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Old 04-27-2016, 12:35 AM   #41
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This is fun. See what knurlgnar24 has to say about this:
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Old 04-27-2016, 09:37 AM   #42
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Seems he says a lot (really long videos) but then not so much to someone who is familiar with the science and engineering. Bottom line is that the useful capacity of a lead acid battery depends on how fast you take energy out! Wherever it goes is not pertinent since it is not accessible to the load. Batteries are chemical reactions and have time constants and nonlinear rate variations, which is all the Peukert said. He points at curves from Trojan, seems to disagree with them and then says they represent the "useful capacity" of the battery...which is what all of us are interested in. Most battery manufacturers state that the capacity figure comes from a measurement that runs down to a totally dead cell, not an inverter shutdown level.

His 1 + 1 = 2.7 undoubtedly represents the same phenomena that Peukert refers to but is only one measurement, stopping at the inverter shutdown voltage and perhaps measured in different terms. In addition, those batteries BTW are really strange AGM units that have a 2 year "shelf life." Not surprising that they might have a different discharge coefficient than a standard deep cycle flooded cell.

Seems the world is still round. More "useful capacity" if you discharge slower than the 20 hour rate, less if you go above that amount. Parallel 12 volt will cut the load in half, but equivalent 6 V units have twice the 20 hour rate anyway, because, they have roughly the same volume and weight and half the voltage so therefore twice the current resulting the same energy per pound or cu/ft.

Agree that this is fun and instructive, but we are probably losing most of the other posters with this "how many pixies can dance on a battery terminal!"
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Old 04-27-2016, 11:26 AM   #43
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I think that sums it up nicely. His practical demonstration of the principles is pretty good in my opinion, but yes, a bit lengthy. But he tries to anticipate the questions and criticisms that he might get, and answer them in the videos.

One major use for those high quality AGM batteries is cell phone tower battery backup. They are used in rather large banks for that purpose. He never says what kind of industrial equipment they came out of in his possession.
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Old 04-27-2016, 11:34 AM   #44
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Good call Tom! ALWAYS CHECK THE GROUND FIRST!!! I was going to mention that but was not sure if the batteries where grounded to the frame on campers, I was going to check that out later. I have been burned so many times on lawn mowers, motorcycles, boats, vehicles etc. that now I check the ground first. A good test is to use jumper cables on the NEGATIVE POST ONLY, and clamp the other end to a clean ground on the frame. See if your problem goes away. Even though the ground looks good, until you remove it you can not be sure.
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Old 04-30-2016, 06:25 AM   #45
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The advice on cleaning the connectors is always a good, because of the corrosion created by connecting dissimilar metals, and the environment. You may want to put some dielectric grease on the connections to help slow down the corrosion.
You said at the beginning you thought the cables may be too small, if they are smaller than 4 gauge I would change them, use the heaviest gauge and shortest length practical. Good luck.
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