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Stupid Solar Question

vtchris
Explorer
Explorer
Let me preface by saying I have a very limited understanding of how solar energy works. My question is why does the voltage in my battery bank (2 new deep cycle sealed 6v), as measured by my volt minder..... with the inverter turned off and no perceivable draw....... drop once the sun starts to go down? It was at 14.0 at 3:00 this afternoon and now at 7PM it is at 13.3. And this will continue all night. It does this every day. First thing in the morning it will be about 12.6. Is it a silly question to ask where did the volts go??? Sure there is the volt minder (which I unplug at night) and then there is the CO detector. But nothing else that I can think of. I have a 135W panel, a 800W inverter and a 35Amp controller on my 21' MH.
25 REPLIES 25

mena661
Explorer
Explorer
bka0721 wrote:


Either upgrade your battery bank to meet your needs, or modify your uses by just shifting the uses to when power is coming in and power going out. What are your priorities?
Good stuff!

bka0721
Explorer II
Explorer II
vtchris wrote:
But then in the evening when the sun goes down is when I want the most juice.....LED lights, fan for heater, 2 laptops. Plus have enough left over for heat in the morning. I have been told to never let the batteries go below 11.9 so get cautious around 12.5 and just turn everything off and go to bed.
Well, what we want and what we do is often changed with life in a RV. During different seasons, your charging and battery capacity changes. Often times you need to learn to adjust something, that being your battery capacity or use of what battery capacity you do have. Your choice.

What I often share with others is something I refer to as Charge shifting. That is simply moving the use of power items to periods when you are rich, in this case, solar harvesting. Use battery devices in the evening and charge them during the day. Such as I use my desktop/laptop during the day, when these power HOGS are not impacting my Solar Harvesting as much as they would during the night, when they are depleting a limited amount of Battery Capacity.

โ€œBut I want to use my Computer at Night! Because I like to play during the day!โ€

Easy solution. Use only what your laptop battery will provide, often 1.5 hours of use, and wait until the solar time of day to plug it in and charge (they use a bunch of juice, just feel the heat in the laptopโ€™s brick on the charge cord). During times when my heater is running more, I use a chargeable LED Lantern for my evening light and a LED Table top AC Light (.1AmpH). Then during the day I plug in the LED Lantern to charge to be ready again to use at night so as not to impact my battery capacity limits.

Either upgrade your battery bank to meet your needs, or modify your uses by just shifting the uses to when power is coming in and power going out. What are your priorities? Mine would be the heater/fan in the winter time. Then at night I turn off my desktop/laptop and use my iPad, or just read a book. The iPad and or book, does not drain down my batteries, until the next day, when I plug them in, readying them to use again once the sun goes down.

b
08 F550-4X4-CC-6.4L Dsl-206"WB GVWR17,950#
09 Lance 1191
1,560wSolar~10-6vGC2-1,160AmpH~Tri-Star-Two(2)60/MPPT~Xantrex 2000W
300wSolar~2-6vAGM-300AmpH~Tri-Star45/MPPT~Xantrex 1500W
16 BMW R1200GSW Adventure
16 KTM 500 EXC
06 Honda CRF450X
09 Haulmark Trlr

vtchris
Explorer
Explorer
My controller is a Magnetek Model 6332 with "Option C" which my manual says "contains an automatic solid-state Battery Charging Section. When 120 VAC power is connected to Power Center, the Charging Section will automatically sense the condition of the RV battery. If it is below full charge, the Charging Section will start charging the batter." So does that mean as smkettner said, I can leave the controller off as long as my batter is 12.2v or better? I have a switch devoted to the controller. And my thinking is no sense is using something if I don't need to. Looks like I dodged a bullet on the battery boiler seeing as my rig is 20 years old and a Toyota.

pianotuna
Nomad III
Nomad III
Hi CAtraveler,

When the solar is operating, the chassis pulls the voltage down. If the "house" batteries are charged, the solar sends a couple of amps to the Chassis. That is with a Blue Sky MPPT charge controller.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

BFL13
Explorer II
Explorer II
With the converter on, you don't cycle the batteries and you don't care if it is cloudy. The converter and the solar will not cause each other any problems.
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

time2roll
Nomad
Nomad
vtchris wrote:
Thanks guys! For the info and the humor! One more question....when I am plugged into shore power is there any reason to turn my converter on?
Not if solar is keeping batteries above 12.2 volts.

CA_Traveler
Explorer III
Explorer III
The only reason I turn my charger off is for testing my new to me solar install. And I might add a switch to disable the isolator to see what the solar does while driving with no alternator influence.
2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
750 Watts Solar Morningstar MPPT 60 Controller
2014 Grand Cherokee Overland

Bob

NinerBikes
Explorer
Explorer
BFL13 wrote:
vtchris wrote:
Thanks guys! For the info and the humor! One more question....when I am plugged into shore power is there any reason to turn my converter on?


Yes.


Unless your convertor is an old model that might roast and boil your batteries dry, then the answer might be no. What model Charge controller do you own?

BFL13
Explorer II
Explorer II
vtchris wrote:
Thanks guys! For the info and the humor! One more question....when I am plugged into shore power is there any reason to turn my converter on?


Yes.
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

vtchris
Explorer
Explorer
Thanks guys! For the info and the humor! One more question....when I am plugged into shore power is there any reason to turn my converter on?

CA_Traveler
Explorer III
Explorer III
I love my lunar panels. :B:B:B

2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
750 Watts Solar Morningstar MPPT 60 Controller
2014 Grand Cherokee Overland

Bob

JiminDenver
Explorer II
Explorer II
Even mid summer when we use the furnace less I am happy to see 12.57v on the grp 27. Cold fall nights take it down to 12.4.
2011 GulfStream Amerilite 25BH
2003 Ford Expedition with 435w tilting portable/ TS-MPPT-45
750w solar , TS-MPPT-60 on the trailer
675 Ah bank, Trip-lite 1250fc inverter
Sportsman 2200w inverter generator

NinerBikes
Explorer
Explorer
I am happy to see anything above 12.06V first thing in the morning. 12.3 to 12.4V is more normal for my usage.

pianotuna
Nomad III
Nomad III
Hi,

Most folks would be happy to see 12.6 volts in the morning.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.