Odyssey AGM and solar experience?

[Sunking]

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.

Pure lead Pb batteries do have excellent performance, but the reason you do not see many of them is because pure lead is very soft and cannot take any shock or vibration abuse. The eold Western Electric Round Cells (Now made by GE) used in telephone offices are Round Cells and can last 50 years in Standby Float service. However not worth a crap in cycle use.

[PNjunction]

The pure lead is very soft, however they are manufactured in a very tight spiral (Optima, Cyclon etc), or are pressed together very tightly. For the Odyssey, the materials are about 30% larger than the case itself, and are highly compressed on each side before insertion into the case. Odyssey was able to obtain the tight compression needed without using a spiral. Marketing likes to tout this as a huge advantage, but it merely means you get a little more capacity for a given size, otherwise the shock performance seems about equal. Even so, neither likes having heavy point-source trauma applied to the cases.

While they have thin plates, (the t in tppl), the deep-cycling ability comes from the fact that there are a LOT of thin plates, hence enough material to do deep cycle. But yes, a dedicated RE agm is ideal. I also like the Concord SunXtender.

These agm batteries (Odyssey, Optima, what have you) really want to see long periods of float, even after the typical 0.1C end-amps is reached in absorb, and we don't have that luxury of time. (specific end-amps are in the application guides...)

In cyclic service, both Odyssey and Optima discuss what is basically the IUI method of charging in cyclic service where time is limited. (CC *after* the normal absorb is finished). Most lower end solar charge controllers don't seem to have a way of programming this.

So in the end, because we have a natural timer based on eventual lack of sunlight, the easiest thing for me to do is merely set my bulk and absorb voltages to the same value and just stay in absorb until the sun goes down. Not great, but better than dropping to float for a very limited time on a solar cyclic daily basis. If one has the means and desire, hammer the tppl's with as much current as you can to get into absorb > float stage that much quicker.

As they age, you may want to set absorb a little higher to 0.3C, but at some point if the current never seems to drop to this point, the battery is just past its prime, or damaged in some way. For fanatics like myself, the cheap yellow/blue Centech battery analyzer that reads impedance (not lab grade mind you) is kind of neat to check with once in awhile, although the CCA readout is of no interest.

I also note that the Concord SunXtender has a nice in-depth application manual, they indicate that 0.2C is the recommended minimum current, but like the others above, they don't want you to shallow-cycle these things because you are running out of daylight. Unlike the tppl's, probably due to the addition of calcium, they have a slightly lower inrush current limitation, with a 2-hour maximum fast charge (what, about 0.5C max or so?), something that in solar isn't really an issue for most.

Optimas, Odysseys (Enersys), Concord (SunXtender, Lifeline, etc) agm's - I dig 'em. Just be sure to get as much of a full-charge as you can in cyclic service, which may mean extending absorb to compensate for lack of an adequate amount of float time.

[Sunking]

The pure lead is very soft, however they are manufactured in a very tight spiral (Optima, Cyclon etc), or are pressed together very tightly.

Yes I know it is the only way they can be made and Optima and Cyclon Jelly Roll is patent protected.

[PNjunction]

It's not a really big deal either spiral or flat these days - although geometrically, flat just has more capacity.

The electrolyte paste has much to do with deep cycle too. For example, the Optima red-top although spiral wound with thin plates and similar to the blue/white and yellow tops internally, has a more acidic paste intended for short-term high-output SLI duties, hence comparatively more sensitive to abuse, and not applicable for deep cycle.

Like I'm telling you something new.

[Sunking]

I have no problem with Optima batteries. Had them in all the company trucks as Aux batteries for the winches and electronic test gear. Competition Audiophiles swear by them in their vehicles to power 1000 watt amps. They just are very small capacity and one does not need the high discharge rates they offer. For cycle service AGM Concorde is my pick as it offers very high capacity and large discharge current if needed.