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Old 10-02-2022, 06:16 AM   #1
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Seem to have a connection issue from my solar controller to my lithium batteries

Hello IRV2!

Was hoping to get some advice about a issue Im having. I have a 400 watt solar panel system on the roof (Renogy) which runs to a MPPT solar charge controller (Also renogy) which then runs to two battleborn lithium batteries on the tongue of our TT.

On a full charge weve been lasting a week long but at the end of 5-7 days our power is gone. There is Solar energy going to the charge controller which I can tell through the app and on the controller also. But I believe the problem to be between the controller and the batteries. Not sure what to check, inspect, ETC as to what the problem is.

The batteries are run in series (12v 100ah) and I do have a disconnect to the camper and one more disconnect in between batteries and charge controller.

Any help would be greatly appreciated, im sure its a bonehead mistake or something simple but Im overlooking it.

Thanks!
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Old 10-02-2022, 10:57 AM   #2
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Is there voltage at the battery terminals? How cold is it where you are?
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Old 10-02-2022, 01:07 PM   #3
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I think you meant the batteries are in parallel (12V system) and not in series (24V system). Confirm that for any follow up responses.
Make sure the solar charge controller is set properly to charge your LiFePo batteries (setting on batteries). Your Solar Charge controller should tell you what voltage and how many amps it is sending to the battery at any given time. If there was a disconnect between the battery and the controller it always say zero. On my controller, you have to connect the battery first and then the Solar Panels.
5-7 days on two 100AH batteries seems like a long time. Obviously, it depends on much power you use. My guess is your system is running correctly (or nearly so), and you just use more power each day than you put in. After 5 to 7 day the batteries are depleted. Lets say you use 80AH per day but only put in 60AH per day, after 10 days your batteries are completely drained.
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Old 10-02-2022, 06:23 PM   #4
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Yes they are connected in parallel, and in the app I do have it set to lithium and 12v so all that checks out.

I have a hunch your also right about that but I couldn’t judge as I figured our consumption was much smaller. We typically are out all day long and have been in a heavily sunny area. I also don’t have a inverter connected in my setup. It’s only being used for 12v appliances and lights etc.

I will have to monitor our app and pay close attention to our consumption vs what’s being charged into the batteries.
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Old 10-02-2022, 11:04 PM   #5
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Do you run your heater a lot or have a 12V fridge?
I have 200AH of FLA and 270W of Solar. I think I can go indefinitely. We leave early and return late. Run lights, water pump, and heater (in the morning only before we get up). Fridge and water heater are on propane. My solar is portable and always optimally pointed for exposure and tilt.
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Old 10-03-2022, 06:52 AM   #6
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use varies, I have 400 solar, 300Ah FLA, I can use 170-190Ah per nite , with either Fridge on 12Vdc or I use heater alot temps (35-45 outside).. My average use when in nice weather, Fridge on propane , so we only pull Lights, TV and maybe a Kuerig or microwave for 5 minutes.. is around 80-110 AH a day and the solar has no issue keeping up with use and recharge as long as I get 4-6 hours of good sun or atleast a day of partial/hitmiss..
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Old 10-03-2022, 07:19 AM   #7
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Quote:
Originally Posted by NtAnthrBNDKR View Post
Hello IRV2!

Was hoping to get some advice about a issue Im having. I have a 400 watt solar panel system on the roof (Renogy) which runs to a MPPT solar charge controller (Also renogy) which then runs to two battleborn lithium batteries on the tongue of our TT.

On a full charge weve been lasting a week long but at the end of 5-7 days our power is gone. There is Solar energy going to the charge controller which I can tell through the app and on the controller also. But I believe the problem to be between the controller and the batteries. Not sure what to check, inspect, ETC as to what the problem is.

The batteries are run in series (12v 100ah) and I do have a disconnect to the camper and one more disconnect in between batteries and charge controller.

Any help would be greatly appreciated, im sure its a bonehead mistake or something simple but Im overlooking it.

Thanks!
I didn't see mention of a shunt based battery monitor. In the above scenario, this pretty much would be a mandatory piece of equipment. This solar system without a monitor is like driving without a gas gauge. This is especially important with lithium batteries as the voltage range is quite narrow as compared to LA batteries.
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Old 10-03-2022, 08:23 AM   #8
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I didn't see mention of a shunt based battery monitor. In the above scenario, this pretty much would be a mandatory piece of equipment.
This
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Old 10-03-2022, 10:00 AM   #9
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No we haven’t used our heater this year yet at all. Our biggest use is with the water pump (and it’s very short usage) the fan above the stove for cooking and maybe the radio.

Other then that just lights. With us have 400 watts (fixed) and I also have a portable panel that would make it 500 watts you would think it could keep up.

I think first steps are just to maybe get a monitor for the batteries so I know what’s up with them and if they’re getting juice at all. Then I can try to address a connection issue etc.
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Old 10-03-2022, 10:20 AM   #10
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I think first steps are just to maybe get a monitor for the batteries so I know whats up with them and if theyre getting juice at all. Then I can try to address a connection issue etc.
This^. It's all guessing until you get actual data. And make sure it uses a shunt for measurements.

I'm using this one:

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Victon also makes a good one, a bit more spendy but ties in nicely with their other stuff.
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Old 10-03-2022, 10:31 AM   #11
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I would recommend the Victron Energy Smart Shunt or BMV-712 which has a display. Both will connect to the Victron app on your phone.

The shunt based monitoring allows you to see actual charge and discharge data at the battery shunt. You can turn different loads on and off and watch what is happening at the battery. It is useful to figure the actual power draw of different systems such as lighting and back ground load when everything is turned off except stuff like 12 volt fridge control, smoke or propane detectors, etc...

If you have a large inverter, turn it off when not in use. There is a large standby power draw with big inverters. I have a Victron Energy Multiplus 3000VA but only leave it on when I am using things like the microwave or other large 120 volt draws.

I have a small inverter that powers my Dish Wally, 40 inch TV and Apple TV. I leave this on for the time we are setup at the campsite so the Wally DVR can record shows 24 hours a day. The small inverter load doesn't draw down the batteries much.

You may find that you have to be more careful with energy usage or consider adding more rooftop solar so your battery charging increases. I started with 605 watts on the roof and now have 1440 watts on the roof. Another option is to use a generator every few days to top up the battery state of charge. The lithium battery will charge faster than lead acid so you won't need to run the generator much if you have a decent battery charger when connected to 120 volt power. A Honda EU2200 would easily support a 100 amp charger providing 100 amps at 14.4 volts to your pair of 100 amp-hour batteries.

The Renogy charge controller only shows how much amperage is heading towards your batteries. It doesn't show the actual battery charging because your other loads may be using some of that energy. The shunt will monitor net power going into or out of the battery and do a reasonable job of tracking battery state of charge.
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Old 10-04-2022, 08:56 AM   #12
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Originally Posted by SteveJ. View Post
I didn't see mention of a shunt based battery monitor. In the above scenario, this pretty much would be a mandatory piece of equipment. This solar system without a monitor is like driving without a gas gauge. This is especially important with lithium batteries as the voltage range is quite narrow as compared to LA batteries.
I agree 100%.......... reminds me of our 63 VW Beetle when I was a kid with no gas gauge

I help people design and install solar systems and the VERY first thing in a build for us is ALWAYS a shunt-based battery monitor...... actually we recommend this for every system even if Solar is in the future..... it's the best way to know how your system performs.
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Old 10-08-2022, 09:42 PM   #13
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Yes to the Victron Smart Shunt!


On to other issues. Check all of the connections from controller to battery. The screw down ones on the solar controller can loosen up.


Your solar controller voltage is set at it's output, not at the battery. So minimize the voltage drop. it's best to have a short run with the heaviest gauge that fits you controller.


Interesting to hear what gauge and wire length you have. Also what Fuses or circuit breakers you have. Cheap knock off CB on amazon are the worse. What Renogy do you have?


Friends don't let friends buy Renogy.
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Old 10-09-2022, 09:47 AM   #14
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A MPPT controller is looking for at least a 5v delta between input voltage and battery voltage. A LFP battery if near 100% SOC at 13.5-13.6v. So if it’s near full, then controller may not turn on. If panels are wired in parallel, they will only be outputting around 18.5v which may not be enough voltage for the MPPT. If panels wired in series or series/parallel, the output voltage becomes more than enough for the MPPT, and it will perform better in morning and evening hours because even as panel current drops, there’s still enough voltage to maximize MPPT performance. So, OP may want to take a look at his controller input voltage in morning and evening, and not have all panels in parallel. A little Tweeking may help.
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