Odyssey AGM and solar experience?

[PNjunction]

Minimum current requirement is very true

Sorry to get so bloggy, but this may be important for those trying to duplicate my efforts...

Discovered what the engineers meant by needing a minimum of .4C to be effective.

With only a single 15watt panel attached to the 18ah PC625 as a test, 1amp will flow into the battery, but you'll never get a terminal voltage above 13.7 volts. All the meanwhile, that 1 amp (as measured on my Fluke) is going in doing something else - heat perhaps?

Found this out accidentally: I totally discharged it by unintentionally leaving my load on overnight, waking to only 11.2 volts ocv measured after a 6 hour rest. Pumped my total of 8 amps from the panel into it, and it recovered just fine in a few hours. Way to go Odyssey!

Then wanted to see if any of my chargers would improve upon a fully charged battery when I ran out of sun. Results:

Noco Genius 7.2amp charger: immediately ramps up to 14.7 volts and goes into trickle.
Noco Genius 3.5 amp charger: same thing as above.
Noco Genius .9 amp charger (3500 in low power mode). STRUGGLES to reach 13.7 volts where it sits, and continues to pump 900ma into it forever just like the undersized panel test did. Yikes.

It doesn't appear to be sulfation since I can consistently measure specified capacity loads after all this was over...

This poses a dilemna for solar: When the solar insolation gets so bad (clouds, haze etc) that there is hardly a shadow, my 8amps of panel current usually turns into 1/10th of it's capabilites. Yup - about 800 milliamps. But with the Odyssey, instead of just slow charging, it is now just heating things up. (I think). This can't be good.

Seems like I'll have to ensure that I have good solar insolation during the timeframe I'm charging them. While they do charge quickly with a lot of current, when there is little current to be had due to clouds or whatever, I may be just generating heat.

Why can't I just for once outsmart the engineers?

[PNjunction]

2 year old Odyssey is promising

Well, after only 8 cycles, the 2 year old 13ah Odyssey is living up to their storage claim.

I pulled 1.2 amps from it for 6.5 hours, and after a 6 hour waiting period of no charge/load, it measured 12.17v ocv - pretty much what is in the manual on their second chart for just under the 50% OCV status.

I used my Fluke 87V and a watts-up inline metering gadget to measure. While not lab-accurate, I do feel that yes indeed, an Odyssey can survive 2 years of no charge neglect - provided it is cool (and as long as it doesn't go below 12.0v first - mine came purchased at 12.43v)

Putting 8 amps surge from my panels into the PWM charge controller set for 14.4v (temp compensated) is working ok. To make sure I get a good charge for this initial analysis, I made sure that I spent some extra time in the sun getting the current down to about 150ma or so before I lost my solar insolation for the day. So while it only took about about 60 minutes to get to absorb, I spent another 4-5 hours to make sure it was really charged well after each cycle. I probably won't have that luxury in the winter.

I was so happy / amazed at something living up to it's promises, that I bought a second Odyssey - the PC 625 - which is cheaper yet has more storage capacity. Thing is, I gotta' stop buying these things because it is eating into my Sun Xtender budget. Until that day comes, I'll be keeping tabs on the life-cycle as I don't plan on getting too close to 50% DOD anyway.

[PNjunction]

Well, even only after 5 cycles, I can say i LOVE hammering agm's that can take it! I'll cycle it 15 or more times before I try to determine what the capacity really is after having sat around for 2 years with no charge - so nothing definitive yet on how much harm that did.

What I'm trying to plan for is winter - even here in SoCal where the solar insolation is not too shabby, I am often hit by intermittent high-altitude cloud cover that tends to linger right in the middle of the good insolation hours. When the sun does finally peek through, I'm dealing with a fast moving shadows from obstructions that are also long, limiting my portable ground mounting. What was good before can turn ugly in 15 minutes and ruin my um, wait for it - daily solar harvest. Frustrating when it is relatively bright outside. One lingering cloud or long shadow can ruin my day.

Even though this little Odyssey is a test/trainer, from what I've seen so far, I KNOW I'll be picking up a Sun-Xtender and hammering that as well with a bit more panel. This little thing is built like a tank, was packaged really well, and I love the docs. Too bad Enersys doesn't make Sun Xtenders in anything smaller than 35ah, so this Odyssey will have to do for now. I'm hooked now. I had to laugh when I stood back and saw 145 watts of total panel power going through my morningstar CC and hitting up a 13ah battery. Wild!

[Sunking]

Well I cannot say I have used them in Solar Applications, but no worries mate as it will be hard to do any harm to them. The only thing to remember with them is do not apply a voltage greater than 15 volts. 14.1 to 14.7 is the sweet spot depending on Temperature.

The battery line you have is a dual purpose hybrid made for both Cranking and Cycling. It is a direct competitor to Optima battery line up. They have very low internal resistances which is a good thing if you have a 20 AH battery trying to power a 200 watt inverter. The CCA on you model is 200 amps out of a 14 AH battery. That means when fully charged the internal resistance is around [12.8 volt - 7.1 volt] / 200 amps = .0285 Ohms. So that battery can deliver 35 amps with only 1 volt drop at the terminals. That is a heck of a current for a little 14 AH battery in excess of 2C.

Do not worry about pumping 8 amps into the battery, as long as it is cool and you stay below 15 volts you can pump 70 amps into it. Heck you can draw as much as 535 amps for 5 seconds out of it if you want. The battery is designed as a Motorcycle starting battery, and popular with the FIGHTING ROBOT crowds or anyone who needs a lot of current from a small package.

As for solar, it will work, just not a lot of cycle life, but you already know that. Hopefully someday we will get an affordable battery with 5C rates and 10,000 cycles.

[PNjunction]

For experimentation, I just picked up a small Odyssey PC535 agm (around 13-14ah) to pump 8a into with my panels. Odyssey specs .4C as the minimum here!

I knew from the beginning that this is the wrong application, and my pwm charge controller method immediately voids the warranty, but I wanted to see what going well beyond the typical C/4 rate for THIS agm felt like. It felt GOOD!

I can't say what will happen now, since I am starting off on the wrong foot - the Odyssey I picked up on a deal was already new-old-stock at 2 years old, and only had 12.43 volts open-circuit. Someday I'll get enough to doing it right with an RE-designed battery, but for now I'll see if I only get 50 cycles out of this thing.

I'm just wondering if anyone else has put solar to an Odyssey and what their experience was.