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Thanks a bunch. Before your post, I was thinking 1,000 amp hours of bank power and a 1,200 watt array to charge. And i was thinking of using a low voltage disconnect for the colder times of the year. Great to know they are a regular thing in solar. Turns out i do have a general idea what i'm doing. I have a friend who works at an automotive parts store, and he has these 200 amp hour deep cycle marine batteries he can get me for around 125 each. My plan was to buy 5 and wire them up in parallel for the bank. Do you think i should lean that way and take his offer, or go with the batteries you advised?
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Apr 3, 2018 16:25
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notanarsonist posted:I have a friend who works at an automotive parts store, and he has these 200 amp hour deep cycle marine batteries he can get me for around 125 each. My plan was to buy 5 and wire them up in parallel for the bank. Do you think i should lean that way and take his offer, or go with the batteries you advised? Can your friend special order anything from the manufacturers catalog? If so that is probably the best way to get the exact battery you want at a slim margin.
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Apr 3, 2018 16:56
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notanarsonist posted:I have a friend who works at an automotive parts store, and he has these 200 amp hour deep cycle marine batteries he can get me for around 125 each. My plan was to buy 5 and wire them up in parallel for the bank. Do you think i should lean that way and take his offer, or go with the batteries you advised? That's a tough call. It really depends on your expectations. The price is attractive for sure. If you can get the make and model number of the batt, we can look up the spec sheet and take a closer look at the Ah ratings, temp ranges, cycle life, etc. It'd be a fun class exercise! 200 Ah on a marine battery is an unusually high rating. I'm not saying impossible, just not common to see a number that high on marines. It could be that is the higher C100 Ah rating, and the C20 rating that is the usual benchmark for discussion is lower. If so, your battery bank could be noticeably smaller than expected, maybe something like 800 Ah with the C20 rating. People use marines as a low cost alternative, they typically can last 2-3 years. Not too fond of 5 parallel strings, but again if the price is right and the specs hold up, okay. Also if the "3 days til 50%" guideline tells us a 1400 Ah bank, and you go with 1000 Ah, or less, you'll be cycling any battery you choose much harder which will also lead to much shorter lifespan. Still, it's not a bad idea. For price, and if you're willing to treat it like a training wheel set of batteries, it's always better to learn on a less expensive set of batteries and gently caress it all up and run them into the ground and learn your lessons that way, than on some "proper" bank that costs 5x as much or more. Internetjack fucked around with this message at 05:40 on Apr 4, 2018 |
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Apr 4, 2018 01:54
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Out of curiosity i went and talked with him again today. We couldn't find the ones from before, but we looked at a few other options. Best price to amp hour ratio he offered me was a "Super Start 31DCM" Marine Battery. It claims to be a 105 amp hour battery, and he says he can get them to me for $76 each if i buy at least 10 of them. The battery should be on O'Reilly Auto Parts website.
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Apr 4, 2018 03:55
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data sheet: https://www.oreillyauto.com/detail/...y/31dcm/4742403 Ah rating: 20 Amp Hour Rate (Ah): 105Ah That's the C20 spec we want, so, cool. The second piece of info we'd want would be a cycle life chart. A "cycle" is typically one day of use. A cycle life chart shows numbers of cycles that can be expected vs the depth of discharge you treat the batteries to. You probably won't find such a chart for a marine battery (I spent at least 45 seconds googling for one), but again 2-3 years off marines is typical. The price is right, but keep in mind qty 18 battery cables for 10 batteries at $10 - $16 a pop adds up too. It's a battery bank of "a lot of smaller pieces" vs "fewer larger pieces", and that is a bit goofy as gently caress, but can still work fine; again the price being the justification. Also, no temp specs on that sheet.
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Apr 4, 2018 04:29
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