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Post by shovelhead on Nov 28, 2017 16:53:48 GMT -8
I have 2 Renogy 100 Watts 12 Volts Monocrystalline Solar Panel's Hooked up to 2 100ah Marine Deep cycle Battery's. Signstek Y Branch MC4 Parallel Connector Adapter M/FF and F/MM Connected with 50 FEET UL Solar Panel Cable Wire's 12 AWG - 600VDC. I had on the Roof 23.70 volts coming out of both panels, After running wires to cc which is a MPPT M20(unknown Brand) I still had 23.70 volts. After hooking up battery's in Parallel and to cc I hooked Panels to CC and probed connections and had 12.23v. Couple questions... Should i have still have the 23.70v at connection on cc From Panel's? why would I have only 12.23v There? I dont think it should be Battery voltage at that point on the cc. I understand that the charge controller drops the voltage down to an acceptable voltage for the 12 volt charge. But i dont understand Why at that point of connection. Next question. Percentage of Battery's Fluctuates, This morning as It got light out,no sun yet it had 94%,as said the cc with a little over 12v coming in. 12 hrs later was at 70%.no volts coming in cause it was dark out. I have no draw on battery's as of yet. Ok that was more info then a Question. So what Im wanting to know is what cause's percentage drop with no draw on battery's? Any info would be greatly appreciated. Also In need to know if i need a in line fuse and where? Im also thinking of adding more Panels And same Bank. Until I figure what draw Im going to be putting on The system. Thanks
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Post by tattoo on Nov 28, 2017 17:19:58 GMT -8
It sounds right to me..
Yes you should still have 23.70 volts coming from the panels. Nothing you did will change that.. Resistance is why it dropped since you checked it at the panels..
Don't worry about the percentage of voltage in the battery.. It means nothing..
You need a fuse between every part. Panels to CC, CC to batteries, batteries to the inverter.. You also need cut offs in there also..
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Post by rabird on Nov 28, 2017 17:30:14 GMT -8
shovelhead. With a mppt ya might consider series connected panels. So the mppt finds the max power pt of say 18v (nothing to do with resistance), look at the panel specs, this changes as the panels get hot, it goes lower and when very cold goes higher. on a 75F day in full sun the back of my panel was 140F! Then the mppt 'bucks' (transforms) the power, (18v by some amperage) to battery voltage and some higher current to charge the battery, as the battery voltage rises this bucking keeps up and continues to match batt voltage. I'd charge your batteries any wayyou can and then monitor the solar charging, a typical charge profile is that the batt voltage should rise to mid 14v and stay there for a few hrs and then the controller should go to 13.?v float. FYI, 12.2v is ~ 50% discharge so ya need to add back 50% or 100ah, 200w panel is ~ 10A in full sun perpendicular to the sun and this time a year you only get 3-4 hrs of full sun over the entire day, so 10A x 3.5 hrs is a return of 35 ahs, it will take a few days to get to FULL. Disregard the % numbers, sorry. Keep monitoring. 14.?v held for a few hrs is nearly 100% full or ya need to get a hydrometer to check the fluid. Check this to see how much sun hrs in a day to multiply by the 10A or so the panels can make. it uses your input for location, pick 'south facing' and then see how different angles at different times of year changes the results. www.solarelectricityhandbook.com/solar-irradiance.html scroll down How llong have these batts been discharged? this white paper may be ehlpful if you are willing, it explains the difference between pwm and mppt and where of the iv curve mppt operates, and how temperature is involved. www.victronenergy.com/upload/documents/White-paper-Which-solar-charge-controller-PWM-or-MPPT.pdf |
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Post by tattoo on Nov 28, 2017 17:38:06 GMT -8
Bird it's awesome to see that you are now thinking that the % of voltage is BS.... COOL
LOL now your pushing a Hydrometer??? What's the world coming to I guess I'm wearing off on you?? Glad to see your coming over to the {KISS} side of solar....
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Post by rabird on Nov 28, 2017 17:40:19 GMT -8
tell me a algorithm that would work for charging and discharging that is based on voltage? up to 14.8v held constant for hrs?
amp hr or energy counters work but need a real capacity to be entered and no one knows their capacity or what capacity might even mean!
The OPs 200ah capacity is spec and not what they are now!!!
owned some sort of hydrometer for 40 yrs.
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Post by tattoo on Nov 28, 2017 17:42:18 GMT -8
tell me a algorithm that would work for charging and discharging that is based on voltage? No need for it.. Like I said above {KISS} solar is the only way to go.. |
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Post by rabird on Nov 28, 2017 17:47:56 GMT -8
Ya can't is the correct answer.
I always thought the battery makers was where to go for batt care and what FULL is.
Trojan even has videos so ya don't need to read.
Flooded lead acid batts that are cycled need to be FULLY charged often for long life. I repeated this many times ....
If ya don't FULLY charge or top charge regularly then the chemical reaction is harder to reverse and some may not reverse which leads to loss of capacity.
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Post by shovelhead on Nov 28, 2017 17:51:34 GMT -8
So connecting them in series makes 24 v 5 amps and that will be ok with the 2 100ah battery's? I did check battery's before I hooked everything up.They were full and and had a good load test of about 6 sec's. Would 2 more panels help me charge batt faster? Im unsure of the load im going to be putting on them so im kinda just seeing how fast i can get them charged before i start connecting inverters. I do know i will be connecting 12 volt lighting to the battery's. About 6 lights using 4.5 watts
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Post by shovelhead on Nov 28, 2017 17:57:34 GMT -8
sorry 12v 3.5 watt bulbs
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Post by rabird on Nov 28, 2017 17:59:28 GMT -8
read the victron white paper, mppt can handle higher voltage cuz it transforms the panels mppt (18v or 36v for 2 in series) to battery voltage. On hot days mppt can be lower severely.
your lights are a small load, left on 24/7 they become a bigger load!!!, 200w ought to deliver 600 wh a day or more in winter and more in spring/summer/fall.
more panel power may be needed but get the batts full, with the controller frilling them up to 14+v and then holding them ther a few hrs to get to know the system and how it works.
is that 6 x 4.5 watts or 4.5 watts total, for how long?
Then there are the days that are so dreary that little panel power is made. Capacity become KING. gotta have it to keep running the lights till the sun comes out!
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Post by rabird on Nov 28, 2017 18:06:54 GMT -8
My landscape lights are 5x1w or 5w for 3 hrs a night or 15wh or ~1 ah, from a 7ah rated AGM battery and 60w panel. The panel is overkill except on the worst of days cuz it should make 4A x 3 hrs or 12ah a day in the winter. Nearly 1000 days and the batts may just be showing signs of age.
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Post by shovelhead on Nov 28, 2017 18:10:09 GMT -8
6 rooms will have 1 light in each. they are 3.5 watts not 4.5 as I stated before. They wont be all on at the same time. just as needed. I would say maybe at the most of 2 on at night. not all night just as needed. Im gonna read the white paper now. Im tring to be more green. Next im working on is hot water from my wood stove.via a coil to my water storage and 12v heater elements. ran into a wall on temp switches that can handle 12v
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Post by tattoo on Nov 28, 2017 18:16:37 GMT -8
Ya can't is the correct answer. I always thought the battery makers was where to go for batt care and what FULL is. Trojan even has videos so ya don't need to read. Flooded lead acid batts that are cycled need to be FULLY charged often for long life. I repeated this many times .... If ya don't FULLY charge or top charge regularly then the chemical reaction is harder to reverse and some may not reverse which leads to loss of capacity. No the correct answer is there is no need for it... My CC does just that every 28 days.... So there is NO need for having to be an Engineer to have a solar system.. See I revert back to my {KISS} solar system |
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Post by tattoo on Nov 28, 2017 18:19:17 GMT -8
You will need yo get a larger CC to add more panels...
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Post by rabird on Nov 28, 2017 18:19:38 GMT -8
Inverter use power all the time unless turned off. There are fancy ones that auto shut off. So that becomes an additional load but if can keep everything 12v then no inverter and their poor effiency.
I'd be hooking up a charger to your batts and getting them FULLER.
FYI, my controller is reporting 60% SoC after a hr or so of 5w load, 12.5v, .44A. I'd guess it more like 90% but who knows.
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