raydas
Solar Devotee
Posts: 166
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Post by raydas on Aug 18, 2019 13:33:06 GMT
****A disclaimer, this thread contains material and discussions that is "...dangerous and not productive...". I guess that warning should satisfy everybody. ****
OK, so maybe a discussion about batteries should be included. In my system I am using two batteries, a used car battery, flooded, and a 100Ah deep cycle SLA. So, in the solar system how do you know, or can tell when the battery is starting to lose its capability to hold the charge. I guess the quickest assumption is when your attached load device starts shutting off very quickly, but aside from that, what other methods are people using.
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Post by tattoo on Aug 18, 2019 13:37:20 GMT
OK, so maybe a discussion about batteries should be included. In my system I am using two batteries, a used car battery, flooded, and a 100Ah deep cycle SLA. So, in the solar system how do you know, or can tell when the battery is starting to lose its capability to hold the charge. I guess the quickest assumption is when your attached load device starts shutting off very quickly, but aside from that, what other methods are people using. It depends on the battery, which you should NEVER be mixed and matched......... With a flooded battery a great test is with a hydrometer...... I test mine once a month............
With a sealed battery when it stops taking a charge and runs down very quickly.........
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Post by tattoo on Aug 18, 2019 13:39:00 GMT
I guess the quickest assumption is when your attached load device starts shutting off very quickly, Not at all..............
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Post by jsb2000 on Aug 18, 2019 14:36:15 GMT
Batteries designed to START things (like cars, boat engines, etc.) shouldn't be used in systems designed to STORE energy (like solar/wind power installations).
Furthermore, you shouldn't mix batteries with dissimilar characteristics (including, but not limited to, age, storage capacity, chemical makeup, and application).
Lastly, choosing to ignore the above advice makes determining whether an individual battery is losing its capacity to hold a charge MUCH more difficult.
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russ
Solar Advocate
Posts: 63
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Post by russ on Aug 18, 2019 14:57:43 GMT
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terracore
Solar Advocate
Chillin at EZwineKIT.com
Posts: 50
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Post by terracore on Sept 8, 2019 2:46:01 GMT
For solar, batteries have to be bought as a set, used as a set, and replaced as a set. You cannot mix/match them or else the charge controllers will destroy them. In these types of configurations, your best battery is only as good as your weakest.
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Post by bupkis on Sept 8, 2019 15:28:32 GMT
using batteries of different chemistry is not the best idea, using start battery is a bad idea.
different aged is a non issue as long as the batteries are being charged or discharged, storage would require disconnect. I just love the way the impedance of battery increases as it fills, with the correct voltage if fills and then stops when full and will not accept anymore. Too long at too high a voltage and you make heat and too much O2 and H2 gases. Excessive water use may not be caught in time!
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russ
Solar Advocate
Posts: 63
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Post by russ on Sept 8, 2019 20:54:22 GMT
For solar, batteries have to be bought as a set, used as a set, and replaced as a set. You cannot mix/match them or else the charge controllers will destroy them. In these types of configurations, your best battery is only as good as your weakest. Mis-matching batteries is a bad idea, but if the currents are not high in relation to the batteries capabilities and the batteries are in parallel, you won't destroy your batteries. For example: a 100 Ah battery and a 50 Ah battery in parallel (again, this is not a good idea) with a 100 watt solar panel and 500 watt hours of power use per 24 hours (about a 1.75 amp current draw). The low current draw and charge rates will not cause problems with the batteries. In fact, with a total of 75 Ah of usable battery capacity, you could draw 900 watt hours in 24 hours from the batteries (a current draw of slightly over 3 amps). Of course, the solar panel could not keep up with that much power use in 24 hours 7 days a week. But the batteries would balance themselves with each other under such a relatively light load. Again, it is a bad idea to configure mis-matched batteries in parallel. It my example above, if you were drawing high current, and/or charging with relatively high current, the batteries would not be able to balance themselves quickly and the smaller battery would be overstressed. Now, if you are connecting batteries in series, then yes, mismatched batteries is a bad idea even with low currents. In series, the batteries cannot balance themselves with each other, so the battery bank is only as strong as the weakest battery.
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Post by mediadogg on Sept 8, 2019 22:02:23 GMT
Wow, what a day for clear expos! Good info all around!
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Post by bupkis on Sept 9, 2019 0:07:09 GMT
parallel circuit, the resistance are different in each battery so the bigger one gets the bigger load and the smaller one gets its share. of course not the best setup but it is not the end of the world esp when charging and discharging cuz the impermanence on one batt caused the other to charge evenly.
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