Solar System Assistance

[DanKegel]

Im lead to believe that the batteries range anything from 5 - 10 years (Depending on usage, recharge cycles etc). Im contemplating on replacing batteries every 8 years.

If I may ask, what batteries are you referring to, and what charge controller should be able to power them? (The ten year thingy)
...
The batteries Im looking at are sealed. Thus should not require mantainince, except for ensuring that they do not reach a 50% depletion level.

You might be able to predict best-case lifetime from the battery's datasheet.

For instance, trojanbattery.com/pdf/AGM_Trojan_ProductLineSheet.pdf has a graph showing how many recharge cycles the battery can handle vs. depth of discharge. At 50% DOD, that Trojan AGM datasheet claims 1000 cycles. So if you were to charge them to 100% every day, and discharge them to 50% every night, the datasheet suggests they'd last three years. (For some definition of 'lasts'; not sure what Trojan considers too worn out, but maybe it's "falls below 70% capacity".)
Looking for a 100AH 12v AGM battery at the site you mentioned, I see something close: sustainable.co.za/media/pdf/SonX/SonX%2012V100Ah%28D%29.pdf Its "Life characteristics of cyclic use" graph suggests that at 50% DOD it would fall below 70% capacity at around 800 cycles... so something over two years.

So before you budget on an 8 year lifetime at 50% DOD, you should probably check the datasheet of the exact battery you're thinking of using, you might be disappointed.

If you can use even unreliable grid power to reduce the number of charge/discharge cycles (or DoD) you subject the batteries to, you might extend their life quite a bit.

The batteries I saw at sustainable.co.za with a ten-year warranty were rather expensive LiFePo4 ones.

Caveat: I've never done an off-grid solar system. My only really hands-on experience with batteries is trickle charging NiCd's and lead-acid batteries when I was a kid, and the main skill I'm using here is knowing that spec sheets exist and that they're worth paying attention to... and that here be dragons You'll want better advice than mine before making decisions. Have you checked the sticky posts at solarpaneltalk.com/forum/off-grid-solar/batteries-energy-storage/lead-acid yet?

[J.P.M.]

Caveat: I've never done an off-grid solar system. My only really hands-on experience with batteries is trickle charging NiCd's and lead-acid batteries when I was a kid, and the main skill I'm using here is knowing that spec sheets exist and that they're worth paying attention to... and that here be dragons You'll want better advice than mine before making decisions. Have you checked the sticky posts at solarpaneltalk.com/forum/off-grid-solar/batteries-energy-storage/lead-acid yet?

If you think your advice is so poorly qualified, why give it ? Ever consider the consequences to others if you're wrong ? Try it sometime. It can be a real eye opener.

Seems to make even less sense to me to attempt to give advice that can be found elsewhere and then in the last paragraph, tell folks you've never done anything relevant to the thread except read spec sheets. Where's the good in that ? You're actions are, as seems common for you adding nothing to the discussion that isn't already known or by your own implication can be better provided by others.

[DanKegel]

Oh, I think it's pretty good advice, backed up by a ragtag life of occasional engineering experience. I offered the caveat out of an abundance of caution, and in recognition that I don't know everything. If you think I gave bad advice, please let me know what in particular was wrong. (So far, as you haven't pointed out any particular error, it sounds like you're just venting.)

The OP seemed to be expecting 8 year life out of batteries with 50% DoD, so pointing him at the data sheets and suggesting he read the part about cycle lifetime vs. DoD seemed useful and appropriate.

The other thing that I perhaps should have mentioned is that, contrary to a remark he made, avoiding too high a depth of discharge isn't just a maintenance issue, it's a system design issue, too. But maybe I misread him.

[DanKegel]

Hey Johan, how's it going? Did you make progress on your system design?

[Sunking]

Hey Johan, how's it going? Did you make progress on your system design?

How would you know Dan? You are a pretender and should not answer any questions.

Battery Cycle Life charts are pretty much for fools like Dan. Batteries have two lives, both Calendar and so called Cycle Life. Whichever comes first. What a user really wants to know is Calendar Life. What is the Calendar Life? Look at the warranty.

Example one of the best entry level FLA batteries out there is the Trojan T-105. The T-105 Cycle Life vs DOD is:

3000 cycles @ 20% DOD
2000 cycles @ 30% DOD
1400 cycles @ 50% DOD
800 Cycles @ 80% DOD

So Dan would have you believe it is a 10 year battery. Warranty is 2 years or 600 cycles. The T-105 is a 2 year battery, up to 3 years with TLC in a controlled environment. Battery Manufacture cycle testing is done in a lab at accelerated rates of 6 to 10 cycles in a 24 hour day.

Below is Trojan Cycle Life vs DOD. Th eT-105 is the RED or SIGNATURE LINE. FWIW Industry standard is 300 cycles per year, which leave 65 to 66 cloudy days in a year.

[DanKegel]

I agree, the warranty's really important to look at; that's why I pointed him to the warranties way back in https://www.solarpaneltalk.com/forum...126#post341126

Johan, you'll have to forgive SK, he's got a bee in his bonnet about me, but he is a really good resource for lead-acid battery questions.

[J.P.M.]

I agree, the warranty's really important to look at; that's why I pointed him to the warranties way back in https://www.solarpaneltalk.com/forum...126#post341126

Johan, you'll have to forgive SK, he's got a bee in his bonnet about me, but he is a really good resource for lead-acid battery questions.

Dan: If the number of those who've raked you and your me-too wannabe and often B.S. posts over the coals is any indication, SK's not the only one.

[DanKegel]

Dan: If the number of those who've raked you and your me-too wannabe and often B.S. posts over the coals is any indication, SK's not the only one.

Right, you seem to have a bee in your bonnet about me, too. If you actually pointed to any factual errors on my part, that'd be great. Until then, your posts about me seem to be mostly content-free ad hominem attacks.

[J.P.M.]

Right, you seem to have a bee in your bonnet about me, too. If you actually pointed to any factual errors on my part, that'd be great. Until then, your posts about me seem to be mostly content-free ad hominem attacks.

OK, here's some content for you:

That's because you present little in the way of facts, just rehashing, and until recently, linking what you've heard to the extent it fits your opinions, those opinions seemingly being based on what I see as simplistic and often simple minded thinking with respect to energy and its future. You've been called out for it by not only me but SK, the mods and admin. To me only, it's partly about what I see as your lack of consideration of others who come here looking, with perhaps with some expectations of finding, reasonably informed answers, and then naively get your bloviating about subjects that you, by your own admission, seem to know little about. I believe that's deceptive and a misrepresentation of the greater portion of reality. I've seen that type of behavior for 40 + years from con men and well meaning but self centered and technically ignorant tree huggers, and the damage it can do, not only to something I changed careers to become a part of, but more importantly to folks who take such crap seriously and get screwed.

By the way, I'd seriously suggest you stop flattering yourself and think mine is a personal attack (what you call ad hominum). It is not. I don't know you and I've never met you. To be clear, I find serious fault with your actions and the damage I see those actions doing. It ain't about you. It's all about the damage I see your irresponsible behavior can potentially and actually do.

[DanKegel]

mine is [not] a personal attack (what you call ad hominum). It is not. I don't know you and I've never met you. To be clear, I find serious fault with your actions and the damage I see those actions doing.

If you're unable to point out a single factual error, then it's an attack on the speaker, not on the facts he's presenting.

[Mike90250]

Dan, you have a well suited signature

17kw. I like science, but I'm no expert.

[DanKegel]

Dan, you have a well suited signature

I added that specifically to address JPM's complaint that I sounded too much like an expert.

[J.P.M.]

I added that specifically to address JPM's complaint that I sounded too much like an expert.

B.S. You had that signature the first time I saw one of your posts and long before I started calling B.S. on you stuff.

[J.P.M.]

[QUOTE=DanKegel;n342364]Right, you seem to have a bee in your bonnet about me, too. /QUOTE]

As well as the others of some substance around here.

[DanKegel]

B.S. You had that signature the first time I saw one of your posts and long before I started calling B.S. on you stuff.

? Well, if it wasn't you, it was somebody else complaining that I sounded too much like an expert... and you're the only one I recall complaining about that.