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Post by jackieblue on Sept 28, 2017 12:52:18 GMT -8
Hi folks. I have recently setup my solar system using a Renogy Rover 40. I have Lithium batteries with 60ah capacities (will add another 20ah soon). I have been using it and starting out the batteries will say 100% charged and voltage will be 12v or above. Using 8.5 amps, 80% of the charge of the Li batteries, it comes out to about 5.5. hours of use. I start getting low voltage warnings after about 4 to 4.5 hours. I think this may be ok as I assume there is some loss running the inverter. My question is that when this low voltage occurs, the charge controller shows the correct voltage, but shows my batteries at 80% charged. Shouldn't it be some number some number considerably lower, like maybe 20%? Or even lower? Everything I have read indicates you can discharge lithium down to 5 to 10% but there seems to be a lot of disagreement on it. The automatic cutoff for these batteries (according to the datasheet) would be 8.25V but I expect the inverter cannot run much below 11 volts (too much energy to convert to 120v AC). Sorry about all the verbiage but wanted it clear that I had thought about this some. Any ideas about the capacity percentage on the Rover?
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Post by rabird on Sept 28, 2017 16:21:17 GMT -8
is there a way to determine SoC during charge or discharge. These controllers should get rid of % cuz it doesn't mean a thing as you have witnessed.
Let's take a battery, a discharged one. Hit it with all ya got and the voltage rises, hit it with enough and it rises to some set pt of the charger say 14.4v. Its been charging for seconds and the % might be 100 or so. it'll be hrs to 100%!
Take the same battery that is FULL and put a large load on it and its voltage drops, use a bigger load and it drops more, it been under load for seconds and the voltage is LOW, what % is it.
These read outs are not amp-hr accumulates they have some sort of agorityym that seems to mean NOTHING. That's the best explanation I have!
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Post by jackieblue on Sept 28, 2017 17:31:11 GMT -8
Thank you. I will ignore it. I think something is off on the batteries somewhere in any case. I reviewed my battery data sheet again and realized that I did my math wrong. I actually have 120ah hooked up now (and will add another 40 soon) so it should be getting close to 8 hours once fully charged. Since I have 3 batteries of 40ah, I suspect that either one of them is not hooked up well or is not charging correctly. This was my first run through and was kind of a hack to test some things out. I will run some of it down and re do some wiring and see where it is next week.
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Post by rabird on Sept 29, 2017 5:17:39 GMT -8
Don't confuse 120v amps to 12v amps.
A 500 watt load on the battery is about 40 amps (12v * 40A), this is only about 4A @ 120v.
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