Odyssey AGM and solar experience?

[Sunking]

So with this Powersonic, am I limited to less than .1C?

Not sure where you are getting your info from but with respect to Power Sonic there are 2 charging profiles. One of Cycle Service and one for Standby Service (Float aka Emergency). I will not address Standby or Float operation.

For cycling every day max charge current is limited to .3C. For a 20 AH battery is 7 amps. There is no low limit you just need to fully recharge.(If you only have 1 or 2 Sun Hours you wil need a very high rate.) For Cycle Service a constant current must be applied until the voltage reaches 2.45 volts per cell (14.7 volts on a 12 volt battery). After 2.45 volts a Constant voltage is maintained until the charge current tapers down to .01C. For a 20 AH battery that would be .01 x 20 = .2 amps. Once that point is reached either disconnect the charger or switch to a FLOAT Mode which is a Constant Voltage of 2.27 volts per cell.

Source Info

Regardless of battery type you have to be able to replace the energy in your alloted Sun Hours. If Sun Hours are short, sorry you need a lot of watts. That is part of the design process. If you use 100 watt hours in a day, and have a 500 watt hour battery with only 1 Sun Hour you need a lot of amps for 1 hour to get the job done like 200 watt panel.

That's all folks.

[Sunking]

Sorry. I forgot the link.

http://www.power-sonic.com/images/po...0_12_Oct_2.pdf

OK they just told you exactly what I just did. You are confusing maximum with minimum. Read their two small paragraphs on Charging.

[Sunking]

Have you read this thread yet? It will answer your questions.

[Sunking]

Would I be correct in adding that if I only have 1 Sun Hour in a given day to replenish X amount of watt hours I've used the night before, BUT my battery has a MAXIMUM recommended amp charge rate that is lower than what it would require me to "get back" (in that hour) what watts I used the night before, I would have to suck it up and wait for the next day to replenish the battery "safely", otherwise, I risk cutting down on the amount of future cycles.

Yes this is why you must design a system under worse case conditions.

Flooded Lead Acid batteries have a fairly narrow charge window of low of C/12 and high of about C/8. If you live in fairly sunny area with good winter isolation Sun Hours no problem. But if you live in some place like Seattle WS where winter Sun Hours is about 1 Hour you need very high charge rates. That means a way over sized solar panel, and you will have to use AGM batteries that can take the high charge rates. Read the thread I linked too in my last post and take a look at the Tuscon Seattle example. Battery size is the same, but not panel wattage.

[inetdog]

Thanks. I had actually read that thread before. I think the hardest thing to grasp is the "C" factor. It took me a long time to sort of grasp it and I still don't fully understand it. There aren't many articles online describing the "C" factor well.

What don't you understand? Or feel uncertain about?
My biggest issue has been the notation and possible confusion there. C by itself does not tell much unless you know the hour rating that is used. The 20 hour rating can be called just that, written out in full, or symbolized as C₂₀. But if someone cannot do subscripts, that ends up being C20, and people get that confused with 20 times C.
Then when you start writing C/5 to represent the result of dividing C by 5 hours to get a current in amps, it gets really confusing.
You cannot divide amp-hours by the pure number 5 and get amps.
The C/5 rate is close to, and proportional to the current which will deliver a full charge from 0% SOC to 100% SOC in five hours.

[inetdog]

So for example:

15 Ah battery (12 volt) at the 20 hour rate.

I guess what would be important to me is the C3 rate as that is what everyone uses for their charging rate on average.

First I would need C1.

C1 would be 1.5 amps right?

Then C3 would be 3.5 amps?

Am I on the right track?

Nope.

For a 15AH battery, C (usually C₂₀) is 15AH.
A charging rate of C/3 (not C3) would be 5A. And it would be too high for FLA batteries but OK for some AGMs.
A charging rate of C/10 would be 1.5A. That would be within the reasonable range for FLA.

NOTE: The "/" sign used in these cases means "divided by", in the same way that amp-hours means amps times hours and amps/hr (or even amp/hrs) means amps per hour which is nonsense in almost all cases.

[Sunking]

So for example:

15 Ah battery (12 volt) at the 20 hour rate.

I guess what would be important to me is the C3 rate as that is what everyone uses for their charging rate on average.

First I would need C1.

C1 would be 1.5 amps right?

Then C3 would be 3.5 amps?

Am I on the right track?

No not yet but I think I can help you out if you have a decent grasp on math as in really simple high-school algebra.

When you see the Term C is C = the battery Amp Hour rating usually specified at the 20 hour discharge rate. However it can be any rate the manufacture wants to use. So lets use a couple of simple Battery math.

Amp Hours = Amps x Hours. AH = A x H

Amps = Amp Hours / Hours. A = AH/H

Hours = Amp Hours / Amps. H = AH/A

So let's put that into practice with a couple of examples. Let's say we have a 100 AH battery rated at the 20 hour rate. So how many amps can we take for 20 hours? 100 AH / 20 H = 5 amps. In otherwords if we connect a 5 amp load to the battery, the battery should supply 5 amps for 20 hours.

I can also turn this around and ask something like I have a 100 AH battery and apply a 5 amp load. How many hours should the battery last. Simple we know H = AH/H, so 100 AH / 5 Amps = 20 Hours.

OK that is the basics but there is a catch called Peukert Law, and battery manufactures play games with the numbers. Peuket Law Simply states: expresses the capacity of a lead–acid battery in terms of the rate at which it is discharged. As the rate increases, the battery's available capacity decreases.

Here is how the catch works. A battery manufacture states the Amp Hour Capacity at some discharge rate usually 20 hours. Going back to our 100 AH battery model what if I discharge that battery at the 1C or 100 amps. You would assume it should be able to supply 100 amps for 1 hours. Well this is where Mr Peukert robs you blind. If you apply a 100 amp load it only takes 22 minutes to fully discharge the 100 AH battery. That means if discharged at the 1 hour rate the battery only has 36 AH, not 100. Now good manufactures publish the Peuket rates like Rolls. Here is a 12 volt 200 AH battery at the 20 hour rate. Look at th eAH rates at various discharge rates. At 100 hour rate (2.66 amps) the battery has 266 AH. At the 1 hour rate (72 amps) the battery only has 72 AH.

[PNjunction]

I am building more of a portable solar generator out of a Pelican case and will only have about 20-25 watts worth of solar panels for it. I guess I'll have to drop my idea of using the Odyssey PC625 now. I had thought it would be a great battery, but at the minimum .4C rate, I would have to put in 7.2 amps to be withing the limits if I go below 50% capacity. Even at a .3C rate, I would have to put in 5.4 amps and that Just wouldn't be doable with the amount of watts I'll be dealing with.

The pure-leads like the Odyssey and Optima's are great for small-scale RE use IF you take care of them, otherwise you are throwing money away. That means .3C or perhaps .2C (50% DOD or less) *provided* you have enough solar-insolation to actually charge them fully by getting into float and staying there until you reach 0.1C or lower. Get there at least every few days / week tops. Large-scale, that may be hard to do.

The reason for this is that they sulfate if you tickle them - even if you eventually get them charged after a long time. I've made the soft ones pass a 20hr load test (West Mountain CBAIV dummy load - fun device), but lightly sulfated like this they don't sustain a large load. The only thing that made them come back to normal was hitting them with at LEAST .2 to .3C *OR MORE*. They can take it. It's one reason Odyssey can sell a 50 amp charger for a dinky PC525. And oh yeah, that's at 14.7 volts absorb - not 14.4, but 14.7!

I've had fun with them just to prove it can be done. But I think a lead-calcium like an East-Penn (Deka, MK, more badges..) which has a MAX of .3C would be a more practical solution. Here again though like East-Penn mentions, getting close to the .3C (max for them) is recommended for longest life. And, they have a bit lower absorb voltage at 14.4v which seems to be easier to obtain with less expensive controllers and auto-parts chargers.

Another small-scale option is to put together some Hawker pure-lead monoblock agm's together - but they too should be taken care of. At this scale, I definitely prefer them to any ups-style agm like Powersonic, Universal Battery, etc. Put some Hawker monoblocks into your small scale projects - now that's very do-able. Your typical jumpstarter will never be the same!

I like these batteries for what they are, but in the long run unless you need the benefit of higher voltage under load, or the ability to throw your solar-setup battery into a vehicle, or maybe start a monster generator from standby, it makes no sense to run a bunch low-current applications like led lights and a camp radio with a pure-lead agm. No doubt the batteries are high-quality, but you need to treat them right to get what you paid for.

The 20 hour test with my new toy programmable dummy load was an eye opener - my 80w panel feeding an Odyssey Platinum Diehard P3 (rebadged odyssey) on a regular basis could pass a 20 hour discharge test but would not sustain a big load eventually. It was literally telling me to stop fooling around and hit it with a big charger. Bingo - big loads are back.....

Weekend goofs with an Odyssey or Optima are one thing - permanent solar installations that aren't large enough (.3C min for Odyssey) to begin with means you'll be buying batteries soon, OR just living with 1/20th of their capability eventually.

[PNjunction]

0.4C update - not really mandatory!

Like Sunking points out, there is nothing magical about the 0.4C minimum spec, other than to make sure you fully charge in a reasonable amount of time for cyclic service. If you can do it with less, then so be it.

The responses from the manufacturer to another owner's question from this thread says basically the same thing starting on page 3 from user "paulgato" about half way down this page:

http://www.wheelchairdriver.com/board/viewtopic.php?f=2&t=3609&start=40

Many of us who like to Read The Fine Manual assumed that 0.4C was more of a chemical requirement, rather than being mainly one of timely charging. Still important, but if you budget your recharge right, it can be done at a lower current as long as you have the time.

Early on, the application guides from 1998 or so used EV charging overnight as an example, and an alternate IUIa algorithm was described to make sure that market segment actually got fully charged in this very quick cycle service. But it didn't mean that it could not be done at lower currents - as long as you have the time (or are willing to live with less cycles), you'll be ok. At least that's my take on it.

At least it removes the mystery of the 0.4C mandate - they just want you to hurry up and wait, rather than consistently undercharge.

That thread also helped me understand the subtle difference between the 14.4v vs 14.7v absorb requirement when I combine it with East-Penn/Deka agm specs.

At 14.7v, you'll encounter some LIGHT gassing and recombination without breaking the vents. This is similar to what Deka considers a "light" EQ of 14.8v to aid in balancing cells. They don't want you to do a HEAVY EQ, like you would with flooded at 15.5v or so! But at 14.7 / 14.8v, you'll be doing light balancing. Under normal use, Deka specs out to only 14.4v recommended.

So you could use 14.4v with an Odyssey or other tppl-agm like an Optima, but you won't be doing the light balancing act. Thus in cyclic service, both Optima and Odyssey favor 14.7v. Deka's non-tppl agm's don't favor doing the light eq all the time, but of course they are not pure-lead.

A single sentence or two in Odyssey's manual about this would have helped us RTFM junkies like me from going nuts.

[Sunking]

PN you are exactly right, it is all about Time Management. In RE applications you have a very small window of time to get it done. With the minimum 5 day reserve capacity requirement and worse case winter Insolation of 4 Sun Hours puts you right at the C/10 charge rate which is perfect for Flooded Chemistry. However not all locations are created equally, far from it. If you live in the Gloomy Doomy Pacific Northwest where winter Insolation drops off to less than 2 Sun Hours means a different battery chemistry that can handle much higher charge rates. With a 2 Sun Hour day puts you at a C/5 charge rate or .2C which pretty much means you now need to use very expensive AGM batteries and the consequence is of course less cycle life which really drives up the cost.

AGM batteries cost roughly twice FLA batteries per Watt Hour of capacity and only have about half the cycle life which when added up is double jeopardy. A good 5 year FLA battery cost roughly $240 per Kwh and over a 5 year life span means you pay roughly 60-cents per Kwh in battery cost. If you are forced to use AGM the cost for a good 3 year AGM are roughly $450 per Kwh which drive up battery cost around $2 per Kwh. It is this very point people fail to realize. Does not matter if you use FLA or AGM, the cost are astronomical because you can buy the same power from the POCO at around 10 to 12 cents per Kwh. Once folks finally figure it out is way too late and have to learn the hard way instead of learning and listening early on. You try to tell them, but they just do not want to hear it.

[PNjunction]

Exactly! And Odyssey's are about the most expensive agm's around.

I also want to mention that I don't admonish using a dinky panel or low-current battery tender as your primary charger either. About the lowest I'd go is 0.1C minimum for agm, otherwise you are looking at doing surface charges, with sulfation going on underneath.

Like all batteries, there is no one-size-fits-all application replacement. You have to carefully weigh the characteristics to see if it fits your needs. My needs are met by agm and Li-ion, but I'll be the first (second maybe) to point out that merely throwing cash around for no reason is a waste.

[Sunking]

Exactly! And Odyssey's are about the most expensive agm's around.

Personally if given the choice I would opt for Concord over Odyssey only because Condorde more or less invented the AGM for Military and Civilian Aircraft. Odyssey is a fine product made by Enersys and very popular with the DIY Electric Vehicle crowd. Both are known for very low Internal Resistance, but Concorde will hold up better in cycle life.

To make Apples to Apples comparison there is:

Odysseys 31-PC2150 @ $320
Concorde GPL-31T @ $315

Both are 12 volt 100 AH, BCI 31 case with an internal resistance of roughly 2.1 milliohms which means you can draw a full C1 or 100 amps with only .25 volt sag, or a CCA of about 2700 amps which is incredible for a BCI 31 cased battery. So you can certainly understand why DIY EV guys like the things. They outperform a like LiPo 100 AH battery pack at 1/5 the price and being the AGM that they are can easily operate from 100 to 20% SOC range.

[Shockah]

Personally if given the choice I would opt for Concord over Odyssey only because Condorde more or less invented the AGM for Military and Civilian Aircraft.
Odyssey is a fine product made by Enersys and very popular with the DIY Electric Vehicle crowd. Both are known for very low Internal Resistance, but Concorde will hold up better in cycle life.

To make Apples to Apples comparison there is:

Odysseys 31-PC2150 @ $320
Concorde GPL-31T @ $315

Both are 12 volt 100 AH, BCI 31 case with an internal resistance of roughly 2.1 milliohms which means you can draw a full C1 or 100 amps with only .25 volt sag, or a CCA of about 2700 amps which is incredible for a BCI 31 cased battery. So you can certainly understand why DIY EV guys like the things. They outperform a like LiPo 100 AH battery pack at 1/5 the price and being the AGM that they are can easily operate from 100 to 20% SOC range.

Thank you for that vote of confidence.
I currently have DieHard Platinum 31 (Re-badged Odyssey) deployed in 4 separate locations.
They're set-up for no more than 20% daily cycle.
I'll be happy to get 3 years out of them... any longer is a bonus.

[PNjunction]

... They outperform a like LiPo 100 AH battery pack at 1/5 the price and being the AGM that they are can easily operate from 100 to 20% SOC range.

I'm glad you said this! This has been my experience between pure-lead agm's and lifepo4. Certainly there is the issue of energy/density-weight, and predicted overall cycle life, but from a performance standpoint based on power alone, high-quality agm comes dang close. And for the backyard solar hobbiest, a lot easier to obtain and maintain properly.

[PNjunction]

.. I currently have DieHard Platinum 31 (Re-badged Odyssey) deployed in 4 separate locations.
They're set-up for no more than 20% daily cycle.

Great deal since they are tppl Odyssey's internally. Convenient to obtain locally, but beware of new-old-stock dumping. However, I took Enersys on their word once and got a 2-year old Platinum that was only showing 12.4 volts ocv at the counter. Ordinarily this is bad news for most agm's. But, after about 5 charge/discharge cycles, I got full capacity back. Cycle-life hit, unknown, but man they seemed like new. Not that I *like* to get new old stock mind you - fresher is better.

Enersys / Odyssey / Sears Platinum are REALLY hung up on a float of 13.6v. No more, no less. This differs from the float requirements of the Concord, so as always, RTFineManual. And Concords can be EQ'ed, but ONLY if done in accord with the manual. For solar, you usually run out of time to do this anyway, so that means an external charger.