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Post by classhd on Dec 24, 2017 6:06:56 GMT -8
I am back! As soon as the Internet arrived I consumed 20 gigabytes reading and watching videos to better understand solar energy. Well now I have a question with the batteries, I have 2 batteries UB121000 100ah connected in parallel and two Renogy Monocrystalline 100w panels, as it is winter I do not know if it is enough to fully charge the batteries. This is my situation: during the whole day I can see in a small voltmeter that the batteries reach 13.2v without any kind of load but when the sun goes down the voltage slowly goes down to 12.6v. In other words at night when I use the system I'm always in 12.6v. I do not know if it is the charge controller that regulates the batteries at that voltage, I do not know if 12.6 is 100% of the battery. Will any solar panel be damaged? Will any battery be damaged? Any help you can give me? Thanks.
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Post by tattoo on Dec 24, 2017 6:14:55 GMT -8
It shouldn't hurt anything... You should see 14.8 in the full sun and 12.7 at night with no load... But 12.6 will work.. but not optimum... It could be your volt meter...
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Post by jimmy2 on Dec 25, 2017 5:32:59 GMT -8
You can search battery voltage chart and it will give you the state of charge. You can only get a true reading at night when the panels are not charging. 12.7 is 100% 12.6 is 90% etc. You cant ever hurt the panels unless you hook it up backwards. You can hurt the battery by draining it too low. For lead acid I hear different things. It is best not to get below 60% which is 12.2. Preferably 80% 12.5. Different controllers do different things Mine never shows above 14.1 full sun no load.
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Post by tattoo on Dec 25, 2017 5:41:37 GMT -8
State of charge means nothing it shouldn't even be their... It should be ignored...
The only true test on a lead acid battery is with a hydrometer and nothing else...
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Post by classhd on Dec 27, 2017 18:11:24 GMT -8
12.6 volts = 100%
12.5 volts = 70%
12.3 volts = 50%
11.4 volts = 20%
And never go down of 50%? That's the rule? I think I have already gone down my 200ah battery bank to 12.1v and I think twice 11.9v.
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Post by tattoo on Dec 27, 2017 18:57:26 GMT -8
12.6 volts = 100% 12.5 volts = 70% 12.3 volts = 50% 11.4 volts = 20% And never go down of 50%? That's the rule? I think I have already gone down my 200ah battery bank to 12.1v and I think twice 11.9v. What are you referring to? What rule? 12.7 is 100% or 1270+with a hydrometer is best of all... |
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Post by rabird on Dec 28, 2017 3:53:58 GMT -8
FULLY charged means that and your batt maker may have a desired charge profile or method to determine FULL for AGM, most likely it would require getting the battery to 14.4v and maintaining it till the current is nil. Repetitive undercharge shortens batt life. classhd,, if you look at a cycle life vs depth of discharge curve for your battery you may find 50% discharge gives the most bang for the buck. But this is based on controlled discharged, controlled temp ... and FULLY recharging ASAP. here is a chart from Trojan, cycle life of T-105, note: all batteries are not alike!  "50% rule explained" www.smartgauge.co.uk/50percent.html |
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jimmy
Solar Lover
Posts: 52 
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Post by jimmy on Dec 29, 2017 16:51:25 GMT -8
My 24 volt battery bank is at 26.5 2hours after dark. I get the same reading from my solar charge controller as my external meter. It should be 25.46 to be a hundred percent. Do I need to change some settings on the charge controller which I just got 2 weeks ago. Am I hurting my batteries?
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