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Old 11-19-2019, 03:17 PM   #1
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Any ideas why my solar setup keeps killing batteries in 1 day?

Dang. Thankful Costco hasn't hassled me I've returned batteries like 4 times in the past couple months, but gosh I wish I understood why my setup keeps seeming to kill my 12v deep cycle marine batteries in like just 1 day...

I wondered if it was my charge controller, bought a better one at 4x the price top rated on Amazon. Wondered if it was the link cable between dual battery setup and this last time I used just a single battery. Plus I'm pretty dang sure on this new big upgrade solar charge controller I set the battery type right to flooded (for Costco/Interstate deep cycle marine battery type). Last solar charge controller in manual made it look like you could set battery type, I couldn't find how to get to that menu, and wondered if that could have been what killed the batteries.

At this point I'm very unsure what is going on and not that smart about electrical and battery stuff, though I am a scientific minded guy. My cable length from charge controller to battery I wonder is maybe like 7ft and no idea if that could be overly long and be the issue. I vaguely remember when looking under RV seeing cabling that attached to the chasis, I suspect that was the ground cable for the internal lighting+water pump+etc, tho as ignorant to electronics I do wonder what if maybe that was connected wrong like interfering with link to negative terminal on battery? Also I wonder if when downgraded to just a single battery if the charge amps is maybe too high (dual 100 amp solar setup I think max generates like 6 amps at full sunlight).

AT this point not sure what to do. Battery working at like 10-20% capacity I think and like next day after installing voltage reported was going up then with no activity I leave for a few hours to work, come back, and it dropped a bunch. I believe it really should take like most the day to charge the battery and I've just been able to get it in a mode at like 10-20% potential where it can go from dead to charged in 1 hour of bright sunlight and clearly that huge drop from full to med charge with no usage isn't right...

Any tips / ideas what I should do? Thx

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Old 11-19-2019, 03:19 PM   #2
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Another questioned issue

Also I've when changing batteries or charge controller not followed any specific sequence when disconnecting & reconnecting cables to batteries. I kind of expected that couldn't kill the batteries instantly, but it's like maybe it can and that could be the problem?

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Old 11-19-2019, 03:22 PM   #3
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Really you just need 13-15 vdc going to the batteries. Eventually it should get to the floating voltage. Pictures would be helpful. At this point you need to draw a diagram of your complete setup and post a pic.

No one should install solar IMO without a quality meter/shunt. With the meter you would know exactly what's going on with the batteries.
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Old 11-19-2019, 03:24 PM   #4
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I see no where where you mention how many and what size your solar panels are? Going dead in one day tells basically one of two things. Either the panels are not connected, or they are not putting out any power for some reason. Have you used a VOM to follow the power from the panels to the battery?
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Old 11-19-2019, 03:26 PM   #5
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What are you running off of the batteries?
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Old 11-19-2019, 03:31 PM   #6
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What do you have running from the batteries ?

Do you have an inverter hooked to the batteries and the RV plugged in to it ?

Are you running a gas/electric fridge on electric, thru an inverter ?
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Old 11-19-2019, 03:41 PM   #7
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More info

Batteries have just 3 things connected: solar charge controller, LED light+water pump cable (no fridge or heating), and a 400w power inverter. LED lighting+water pump is so minimal it is no problem and really it's only when I use the inverter when I exhaust the battery. All my devices are pretty low watts and clearly the battery is working at very low potential (maybe like 15% what it should). This is after 1 day of use when out of nowhere the charge controller should have been leading up to full charge and stopping sending electricity, but instead of that I come home (no use while gone) and the charge is lower than when I left. When I left it maybe was like 75% charge then get home and 50% charge (seriously no use between). Plus after that point it isn't just 50% it's like that plus + damaged where top potential now is maybe 15% what it should be.

Currently just two 100w solar panels, a 30amp nice solar charge controller, and a 140RC interstate (from Costco) deep cycle marine battery.

I'm ignorant the overhead with my power inverter converting 12V to outlet style power. Seriously I run pretty low though with # of watts like I have a meter saying my usage is maybe like 20 watts on average and I think it should be able to last 2+ full days on this 140RC battery, yet it's like I can't even make it 1/2 of a cloudy day...
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Old 11-19-2019, 03:49 PM   #8
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Can you confirm 12v coming from the solar? If 24v wouldnt it prematurely fry batteries?
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Old 11-19-2019, 07:53 PM   #9
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Uh, what are you running on the inverter, and for how long?

400 watts at 12 VDC draws 33 amps from the battery. A 140RC battery has 140 minutes of power at 25 amp current draw before the battery voltage drops to 10.5 volts.

140 minutes = 2 hours and 20 minutes. That reserve capacity roughly equates to 58 amp hours. Your 33 amp inverter draw at full load would kill that battery in less than an hour and 45 minutes.

6 amps of solar would take well over 10 hours of full sun to fully charge that battery, allowing for various inefficiencies, and not allowing for any continuous loads during the day.

I don't think there is anything electrically wrong with your system. It sounds to me like you are overdrawn at the electrical bank, spending more watt hours that you are earning. Please post more details. For instance, this concerns me: the downgrade of 2 batteries to one.

You need a good DVM or battery monitor, and a better handle on your loads.
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Old 11-19-2019, 08:32 PM   #10
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I don't run that much. I have a Wifi system that connects to house accross the street which runs like 5 watts or something like that. Then I likely will be running my TV or laptop which might add an extra 15 watts or something. On bright sun my system shows full depleted to full charge sometimes maybe in about 1-2 hours... obviously battery system malfunctioning, as reflected by sign I mentioned which was 0 use and left home w/ 75% charge coming home to 50% charge and thereafter always appearing like 15% max potential vs what it should...
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Old 11-19-2019, 09:21 PM   #11
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Do you disconnect the inverter when away ?

Most inverters draw energy with nothing on. Some draw more then others. I had one that used 4 amps with nothing plugged in to it. That's a lot of energy.
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Old 11-20-2019, 08:23 AM   #12
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How do you know your solar array
I think max generates like 6 amps at full sunlight

On bright sun my system shows full depleted to full charge sometimes maybe in about 1-2 hours...

What device are you using to tell you this? From your description, it sounds like you may be using the 4 LEDs on a monitor panel. These are simply a 4 level voltmeter, and not an accurate indicator of the state of charge in your battery. You should install a battery monitor with a current measuring shunt that can measure amp hours in and out of the battery.

How do you know for sure that the solar array is

Rather than assuming
runs like 5 watts or something like that.... my TV or laptop which might add an extra 15 watts or something.
, please check the nameplate of the appliances and tell us what the manufacturer says the power ratings are. For instance, the little 18" TV on my desk is rated at 35 watts, my smallest 7" EEE PC 22 watts, and a 15.5" Dell laptop 65-60 watts.

There are enough unknowns and assumptions here that I would not be surprised that all the individual parts are working as they should, but that the loads outweigh the charging ability and battery capacity.
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Old 11-20-2019, 09:08 AM   #13
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You can find all the help you need at the solar electric store in Scottsdale , AZ.
rvsolarelectric. com
You might even consider making an appointment and driving to Scottsdale.
RV Solar Electric Store has been in the RV solar business for many years.
Good luck on your troubleshooting.
Keep us informed.
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Old 11-20-2019, 12:31 PM   #14
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Lots of good points here about energy consumption. I would put a CB/switch in line with the inverter.

My gaming laptop has a 90W power brick. 100w panels do not produce enough to sustain hour per hour use. Especially if you use an inverter and the laptops 110v power brick. It would be far more efficient to use a 12v Car Charger that is made for your laptop. They are getting easy to find on Amazon.
This works with my laptop: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Likewise there are RV TVs that can run on 12v or around 20v (add in a 12v-20v boost brick).

Also noticed. Connect the solar controller to the battery first, then the panels. It needs to know its connected to a 12v battery so that it does not try to charge it as a 24v battery.

Wire length from solar controller to battery should be shorter. Battery voltage is sensed at the controller, so wires voltage drop could degrade performance. I don't see how it would drain the batteries.

I like this. It's accurate enough and easier than using my DVM.
INNOVA 3721 Battery and Charging System Monitor

I use this for auxiliary battery connection:
NOCO GC018 12-Volt Adapter Plug Socket with Eyelet Battery Terminals

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