge controler and blue top batte

Ok, here it comes...

"C" means the 20hr rated capacity. My D34M Blue Top is rated at 55ah, so C=55. In your case, I believe you have a 75ah Optima. When I say 0.5C that's 0.5 * C, or put another way, C/2. When I fast charge my 55ah battery, I go no higher than 0.5C, or 0.5 * 55 = 27.5A from a charger.

Solar insolation is the amount of "usable" solar light as compared to mere visible daylight. Solar charging is very weak during the early morning and late afternoon hours and is not used when you calculate your overall solar recharge capability. It also depends on your geographical location. To find yours, see this nifty set of graphs from NREL right here on our own forum host:

http://www.solar-electric.com/solar-insolation-maps.html

When figuring out your hours, many prefer to use the worst-case scenario to give yourself some headroom, which here would be the "Winter" hours. In Southern California, that would be about only 4 hours usable. Since my 80W panel only provides about 4.5A of current, the max I could put into a battery during this timeframe would be about 18ah or so. If I had your 75ah battery, and drained half of it away, with my current setup, I could never get that battery fully charged in a single day. There are more great examples from the gurus here that will help. It all starts with what your LOAD is, that is, how much power are you pulling, and for how long each day, and then you figure out your battery needs, and then how much panel wattage you need to get to a full charge.

Which conveniently brings us to "DOD" or Depth Of Discharge. Basically it is how much capacity left in the battery. 50% DOD means the battery is half full / empty. 100% DOD means empty. 10% DOD means you have 90% left.

Unlike the old days when EV was starting to take off, agm battery manufacturers initially hyped their batteries about how many cycles they could last going to 80% DOD. You may still see this in some cases, like Odyssey. However over the years we found out that was too deep of a discharge for reasonable cycle life, so nearly everyone uses and calculates their DOD to go no lower than 50%. Ideally, one strives to go no lower than 20-25% DOD for the most cycle life. For the simplest of calculations, one figures out how much power they draw each day, and DOUBLE that amount for their battery capacity needed - ie for the typical 50% DOD worst case setup.

Ok, 14.7v bulk and boost (boost also known as "absorb") and then 13.7v for float because you are cyclic. If you were just letting this thing sit in garage doing nothing but floating its whole life, then Optima recommends lowering float to 13.5v. But you are cyclic, ie actually using it once in awhile. If you can't get these exact voltages, just try to get close - but that's Optima's somewhat looser specification stance. If you had an Odyssey, you have very strict voltages where even a 10th of a volt either way could get you into warrantee trouble.

Note that i don't hammer my Optimas with 0.5C current from a charger all the time. They just sip on my 80w panel output of about 4.5A. However, since they are TPPL, my own tppl research indicates that giving them a decent charge current once in awhile is actually healthy for them, kind of like a deep-pore cleansing. So, about every month or two, I'll drag it down to about 60% DOD, and hit it up with my 25A AC charger. Just beware that there are chargers that are NOT within spec, or do things behind your back, so vetting their voltages, especially if they are not documented by the manufacturer are mandated. Either validate it yourself, or perhaps think along the lines of an Iota charger, which our host carries if you are interested.

I like Optimas / Odyssey / Hawker Cyclons, but they are NOT "RE" or Renewable Energy deep-cycle. True deep cycle RE batteries have very thick plates and basically will provide many more cycles of deep discharge than our dual-purpose types do. Even though the Optimas / Odyssey/Cyclons have "tppl" or thin-plate-pure-lead, these thin plates of pure lead give a measure of deep-cycling as compared to other agm's, along with the ability to be fast charged / discharged as long as voltage requirements are met. The percentage of acid in the electrolyte determines an Optimas SLI or dual-purpose faux deep cycle capability.

Some of the big players in the true deep cycle field are Rolls-Surrette, Trojan, Concorde etc.. But for now, your Optima will do just fine as a learner battery.

Re: Question about bulk / boost / float charge of my charge controler and blue top batte

My pleasure. Note that I edited the second line in the post above to mean a battery's 20-hour rate, and not 20ah.

In addition to your solar setup, having a decent charger for the Optima is a good idea as a backup, or for making sure it starts off and stays properly charged in case something goes wrong.

Unfortunately, many places that sell Optimas also sell chargers that are NOT optimum for it. Optima sells their own charger of course. (Update - free or discounted Optima chargers if you bought yours in April 2014). IOTA is also good way to charge it. I have tested three Schumacher Speed Chargers, and they went over-voltage and were quickly taken out of service, despite using the agm setting.

If you need something locally, I personally use a Stanley BC-1509 15A charger on my Optimas. It does so at the right bulk/boost/absorb voltage and also a good float voltage. The other automotive options it has I just don't use. If you watch their official Optima videos, the tech actually mentions that anything from 8 to 15A is ok, even though they just recommend 10A to keep it easy to remember. As a tppl battery, I have no problems hitting them with 15A from a charger. I use other chargers as well, but the Stanley is pretty easy to get locally at your home and garden store.

Have fun with your Optima!

Re: Question about bulk / boost / float charge of my charge controler and blue top batte

PNjunction wrote: »

"C" means the 20hr rated capacity. My D34M Blue Top is rated at 55ah, so C=55. In your case, I believe you have a 75ah Optima. When I say 0.5C that's 0.5 * C, or put another way, C/2. When I fast charge my 55ah battery, I go no higher than 0.5C, or 0.5 * 55 = 27.5A from a charger.

Since there are some applications for which a rate other than the 20 hour rate is the standard measurement, you will also see C₂₀ used to symbolize the twenty hour rate. Also sometimes written C20.
Not to be confused with 20C, C/20 or any of the other totally different numbers.