Hello everyone,
I'm new to this forum and have browsed through old threads briefly trying to find someone having the same sort of problem I am, but to no avail. My girlfriend and I are currently building a trailer to cruise around the US in and while building it are living in an older camper on my father's property in Vermont. We are piecing together a solar system and currently have as follows:
2x 12V 200AH Renogy AGM batteries wired in series to make a 24V bank. We figured that staying above 50% SOC we have about 2400 wH, and total battery bank storage of 4800 wH
Midnite BRAT 30A Charge controller
Gopower 2000w pure sine wave inverter
IOTA Engineering DLS-27-25 25A, 24V power converter with the Q4 smart charger
Midnite solar battery SOC meter
And a mismatch of PV mods wired in parallel that are:
Canadian solar
Pmax 330 W
Vmp 37.2 V
Imp 8.8 A
Voc 45.6 V
Isc 9.45 A
Astron Energy
Pmax 260 W
Voc 37.78 V
Isc 8.93 A
Vmp 30.9 V
Imp 8.48 A
We just got a pair of Trina 415W panels that we have not set up yet.
Now, we calculated our loads (pretty severely overestimating our time using various devices to be much higher than we really anticipated) to come out to be 2800wH for 24 hours. While living in the camper in the meantime, we are hooking up the shore power cord into our inverter. I know we are going through a couple steps that will be losing efficiency (namely going from DC from the battery bank back to AC for the inverter and then back into DC again to run 12V appliances through the camper.) But to find out how much power we are using after being plugged into the inverter, I hooked up a kilowatt meter in between the inverter and the shore power cord, and it says that we have a constant 50W draw. This accounts for our 12V propane refrigerator and the power converter inside the power center of the camper. There was a battery charger but we disconnected the battery and it isn't sending any power to it any more.
We figured that here, in the height of summer, we have about 12-14 hours that are not making solar production to charge the batteries and are running just off our battery storage. The problem is, when we wake up in the morning, our battery monitor is usually telling us that we are at 50-60% SOC, which is where I'm confused. The manual for the inverter said it draws 1.5A when converting power. For us, the inverter runs all the time, not just when we use AC appliances, because we are plugged directly into the inverter with an extension cord that runs to the power center in the camper. Adding the current draw from the inverter to the 50w load that we have coming from the refrigerator and power converter overnight (well say 14 hours to be safe), it totals to be about 1200wH, which should only be about 50% of our total usable wH capacity. (Usable meaning staying above 50% SOC) This should mean the battery meter should be telling us 25%
The documentation that comes with the voltage reader says that the voltages from 10-100% SOC are from 10% meaning 23.3V up to 100% meaning 25.5%. Once the sun sets and we turn on any devices that aren't lights, we have been running our generator through our converter charger until we go to bed to get back up to 100% to last throughout the night without dropping down below 50% SOC. Take tonight for example. It is 9:00 PM as I post this, the array has not been making any major power for about 3 hours, and our battery bank is already at 70% SOC. My voltmeter reads 25.1 when touched to the batteries with the inverter off. There is a load of 50w when only running a small 12V fan and the refrigerator.
Our inverter, charge controller and PV mods are the only things that we have that are not new. Could it be inverter inefficiency that is adding to how much we are really drawing out of our bank at night? How can I investigate that further? I know there can be some inverter inefficiencies, and since the inverter has to be on all the time, I could see how that would add up to have a pretty significant impact on energy usage. It seems like maybe there could be more energy loss before the inverter (resistance?) that I'm not seeing since the kilowatt meter isn't telling me how much energy is being used before the inverter converts the electricity. Or could it be that my storage calculations for our battery bank is wrong? (2X 12V, 200AH batteries=4800wH) I just can't believe that with all of our battery capacity, we can be that low in the morning, based on having a 4800wH total storage capacity. I just don't know what I'm missing here. I appreciate any input anyone has and if there is any more information needed, I'll be happy to provide it.
I'm new to this forum and have browsed through old threads briefly trying to find someone having the same sort of problem I am, but to no avail. My girlfriend and I are currently building a trailer to cruise around the US in and while building it are living in an older camper on my father's property in Vermont. We are piecing together a solar system and currently have as follows:
2x 12V 200AH Renogy AGM batteries wired in series to make a 24V bank. We figured that staying above 50% SOC we have about 2400 wH, and total battery bank storage of 4800 wH
Midnite BRAT 30A Charge controller
Gopower 2000w pure sine wave inverter
IOTA Engineering DLS-27-25 25A, 24V power converter with the Q4 smart charger
Midnite solar battery SOC meter
And a mismatch of PV mods wired in parallel that are:
Canadian solar
Pmax 330 W
Vmp 37.2 V
Imp 8.8 A
Voc 45.6 V
Isc 9.45 A
Astron Energy
Pmax 260 W
Voc 37.78 V
Isc 8.93 A
Vmp 30.9 V
Imp 8.48 A
We just got a pair of Trina 415W panels that we have not set up yet.
Now, we calculated our loads (pretty severely overestimating our time using various devices to be much higher than we really anticipated) to come out to be 2800wH for 24 hours. While living in the camper in the meantime, we are hooking up the shore power cord into our inverter. I know we are going through a couple steps that will be losing efficiency (namely going from DC from the battery bank back to AC for the inverter and then back into DC again to run 12V appliances through the camper.) But to find out how much power we are using after being plugged into the inverter, I hooked up a kilowatt meter in between the inverter and the shore power cord, and it says that we have a constant 50W draw. This accounts for our 12V propane refrigerator and the power converter inside the power center of the camper. There was a battery charger but we disconnected the battery and it isn't sending any power to it any more.
We figured that here, in the height of summer, we have about 12-14 hours that are not making solar production to charge the batteries and are running just off our battery storage. The problem is, when we wake up in the morning, our battery monitor is usually telling us that we are at 50-60% SOC, which is where I'm confused. The manual for the inverter said it draws 1.5A when converting power. For us, the inverter runs all the time, not just when we use AC appliances, because we are plugged directly into the inverter with an extension cord that runs to the power center in the camper. Adding the current draw from the inverter to the 50w load that we have coming from the refrigerator and power converter overnight (well say 14 hours to be safe), it totals to be about 1200wH, which should only be about 50% of our total usable wH capacity. (Usable meaning staying above 50% SOC) This should mean the battery meter should be telling us 25%
The documentation that comes with the voltage reader says that the voltages from 10-100% SOC are from 10% meaning 23.3V up to 100% meaning 25.5%. Once the sun sets and we turn on any devices that aren't lights, we have been running our generator through our converter charger until we go to bed to get back up to 100% to last throughout the night without dropping down below 50% SOC. Take tonight for example. It is 9:00 PM as I post this, the array has not been making any major power for about 3 hours, and our battery bank is already at 70% SOC. My voltmeter reads 25.1 when touched to the batteries with the inverter off. There is a load of 50w when only running a small 12V fan and the refrigerator.
Our inverter, charge controller and PV mods are the only things that we have that are not new. Could it be inverter inefficiency that is adding to how much we are really drawing out of our bank at night? How can I investigate that further? I know there can be some inverter inefficiencies, and since the inverter has to be on all the time, I could see how that would add up to have a pretty significant impact on energy usage. It seems like maybe there could be more energy loss before the inverter (resistance?) that I'm not seeing since the kilowatt meter isn't telling me how much energy is being used before the inverter converts the electricity. Or could it be that my storage calculations for our battery bank is wrong? (2X 12V, 200AH batteries=4800wH) I just can't believe that with all of our battery capacity, we can be that low in the morning, based on having a 4800wH total storage capacity. I just don't know what I'm missing here. I appreciate any input anyone has and if there is any more information needed, I'll be happy to provide it.