In the woods having trouble with my RV system

[Ben2022]

Hi guys I’m hoping for some advice on diagnosing a problem with my RV set up.



Setup:

2x ampear time 200AH batters 12v

EpEver solar charge controller

4000w inverter charger

900W of solar



My EpEver died suddenly and I’m not sure why. I noticed when my batteries died and the BMS cut them off. I replaced it and charged the batteries back up.



I went to bed last night around 11 pm with 13.5v showing. The only 110v draw running were a phone charger, 2 led TVs that are off (so standby draw) and the lcd on the microwave. 12v draws included the fridge (on gas mode) and my CPAP drawing 80w.



6am my CPAP shuts down waking me up. The batteries are flat and in shutdown mode.



What gives? Last year I ran the whole system for nearly two days with virtually no solar input (due to weather) AND I was using 12v lighting. Nothing is more than 3 years old. The batteries are only about 1.5 years old. Both the inverter and EpEver are set to charge Lithium batteries. So did a battery take a crap? If so how do I tell? I would think even 1 200AH battery would hold up longer.



Thanks in advance

 

[JeromeS13]

Do you have a shunt to show your idle amperage draw from the batteries?

 

[Solar Guppy]

Watts out > Watts in.

During the day does the battery indicate it is fully charged before you start the night time drain?
Do you have shading with the solar?
Are you drawing more energy from the battery than was put in?

10 hours just on the 12V loads would use half energy of the battery is capable of, then the inverter idle draw plus its loads.

 

[Tomthumb62]

So you’ve got 400Ah 12v total battery? Even with severely unbalanced cells, that should get you through the night.

Even still it might help to try to balance them.

Have you ever separated the two batteries, fully discharged to BMS cutoff then fully charged back up to 14.4-14.6v? If the battery’s cells are unbalanced, a full cycle like that (with an AC charger) can help. If it helps a little bit, it might help to do that once more.

Also, what are your settings for the Epever?

 

[Ben2022]

Do you have a shunt to show your idle amperage draw from the batteries?

I don’t. Guess I’m going to have to buck up the $130 for one though.

 

[Ben2022]

Battery was showing 13.5 v before night time draw started. Per AT documentation that’s “full” Generic meter on inverter showed full bars too.

Watts out > Watts in.

During the day does the battery indicate it is fully charged before you start the night time drain?
Do you have shading with the solar?
Are you drawing more energy from the battery than was put in?

10 hours just on the 12V loads would use half energy of the battery is capable of, then the inverter idle draw plus its loads

 

[Ben2022]

These are the settings I loaded into the EpEver (both the prior one that died and the new one).
I have 2 200ah 12v wired in parallel with 2/0 cable.

 

[jasonojordan]

Lifepo4 batteries are hard to base it off just voltage since it drops so little over the course of the discharge. A shunt based SOC meter is the best way to know your SOC with lifepo4

 

[Ben2022]

So you’ve got 400Ah 12v total battery? Even with severely unbalanced cells, that should get you through the night.

Even still it might help to try to balance them.

Have you ever separated the two batteries, fully discharged to BMS cutoff then fully charged back up to 14.4-14.6v? If the battery’s cells are unbalanced, a full cycle like that (with an AC charger) can help. If it helps a little bit, it might help to do that once more.

Also, what are your settings for the Epever?

Sorry my post didn’t tag as a reply. Cell service is really spotty! I posted below.

 

[Ben2022]

Inverter is AIMS 4000w pure sine wave. “Sleep” draw is 0.5 amps per hour.

 

[Ben2022]

So you’ve got 400Ah 12v total battery? Even with severely unbalanced cells, that should get you through the night.

Even still it might help to try to balance them.

Have you ever separated the two batteries, fully discharged to BMS cutoff then fully charged back up to 14.4-14.6v? If the battery’s cells are unbalanced, a full cycle like that (with an AC charger) can help. If it helps a little bit, it might help to do that once more.

Also, what are your settings for the Epever?

 

[Solar Guppy]

Inverter is AIMS 4000w pure sine wave. “Sleep” draw is 0.5 amps per hour.

Your inverter specifications list sleep mode is 25 watts, active is 52 watts, with loads with won't be in sleep mode. If you don't need 120V, disconnect the inverter at night should help.

I would recommended you added something like this , I have the ECO-Worthy version on my golf cart.

 

[Ben2022]

Your inverter specifications list sleep mode is 25 watts, active is 52 watts, with loads with won't be in sleep mode. If you don't need 120V, disconnect the inverter at night should help.

I would recommended you added something like this , I have the ECO-Worthy version on my golf cart.

I just bit the bullet (I had enough cell service where I’m sitting) and bought the Victron shunt from Amazon for $130. It won’t help me until I can get home to get it and install it but eventually it will.

 

[Tomthumb62]

Inverter is AIMS 4000w pure sine wave. “Sleep” draw is 0.5 amps per hour.

Your inverter specifications list sleep mode is 25 watts, active is 52 watts, with loads with won't be in sleep mode. If you don't need 120V, disconnect the inverter at night should help.

I would recommended you added something like this , I have the ECO-Worthy version on my golf cart.

Do you NEED that 4000w inverter? It’s sucking your battery dry just being powered on.

We went from a poor quality 2000W inverter to a high quality Victron 1000W inverter. Idle draw was 540Wh but now down to 60Wh. Makes our 2560Wh battery last much longer on multiple cloudy days. Four cloudy days would use 84% of our battery capacity, just from idle draw of the inverter alone. Now it only uses 9% for those same four days of clouds with a better inverter.

And while the Victron is advertised as only 1000W, it powers my air compressor, skill saw and 1850W (2400W startup surge) Dyson vacuum. It won’t power the vacuum for much longer than a minute, but that’s long enough to vacuum our tiny trailer floor.

The cheapo inverters might advertise 2000W/4000W, but that 4000W is for less than a half second, which isn’t long enough to be useful for anything other than advertising a “4k surge”. My 120v mid size fridge needs about 1.75 seconds of surge to get powered up and I highly doubt my Dyson vacuum would run on a Renogy 1000W cheapo inverter.

 

[Rocketman]

The Victron Smartshunt will help lots once you get it installed.

After it is running and during your next trip - use the trends to see how you used/gained power over the last 24hrs. That way if something happens - you will know how to troubleshoot the problem time.

 

[Ben2022]

Do you NEED that 4000w inverter? It’s sucking your battery dry just being powered on.

We went from a poor quality 2000W inverter to a high quality Victron 1000W inverter. Idle draw was 540Wh but now down to 60Wh. Makes our 2560Wh battery last much longer on multiple cloudy days. Four cloudy days would use 84% of our battery capacity, just from idle draw of the inverter alone. Now it only uses 9% for those same four days of clouds with a better inverter.

And while the Victron is advertised as only 1000W, it powers my air compressor, skill saw and 1850W (2400W startup surge) Dyson vacuum. It won’t power the vacuum for much longer than a minute, but that’s long enough to vacuum our tiny trailer floor.

The cheapo inverters might advertise 2000W/4000W, but that 4000W is for less than a half second, which isn’t long enough to be useful for anything other than advertising a “4k surge”. My 120v mid size fridge needs about 1.75 seconds of surge to get powered up and I highly doubt my Dyson vacuum would run on a Renogy 1000W cheapo inverter.

This one is 4k with 12k surge. The plan was if I needed to run the AC in the RV even for a small time OR power another RV for a short time. It’s certainly wasn’t cheap. Everything I read said AIMs had good inverters. So you think the 25w .5 amp sleep cost is too much? It’s 51w when not asleep. The crazy part is I haven’t had this issue until this year. The system has been together for nearly 3 years.

 

[Tomthumb62]

This one is 4k with 12k surge. The plan was if I needed to run the AC in the RV even for a small time OR power another RV for a short time. It’s certainly wasn’t cheap. Everything I read said AIMs had good inverters. So you think the 25w .5 amp sleep cost is too much? It’s 51w when not asleep. The crazy part is I haven’t had this issue until this year. The system has been together for nearly 3 years.

Ok that makes more sense. However, if you don’t intend to run the A/C from inverter except on occasion, that’sa huge energy cost in idle wattage per day. Maybe get a smaller one, after you do an energy audit, to learn how small you can go.

 

[Ben2022]

Ok got the Victron shunt installed. Below is the amp draw when I go to sleep. This included my CPAP (I assumed), phone charger, and the “standby” power from two LED TVs and the clock on the microwave.

If I turn the inverter to “off” it drops all of the standby power but I can’t charge my phone.


This brought up another thought.- my regular 12v draw for the RV comes straight off the battery. This includes the heater blower, minimal power for the gas fridge and my CPAP (12v adapter).

If this shunt is installed between the negative battery and the negative inverter connection with one sensor to the positive- would it even see the draw from the standard trailer 12v items? I didn’t have time to experiment with it before I had to come back down the mountain.

Can I somehow use the AUX port of the shunt to monitor the trailer draw or does it already somehow see it?

Additional info- the AIM inverter/charger I’m using completely replaced the RV factory charging unit. Power wires run to and back from the main panel of the RV inside the living space. The 12v wires that were initially connected to the batteries in the battery box are now connected to a junction bar powered directly from the new Li batteries I installed.


While I “think” my original problem arose from the EpEver dying on me and not being able to truly get an accurate state of charge- now I’m down a rabbit hole of trying to make sure I utilize my $130 shunt to its maximum capability.

 

[JeromeS13]

All DC loads should be connected to one side of the shunt (including the battery negative) and the other side of the shunt should be connected to the ground. That way, the shunt measures all DC loads.