I need help. My system seems to drain way to fast.

[MilehighMike]

On my RV, I have 2-325 watt 12-volt panels. A Renogy 40 amp solar controller. 800 AH lithium batteries. 2-300 AH & 1 200 AH. A 3000-watt Krieger inverter. I have the inverter connected to busbars & the batteries connected to the same bars. Very often, my system seems to drain very quickly, even when I only have the fridge or a medium-sized fan running all night. The fridge is small & does not draw much. My batteries never charge above 13-13.20. If I get more than 2 or 3 days of cloud cover, it seems to drain, too. I tried to run a portable AC 6,000 BTU with fully charged batteries & it drained the batteries to 65% in about 20 min. The inverter also got very hot & kept tripping. I only had 400 AHs of batteries for a few years & had the same issues without running anything big like an AC. I thought if I put in the bigger inverter & batteries, it would solve all my problems, but it hasn't. Last night, I went to bed with 65% of power & was running the small fridge & a small fan & the alarm was going off by 630 am & the batteries were only at 11 volts after a couple of hours of sunlight. They seem to charge very slowly for a couple of days after this happens. Do I need a bigger inverter? I saw a guy on YT run a 5k BTU AC for 3 hrs on one 100 AH battery. I live & travel in my RV full-time, totally off the grid & this is such a pain. I just can't figure out what the problem is. Any help will be greatly appreciated. Thank you so much.

​

 

[aliarifat794]

Use a power meter to measure the actual consumption of each appliance. Try to limit the use of high-power devices when solar input is low.
Perform a capacity test on your batteries to ensure they are providing their rated capacity. Consider professional testing or a battery management system (BMS) with detailed diagnostics. If needed, perform the wattage calculation once again: https://www.theengineeringprojects....-wattage-of-solar-panel-i-need-to-choose.html

 

[MilehighMike]

Use a power meter to measure the actual consumption of each appliance. Try to limit the use of high-power devices when solar input is low.
Perform a capacity test on your batteries to ensure they are providing their rated capacity. Consider professional testing or a battery management system (BMS) with detailed diagnostics. If needed, perform the wattage calculation once again: https://www.theengineeringprojects....-wattage-of-solar-panel-i-need-to-choose.html

Thank you. I recently replaced the factory fridge & I even had the same issue when I would run the old one on propane. Aside from that my Inverter usually only shows about 200-300 watt draw. How or where do I do the professional BMS diagnostic? Thanks again.

 

[Q-Dog]

Do you have a shunt or battery meter? Your inverter may show how much power it is putting out but it likely does not show how much power it needs to run.

 

[MilehighMike]

Do you have a shunt or battery meter? Your inverter may show how much power it is putting out but it likely does not show how much power it needs to run.

My Solar controller has a Bluetooth app I use that tells me how much solar is coming in & the state of the battery.

 

[seneysolar]

How old is the rv?

Exactly how much does the fridge draw? What type is it?

Original converter in rv disabled?

 

[Q-Dog]

My Solar controller has a Bluetooth app I use that tells me how much solar is coming in & the state of the battery.

This does not tell how much power you are drawing from the system. The inverter provides power, but it also uses power to do the conversion from DC to AC, and cheap inverters are notorious for poor efficiency and high idle draw.

 

[Suijkerbuijk]

Float is to low .
For full charge you need 3.45 volt that is 13.8 volt Float on a 12 volt battery.

Than easy calculation for you.

See what you A.C use.
Watt are watts its only the power that is use.
A inverter have lost of 10% on an brand and no brand easy 20 % lost .

See if your AC use a 1000 watts a hour.
You take that 1000watt : by 60 min (60min =1 hour)
Than you see how long it Run .
If you have a AC new systeem with a pump that is variable.
U need a watt meter to see what is use on that moment.

So
1000watts :60min =16 watts : 12 volt = 1.3a a min +10% lost inverter =1.45a .
1.45 a min X runtime of 15 min in a hour = 22a
22a use x 10 hour run for the night = 220Ah use to run a ac .

Now if you use les power like thanks to a variable pomp

That unit can run just 350watts.
Well with the calculation above you can now calculate all wat u use on your RV
Even stuf that do not use a inverter , you only thake out the inverter los out of je calculation.

Easy and it works.

 

[HarryN]

The renogy charge controllers are known for having a high standby power use.

 

[MichaelK]

Is this your inverter? Be aware that this is a modified sine-wave inverter, and not the best choice for running anything with an electric motor.

How are your panels oriented on your roof? Flat? Assume that when at less than optimal orientation to the sun, you might only be getting about 60% of what the panels are capable of. What is the most charging amps you have ever seen going into the batteries?

You can gauge the maximal output of your panels by putting a load on your system at noon that is as big or bigger than the total array wattage. Run something at noon that consumes at least 650W and look to see how many charging amps are coming in.

Once you have that number, you can gauge how much extra solar you need to add to maximize your controller. Let's say you a max input of 20A of charging current. That means you could double the amount of solar but still stay within your 40A limit.

Just doubling the solar may or may not help you solve your problem. Your problem is not enough charge, and keeping a 40A controller limits what you can accomplish. You may find that to optimize your system, you need to both increase the solar, and increase the amperage capacity of your charge controller.

 

[mikefitz]

A Renogy 40 amp solar controller.

If this controller is only charging to just over 13 volts, then the battery is not being charged correctly. The battery voltage under charge needs, to exceed 13.8 volts to get near full charge.
The battery SOC given by the controller will not be correct.
650 watts of solar should be giving a maximum charge current of 30 to 40 amps on good solar day, and 2 to 3kw of power per day.
The Renogy solar controller may have issues and the default values are not ideal.
You three batteries need investigating seperatly for charge/discharge caperbility and capacity.

Work through the system testing each part seperatly.

For example, the solar panels need disconnecting from the controller and testing for output voltage and short circuit current.

 

[Suijkerbuijk]

Pure vs Modified Sine Wave Inverter | Wiltronics

Here, we have broken down the difference between pure vs modified sine wave inverter so you can pick the best inverter for your installation!

www.wiltronics.com.au

When it comes to the cost, modified sine waves are simpler to produce with fewer components. This makes them cheaper than their pure counterparts.

Pure sine wave may be more expensive to produce, thus making it a bit costly. But it provides more efficient power and minimal interference.

As for the modified efficiency, it produces smaller wave power than the pure. It uses up to 30% more power and cannot run its full capacity. This could cause a buildup of excess waste heat, damaging the equipment long-term.

Trow that inverter out of the windows.
Its only good for brick to hold paper on your table.
And you can not run a inverter on that .

 

[Rednecktek]

Just to check on something, but is your inverter connected to the converter in the RV? If so, your house batteries are powering the inverter that powers the converter which charges the house batteries that feed the inverter that powers the converter that charges the house batteries that... well... you see the problem there.

Your SCC is undersized but if your panels are laying flat you should still be able to max out your charge controller.

If your batteries are only getting to 13.2, they're not getting fully charged. Check the settings on the SCC and make sure they're charging up at the right voltage. Even then, with 800Ah of battery I doubt you could fully charge the batteries before you lose the light. You're looking at 20 hours (800ah / 40a of SCC) of perfect sun to recharge that bank fully. With the average being 4 hours that's 5 days of charging assuming you don't turn on anything in the meanwhile.

Do you have a proper shunt and not just a battery meter installed? Can you throw one in? You don't need anything fancy, a basic Aili will do the job of measuring amps in and out.

 

[Rocketman]

Get a Victron Smartshunt or BMV712 ASAP!

Once that is installed you can see what is going in & out of the batteries.

My guess is the same as above. Although with only 650w of solar you MAY not be getting the batteries recharged during the day- that is why a shunt based battery monitor is vital. You can see and track what is going in & out of batteries.

 

[HRTKD]

@MilehighMike , I have a similar system. 640 watts of PV and 560Ah of LiFePO4. My system rarely goes below 80% state of charge. I've been running the absorption refrigerator off of 120vac instead of propane because I have so much capacity. I tend to switch to propane at night, but could probably make it through the night with the refrigerator on AC.

As stated by many in this thread, your batteries simply are not getting charged properly.

I use a Victron SmartSolar MPPT 100/50 solar charge controller, Victron shunt and a Victron Multiplus 12/3000.

 

[hwy17]

Batteries need to get to 13.6 at least.

And they probably need a balance now so they could use a good long charge like 8 hours held at 13.75 to let them do their balancing work.

 

[MilehighMike]

How old is the rv?

Exactly how much does the fridge draw? What type is it?

Original converter in rv disabled?

2010 Winne, 3 amps, Yes, it is disabled.

 

[MilehighMike]

Batteries need to get to 13.6 at least.

And they probably need a balance now so they could use a good long charge like 8 hours held at 13.75 to let them do their balancing work.

They really never get above 13.20. I am going to add a couple more panels next week & see if that helps. The curet ones are mounted flat on the roof & very often, I only get 400 or so watts.
I did order a new

Xantrex Freedom X 3000 Truesine Inverter. The old one 3000 watts would get very hot & trip.​

 

[MilehighMike]

Is this your inverter? Be aware that this is a modified sine-wave inverter, and not the best choice for running anything with an electric motor.

How are your panels oriented on your roof? Flat? Assume that when at less than optimal orientation to the sun, you might only be getting about 60% of what the panels are capable of. What is the most charging amps you have ever seen going into the batteries?

You can gauge the maximal output of your panels by putting a load on your system at noon that is as big or bigger than the total array wattage. Run something at noon that consumes at least 650W and look to see how many charging amps are coming in.

Once you have that number, you can gauge how much extra solar you need to add to maximize your controller. Let's say you a max input of 20A of charging current. That means you could double the amount of solar but still stay within your 40A limit.

Just doubling the solar may or may not help you solve your problem. Your problem is not enough charge, and keeping a 40A controller limits what you can accomplish. You may find that to optimize your system, you need to both increase the solar, and increase the amperage capacity of your charge controller.
View attachment 228195

Yes, it is. I just ordered a Xantrex Freedom X 3000. I am picking up 2 more 400-watt panels on Monday. I have the current panels mounted flat & there is no more room on the Rigs roof for more, but I pull a 16' box trailer & will mount the additional panels on those & and tail them to the system. I think you may be correct about the controller as well. It seems like it never charges above 13.20, sometimes I will get 13.30 but only briefly. I will mount the new panels on the trailer so I can tilt them toward the sun when I am parked.

Xantrex Freedom X 3000 Truesine Inverter​

 

[MilehighMike]

Pure vs Modified Sine Wave Inverter | Wiltronics

Here, we have broken down the difference between pure vs modified sine wave inverter so you can pick the best inverter for your installation!

www.wiltronics.com.au

When it comes to the cost, modified sine waves are simpler to produce with fewer components. This makes them cheaper than their pure counterparts.

Pure sine wave may be more expensive to produce, thus making it a bit costly. But it provides more efficient power and minimal interference.

As for the modified efficiency, it produces smaller wave power than the pure. It uses up to 30% more power and cannot run its full capacity. This could cause a buildup of excess waste heat, damaging the equipment long-term.

Trow that inverter out of the windows.
Its only good for brick to hold paper on your table.
And you can not run a inverter on that .

Thank you. I felt the inverter was not working well as it would trip small loads. I have ordered a new Xantrex Freedom X 3000. I will be adding additional panels next week & I think I will also change out the charge controller soon. Thanks for the tips.

 

[MilehighMike]

Do you have a shunt or battery meter? Your inverter may show how much power it is putting out but it likely does not show how much power it needs to run.

Is there a shunt you recommend?

 

[MilehighMike]

Just to check on something, but is your inverter connected to the converter in the RV? If so, your house batteries are powering the inverter that powers the converter which charges the house batteries that feed the inverter that powers the converter that charges the house batteries that... well... you see the problem there.

Your SCC is undersized but if your panels are laying flat you should still be able to max out your charge controller.

If your batteries are only getting to 13.2, they're not getting fully charged. Check the settings on the SCC and make sure they're charging up at the right voltage. Even then, with 800Ah of battery I doubt you could fully charge the batteries before you lose the light. You're looking at 20 hours (800ah / 40a of SCC) of perfect sun to recharge that bank fully. With the average being 4 hours that's 5 days of charging assuming you don't turn on anything in the meanwhile.

Do you have a proper shunt and not just a battery meter installed? Can you throw one in? You don't need anything fancy, a basic Aili will do the job of measuring amps in and out.

I'm addind two additional 400 watt panels next week. What size SCC would you recomend? Thanks again.

 

[MilehighMike]

Get a Victron Smartshunt or BMV712 ASAP!

Once that is installed you can see what is going in & out of the batteries.

My guess is the same as above. Although with only 650w of solar you MAY not be getting the batteries recharged during the day- that is why a shunt based battery monitor is vital. You can see and track what is going in & out of batteries.

Thank you. Just ordered one.

 

[Suijkerbuijk]

They really never get above 13.20. I am going to add a couple more panels next week & see if that helps. The curet ones are mounted flat on the roof & very often, I only get 400 or so watts.
I did order a new

Xantrex Freedom X 3000 Truesine Inverter. The old one 3000 watts would get very hot & trip.​

You have manuel adjust the out put volts on the pwm/mppt solar charger
See your manuel how to do it .
The owner here for have select 13.20 volts
Reason like a lot of people think that is the Float charge.


The charging voltage

Mastervolt Gel (2 V, 12 V) and Mastervolt AGM (6 V, 12 V) batteries should be charged with a voltage of 14.25 V at 25 °C for 12 V installations, and 28.5 V at 25 °C for 24 V installations. After the Absorption phase follows the Float phase (see 3-Stage+ charging characteristic on page 242) in which the voltage is reduced to 13.8 V at 25 °C for 12 V installations, and 27.6 V at 25 °C for 24 V installations.

For wet lead-acid batteries, the absorption voltage is 14.25 V at 25 °C for 12 V installations, and 28.5 V at 25 °C for 24 V installations. The float voltage for this type of battery is 13.25 V at 12 V and 26.5 V for 24 V installations, both at 25 °C.

Lithium Ion batteries are charged with an absorption voltage of 14.25 V for 12 V, and 28.5 V for a 24 V system. The float voltage is 13.5 V for 12 V, and 27 V for 24 V systems

So that is your problem that your battery is not charging to full..

 

[brucey84]

Thank you. I felt the inverter was not working well as it would trip small loads. I have ordered a new Xantrex Freedom X 3000. I will be adding additional panels next week & I think I will also change out the charge controller soon. Thanks for the tips.

What kind of wires and size are you using to connect battery to inverter? 12volt on 3000 watts is close to 220 amps.